Araiochelys, Gaffney & Tong & Meylan, 2006

GAFFNEY, EUGENE S, TONG, HAIYAN & MEYLAN, PETER A, 2006, EVOLUTION OF THE SIDE-NECKED TURTLES: THE FAMILIES BOTHREMYDIDAE, EURAXEMYDIDAE, AND ARARIPEMYDIDAE, Bulletin of the American Museum of Natural History 300 (300), pp. 1-698 : 301-343

Araiochelys is slightly narrower than in B. maghrebiana , but about the same as in C. hutchisoni .

JUGAL (figs. 122–125)

Preservation: The jugal is preserved in THUg 3338 on the palate, in the right fossa orbitalis, and on both cheeks. The posterior and ventral limits are probably only represented by broken edges on both sides. The posteroventral edge of the jugal is not known, and it is shown as incomplete in the restoration.

Contacts: The jugal in Araiochelys has a complex contact pattern. On the ventral surface the jugal contacts the maxilla anterolaterally and the palatine medially. There is a narrow posteromedial contact with the pterygoid. In Bothremys , Zolhafah , and Rosasia , the jugal is also exposed on the palate between maxilla and palatine, but the degree of exposure varies. In B. cooki the jugal is widely exposed, with the maxilla and palatine being widely separated posterior to the jugal. In B. maghrebiana the jugal has its smallest exposure; it is present only in the dorsal tip of the triturating surface pit, and a broad palatine-maxilla contact is present posterior to the jugal. Araiochelys has an intermediate condition with the jugal exposed in the pit and in a narrow band from the pit to the edge of the fossa temporalis inferior. The palatine and maxilla are separated by the jugal, but not to the extent seen in B. cooki . In Zolhafah and Rosasia the pit is not as completely conical as in Bothremys and Araiochelys , even though the top of the pit is still formed by the jugal at its tip. In both there is no palatine-maxilla contact and the jugal is closer to the fossa temporalis inferior than it is in Bothremys and Araiochelys .

On the lateral surface of the skull in Araiochelys , the jugal contacts the maxilla anteroventrally and the postorbital dorsally. Its likely contact with the quadrate and/or quadratojugal is not determinable due to damage. In the floor of the fossa orbitalis the jugal contacts the palatine medially and the maxilla anterolaterally.

Structures: The jugal forms part of the triturating surface and part of the cheek. The triturating surface is dominated by the large conical pit formed by jugal, maxilla, and palatine. The upper part of the pit and part of the wall between the pit and the fossa temporalis inferior are formed by the jugal. In contrast to Araiochelys , the jugal in Bothremys cooki forms all of the pit and the wall, and in B. maghrebiana the jugal forms only the dorsal tip of the pit.

The cheek in THUg 3338 is not well preserved. The jugal lies at the posteroventral corner of the orbital margin, and this part of the jugal is well preserved, particularly on the right side. As in other Bothremydini , it lies between the postorbital and maxilla. The cheek in other Bothremydini is not preserved either. It is missing in Bothremys cooki and Zolhafah . It is preserved in B. maghrebiana , but the jugal-quadratojugal sutures are indistinct. In Rosasia the jugal contacts the quadratojugal and not the quadrate, being placed relatively high in the cheek. In Araiochelys the jugal is small, as in the other Bothremydini , and may not have contacted the quadrate. The extent of the cheek in Araiochelys can be restored, showing that the jugal was probably separated from the cheek margin by a quadrate-maxilla contact, as in B. maghrebiana and Rosasia .

[M. Stalcup and F. Ippolito, del.]

QUADRATOJUGAL (figs. 122, 125)

Preservation: The quadratojugal in THUg 3338 is poorly preserved. It is missing on the left side and indistinct on the right. What appears to be the quadratojugal-postorbital suture is in an area of minute breakage, but the quadrate-quadratojugal suture is clear.

Contacts and structures: The quadratojugal is a long flat element as interpreted here, with an exposure posteriorly on the temporal emargination between the postorbital and quadrate. The medial contact with the postorbital runs slightly laterally as it extends anteriorly. The quadrate contact is the usual curved suture roughly paralleling the cavum tympani. The anterior contact of the quadratojugal is missing, but it may have contacted the jugal and maxilla, as in Rosasia . The quadratojugal did not extend ventrally to reach the cheek margin as in Foxemys and Polysternon , due to the quadrate-maxilla contact (see Quadrate).

SQUAMOSAL (figs. 122, 125)

Preservation: The squamosals in THUg 3338 are present on both sides, but the edges have been damaged. The left one is more complete, but it is supported by matrix ventrally and has some missing areas dorsally.

Contacts: The squamosal contacts in Araiochelys are the same as in Bothremys maghrebiana , as far as can be determined.

Structures: The squamosal in Araiochelys agrees closely with that bone in Bothremys maghrebiana . Unfortunately, complete squamosals are rare in the tribe Bothremydini ; B. cooki has none, and squamosals are missing posteriorly in Zolhafah , Rosasia , and Chedighaii hutchisoni . In B. maghrebiana and Chedighaii barberi , the squamosal has a posterior process that has a low ridge ventrally and a low trough on its dorsal surface, nearly identical to the squamosal of Araiochelys .

POSTORBITAL (figs. 122, 125)

Preservation: The postorbital is nearly complete on the right side of THUg 3338, but only its anterior end is present on the left side.

Contacts and structures: As in Bothremys maghrebiana , the lateral plate of the postorbital of Araiochelys contacts the frontal anteromedially, the jugal anterolaterally, the quadratojugal posterolaterally, and the parietal medially. The medial process of the postorbital is mostly covered by matrix in THUg 3338, but the jugal contact can be seen in the anterior wall of the fossa temporalis inferior.

PREMAXILLA (figs. 122–125)

Preservation: Both premaxillae are present and well preserved with clear sutures in THUg 3338.

Contacts: The premaxilla of Araiochelys contacts the maxilla posterolaterally, the other premaxilla on the midline, and the vomer posteriorly.

Structures in dorsal view: The premaxilla forms the anterior part of the fossa nasalis and apertura narium externa. In Araiochelys the fossa and apertura are relatively large, as in Bothremys and Chedighaii and in contrast to the smaller apertura and fossa in Foxemys and Rosasia . The orientation of the opening is more lateral in Araiochelys than in the other members of the Bothremydini . Araiochelys also differs in having a completely divided or almost completely divided apertura rather than the partially divided or figure eight-shaped apertura in Bothremys cooki and Chedighaii . Each premaxilla in Araiochelys has a dorsal process adjacent to the midline that together form the lower part of the nasal division. The base of the process is thick and is similar to the lower dorsal process in Bothremys maghrebiana . Both Chedighaii and B. cooki are damaged or lack a premaxilla. However, B. cooki has enough of the premaxilla preserved to show that some midline process was present, although its extent is not determinable. The premaxillary dorsal process in Araiochelys is continuous with a posterior midline ridge on the floor of the fossa nasalis. A similar, but lower ridge is present in B. maghrebiana and probably B. cooki . The anterior margin of the premaxilla in Araiochelys protrudes well anteriorly to the prefrontal in dorsal view, as in Bothremys and Chedighaii but in contrast to Rosasia and Foxemys .

Structures in ventral view: The premaxilla forms the anteromedial part of the triturating surface and consists of a more vertical labial ridge with a more horizontal plate posteriorly. In Araiochelys the labial ridge has a slight median upturn to form a shallow notch similar to Bothremys but in contrast to Foxemys . Chedighaii is not preserved in this area, although C. barberi shows a ventral curve on the portion of premaxilla preserved. The labial ridge in Araiochelys has a sharp edge but a broad base, as in Bothremys . However, the labial ridge is thinner and has a more acute angle in Araiochelys than in Bothremys .

The premaxillary triturating surface behind the labial ridge in Araiochelys forms a relatively deep midline concavity, similar to that in Bothremys but slightly narrower. The lingual ridge forms the anterior and lateral margin of the concavity and marks the edge of the foramina-rich triturating surface. The ridge is higher and more distinct in Araiochelys and Bothremys maghrebiana than it is in B. cooki , which has a low ridge and shallow midline concavity. The premaxilla in Araiochelys forms all of the foramen praepalatinum, which lies in the midline concavity near the vomer suture, as in Bothremys .

MAXILLA (figs. 122–125)

Preservation: Both maxillae are present in THUg 3338. They are complete and well preserved except for the posterolateral limits on the cheek, which are represented by broken edges on both maxillae.

Contacts: The maxilla contacts in Araiochelys for both the vertical and horizontal plates are the same in Araiochelys and Bothremys except for the area around the triturating surface pit. In Araiochelys and Bothremys cooki there is no maxilla-palatine contact posterior to the pit, while in Bothremys maghrebiana there is a contact. On the cheek, there is no posterior contact of the maxilla with anything as preserved. However, on the right side the quadrate has a long anterior process with a broken anterior margin that nearly reaches the maxilla with a broken posterior margin. It is very difficult to see how any of the other cheek elements could have extended between the quadrate and maxilla to separate them. It is possible that a narrow space was present between them, but this seems unlikely, and the restoration has been done with a quadrate-maxilla contact as in Bothremys maghrebiana .

Structures of vertical plate: The dorsal process of the maxilla is wider in Bothremys and narrower in Araiochelys and Chedighaii . For Araiochelys this is a function of the large apertura narium externa, while in Chedighaii the orbits are closer to the apertura.

The maxilla forms the lower margin of the fossa orbitalis, and in most bothremydids this is a narrow ridge. In Bothremys this ridge is either absent ( B. cooki and B. maghrebiana AMNH 30561) or very low ( B. maghrebiana AMNH 30041, AMNH 30522, MHNL 20- 268370, and AMNH 30234). In Araiochelys it is a distinct raised ridge clearly separating cheek from fossa orbitalis. The fossa orbitalis itself is comparatively larger and faces more laterally in Araiochelys than in Bothremys and Chedighaii .

The vertical plate of the maxilla forms the suborbital part of the cheek and the labial ridge. In dorsal view the external surface of this plate is a nearly straight, more vertical sheet in Araiochelys . In Bothremys the maxilla is convex anterolaterally, forming a curved margin. The degree of swelling is greater in Bothremys than in any of the other bothremydids. However, the two species of Chedighaii have expanded maxillae, with C. barberi being relatively straight, although the skull is wide in contrast to Araiochelys . In C. hutchisoni the maxilla edge is broken and it may have been curved. The maxillary plate below the orbit is unusually deep in Bothremys and Chedighaii , but in Araiochelys it is shallower.

The labial ridge in Araiochelys is acute along its edge, as in Bothremys and Chedighaii barberi (missing in C. hutchisoni ), but in Bothremys the bone thickens dorsally more than in Araiochelys . The entire maxillary plate in Bothremys is thicker than in Araiochelys . Chedighaii hutchisoni is thick, as in Bothremys , but C. barberi is thinner, as in Araiochelys .

Structures of horizontal plate of maxilla: The maxilla of Araiochelys is relatively narrow compared to Bothremys and Chedighaii hutchisoni (fig. 123). The shape is not as triangular as in the other Bothremydini . The apertura narium interna is slightly narrower in Araiochelys than in Bothremys maghrebiana , but not as narrow as in B. cooki . The apertura in both Araiochelys and B. maghrebiana is larger than in B. cooki .

The triturating surface of Araiochelys is defined medially by a low lingual ridge. In common with Bothremys but in contrast to Chedighaii , there is a well-developed pit in the posterior part of the triturating surface. The maxilla forms the anterior and lateral cone-shaped surface that forms the outer part of the pit; the tip is formed by the jugal (see Jugal). This part of the maxilla in Araiochelys , the area between the pit and the labial ridge, is much narrower than in Bothremys . The differences in this part of the triturating surfaces between Araiochelys and Bothremys might be compared with differences found between males and females in Graptemys ( Lindeman, 2000) , Emydura ( Cann, 1998) , and trionychids ( Dalrymple, 1977) (see Discussion in Systematics). In Bothremys there is also an expansion of the palatine part of the triturating surface medial to the pit. The more anterior part of the triturating surface in Araiochelys has a low lingual ridge medial to a shallow trough.

