Pseudopus, Merrem, 1820
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publication ID |
https://doi.org/ 10.5252/geodiversitas2020v42a20 |
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publication LSID |
urn:lsid:zoobank.org:pub:8FF2A078-CE45-4BF1-A681-00136F57375E |
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DOI |
https://doi.org/10.5281/zenodo.4447716 |
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persistent identifier |
https://treatment.plazi.org/id/03C587C7-430F-FFE9-FEC3-FB8849C5F91E |
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treatment provided by |
Felipe |
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scientific name |
Pseudopus |
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Pseudopus sp.
( Fig. 5 View FIG E-Q)
Pseudopus sp. – Ivanov et al. 2006: 229, table 2 (in part).
MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: maxilla, 1/2001 Turtle Joint: one right dentary (Pal. 1403), three trunk vertebrae (Pal. 1404-1406); 2/2003 Reptile Joint: left maxilla (Pal. 1575), left quadrate (Pal. 1576).
DESCRIPTION
Maxilla
Only the posterior region of a left maxilla is partly preserved. It bears four teeth still attached to the bone. An oval superior alveolar foramen is located at the level of the third tooth (counted from posterior). The whole preserved section of the maxilla gradually narrows posteriorly rather than being stepped, but the posterior termination is broken off. Here, a wedge-shaped facet for the jugal is present. It reaches almost to the level of the last preserved tooth. The lateral surface of the preserved portion is pierced by three labial foramina located dorsal to the teeth. The nasal process is only partly preserved, rising dorsally in this region.
Quadrate
The left quadrate is completely preserved, being robustly built. In lateral aspect, its dorsal portion is anteroposteriorly expanded.
The dorsal margin of this portion is irregularly rounded.In dorsal aspect, this region is clearly divided by a central constriction into two large areas with roughened surfaces. The posteriorly located one is formed by a large cephalic condyle, having a face for the squamosal on the lateral side. The anterior portion is formed by a massive dorsal tuber (sensu Klembara et al. 2017a). Here, the quadrate reaches the highest level dorsally. From the posterior region of this anterior portion, a sharp tympanic crest (sensu Oelrich 1956) runs along the entire central region ventrally, being laterally expanded. In the dorsal region, a short anterolateral crest (sensu Klembara et al. 2017a) is located anterior to the tympanic crest. A small depression divides these two structures. The posterior region of quadrate is bordered by a markedly rounded (concave) posterior crest. In anterior view, the mandibular condyle is mediolaterally broad.Its ventral side is shallow, W-shaped with blunt peaks. On the medial surface of the quadrate, there is a prominent medial crest (sensu Oelrich 1956). Its ventral portion protrudes medially slightly more than the dorsal portion, as a result of bearing a distinct facet for the quadrate process of the pterygoid. A small, rounded quadrate foramen pierces the quadrate at approximately the mid-length of the posterior surface.
Dentary
The body of the right dentary (Pal. 1403) is slightly concave. However, this element is badly preserved, especially on the medial side.Here, the almost entire region of the subdental shelf (sensu Rage & Augé 2010) and the intramandibular septum are broken off and missing. For this reason, the alveolar canal is exposed. In the posterior region, only the splenial articulation and the coronoid articulation are partly preserved. They are separated from each other by a small gap formed by a bony ridge. As preserved,the dentary possesses twelve tooth positions, but only one tooth is still attached (the actual tooth number of the complete tooth row was probably slightly higher). The lateral surface of the bone is pierced by four labial foramina.
Dentition
A pleurodont tooth implantation is present.Teeth are amblyodont, being enlarged posteriorly to form blunt robust cylinders. No striations can be observed on the tooth crowns (this could be due to poor preservation or wearing of the occlusal surfaces). The penultimate maxillary tooth has a large tooth crown with a distinctly constricted neck. Thus, this tooth is mushroom-like shape. The tooth bases of maxillary teeth are ankylosed to their sockets and surrounded by a spongy (porous) bony tissue. The tooth crown of the dentary tooth is extremely weathered.
Trunk vertebrae
Several trunk vertebrae are present. They are robustly built. The neural spine starts to rise dorsally approximately at the
coronoid; cpr, cranial parietal ridge; ct, cotyle; dt, dorsal tuber; fo, foramen; fst, facet for supratemporal; lf, labial foramina; mac, mandibular condyle; mc, medial crest; ms, muscular surface; nc, neural canal; ns, neural spine; np, nasal process; ocs, occipital shield; pas, parietal shield; pf, parietal fossa; pfc, postfoveal crest; prf, prezygapophyseal articular facet; poc, posterior crest; pof, postzygapophyseal articular facet; sa, smooth area; saf, superior alveolar foramen; sf, facet for splenial; srs, supradental shelf; stp, supratemporal process; syn, synapophysis; tc, tympanic crest; vlr, ventrolateral ridge; vls, ventrolateral surface. Scale bars: 2 mm.
mid-length of the neural arch. However, this structure is damaged in all vertebrae, thus its exact shape is unknown. In dorsal view, the neural spine widens gradually slightly in a posterior direction and, based on the preserved portion, it probably did not exceed the condyle posteriorly. Anteriorly, a low medial ridge runs to the end of the neural arch, where it forms a small spike. The oval neural canal is small. Pre- and postzygapophyses are well expanded laterally. The interzygapophyseal constriction is well developed and deep. The prezygapophyses are dorsally inclined in an angle of around 30°. The articular surfaces are large, elliptical and oblong laterally. In anterior aspect, a pair of foramina is located ventral to the prezygapophyses, close to the neural canal ( Fig. 5O View FIG ). In lateral aspect, the postzygapophyses reach posteriorly approximately to the level of the mid-region of the condyle. Both condyle and cotyle are markedly depressed. The cotyle has an anteroventral orientation, whereas the condyle is posterodorsally oriented and they lack a precondylar constriction. The synapophyses are well-developed in the anterior region, being slightly posterolaterally oriented. The ventral region of the centrum is flat and the subcentral ridges are straight and gradually converge from anterior to posterior region.
REMARKS
In the posterior region of the dentary (Pal. 1403), splenial articulations is present, located anterior to the coronoid articulation. In modern P.apodus , the coronoid extends further anteriorly and there is no facet for the splenial in this region (e.g., Klembara et al. 2010, 2014). However, the same dentary features seen in the dentary from Mokrá, can be observed in P. ahnikoviensis and P. laurillardi . Unfortunately, the medial side of the dentary is badly preserved and lacks most of the diagnostic features. P. ahnikoviensis is characterized by the presence of a surangular spine, whereas an autapomorphic feature of P. laurillardi is a medially expanded subdental shelf ( Klembara et al. 2010; Klembara et al. 2014). Neither of those features can be demonstrated on the dentary from Mokrá and we decided to allocate it only to Pseudopus sp. The morphology of the quadrate strongly corresponds to that of Pseudopus (for P. apodus see Klembara et al. 2017a: fig. 27) and this specimen most likely belongs to this taxon. The trunk vertebrae described in this section possess two features characteristic for Pseudopus ( Čerňanský et al. 2019) : 1) the lateral margins of the centrum (subcentral ridges) are straight rather than concave ( Ophisaurus ) or parallel with their anterior-most sections being expanded laterally ( Anguis ); and 2) the height of the neural canal is distinctly less than the height of the cotyle.
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Museu Nacional, Universidade Federal do Rio de Janeiro |
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