Most of the dorsal surface of the maxilla is covered by matrix, but some is visible in the floor of the right fossa orbitalis. The maxilla only forms a narrow part of the fossa, lateral to the palatine.

VOMER (figs. 122–125)

Preservation: The vomer in THUg 3338 is nearly complete; the posterior contact with the palatines is damaged.

Contacts: The vomer contacts in Araiochelys are as in Bothremys : premaxilla anteriorly, maxilla anterolaterally, and palatine posteriorly. Chedighaii hutchisoni lacks the maxilla contact. The anterior end has a short maxilla contact, as in B. maghrebiana , rather than the long one in B. cooki .

Structures: The vomer in Araiochelys is dumbbell shaped as in Bothremys . Only its ventral surface is visible. The vomer separates the paired apertura narium interna, as in Bothremys and Chedighaii (see Maxilla).

PALATINE (figs. 122–125)

Preservation: Both palatines are present in THUg 3338. They are only damaged where they form the posterior margin of the apertura narium interna, and only a small amount of bone seems to be missing. Only the ventral surface of the palatine is visible.

Contacts: The contacts of the palatine in Araiochelys are the usual bothremydid ones: maxilla anteriorly, vomer anteromedially, palatine medially, and pterygoid posteriorly. In addition, Araiochelys has a lateral jugal contact beginning in the triturating surface pit and extending posteriorly to the usual palatine-jugal contact. In contrast to Bothremys maghrebiana , there is no palatine-maxilla contact posterior to the pit (see Maxilla, Jugal).

Structures on ventral surface (dorsal surface obscured by matrix): The triturating surface in Araiochelys has a significant contribution from the palatine, which forms the posteromedial part of the surface and the posterior part of the lingual ridge (see Maxilla). This portion of the palatine is narrower in Araiochelys than in Bothremys and Chedighaii . The palatine forms the posterior and posterolateral margins of the apertura narium interna. It is very similar in Araiochelys and Bothremys maghrebiana . The foramen palatinum posterius is formed by both palatine and pterygoid, as in Bothremys and Chedighaii . The degree of palatal arching and choanal formation is very similar in Araiochelys , Bothremys , and Chedighaii .

QUADRATE (figs. 122, 125, 126)

Preservation: Both quadrates are present in THUg 3338, but both are incomplete on their anterior margins in the cheek. Both have also been crushed slightly dorsoventrally.

Contacts in lateral view: The quadrate in Araiochelys contacts the squamosal posterolaterally, as in the other Bothremydini . There is probably a quadrate-maxilla contact on the cheek (see Maxilla) on the right side, as seen in Bothremys . Anterodorsally the postorbital contacts the quadrate but the suture in unclear (see Postorbital). Although unlikely, a jugal contact is possible due to the poor condition of the cheek in THUg 3338 (see Jugal). The dorsal margin of the quadrate is a broken edge on both sides in THUg 3338, so that the presence or absence of a squamosal-quadratojugal contact is indeterminate. Thus, the exposure of the quadrate on the temporal emargination as it is preserved is unlikely to have been its original condition.

Structures in lateral view: The cavum tympani in Araiochelys is similar to that in Bothremys maghrebiana . The incisura columellae auris is completely closed, as in other taxa in the subtribe Bothremydina , and the stapes lies in a bony canal. As in B. maghrebiana , Araiochelys has a low ridge extending posteriorly from the incisura to the sulcus eustachii. The sulcus is a deep cleft in Araiochelys and Bothremys (it is not well preserved in Chedighaii ) with a lateral overhang made up of quadrate and squamosal and a ventrolateral shelf formed by the quadrate. The antrum postoticum in Araiochelys is very similar to that in B. maghrebiana , although there is some variation in size of the antrum among the four specimens of that species. The antrum postoticum of Araiochelys faces anterolaterally, as in B. maghrebiana , and it is about the same size as in AMNH 30561, a little larger than in AMNH 30234, and smaller than in AMNH 30041.

The cavum tympani in Araiochelys is a deep cone, becoming shallower anteriorly, with a large lateral shelf ventrally, all as in Bothremys (it is not completely preserved in Chedighaii ). The cavum in THUg 3338 is partly distorted by dorsoventral crushing so that the shelf now forms a pocket at the bottom of the cavum tympani, but this pocket is due to crushing, and the shelf was like that in Bothremys maghrebiana (AMNH 30041). There is no fossa precolumellaris.

Contacts and structures in dorsal view: In Araiochelys the quadrate contacts in dorsal view on the otic chamber are as in the other Bothremydini (except for Zolhafah ): prootic anteromedially, opisthotic posteromedially, supraoccipital medially, and squamosal posteriorly. The foramen stapedio-temporale lies on the anterior face of the otic chamber and, as in other Bothremydini , is not visible in dorsal view.

Contacts in ventral and posterior view: As in the other Bothremydidae , Araiochelys has these contacts: pterygoid anteromedially, basisphenoid medially, basioccipital posteromedially, exoccipital posteromedially behind the basioccipital, and squamosal posterolaterally.

Structures in ventral and posterior view: The foramen posterius canalis carotici interni in Araiochelys is formed in the pterygoid-quadrate suture, as in Bothremys and Chedighaii . As in those genera, the quadrate forms more of the foramen and has an anteromedially trending trough that leads into the foramen.

The fenestra postotica in Araiochelys is an oval opening (fig. 126), separated laterally from the foramen jugulare posterius by a broad sheet of quadrate, exoccipital, and opisthotic, as in Bothremys and Chedighaii . The fenestra postotica is not divided but is figure eight-shaped with a more ventrolateral channel and a more dorsomedial one. The opisthotic forms the dorsomedial part of the fenestra postotica.

On the posterior surface of the processus articularis of the quadrate is a posteriorly directed ridge or flange running roughly horizontally (‘‘quadrate pocket’’ in fig. 126). This flange is downturned along its posterior margin to enclose a trough or pocket on the back of the quadrate. This area is the attachment for the M. depressor mandibulae in other turtles, so presumably this pocket contained at least part of the attachment for this muscle. Bothremys maghrebiana and Chedighaii barberi both have a distinct ridge in this position, but not the downturned edge making it a partially enclosed pocket. B. cooki and C. hutchisoni lack this area, and AMNH 29444, B. cooki , has the same ridge as in C. barberi . In the roof of this quadrate pocket in Araiochelys is the posterior opening for the chorda tympani, the foramen chorda tympani inferius, completely hidden in posterior view as well as in the oblique view of the ear.

The internal cavum acustico-jugulare and aditus canalis stapedio temporalis are not visible due to matrix. The condylus mandibularis is slightly anterior to the condylus occipitalis, as in Bothremys and Chedighaii ; it is not anterior to the main body of the basisphenoid, as in Polysternon .

PTERYGOID (figs. 122–125)

Preservation: Both pterygoids are present in THUg 3338 with the dorsal and most of the lateral surfaces covered by matrix. Only the proximal part of the pterygoid flange remains, but all (left) and nearly all (right) of the processus trochlearis pterygoidei are present.

Contacts in ventral view: Araiochelys has the usual contacts of the Bothremydini : palatine anteriorly, pterygoid anteromedially, basisphenoid posteromedially, and quadrate posterolaterally. Araiochelys lacks the pterygoid-maxilla contact posterior to the triturating pit seen in B. maghrebiana , also present in the other Bothremys species. Nearly all of the dorsal and lateral surfaces of the pterygoid are covered by matrix in THUg 3338, but at the base of the processus trochlearis pterygoidei in the postorbital wall can be seen the jugal and postorbital contacts of the pterygoid.

Structures on ventral surface: The pterygoid in Araiochelys is very similar to that in Bothremys . The processus trochlearis pterygoidei is well preserved in Araiochelys and agrees closely with that in Bothremys . The quadrate ramus bears the pterygoid flange (preserved only in B. maghrebiana ). There is no fossa pterygoidea in Araiochelys , Bothremys , or Chedighaii as occurs in Foxemys and Polysternon . The foramen posterius canalis carotici interni has the pterygoid forming its anterior edge, as in Bothremys and Chedighaii (see Quadrate). The foramen palatinum posterius is formed by palatine and pterygoid (see Palatine). The pterygoid of Araiochelys has a narrow ridge paralleling the pterygoid-basisphenoid suture. This is seen in B. maghrebiana but not in Chedighaii or B. cooki .

SUPRAOCCIPITAL (figs. 122, 125)

Preservation: ThesupraoccipitalinTHUg 3338 is complete and not obscured by matrix.

Contacts: As in the other Bothremydini , the supraoccipital of Araiochelys contacts are parietals anterodorsally, the prootic anterolaterally, the quadrate laterally, the opisthotic posterolaterally, and the exoccipital posteroventrally. These contacts in Araiochelys are very similar to those in Bothremys and Chedighaii .

Structures: The crista supraoccipitalis in Araiochelys is short and relatively shallow, similar to that in Bothremys maghrebiana and Chedighaii hutchisoni . In Araiochelys , howev- er, the ventral margin of the crista is thin, while in Bothremys and Chedighaii there is a swelling along its ventral edge that is thicker than the plate itself. As in everything, the supraoccipital forms the top of the foramen magnum.

EXOCCIPITAL (figs. 122, 125, 126)

Preservation: Both exoccipitals in THUg 3338 are preserved and are complete with the sutures clear.

Contacts: As in the other Bothremydini , the exoccipital of Araiochelys contacts the supraoccipital dorsally, the opisthotic laterally, the quadrate ventrolaterally, and the basioccipital ventrally.

Structures: The foramen magnum and condylus occipitalis are very similar in Araiochelys and Bothremys maghrebiana (missing in B. cooki ). The condyle is formed entirely by exoccipital, with the basioccipital not even entering the neck of the condyle.

The foramen nervi hypoglossi are nearly the same in position in Araiochelys , Chedighaii , Bothremys maghrebiana , and B. cooki (AMNH 29444). Two foramina are present, with the medial one being larger and more dorsal and the lateral one being smaller and more ventral. The foramen jugulare posterius is also very similar in the three genera, except that it is larger in AMNH 29444 than in Araiochelys , B. maghrebiana , and Chedighaii . The foramen is completely closed, with the exoccipital being prevented from meeting itself by a small process of opisthotic. Above the foramen jugulare posterius, the exoccipital forms the medial portion of an overhanging ridge, similar to that in Bothremys maghrebiana but much larger (see Opisthotic).

BASIOCCIPITAL (figs. 122, 125, 126)

Preservation: The basioccipital in THUg 3338 is complete with clear sutures. Only its ventral surface is visible.

Contacts: As in the other Bothremydini , the contacts of the basioccipital in Araiochelys are the basisphenoid anteriorly, the quadrate laterally, and the exoccipitals dorsally.

Structures: The condylus occipitalis completely excludes the basioccipital, which has only a small process at the exoccipital median suture. There is a low, blunt tuberculum basioccipitale in Araiochelys , as in Bothremys maghrebiana, AMNH 29444, and Chedighaii . Also as in these taxa, Araiochelys has a shallow median concavity ahead of the condylus occipitalis. The basioccipital in Araiochelys is very short and wide, as in Bothremys and Chedighaii .

PROOTIC (figs. 122, 125)

Preservation: Both prootics are presumably present and complete in THUg 3338 but are mostly covered by matrix. Both are visible in dorsal view, and the right one has its anterior surface exposed.

Contacts: As exposed, the prootic in Araiochelys contacts the quadrate laterally, the parietal medially, and the supraoccipital posterodorsally, all as in Bothremys and Chedighaii . All three lack a prootic-opisthotic contact.

Structures: Few prootic structures are visible. The foramen stapedio-temporale lies on the anterior surface of the prootic, but the medial margin and the foramen nervi trigemini are covered by matrix. No internal surfaces are visible.

OPISTHOTIC (figs. 122, 125, 126)

Preservation: Both opisthotics are present in THUg 3338 and are complete with most sutures clear, although the most lateral sutures are difficult to make out.

Contacts: As in the other Bothremydini , the opisthotic of Araiochelys contacts are the supraoccipital anteromedially, the quadrate anterolaterally, the squamosal posterolaterally, and the exoccipital posteromedially. There is no prootic contact.

Structures: The opisthotic barely enters the margin of the foramen jugulare posterius (see Exoccipital). The opisthotic forms the dorsomedial part of the fenestra postotica (see Quadrate). In Araiochelys , the opisthotic and exoccipital form an overhanging ridge above the foramen jugulare posterius and fenestra postotica. This ridge appears to be the same as that seen in Chedighaii hutchisoni (broken in C. barberi ) and Bothremys .

BASISPHENOID (figs. 122–125)

Preservation: The basisphenoid in THUg 3338 is complete with clear sutures; only its ventral surface is visible.

Contacts: As in the other Bothremydini , the basisphenoid of Araiochelys contacts are the pterygoids anteriorly, the quadrate laterally, and the basioccipital posteriorly. As in Bothremys maghrebiana , B. cooki (AMNH 29444), and Chedighaii , the pterygoid contact is long and the quadrate contact very short.

Structures: The basisphenoid in Araiochelys is totally flat and featureless.

Bothremys cooki

The skull of Bothremys cooki is the original bothremydid skull from the (probably) Late Cretaceous of New Jersey that was first described by Leidy (1865) (see fig. 19). It lacks the otic chambers and the occiput, but the remaining areas are well preserved, free of matrix, with visible internal areas. The basisphenoid is separate and its dorsal surface is visible. An otic chamber from North Carolina (AMNH 29444) is referred to this species, although there is only a very slight morphologic overlap, the size agrees, and it belongs in this group. The otic chamber is described and figured in this section but it is not used in the reconstructions except for the additional side view (fig. 127D). The skull of Bothremys cooki was described in detail in Gaffney and Zangerl (1968), in the senior author’s first paper. I hope I get it right this time.

PREFRONTAL (figs. 127, 130)

Preservation: The right prefrontal is nearly complete; the left one is missing its anterior portion.

Contacts: The prefrontal in Bothremys cooki has the usual Bothremydini contacts: the maxilla anteroventrolaterally, the other prefrontal medially, and the frontal posteriorly. There is no anteroventral contact with the premaxilla as in Araiochelys and B. kellyi . The ventral process of the prefrontal has a broad contact with the palatine in the orbital floor. The dorsal process of the maxilla extends anteromedially to restrict the exposure of the prefrontal in B. cooki and B. maghrebiana .

Structures: The dorsal margin of the apertura narium externa has the midline protrusion or process seen in the other Bothremys species and most bothremydids. The interorbital distance in Bothremys cooki is less than in B. kellyi and about the same as in B. maghrebiana .

FRONTAL (figs. 127, 130)

Preservation: Both frontals are present and nearly complete.

Contacts: As in the other Bothremys , the frontal of B. cooki contacts the prefrontal anteriorly, the parietal posteriorly, the postorbital posterolaterally, and the other frontal medially. The frontal in B. cooki is slight longer and slightly narrower than in B. maghrebiana , but it is very similar to B. kellyi .

Structures: The frontal in Bothremys is only narrowly exposed in the orbital margin, in contrast to Rosasia and Zolhafah , although the degree of exposure is only slightly less than in Araiochelys , Polysternon , and Foxemys . The sulcus olfactorius (see Gaffney and Zangerl, 1968: fig. 21, for endocast) is similar in all Bothremys and is lower and wider than in forms like Galianemys .

PARIETAL (figs. 127, 130)

Preservation: Both parietals are present, but they lack the entire posterolateral emargination. The processus inferior parietalis is present and visible internally and externally on both sides of the skull. The right one is nearly complete, but both parietals have some breakage along their lower margins.

Contacts of dorsal plate: As in B. maghrebiana . The ventral process of the parietal lateral to the sulcus palatinopterygoideus (fig. 278B) contacts the postorbital laterally and probably the pterygoid ventrally. Although the contact is missing, the space would have been filled by the parietal.

Structures of dorsal plate: The degree of temporal emargination is not determinable in B. cooki . The ventral process of the parietal that forms the roof for the sulcus palatinopterygoideus is unusually deep in the other species of Bothremys , and this is apparent in B. cooki , resulting in a low sulcus palatinopterygoideus. The parietal has a ventrolateral process lateral to the sulcus palatinopterygoideus that descends alongside the postorbital. The ventral end of the process is broken off on both sides, but on the right side the pterygoid has a suture as its dorsal margin, and only the parietal would have filled the space and reached the pterygoid ( Gaffney and Zangerl, 1968: 211, fig. 13). This process and contact also occur in Chedighaii hutchisoni , Bothremys maghrebiana , and Bothremys arabicus .

Contacts of processus inferior parietalis: The processus contacts the palatine anteroventrally, the pterygoid ventrally, the prootic posteroventrally, and the supraoccipital posteriorly, as in other bothremydids.

Structures of processus inferior parietalis: The foramen interorbitale is low in Bothremys cooki , as it is in B. maghrebiana (fig. 144), Chedighaii hutchisoni , Araiochelys , Rosasia , and Foxemys . The foramen nervi trigemini has the usual bones forming it: parietal anterodorsally, prootic dorsolaterally, and pterygoid ventrally.

JUGAL (figs. 127, 128, 130, 133)

Preservation: The jugal is present and missing its posterior margin on both sides.

Contacts of lateral plate: The jugal plate in Bothremys cooki contacts the maxilla anteroventrally in a long, interdigitating suture. The postorbital contact is along the upper edge of the jugal, but the postorbital sends a small process ventrally along the anterodorsal margin of the jugal in the orbital rim. The ventral edge of the jugal entirely contacts the maxilla. The posterior edge is broken, so the contact is indeterminate.

Structures of lateral plate: The jugal forms a small part of the orbital margin, less of it in Bothremys cooki than in B. maghrebiana and B. kellyi . B. cooki has a low ridge but no acute rim marking the ventral orbital margin. This is the condition in B. maghrebiana also, but both B. kellyi and Bothremys arabicus have a distinct rim with an acute ridge.

Contacts of medial process: On the ventral surface, the jugal in B. cooki is broadly exposed on the triturating surface, contacting the maxilla anteriorly, the palatine medially, and the pterygoid posteromedially. The broad pterygoid contact on the ventral surface is unique to B. cooki . The jugal in B. maghrebiana has a much smaller exposure; the palatine-maxilla contact prevents jugal exposure along the fossa temporalis margin as seen in many other Bothremydini .

The postorbital wall in posterior view shows the jugal forming its lower half, contacting the postorbital dorsally and the pterygoid medially. The postorbital wall in anterior view shows less jugal, as it lies primarily in the fossa orbitalis floor, contacting the postorbital dorsally and the palatine medially.

Structures of medial process: The jugal in Bothremys cooki is unique among bothremydids in its extensive exposure on the palate (figs. 128, 133). It forms most of the characteristic pit and extends posteromedially, forming most of the wall between the fossa temporalis and the pit ( Gaffney and Zangerl, 1968: fig. 20). As in the other pitted bothremydids, the jugal forms the roof of the pit and is exposed on the dorsal surface near the orbit directly above the pit, as in the nonpitted forms. So the pit development does not involve the relative movement of the jugal onto the triturating surface, it perchance is the result of exposure of the overlying jugal by removal of maxilla and palatine.

QUADRATOJUGAL Preservation: Not preserved.

SQUAMOSAL Preservation: Not preserved.

POSTORBITAL (figs. 127, 130)

Preservation: The anterior part of both postorbitals are present, but the posterior part of the lateral plates that make up the temporal roof are gone.

Contacts of lateral plate: The postorbital contacts the jugal anteroventrally, the frontal anteromedially, and the parietal posteromedially, as in the other Bothremys species. The jugal contact has a narrow, anteroventral process that extends along the orbital margin, not seen in other Bothremydini .

Structures of lateral plate: The postorbital in B. cooki forms more of the orbital margin than in B. maghrebiana and B. kellyi , comparable to that in Rosasia .

Contacts of medial process: In the posterior wall of the fossa orbitalis, the postorbital of B. cooki contacts the palatine anteromedially, the jugal anterolaterally, and the parietal medially, as in B. maghrebiana . In the anterior wall of the fossa temporalis, the postorbital contacts the jugal ventrolaterally, the parietal medially, the maxilla ventrally, and the pterygoid ventromedially. There does not appear to be a palatine contact as in B. maghrebiana .

Structures of medial process: The medial postorbital process in B. cooki forms part of the roof and lateral wall of the sulcus palatinopterygoideus (fig. 279B), which in Bothremys and Chedighaii is lower than in other Bothremydini . The posteroventral part of the fossa orbitalis is enlarged in Bothremys , Chedighaii , Araiochelys , and Rosasia , in contrast to remaining Bothremydini .

PREMAXILLA (figs. 127, 128, 130)

Preservation: Parts of both premaxillae are present in AMNH 2521. The right one is nearly complete except for an area missing along the midline suture. The left one is missing more of the medial area.

Contacts: As in Bothremys maghrebiana .

Structures on dorsal surface: The fossa nasalis and apertura narium externa in B.

cooki are very similar to those in B. maghrebiana . Although not completely preserved, the premaxilla in B. cooki has a dorsal process partially dividing the apertura, as in B. maghrebiana . The anterior surface of the premaxilla slopes anterodorsally in both so that the rim of the apertura narium externa is anterior to the labial ridge. The ventral margin of the apertura is also well anterior to the prefrontal as well.

Structures on ventral surface: The labial ridge in Bothremys cooki is very similar to that in B. maghrebiana . It is blunt, not as blunt as in Zolhafah , but more obtuse than the acute ridge of Foxemys . Actually, all of this crap is pretty obtuse in my opinion. The labial ridge in B. kellyi is slightly thicker than in B. cooki and B. maghrebiana ; the ridge is not preserved in Bothremys arabicus . The snout of B. cooki is slightly pinched, as it is in B. kellyi , B. maghrebiana , Rosasia , Polysternon , and Foxemys .

The midline concavity formed by the lingual ridge on the palate is very similar in both B. cooki and B. maghrebiana . It is shallower in B. cooki than in B. maghrebiana . The concavity is narrower in these two species, along with Rosasia and Araiochelys (and probably Chedighaii barberi ), in contrast to the other Bothremydini . The foramen praepalatinum is close to and may be within Contacts of vertical plate: The maxilla the premaxilla-vomer suture. contacts the premaxilla anteromedially, the jugal posterodorsally, and the prefrontal MAXILLA (figs. 127, 128, 130, 133) anterodorsally. The quadrate and quadrato- Preservation: Both maxillae are present jugal contacts are not determinable.

in AMNH 2521, and they are complete Structures of vertical plate: The maxilla except for their posterolateral margins, which forms the lower margin of the orbit, which in are broken edges. Bothremys cooki and B. maghrebiana is a low,

rounded surface, not an acute ridge, as in B. kellyi . The fossa nasalis and choanal passages in B. cooki are the same size and shape as in B. maghrebiana . There is no indication of a cheek emargination. B. cooki differs slightly from both B. maghrebiana and B. kellyi in having a slightly deeper maxilla below the orbit. The dorsal process of the maxilla is broad in B. cooki , B. maghrebiana , B. kellyi , and probably Bothremys arabicus , in contrast to the narrower process in other Bothremydini .

Contacts of horizontal plate: The maxilla contacts the premaxilla anteromedially, the vomer medially, the palatine posteromedially, and the jugal posterolaterally. There is no midline contact of the maxillae. Bothremys cooki differs from B. maghrebiana in lacking a maxilla-palatine contact posterior to the jugal. The vomer-maxilla contact is much wider in B. cooki than in B. maghrebiana .

Structures of the horizontal plate: The maxilla of B. cooki is dominated by the large pit formed by maxilla, jugal, and palatine (fig. 133). Nearly all of the triturating surface is sloping into the pit, as in B. maghrebiana , B. kellyi , and Bothremys arabicus , in contrast to Araiochelys , in which the anterior part of the surface is flat or slopes away from the pit. The dorsal surface of the horizontal plate forms the floor of the fossa orbitalis, as in B. maghrebiana , and part of the postorbital wall.

VOMER (figs. 127, 128, 130)

Preservation: A nearly complete vomer, possibly missing some of its anterior margin, is preserved in AMNH 2521.

Contacts: The vomer contacts the premaxilla anteriorly, the maxilla anterolaterally, and the palatine posteriorly. The maxilla contact is relatively wide, uniquely so among Bothremydini . The vomer has an elongated anterior end followed by a narrow bar separating the apertura narium interna (not the apertura narium externa as stated incorrectly in Gaffney and Zangerl, 1968: 219). Foxemys and Rosasia also have a wide maxilla-vomer contact, but it is short in Araiochelys , Zolhafah , and B. maghrebiana . There does not seem to be a vomer-maxilla contact in Chedighaii hutchisoni .

Structures: The vomer is higher than wide in cross section and has a shallow groove, the sulcus vomeri, running along its dorsal surface. The posterior half of the vomer rises dorsally above the level of the median concavity on the palate.

PALATINE (figs. 127, 128, 130)

Preservation: Both palatines are present. The right one is missing some bone medially, and the left one is damaged along its lateral and ventrolateral edge. Both are damaged posteriorly. This breakage can be seen in the 1865 figures of Leidy (pl. 18. fig. 7; reproduced as fig. 19 in this paper).

Contacts: The palatine in Bothremys cooki contacts the maxilla anterolaterally, the jugal laterally, the pterygoid posteriorly, and the vomer anteromedially. The palatine of B. cooki does not contact the maxilla posterior to the pit as it does in B. maghrebiana . In the floor of the fossa orbitalis the palatine contacts the maxilla anteriorly, the jugal laterally, the postorbital posterolaterally, and the pterygoid in the floor of the sulcus palatinopterygoideus.

Structures on dorsal surface: The floor of the fossa orbitalis in B. cooki has the posteroventral pocket also seen in Chedighaii and the other Bothremys species. The palatine sends a low process dorsally to meet the anterior part of the processus inferior parietalis and has a dorsal process in the lateral wall of the sulcus palatinopterygoideus that meets the postorbital. The sulcus is continuous with the medial part of the fossa orbitalis.

Structures on ventral surface: The palatine forms the posteromedial part of the triturating surface, agreeing with B. maghrebiana and B. kellyi (see B. maghrebiana and B. kellyi for description). The lingual ridge is nearly the same in all three, with nearly all of the triturating surface sloping into the pit. The palatine forms the lateral margin of the apertura narium interna. The apertura in B. cooki is a nearly circular, paired opening, while in B. maghrebiana , the apertura is more elongate and slightly larger. Part of the apertura edges are damaged in B. kellyi . In Bothremys arabicus the apertura is also circular but larger.

QUADRATE (figs. 132, 135)

Preservation: The quadrate is not known in the type skull, only in AMNH 29444. This otic chamber has most of the quadrate but lacks all of the lateral sutural edges with the cheek bones, as well as some of the anterior cavum tympani. The antrum postoticum is broken open along both quadrate and squamosal, revealing its extent. The medial and ventral parts of the quadrate in AMNH 29444 are complete.

Contacts on lateral surface: Only the posterodorsal contact with the squamosal is preserved.

Structures on lateral surface: The lateral structures consist of the cavum tympani and associated features and the condylus mandibularis, all of which agree closely with Bothremys maghrebiana . The incisura columellae auris is a canal completely encased by bone, opening at the most medial part of the cavum tympani. The sulcus eustachii is a broad groove extending posteriorly, not a narrow, deep channel as in B. kellyi . The antrum postoticum is slightly larger than in B. maghrebiana , about as large as in B. kellyi .

Contacts on dorsal and anterior surface: As in Bothremys maghrebiana .

Structures on dorsal and anterior surface: The foramen stapedio-temporale is placed well anterior and medial on the otic chamber, just lateral to the foramen nervi trigemini. The quadrate only enters the ventrolateral part of the foramen stapedio-temporale in AMNH 29444. The anterior surface of the otic chamber is nearly vertical in AMNH 29444, but in Bothremys kellyi the otic chamber is greatly enlarged anteriorly, above the level of the condylus mandibularis. Most of this is formed by quadrate. B. maghrebiana has a slight enlargement, greater than in AMNH 29444, but nothing like that in B. kellyi .

Contacts on ventral surface: As in Bothremys maghrebiana .

Structures on ventral surface: There is no fossa pterygoidea, although there is a slight depression around the foramen posterius canalis carotici interni. The foramen is formed between the pterygoid and quadrate, as in B. maghrebiana , Araiochelys , and Chedighaii , but in contrast to B. kellyi in which the foramen posterius canalis carotici interni is formed by the basisphenoid as well as pterygoid and quadrate. The condylus occipitalis in AMNH 29444 is nearly on the plane of the condylus occipitalis, as in all the other Bothremydini except Polysternon .

Contacts on posterior surface: As in Bothremys maghrebiana .

Structures on posterior surface: As in Bothremys maghrebiana except for the bony subdivision of the fenestra postotica in AMNH 29444. The more dorsomedial part, for the stapedial artery, of the fenestra postotica is separated by bone from the more ventrolateral part, for the lateral head vein, in AMNH 29444, in contrast to B. maghrebiana in which they are not separated by bone.

PTERYGOID (figs. 127, 128, 130, 132, 134)

Preservation: In AMNH 2521 , the type skull, parts of both pterygoids are preserved. The left one is more complete ; it is missing the quadrate ramus and has breakage along the anterior margin and processus trochlearis pterygoidei. The right one consists only of the medial part and the base of the processus trochlearis pterygoidei. The right otic chamber, AMNH 29444 , has the quadrate ramus of the pterygoid preserved .

Contacts on ventral surface: The type skull, AMNH 2521, has the pterygoid contacts with the palatine anteriorly, the basisphenoid posteromedially, and the other pterygoid anteromedially. AMNH 29444 shows the quadrate contact.

Structures on ventral surface: The processus trochlearis pterygoidei in Bothremys cooki has the same morphology as in B. maghrebiana . The quadrate ramus (AMNH 29444) is also as in B. maghrebiana . There is no fossa pterygoidea (AMNH 29444), but there is a slight depression around the foramen posterius canalis carotici interni. In AMNH 29444, the foramen posterius canalis carotici interni is formed by the pterygoid anteriorly and the quadrate posteriorly, as in B. maghrebiana , B. arabicus , Chedighaii , and Araiochelys , but in contrast to B. kellyi , which has the basisphenoid in the margin. The foramen palatinum posterius in B. cooki is only on the right side and is the same as in B. maghrebiana .

Contacts on dorsal surface: The pterygoid at the base of the processus trochlearis pterygoidei contacts the postorbital dorsolaterally, the parietal (see Parietal) dorsomedially, and the jugal dorsolaterally, all as in B. maghrebiana , Chedighaii , and B. arabicus . The crista pterygoidea contacts the processus inferior parietalis dorsally and anteriorly and the prootic posteriorly, as seen in AMNH 2521. In AMNH 29444, the more posterior contacts with the prootic posterodorsally and the quadrate posterolaterally are visible.

Structures on dorsal surface: The pterygoid forms the floor of the sulcus palatinopterygoideus, as in the other bothremydids. There is no indication of the foramen nervi vidiani, but this area is not perfectly preserved. The crista pterygoidea is similar in size and shape to that in B. maghrebiana . The foramen nervi trigemini has the usual formation: parietal dorsally, pterygoid ventrally and anteroventrally, and prootic posterodorsally.

SUPRAOCCIPITAL (figs. 127, 130, 132)

Preservation: Only the anterior part of the supraoccipital is present in the type skull, AMNH 2521. In AMNH 29444 the right lateral process is preserved.

Contacts: In AMNH 2521 the supraoccipital contacts the parietals dorsally and anteriorly, as in other bothremydids. It contacts the prootic anterolaterally, but other contacts are lost due to breakage. In AMNH 29444 the supraoccipital contacts the prootic anterolaterally, the quadrate laterally, the opisthotic posterolaterally, and the exoccipital posteroventrally, as in Bothremys maghrebiana .

exoccipital is complete except for the ventromedial area and the condylus occipitalis.

Contacts: The exoccipital contacts the supraoccipital dorsally, the opisthotic laterally, the quadrate ventrolaterally, and the basioccipital ventrally, all as in B. maghrebiana and other Bothremydini .

Structures: The foramen magnum is the same as in B. maghrebiana . The condylus occipitalis is missing, and not enough of it or the basioccipital is preserved to determine the composition of the missing condylus occipitalis. All of the posterior surface of the exoccipital is in the same vertical plane in B. cooki, AMNH 29444, but in B. maghrebiana the lower part is inclined anteroventrally, and in B. kellyi it is concave, similar to Chedighaii hutchisoni .

The foramen nervi hypoglossi in AMNH 29444 appear to be three in number, with a large medial one and two small ventrolateral ones, as in Araiochelys and some B. maghrebiana . The foramen jugulare posterius is formed by the exoccipital except laterally, where it is closed by the opisthotic and quadrate. The foramen is relatively large, larger than in B. kellyi , B. maghrebiana , Bothremys arabicus , and Araiochelys , but similar to that in Chedighaii .

Structures: The crista supraoccipitalis is represented only by a short broken edge in AMNH 2521, but it agrees with B. maghrebiana . The ventral surface shows only a small part of the foramen magnum and some of the cavum labyrinthicum (see Gaffney and Zangerl, 1968: fig. 16). The other specimen, AMNH 29444, shows most of the foramen magnum on the right side and part of the base of the crista supraoccipitalis. These agree with B. maghrebiana .

EXOCCIPITAL (figs. 132, 135)

Preservation: The exoccipital is not preserved in the type of Bothremys cooki, AMNH 2521 , but it is partially present on the right side of AMNH 29444. This BASIOCCIPITAL (figs. 132, 135)

Preservation: The type skull of Bothremys cooki, AMNH 2521 , lacks the basioccipital. AMNH 29444 has the right half of one, with the posterior edge having a broken surface.

Contacts: The basioccipital in AMNH 29444 contacts the basisphenoid anteriorly, the quadrate laterally, in a contact that is much wider than in B. kellyi and B. maghrebiana , and the exoccipitals posterodorsally.

Structures: The condylus occipitalis in AMNH 29444 is broken away, and the broken surface does not allow the extent of the basioccipital to be determined. There is no tuberculum basioccipitale and no ventral median concavity; the ventral surface of the basioccipital is flat. The bone is a bit longer than in the other species of Bothremys .

PROOTIC (figs. 132)

Preservation: Parts of both prootics are preserved in the type skull of Bothremys

The medial surface of the prootic in AMNH 29444 preserves part of the hiatus acusticus and the cavum labyrinthicum. The hiatus has the foramen nervi acustici, which is single as preserved, but the posterior part of the hiatus is missing. The foramen nervi facialis is also preserved.

cooki, AMNH 2521 . The right one consists of most of the upper part of the bone and its anterior surface. The left one is less preserved laterally and is more damaged by pyrite. The otic chamber, AMNH 29444, has the right prootic nearly complete, lacking only its medial edge.

Contacts: The prootic in AMNH 2521 contacts the parietal dorsomedially, and the pterygoid ventrally on its anterior surface. On its dorsal surface it contacts the supraoccipital posterodorsally, but the other contacts are missing. In AMNH 29444, the prootic shows all the contacts seen in Bothremys maghrebiana except for the parietal, which is broken away.

Structures: Both prootics show a close similarity to the prootic of B. maghrebiana . They lack the dorsal ridge and strong anterior overlap seen in B. kellyi , Chedighaii , and some B. maghrebiana . The foramen nervi trigemini has the usual formation of parietal anterodorsally, prootic dorsally, and pterygoid posteroventrally. The foramen is preserved in both AMNH 2521 and AMNH 29444, and it is the same size and position in both. In AMNH 29444 the foramen cavernosum lies on the posteroventral margin of the foramen nervi trigemini, showing where the canalis cavernosus becomes the sulcus cavernosus. The foramen nervi trigemini and the foramen stapedio-temporalis are close together, separated only by a narrow bar of prootic.

OPISTHOTIC (figs. 132, 135)

Preservation: The opisthotic is not preserved in the type of Bothremys cooki, AMNH 2521 . A nearly complete right opisthotic is preserved in AMNH 29444. This opisthotic is missing a small part along its posterior edge.

Contacts: The opisthotic in AMNH 29444 has the same contacts as in Bothremys maghrebiana .

Structures: The foramen jugulare posterius in AMNH 29444 is larger than in most other Bothremydini . It is closed laterally by both opisthotic and quadrate joining to form the margin. The fenestra postotica is completely closed and subdivided by a narrow but complete bony separation into a more dorsomedial foramen for the stapedial artery and a more ventrolateral foramen for the lateral head vein. On the dorsal surface, the opisthotic has a broad, posteriorly facing concavity formed by the opisthotic and squamosal that occurs in B. kellyi and Chedighaii and, to a lesser extent, in most Bothremydini .

BASISPHENOID (figs. 127, 130, 134)

Preservation: The type skull of Bothremys cooki, AMNH 2521 , has most of the basisphenoid preserved, but it is a bit chewed up along its posterior margin. It is also missing some of the posterolateral edges. AMNH 29444 has only the posterolateral third or so of the bone preserved.

Contacts on ventral surface: The basisphenoid of B. cooki has the usual contacts as seen in B. maghrebiana . The quadrate contact is narrow, as in B. maghrebiana , but not as narrow as in B. kellyi .

Structures on ventral surface: The foramen posterius canalis carotici interni is not formed by the basisphenoid in AMNH 29444, as it is in B. kellyi . The surface is flat, with no concavities or depressions.

Contacts on dorsal surface: The dorsal surface is visible in AMNH 2521 ( Gaffney and Zangerl, 1968: fig. 19). The crista pterygoidea contacts the processus inferior parietalis, but not the frontal. There is no palatine contact, but the basisphenoid overlaps the pterygoids anteriorly, as in nearly all turtles.

Structures on dorsal surface: The rostrum basisphenoidale in Bothremys cooki (fig. 134) is rodlike but fairly short, very similar to that in Chedighaii barberi, YPM PU 12951, an endocast (fig. 167). The dorsum sellae and sella turcica are also very similar, with the dorsum sellae overhanging the sella turcica and forming a teardrop-shaped opening. The foramen anterius canalis carotici interni is visible at the posterolateral corner of the sella turcica. The processus clinoideus is absent, as in Chedighaii (it is indeterminate in the other Bothremys ). The foramen nervi abducentis seems to be absent as a fully formed canal, also as in Chedighaii barberi .

Bothremys maghrebiana

There are five good skulls of Bothremys maghrebiana , making it morphologically the best known taxon in the tribe Bothremydini , and the more extensive description and figures reflect this. There is some individual variation, particularly with MHNL 20- 268370, and this is noted in the description. There are four species in Bothremys at present. B. maghrebiana is most similar to B. cooki , although the analysis only weakly supports a sister-taxon relationship (fig. 288).

PREFRONTAL (figs. 136, 143)

Preservation: At least parts of the prefrontal are present in all five Bothremys maghrebiana skulls, but it is most complete in AMNH 30041, AMNH 30561, and MHNL 20-268370.

Contacts: The prefrontal of Bothremys maghrebiana has the same contacts as in Bothremys cooki and the other bothremydids: maxilla anteroventrolaterally, frontal posteriorly, and other prefrontal medially.

Structures: The prefrontal in Bothremys maghrebiana has an anterior projection on the midline that is also present in B. cooki and Chedighaii . In all the Bothremys species this helps form the distinctive figure eight-shaped apertura narium externa. In Chedighaii the lower margin is missing. Foxemys and Polysternon , as well as Cearachelys , have a transverse, not protruding margin to the apertura.

The sulcus olfactorius of Bothremys maghrebiana is slightly shallower than in B. cooki and is much shallower than in Chedighaii . It is very variable among the bothremydids.

FRONTAL (figs. 136, 143)

Preservation: The frontals are preserved in all five Bothremys maghrebiana skulls, although there is some damage to them in both AMNH 30234 and AMNH 30041.

Contacts: The frontal in Bothremys maghrebiana has the usual bothremydid contacts: prefrontal anteriorly, postorbital posterolaterally, parietal posteriorly, and frontal medially. The frontal in B. maghrebiana differs from the other bothremydids in being much wider than long. In B. cooki the frontal is nearly square, and in the others the frontal is relatively narrower than in B. maghrebiana .

Structures: The size and position of the orbits in the Bothremydini are variable. Bothremys and Chedighaii have unusually small and upward-facing orbits. In Rosasia and Zolhafah the orbits are larger, while in Polysternon and Foxemys the orbits are largest. To a certain extent this size difference is subjective, and Zolhafah has incomplete orbits. Also, the orientation of the orbits is distinctly dorsally facing in Bothremys and Chedighaii hutchisoni . In the other Bothremydidae there is usually a more lateral component to the orbital orientation.

PARIETAL (figs. 136, 143, 278B)

Preservation: The parietal is present at least in part in all five Bothremys maghrebiana specimens, but its posterior margin is complete only in AMNH 30234 and MHNL 20-268370. In AMNH 30041 the dorsal plate of the right parietal is completely missing, revealing the cavum cranii. AMNH 30234 is probably missing a small part near the midline at its posteriormost limit.

Contacts of dorsal plate: As in the other Bothremydinae , the parietal of Bothremys maghrebiana contacts the frontal anteriorly, the postorbital laterally, and the other parietal medially. There is no parietal-quadratojugal or squamosal contact.

Structures of dorsal plate: Among the Bothremydini the complete temporal roof is known in Polysternon , Foxemys , Araiochelys , and Chedighaii . The extent of the roof is very similar in Bothremys maghrebiana and Foxemys ; it is slightly more extensive than in Polysternon . However, in Chedighaii it is more emarginate than in these three, completely exposing the otic chamber rather than partially exposing it. However, the difference is not great and could very well be within individual variation of some or all of these taxa.

The ventral surface of the parietal lateral to the sulcus palatinopterygoideus has a ventral process in Bothremys maghrebiana . In other bothremydids and pleurodires in general the parietal forms the roof of the sulcus, actually a tunnel-shaped structure in most Pelomedusoides, but not part of the lateral wall. In both B. maghrebiana and B. cooki there is a well-developed ventral process attached to the medial edge of the postorbital (fig. 278B). In B. maghrebiana it reaches the palatine (on the anterior surface, not on the posterior surface, which is shown in fig. 278); in B. cooki it is more extensive posteriorly and contacts the pterygoid. The process is best seen in the anterior view of the postorbital wall of the fossa orbitalis in B. maghrebiana, AMNH 30041, and in the posterior view of

30234 with additions from AMNH 30041 and AMNH 30561 holotype. [F. Ippolito, del.]

the postorbital wall in B. cooki, AMNH 2521 .

Contacts of processus inferior parietalis: The processus is clearly visible only in AMNH 30041, although its anterior margin is revealed in AMNH 30234. Sutures are clear on the right processus inferior parietalis of AMNH 30041, although there is some fragmentation due to crushing. The contacts are the usual in Bothremydinae : palatine anteroventrally, pterygoid ventrally, prootic posteroventrally, and supraoccipital posteriorly.

Processus inferior parietalis: The foramen interorbitale (fig. 144) in Bothremys maghrebiana is nearly the same as in B. cooki , although some crushing in B. maghrebiana makes close comparisons difficult. The foramen is longer in Bothremys (not known in B. kellyi ) than in Chedighaii , but it is very similar in Rosasia and Foxemys .

The foramen nervi trigemini in B. maghrebiana is formed by the usual bones seen in other Bothremydinae : parietal anterodorsally, prootic dorsolaterally, and pterygoid ventrally. The foramen nervi trigemini in B. maghrebiana is very close to the foramen stapedio-temporale.

JUGAL (figs. 136, 137, 139, 143, 278B)

Preservation: The jugal is present in all five Bothremys maghrebiana specimens, but it is complete only in AMNH 30234, and sutures are not entirely clear in this skull. Sutures are clear in AMNH 30041 and 30561, which are lacking parts of the lateral plate of the jugal.

Contacts of lateral plate: In B. maghrebiana the laterally exposed portion of the jugal contacts the maxilla anteroventrally and the postorbital dorsally. In AMNH 30041 and 30561, which have clear sutures, the jugal ends posteriorly in a broken edge. In AMNH 30234 the sutures are obscured by cracking and poor preservation. It is likely that the quadratojugal-jugal suture lies above the maxilla-quadrate suture and that the jugal does not contact the quadrate. This condition would be nearly the same as in Rosasia . In Chedighaii , Polysternon , and Foxemys there is no maxilla-quadrate contact. In B. cooki and Zolhafah the cheek is missing.

Structures of lateral plate: The jugal in Bothremys maghrebiana is exposed in the posterior wall of the orbit and forms part of its margin. There is no cheek emargination in B. maghrebiana , and the jugal does not reach the cheek margin.

Contacts of medial process: The orbital floor of Bothremys maghrebiana is best seen in the left orbit of AMNH 30041. The contacts are with the maxilla anteriorly and laterally and with the palatine medially, as in the other Bothremydini . At least some of the jugal is exposed in the orbital floor in all five skulls, but sutures are clearly visible only in AMNH 30041 and 30522. They show contact laterally with the maxilla, ventromedially with the palatine, and dorsomedially with the postorbital. On the triturating surface the jugal contacts the maxilla anteriorly and the palatine posteriorly.

Structures of medial process: The jugal is a complex element that forms part of three surfaces. Its dorsal surface forms part of the floor of the fossa orbitalis, and in Bothremys maghrebiana its ventral surface is exposed in the tip of the pit formed on the triturating surface (figs. 136, 137). This condition is best seen in AMNH 30041, on the left side, and in AMNH 30561, also on the left side. The dorsal sutures are clear, but the ventral ones are harder to interpret. However, both AMNH 30561 and AMNH 30041 have the pits broken through by a hole into the orbit that makes identification easier. The bone at the tip of the pit is very thin (as it is in Bothremys cooki ) and easily broken. In both skulls the jugal on the dorsal surface can be followed into the broken edge and onto the ventral surface in the pit apex. The sutural contact with maxilla and palatine is irregular in both skulls and obscured by nutrient foramina and fusion, but the general position of the jugal forming the apex of the pit is clear.

In Bothremys cooki the pit is formed almost entirely by the jugal, which is broadly exposed along the edge of the fossa temporalis inferior. In Zolhafah and Rosasia much of the pit is also formed by the jugal, which is also exposed along the fossa temporalis inferior margin, although not to the extent seen in B. cooki . Thus, B. maghrebiana differs from all these in having no exposure of the jugal on the margin of the fossa temporalis inferior due to broad contact of the maxilla and palatine. Cearachelys and Galianemys whitei also have exposure of the jugal along this margin, but exposure on the triturating surfaces is slight. In Chedighaii there are no pits and no exposures of the jugal.

The third area of jugal exposure is on the posterior surface of the septum orbitotemporale in the fossa temporalis superior (fig. 278B). The jugal here is bound by the maxilla laterally and the postorbital dorsomedially. On the right side of AMNH 30041 the palatine contacts the jugal ventromedially, but on the left side it seems that the palatine does not extend laterally to reach the jugal, although it is not entirely clear. On both sides of this specimen, however, there is a clear ventral suture of the jugal showing that it does not extend anteriorly to meet the jugal exposed in the pit.

QUADRATOJUGAL (figs. 136, 141)

Preservation: The quadratojugal is missing in AMNH 30041 and 30561. It is present but not clearly defined by sutures in AMNH 30234, AMNH 30522, and MHNL 20- 268370.

Contacts: The quadratojugal in Bothremys maghrebiana contacts the quadrate ventrally and the postorbital medially, as seen on the right side of AMNH 30234. On the left side can be seen a narrow, posterolateral contact with the squamosal. The definite maxilla-quadrate contact preserved in AMNH 30561, 30522, and 30041 shows that a C-shaped quadratojugal extending to the cheek margin could not be present in B. maghrebiana . The quadratojugal is restricted to the area above the quadrate, as in Rosasia and B. kellyi . The jugal-quadratojugal suture is not clearly discernable although it is likely in the area posterior to the maxilla-quadrate contact, in which case there would be no quadratojugal-maxilla contact.

Structures: The quadratojugal of Bothremys maghrebiana forms part of the temporal roof and is exposed on the edge of the skull roof. There is no cheek exposure of the quadratojugal in B. maghrebiana .

SQUAMOSAL (figs. 136, 139)

Preservation: The squamosal is present in all five skulls, but it is most complete in AMNH 30234 in which only a small part of the temporal margin seems to be missing. Sutures are visible in all five skulls, but they are best seen in AMNH 30561 and 30041.

Contacts: The squamosal contacts the quadrate anteriorly, the opisthotic medially, and the quadratojugal anterodorsally.

Structures: The squamosal of Bothremys maghrebiana is a cone-shaped bone fitting around the relatively well-developed antrum postoticum of the quadrate. The bone is not preserved in B. cooki , B. arabicus , and Rosasia , and it is only partially preserved in Chedighaii , Zolhafah , and Polysternon . Foxemys , along with B. maghrebiana , has the best preserved squamosals among the Bothremydini . The bone has a low ventral ridge in all the taxa with it preserved, in contrast to the deep ridge seen in some Taphrosphyini .

POSTORBITAL (figs. 136, 141, 278B)

Preservation: The anterior part of the postorbital is present in AMNH 30561 and 30041, but only AMNH 30234 has the bone nearly complete. Sutures are clear in AMNH 30561, 30041, and 30234.

Contacts of lateral plate: The postorbital of Bothremys maghrebiana contacts the frontal anteromedially, the jugal anteroventrally, the quadratojugal posteroventrally, and the parietal medially.

Structures of lateral plate: The postorbital has a wide exposure in the posterior orbital margin in B. maghrebiana , as in the other bothremydines. The postorbital of B. maghrebiana is slightly narrower than that bone in Foxemys , Polysternon , and Chedighaii . It is incomplete or missing in B. cooki , Rosasia , and Zolhafah . The postorbital forms part of the posterior margin of the temporal roof in B. maghrebiana , as in the other Bothremydini .

Contacts of medial process: The medial process of the postorbital in Bothremys maghrebiana is preserved in all three skulls but is clearest in AMNH 30041. The postorbital is exposed in the fossa orbitalis and the posterior surface of the postorbital wall (fig. 278B). In the fossa orbitalis the postorbital contacts the jugal laterally, the palatine anteroventrally, and the parietal medially. In B. maghrebiana there is a descending process of the parietal between the postorbital and the sulcus palatinopterygoideus, as in B. cooki . In the posterior view of the postorbital wall the postorbital contacts the jugal laterally, the palatine and maxilla ventrally, the pterygoid medially, and the parietal dorsomedially.

Structures of medial process: The postorbital bone in Bothremys maghrebiana makes up part of the roof and lateral wall of the sulcus palatinopterygoideus, as in other pleurodires, but in Bothremys the descending process of the parietal covers much of the postorbital exposure. The postorbital wall in both Bothremys and Rosasia is placed more posteriorly in comparison to other bothremydids. The sulcus palatinopterygoideus (fig. 144) is therefore shorter in Bothremys than in the other bothremydids. The postorbital forms part of the dorsal pocket of the fossa orbitalis, characteristic of bothremydids (character 27).

PREMAXILLA (figs. 136, 137, 143)

Preservation: At least some of the premaxilla is present in all five Bothremys maghrebiana skulls; sutures are visible in AMNH 30041, 30522, and 30561.

Contacts: The premaxilla in B. maghrebiana contacts the maxilla posterolaterally, the other premaxilla medially, and the vomer posteriorly. These contacts are very similar in the other Bothremys species.

Structures in dorsal view: The premaxilla in Bothremys maghrebiana is very similar to that in B. cooki . They both are distinctly protuberant, extending anteriorly past the anterior limit of the prefrontal at the dorsal margin of the apertura narium externa. A protuberance of the premaxilla is also present in Rosasia . The condition in Chedighaii and Zolhafah is not determinable.

Structures in ventral view: The premaxilla in all species of Bothremys is very wide anteriorly and triangular in shape. This is also the condition in Chedighaii , Rosasia , and Zolhafah , but not in Foxemys , where it is more parallel-sided. In ventral view the premaxilla of Bothremys maghrebiana is very similar to that bone in B. cooki . The labial ridge is blunt but not as blunt as in Zolhafah , and it is more blunt than the acute ridge of Foxemys . All Bothremys species have an anterior profile of the premaxillae with a shallow rise on the midline of the labial ridge, comparable to that in Foxemys , but not flat, as in Kurmademys . All Bothremys species have a similar midline concavity developed on the premaxillae, vomer, and maxillae. This concavity is defined anteriorly and laterally by the lingual ridge and is a surface that lacks the highly vascularized texture of the triturating surface. It is typically distinct and deep in most but not all bothremydids. In B. maghrebiana and B. cooki it is relatively narrow, in contrast to B. kellyi , B. arabicus , Foxemys , and Polysternon . It is much narrower in Rosasia .

The foramen praepalatinum is best preserved in Bothremys maghrebiana in AMNH 30561. This paired foramen is almost completely formed by the premaxilla at its posterior limit, close to but not within the vomer-premaxilla suture. It is situated in a very similar position in B. cooki .

MAXILLA (figs. 136, 137, 143)

Preservation: At least one nearly complete maxilla is present in all five Bothremys maghrebiana specimens. It is best preserved with clearest sutures in AMNH 30561, but good sutures are visible also in AMNH 30041, 30234, and 30522. Only the right maxilla is well preserved in MHNL 20- 268370.

Contacts of vertical plate: The more vertical or lateral portion of the maxilla in Bothremys maghrebiana contacts the premaxilla anteromedially, the jugal posterodorsally, the quadrate posteriorly, and the prefrontal anterodorsally. The posterodorsal sutures are not clear in AMNH 30234, which is the only specimen to preserve this area. It is likely that there is a small maxilla-quadratojugal contact as in Rosasia , but this is ambiguous. In common with Rosasia , the maxilla in B. maghrebiana contacts the quadrate posteriorly without the quadratojugal intervening, as in Polysternon , Foxemys , and Chedighaii , among the Bothremydini .

Structures of vertical plate: The relations of the dorsal process of the maxilla do not vary much among the Bothremydini . In Bothremys maghrebiana the suture between the maxilla and prefrontal extends from the dorsolateral corner of the apertura narium externa to the anterior margin of the orbit, as it does in other Bothremydini . The length of the suture, which reflects the width of the dorsal process, however, does vary among these. In the Bothremys species this process is wider than in any of the other Bothremydini . Chedighaii also has a wide process, wider than in other Bothremydini except for Bothremys .

The maxilla forms the lateral margin of the apertura narium externa. In Bothremys the narium is relatively wide, as it is in most Bothremydini except Rosasia , Foxemys , and Polysternon . The extent of the maxilla from the orbit to the lower cheek margin is great in all species of Bothremys and in Chedighaii , more so than in other Bothremydini . The labial ridge in Bothremys maghrebiana is broadly curved as in B. cooki ; both are very similar in shape laterally and ventrally.

Contacts of horizontal plate: In Bothremys maghrebiana the maxilla contacts the premaxilla anteromedially, the vomer medially, the palatine posteromedially, and the jugal posteriorly. The vomer contact in B. maghrebiana is short in contrast to B. cooki , which has a long vomer-maxilla contact that is related to the longer anterior portion of the vomer and greater separation of the apertura narium interna from the front of the snout. The jugal contact in B. maghrebiana is also significantly different from that in B. cooki and is related to the way in which the triturating pits are formed (see below). In B. maghrebiana the jugal (see Jugal) is visible on the left side of AMNH 30041 and both sides of AMNH 30561. The jugal has an irregular, circular contact with the maxilla except for its posterior margin where it contacts the palatine. The maxilla also contacts the jugal dorsomedially in the posterior surface of the postorbital wall.

Structures of horizontal plate: In Bothremys maghrebiana as in B. cooki and the other Bothremydini , except Araiochelys , the maxilla horizontal plate is very wide and triangular, forming most of the distinctive triturating surface.

The triturating surface in Bothremys maghrebiana is most similar to that in B. cooki and B. kellyi among the Bothremydini , but there are important differences. The shape of the labial ridge is quite similar in B. cooki and B. maghrebiana , differing from Rosasia in being more acute and not as curved anteriorly. The ridge in Zolhafah is very blunt and much straighter than in any of the other Bothremydini . The labial ridge margin is missing in Chedighaii hutchisoni but it is acute in C. barberi . The medial and more horizontal surface of the triturating surface in B. maghrebiana is broadly curved, forming the outer parts of the surface leading into the pit, so that most of the pit is formed by the maxilla in B. maghrebiana . Only the tip is formed by the jugal. In the other species of Bothremys much more of the pit is formed by the jugal. However, the area of the triturating surface formed by the jugal in B. cooki is formed mostly by the palatine in B. maghrebiana , so the maxilla itself is similar in extent in these two species. The maxilla in both species reaches the edge of the temporal fossa to form part of the postorbital wall. This part of the triturating surface is also similar to that in Rosasia and Zolhafah ; both of these have the jugal making up the tip of the pit, but the pit is shallower and lies closer to the temporal fossa edge, lacking the well-developed posterior wall seen in other Bothremys species. The maxilla in B. maghrebiana between the pit and the premaxilla is much less extensive than it is in B. cooki . Chedighaii lacks the triturating surface pits and lacks any exposure of the jugal on the triturating surface.

Medially the maxilla in Bothremys maghrebiana forms part of the lingual ridge, much as in the other Bothremydini . The lingual ridge is not a ridge in the Bothremydini ; rather, it forms a raised margin where the triturating surface is separated from the depressed area around the apertura narium externa. This area is very similar in the other Bothremys species.

On the dorsal surface, the maxilla forms part of the floor of the fossa orbitalis and the orbital margin. The maxilla in B. maghrebiana forms the lateral edge of the foramen orbitonasale and the anterior part of the fossa orbitalis, as in B. cooki and the other Bothremydini . The maxilla in Bothremys maghrebiana forms a small part of the posterior surface of the postorbital wall. The maxilla forms part of the ventral pocket in the posterior part of the fossa orbitalis (fig. 144).

VOMER (figs. 136, 137, 143)

Preservation: In Bothremys maghrebiana the vomer is present in AMNH 30234, 30522, and 30561. It is well preserved with clear sutures in AMNH 30561 and 30522.

Contacts: The contacts of the vomer in Bothremys maghrebiana are with the premaxillae anteriorly, the maxillae anterolaterally, and the palatines posteriorly, as in other Bothremydidae .

Structures: The vomer in Bothremys maghrebiana is dumbbell-shaped, widened at each end with a narrow central bar. In B. cooki the anterior expansion is much more extensive and the maxillary contact is longer than in B. maghrebiana . Zolhafah also has a small or absent vomer-maxilla contact, but Rosasia has an anteriorly expanded vomer. Chedighaii has a vomer that lacks an anterior expansion of the sort seen in B. cooki , but the degree of maxilla contact is unclear.

The vomer forms the medial margin of each apertura narium interna. In Bothremys maghrebiana the apertura is slightly larger than in B. cooki and is placed more anteriorly. The shape of the apertura is circular in B. cooki but oblong in B. maghrebiana . The foramen praepalatinum in B. maghrebiana is formed almost completely by the premaxilla.

PALATINE (figs. 136, 137, 143)

Preservation: Most of both palatines are missing in MHNL 20-268370, but the remaining four have the bone nearly complete on one or both sides. Sutures are clearest in AMNH 30561 and 30522.

Contacts: The palatine in Bothremys maghrebiana contacts the maxilla in a long, roughly transverse suture trending anteromedially to posterolaterally with a short interruption in the middle for the jugal. This is in strong contrast to B. cooki , which has only the anteromedial part of the contact, as the larger jugal prevents more lateral contact with the maxilla. The anteromedial corner of the palatine has a short contact with the vomer. There is a long midline contact with the other palatine and a nearly transverse posterior contact with the pterygoid.

On the dorsal surface of the palatine in B. maghrebiana there is the usual parasagittal contact with the processus inferior parietalis of the parietal. In the floor of the orbit the palatine contacts the maxilla anterolaterally, the jugal laterally, and the postorbital posterolaterally.

Structures on dorsal surface of palatine: The orbital floor in Bothremys maghrebiana is exposed clearly in AMNH 30561 and 30041. The palatine exposure in B. maghrebiana is much as in B. cooki ; there is not a great deal of variation within the Bothremydini in any case. The foramen orbitonasale is also similar in the other Bothremys species. There is no dorsal process of the palatine on either anterior or posterior postorbital wall surfaces.

Structures on ventral surface of palatine: The palatine of Bothremys maghrebiana forms a significant part of the triturating surface, the posteromedial third, as in the other Bothremydini . This part of the palatine is broadly curved, forming the posteromedial part of the pit on the triturating surface. The triturating surface area of the palatine has the characteristic nutrient foramina up to the low lingual ridge that roughly trends anteromedially to posterolaterally, as in B. cooki .

The palatine forms the dorsal and lateral walls of the apertura narium interna and the broadly curved choanal passage leading into it. This area is very similar in Bothremys maghrebiana and B. cooki .

QUADRATE (figs. 136, 137, 139, 145, 286B)

Preservation: The quadrate is present on both sides in AMNH 30234, AMNH 30561, and MHNL 20-268370, but it is missing on the right side of AMNH 30041 and is damaged on the right side of AMNH 30522. All five skulls show sutures.

Contacts in lateral view: The quadrate in Bothremys maghrebiana contacts the maxilla anteriorly, the quadratojugal dorsally, and the squamosal posterodorsally.

Structures in lateral view: The cheek in Bothremys maghrebiana is completely lacking any emargination and is very similar to Rosasia in this feature. Zolhafah and B. cooki do not have the cheek area preserved, and Chedighaii hutchisoni has a shallow emargination.

The cavum tympani in Bothremys maghrebiana is similar to that in the other Bothremydini in which it is known (fig. 286B). Unfortunately, it is missing in the type specimen of B. cooki , although it is preserved in AMNH 29444, which is probably B. cooki . Rosasia and Zolhafah have only part of it preserved, so B. maghrebiana represents one of the best preserved ears in the Bothremydini ! Only Polysternon and Foxemys have good ear regions preserved and they differ significantly from B. maghrebiana and the other Bothremydini in having an open incisura columellae auris (fig. 281).

The cavum tympani of Bothremys maghrebiana is a deep, hemispherical cone, as is typical of the infrafamily Bothremydodda , which have a nearly horizontal, shelflike platform forming its ventral edge. This area is not preserved in the type skull of B. cooki , but AMNH 29444 does have this shelf. The cavum tympani in B. maghrebiana has no fossa precolumellaris, a structure lacking in the other Bothremydidae except Kurmademys . As in all other Bothremydidae , B. maghrebiana has an extensive bony separation between the stapes and eustachian tube. There is a distinct groove and notch for the eustachian tube in B. maghrebiana , as in AMNH 29444 and both species of Chedighaii .

The antrum postoticum in Bothremys maghrebiana shows some variation among the five skulls. In AMNH 30234, AMNH 30522, MHNL 20-268370, and AMNH 30561, the antrum is smaller than in AMNH 30041, the smallest skull. The smaller size of the antrum in the larger skulls suggests that it may be growth related, as in many living turtles. The antrum postoticum is often relatively larger in the juveniles of a species than in the adults, and the small condition in the larger skulls of B. maghrebiana may be the adult condition of this species. It is somewhat subjective to discriminate between ‘‘moderate’’ and ‘‘small’’ character states in the size of the antrum postoticum in bothremydids. However, the interpreted adult condition of B. maghrebiana is the same size as in the other Bothremys species and Chedighaii , but it is distinctly smaller than in Polysternon and Foxemys . The smallest B. maghrebiana skull, AMNH 30041, however, has an antrum postoticum about the same relative size as in these latter genera.

Contacts in dorsal view: The quadrate in Bothremys maghrebiana has the usual contacts of most Bothremydini : prootic anteromedially, supraoccipital medially, opisthotic posteromedially, and squamosal posteriorly and posterolaterally.

Structures in dorsal view: The only varying structure here is the position of the foramen stapedio-temporale. In Bothremys maghrebiana it is in the advanced bothremydid position on the anterior face of the otic chamber.

Contacts in ventral view: The quadrate in turtles is a complex element that in bothremydids typically contacts nine bones (basisphenoid, basioccipital, pterygoid, opisthotic, prootic, supraoccipital, maxilla, quadratojugal, and squamosal; see fig. 136). These contacts are all present in Bothremys maghrebiana , and seven are visible in ventral view (all of the above except the supraoccipital and prootic). The medial process of the quadrate contacts the pterygoid anteromedially, the basisphenoid medially, and the basioccipital posterodorsally. These contacts are very similar in B. cooki (AMNH 29444) and Zolhafah . The basisphenoid suture is longer in Foxemys and Polysternon and much shorter in Chedighaii . Most of the basioccipital suture in Rosasia is eroded, but the basisphenoid suture seems similar in length to that in B. maghrebiana .

Structures in ventral view: In ventral view the quadrate of Bothremys maghrebiana shows only the slightest imprint of the pterygoideus musculature, in strong contrast to the deep fossa pterygoidea seen in Foxemys and Polysternon . This concavity is also absent in Chedighaii , Zolhafah , and B. cooki (AMNH 29444), but a moderately developed one is present in Rosasia .

The foramen posterius canalis carotici interni is formed between the quadrate and pterygoid in Bothremys maghrebiana (fig. 277B), as in B. cooki (AMNH 29444), Chedighaii , and B. arabicus , but in contrast to B. kellyi . The foramen is best preserved on the right side of AMNH 30041 and on the left side of AMNH 30234.

The condylus mandibularis is at about the level of the basioccipital, just anterior to the condylus occipitalis, as in Foxemys , Chedighaii , Zolhafah , and B. cooki (AMNH 29444). It is distinct from the much more anterior placement seen in Polysternon .

Contacts in posterior view: In Bothremys maghrebiana the quadrate contacts the squamosal dorsolaterally, the opisthotic dorsomedially, and the exoccipital medially. These are the usual contacts found in all the other Bothremydini .

Structures in posterior view: The fenestra postotica of Bothremys maghrebiana is a single opening, partially divided by a shallow, dorsal ridge into a more medial and a more lateral portion (fig. 145). The dorsomedial part of the fenestra (fig. 145) is formed by the opisthotic, as in the other Bothremydini . In B. cooki (AMNH 29444, fig. 135), the fenestra is completely subdivided by bone into two openings, but its size is very similar to that in B. maghrebiana . The foramen chorda tympani inferius (fig. 145) is preserved on the posterior surface of the processus articularis of the quadrate in all B. maghrebiana specimens.

PTERYGOID (figs. 136, 137, 139, 277B)

Preservation: The pterygoid is present on both sides in all five skulls, with AMNH 30041, 30522, and 30561 showing clear sutures.

Contacts on ventral surface: In Bothremys maghrebiana the pterygoid contacts the palatine anteriorly, the other pterygoid anteromedially, the basisphenoid posteromedially, and the quadrate posterolaterally. These contacts are as in the other Bothremydini , but the anteromedial pterygoid contact is very short in B. maghrebiana , shorter than in any other Bothremydini , but closest to B. cooki .

Structures on ventral surface: The processus trochlearis pterygoidei is present on both sides in all five Bothremys maghrebiana skulls, and it appears to be nearly complete and undamaged in AMNH 30041. It is angled posterolaterally at about 45 °, more posterior than the process in Foxemys , Polysternon , and Chedighaii , but about the same as in B. cooki , Zolhafah , and Rosasia . Compared with Podocnemis , the processus in B. maghrebiana is relatively small, but compared with Pelusios and Pelomedusa it is about the same size. In comparison with the Pelomedusidae , however, the processus in those Bothremydini that have it well preserved show its position to be significantly closer to the otic chamber than in the Pelomedusidae . The web or flange of bone extending ventrally between the processus trochlearis pterygoidei and the quadrate ramus of the pterygoid is at least partially preserved in AMNH 30234, which shows it to be relatively extensive, as in the Pelomedusidae . The attachment margin of the pterygoideus muscle is marked in B. maghrebiana only by a low ridge or step extending transversely along the quadrate ramus of the pterygoid.

The foramen posterius canalis carotici interni is formed anteriorly by the pterygoid (for description see Quadrate). The foramen palatinum posterius is in the suture between the pterygoid and palatine, which tends to be more transverse in Bothremys maghrebiana than in B. cooki and Foxemys . The foramen is slightly larger in B. maghrebiana than in B. cooki , which has a foramen smaller than other Bothremydini .

Contacts on dorsal surface: The base of the processus trochlearis pterygoidei in Bothremys maghrebiana contacts the postorbital dorsolaterally, the parietal dorsally (see Parietal), and the palatine ventrolaterally (AMNH 30041). The crista pterygoidea, visible internally and externally in AMNH 30041, contacts the processus inferior parietalis dorsally, the prootic posterodorsally, and the quadrate posterolaterally.

Structures on the dorsal surface: The sulcus palatinopterygoideus is formed between the processus trochlearis pterygoidei laterally and the processus inferior parietalis medially (fig. 144). In Bothremys maghrebiana this structure is completely enclosed by the pterygoid and parietal, but not the postorbital as in most other Bothremydini (fig. 278B). The sulcus enclosure is relatively short in B. maghrebiana as it is in B. cooki and the Chedighaii endocast (fig. 167), but in contrast to the Podocnemididae , which have a longer, more tunnel-like sulcus palatinopterygoideus. Although the sulcus in Bothremys is short, it is preceded anteriorly by an enlarged space in the posterior portion of the fossa orbitalis (see Postorbital). This space seems to be missing in the Chedighaii endocast, which shows a distinct ridge separating the nearly spherical fossa orbitalis from the sulcus palatinopterygoideus.

The foramen palatinum posterius lies in the posterior floor of the sulcus palatinopterygoideus. It is slightly larger than in Bothremys cooki and much larger than the one in the Chedighaii endocast, AMNH 12951.

The foramen nervi trigemini in Bothremys maghrebiana is formed by the pterygoid for its ventral length with the parietal entering it anterodorsally and the prootic posterodorsally. This is the same as in Bothremys cooki and Zolhafah . The pterygoid forms the floor of the sulcus/canalis cavernosus, which lies between the foramen nervi trigemini laterally and the processus clinoideus of the basisphenoid, with the foramen cavernosum just medial to the posterior margin of the foramen nervi trigemini. In B. maghrebiana the foramen stapedio-temporale is very close to the foramen nervi trigemini, as it is in most Bothremydini . The wall between the foramen stapedio-temporale and the foramen cavernosum is thinner in B. maghrebiana than it is in B. cooki (AMNH 29444). It is not preserved in the type skull of B. cooki . In Zolhafah it is completely eroded, exposing the canalis cavernosus as well as the canalis stapedio-temporalis.

SUPRAOCCIPITAL (figs. 136, 139)

Preservation: The occipital part of the supraoccipital is preserved in all five skulls, but the more posterior crista supraoccipitalis is complete in MHNL 20-268370 and AMNH 30041. AMNH 30561 is missing nearly all of the crista, and it is partially present in the others.

Contacts: The supraoccipital contacts in Bothremys maghrebiana are with the parietals dorsally and anteriorly, the prootic anterolaterally, the quadrate laterally, the opisthotics posterolaterally, and the exoccipitals posteroventrally (seen best in AMNH 30561 and 30041). The quadrate-supraoccipital contact is found in all Bothremydini except Zolhafah and in all other Bothremydidae except the Taphrosphyini .

Structures: The crista supraoccipitalis in Bothremys maghrebiana is relatively short, thickened along its ventral edge, and not projecting very far beyond the edge of the skull roof. The foramen magnum is formed by the supraoccipital dorsally, as in other pleurodires. The cavum labyrinthicum is not exposed in any of the B. maghrebiana skulls.

EXOCCIPITAL (figs. 136, 145)

Preservation: Both exoccipitals are present in all five Bothremys maghrebiana skulls; the best sutures are in AMNH 30561, although most sutures can be seen in all of them.

Contacts: As in the other Bothremydini , the exoccipital of Bothremys maghrebiana contacts the supraoccipital dorsally, the opisthotic laterally, the quadrate ventrolaterally, and the basioccipital ventrally.

Structures: The foramen magnum in Bothremys maghrebiana is formed laterally and ventrally by the exoccipital. The condylus occipitalis is formed entirely by the exoccipitals; the basioccipital does not extend posteriorly as in Cearachelys .

There is only one foramen nervi hypoglossi in Bothremys maghrebiana , as in Polysternon and in contrast to Zolhafah , Chedighaii , Foxemys , and B. cooki (AMNH 29444), all of which have two. The single foramen of B. maghrebiana is placed close to the positions of the paired foramina in the other taxa, between the condylus occipitalis and the foramen jugulare posterius.

The foramen jugulare posterius in Bothremys maghrebiana is fully enclosed. In AMNH 30561 it can be seen that the exoccipital forms the medial, dorsal, and ventral margins with the quadrate, with a very narrow edge of the opisthotic filling it in laterally. This is the same as in Zolhafah . In Chedighaii hutchisoni the opisthotic does not enter the foramen, but otherwise it is also the same. In B. cooki (AMNH 29444) the opisthotic does enter the foramen, but in NCSM 18650, a possible Chedighaii , it does not. The type skulls of B. cooki and C. barberi are indeterminate. In B. maghrebiana the foramen jugulare posterius has its lateral margin placed more anteriorly than the medial margin and it is overhung by the opisthotic. The size of the foramen jugulare posterius varies among the Bothremydini . In B. cooki (AMNH 29444) and NCSM 18650 it is much larger than in B. maghrebiana and the other Bothremydini . Among the B. maghrebiana specimens, the foramen jugulare posterius is smaller in AMNH 30234 than in the other skulls.

BASIOCCIPITAL (figs. 136, 137, 277)

Preservation: The basioccipital is present in all five skulls; sutures are best in AMNH 30561, 30522, and 30041.

Contacts: The basioccipital in Bothremys maghrebiana agrees with those in other Bothremydini . It contacts the basisphenoid anteriorly, the quadrate laterally, and the exoccipitals dorsally.

Structures: The basioccipital of Bothremys maghrebiana does not contribute to the condylus occipitalis or its neck. There is a paired tuberculum basioccipitale that is quite low, as in Zolhafah and Polysternon but in contrast to Foxemys and Chedighaii . The ventral surface of the basioccipital in B. maghrebiana has a shallow concavity similar to that seen in most other Bothremydini .

PROOTIC (figs. 136, 143)

Preservation: Both prootics are present in all five skulls, but the bone is best seen with clear sutures in AMNH 30561 and especially AMNH 30041, where preparation is most extensive.

Contacts: The prootic of Bothremys maghrebiana has the usual Bothremydini contacts: the parietal medially, the quadrate laterally, the supraoccipital posterodorsally, and the pterygoid ventrally.

Structures: The prootic of Bothremys maghrebiana contains the foramen stapedio-temporale, which is formed in the suture between the prootic and quadrate. The sutures around the foramen stapedio-temporale clearly show that, as in nearly all turtles, the quadrate and prootic make up the foramen. However, it is possible that a small part of the pterygoid enters it because the quadrate-pterygoid suture cannot be clearly seen in the region of the foramen stapedio-temporale. A groove connects the foramen stapedio-temporale medially with the lateral edge of the foramen nervi trigemini. The bar of bone between the two foramina seems to be the prootic, but this is also uncertain as the prootic-pterygoid suture is unclear and some of the bar could be pterygoid. The only other Bothremydini specimen that is well preserved in this area is B. cooki (AMNH 29444), and it shows the prootic nearly surrounding the foramen stapedio-temporale with only a small area of quadrate at its ventrolateral border (fig. 132). The bar of bone separating the two foramina in this specimen is entirely prootic.

On the left side of AMNH 30041 the quadrate is missing along the prootic suture. This shows the path of the canalis stapedio-temporalis, the canalis cavernosus, and the cavum labyrinthicum.

OPISTHOTIC (figs. 136, 143, 145)

Preservation: The opisthotic is present on both sides of all five skulls. Sutures are clearest in AMNH 30561, but the absence of the quadrate in AMNH 30041 makes the internal area of the opisthotic visible.

Contacts: The opisthotic contacts in Bothremys maghrebiana are as in other

Bothremydini : supraoccipital anteromedially, squamosal posterolaterally, quadrate anterolaterally, and exoccipital posteromedially. In the cavum cranii, the opisthotic is visible in AMNH 30041, and the opisthotic does not seem to contact the basioccipital or basisphenoid, but this is not certain.

Structures: In posterior view the opisthotic forms a horizontal ridge from the exoccipital to the squamosal in Bothremys maghrebiana and most Bothremydini . Ventral to the ridge at the lateral edge of the opisthotic, this bone forms the dorsomedial margin of the fenestra postotica, most of which is formed by the quadrate (see Quadrate).

In AMNH 30041 the roof of the cavum acustico-jugulare can be seen, largely made of opisthotic. The fenestra ovalis is visible medially, formed posteriorly by the (mostly missing) opisthotic and anteriorly by the prootic, as in all turtles. Much of the cavum labyrinthicum is also visible, also agreeing with other turtles.

BASISPHENOID (figs. 136, 137, 139, 277B)

Preservation: The basisphenoid is present in all five skulls. Sutures are best seen in AMNH 30561, 30522, and 30041. The dorsal surface is visible in AMNH 30041.

Contacts in ventral view: The basisphenoid of Bothremys maghrebiana has the usual contacts of the Bothremydini : pterygoid anterolaterally, basioccipital posteriorly, and quadrate posterolaterally.

Structures in ventral view: The basisphenoid of Bothremys maghrebiana is nearly triangular with a sharp apex that almost completely separates the pterygoids and nearly reaches the palatines. B. cooki is similar but not as extreme, while the other Bothremydini have longer midline pterygoid contacts.

Contacts in dorsal view: The basisphenoid of Bothremys maghrebiana completely separates the pterygoid and reaches the palatines on the dorsal surface, in the floor of the cavum. The other contacts are as in turtles generally: prootic laterally and basioccipital posteriorly.

Structures in dorsal view: The rostrum basisphenoidale in Bothremys maghrebiana and the other Bothremydini is fused into a midline process similar to that seen in Pelusios (fig. 23). The rostrum of B. cooki , Chedighaii barberi , and the Chedighaii endocast, YPM PU 12951 (fig. 167), are longer and narrower, as in Podocnemis ( Gaffney, 1979a: fig. 54). The sella turcica in B. maghrebiana is slightly wider than in B. cooki so that the paired foramen anterius canalis carotici interni are visible in dorsal view. The dorsum sellae does not overhang the sella turcica in B. maghrebiana to the extent it does in B. cooki or YPM PU 12951. The basisphenoid in Zolhafah is not well preserved or completely prepared, but the rostrum is short, as in B. maghrebiana .

The processus clinoideus in nearly all turtles is penetrated at or near its base by the canal for the abducens nerve ( Gaffney, 1979a). In Bothremys maghrebiana , B. cooki , Chedighaii endocast, YPM PU 12951, and probably Chedighaii barberi , the processus clinoideus is absent and the canalis nervi abducentis is a groove ( Gaffney, 1977a: fig. 3). The distribution of this character is hard to determine, but it may be unique to Bothremys + Chedighaii .

Bothremys kellyi

Known from one relatively well-preserved skull, this taxon is allied (although weakly, see fig. 288) with the other large Bothremydini , Bothremys arabicus , from the Late Cretaceous of Jordan. The basicranium is damaged but the remaining parts of the skull are intact and the sutures are clear.

PREFRONTAL (figs. 146, 149)

Preservation: Both prefrontals are nearly complete.

Contacts: The prefrontal in Bothremys kellyi has the usual Bothremydini contacts: the maxilla anteroventrolaterally, the other prefrontal medially, and the frontal posteriorly. There is also an anteroventral contact on the midline with a dorsal process of the premaxilla, as in Araiochelys but in contrast to all other Bothremydini .

Structures: The dorsal margin of the apertura narium externa has a midline protrusion formed by the prefrontal in B. kellyi , other Bothremys , and most Bothremydini . The dorsal margin of the orbit is widely separated from the midline in B. kellyi , slightly more than in other Bothremys species. The sulcus olfactorius is slightly wider in B. kellyi than in other Bothremys species. Although the area is damaged on both sides, it is highly likely that there is a wide prefrontal-palatine contact in the anterior part of the fossa orbitalis, as in B. maghrebiana .

FRONTAL (figs. 146, 149)

Preservation: Both frontals are present and complete.

Contacts: As in Bothremys cooki . The frontal of B. kellyi is slightly wider than in B.