Bothriolepis ciecere Lyarskaja

Lukševičs, Erwin, 2001, Bothriolepid antiarchs (Vertebrata, Placodermi) from the Devonian of the north-western part of the East European Platform, Geodiversitas 23 (4), pp. 489-609 : 578-594

Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974 ( Figs 63-76 )

Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974: 99-104, pl. I, fig. 1.

Bothriolepis ornata Eichw. – Gross 1933: 41.

Bothriolepis cf. ornata Eichw. – Gross 1942: 421-422, abb. 2. — Lyarskaja & Savvaitova 1974: 97.

Bothriolepis pavariensis – Lyarskaja & Savvaitova 1974: 104, pl. I, figs 5-7; text-figs 9-10.

HOLOTYPE. — AMD LDM 43 /303.

MATERIAL EXAMINED. — LDM 43/301, 43/303-306,

43/337, 43/5082, 43/5095, 43/5120, 57/1-97, 57/398, 57/721, 57/722, 57/724-726, 57/728-733, 57/896, 57/906, 57A/1, 81/1-41, 81/43-46, 81/48-94, 81/96-98, 81/126, 81/127, 81/136-155, 81/157-164, 81/170-183, 81/190-275, 81/279-351, 81/356-358, 81/360-363, 81/365-377, 81/380-393, 81/406-504, 81/533-549, 81/554-556, 81/558-577, LGI 5/2020 - 5/2044): articulated head-shields and their fragments, disarticulated plates of the head-shield, trunk-armour and pectoral appendage. LOCALITIES AND HORIZON. — The type locality is an outcrop at the left bank of Ciecere River downstream from the Pavāri hamlet; upper Famennian, the middle Member of the Ketleri Formation. Other material comes from an outcrop exposing light sand and sandstone at the right bank of Venta River 1 km W from Ketleri hamlet; the upper Member of the Ketleri Formation. A probable other undescribed subspecies of B. ciecere comes from Rybnitsa quarry, Oryol region of Russia; Turgenevo Beds of the Plavsk Regional Stage, Famennian ( Lebedev 1995; Lebedev & Lukševičs 1996).

DIAGNOSIS. — Rather large Bothriolepis with a median dorsal armour length of at least 200 mm. Dorsal wall of moderate width, B/L index of trunk-armour about 77. B/L index of the headshield of 120. Preorbital recess of trifid type. Orbital edges of Prm and La thickened. Anterior margin of the head-shield is rounded. Orbital fenestra is not large. Prm broad, posterior margin is slightly shorter than anterior margin. Nu strongly vaulted, moderately broad, L/B index of 80. AMD moderately broad, B/L index 87. Posterior margin of AMD and anterior margin of PMD are very narrow. Median dorsal ridge poorly developed. Dorsolateral ridge well-marked, bears smooth tubercles. Ventrolateral ridge strongly developed forming a well-defined crest in a posterior part of armour. Ornamentation typically reticulate, in quite large individuals becoming coarser and sparser.

DESCRIPTION

The head-shield ( Figs 63 A-C; 65A, B) was not described by Lyarskaja ( Lyarskaja & Savvaitova 1974). It is strongly vaulted both rostrocaudally and transversely. The rostral margin is strongly convex, much shorter than the posterior margin, which is weakly convex. There are well-defined anterolateral corners (alc) and the deep prelateral notch (nprl). The obtected nuchal area (nm) is short, broadest on the Nu, with slightly defined lateral and median processes. The orbital fenestra is relatively small, with a B/L index about 190 (n = 6). The orbital edges of the Prm and La are thickened, similarly as in B. ornata , B. macphersoni and B. karawaka .

The visceral skull surface ( Fig. 63B, C ) shows the broad otico-occipital depression (ood), which is well-defined by the paramarginal cristae (cr.pm). The antero-lateral corner of oticooccipital depression (pr.po) is broad in its base, postero-lateral corner is rounded and extends laterally over the middle of the Pn’s posterior margin. The transverse lateral groove (tlg) is moderately broad and clearly defined. A broad shallow depression anteriorly from the anterolateral corner of preorbital recess is the lateral pit (p), which is situated equally spaced from an orbital edge of La and prelateral notch. The lateral margin shows very broad attachment areas for the Sm with the strikingly short posterior one (a.2Sm). The attachment area for the Prl is almost laterally rather then ventrally faced. The median occipital crista (cr.o) is slightly defined, often it consists of several radially situated small ridges.

The Prm ( Figs 63O, P ; 65C, D ) with B/L index 94-118. A rostral angle (ac) is present in half of large individuals. The orbital margin bears gently defined nasal notch (pnn). The anterior section of the supraorbital sensory line (soc) is observed not always. There are several tubercles and pits of various shape and size usually situat- ed on the dorsal surface of the preorbital recess. The La ( Figs 63O, P ; 64 A-D; 65E-G) is moderately broad with the L/B index 136 on the average. The rostral margin is of moderate breadth and almost straight, the antero-median and antero-lateral corners are well-defined.

The Pi ( Figs 63 E-J; 65K) was for the first time described by Lukševičs (1991), it is known only from the Ketleri locality. Pi is relatively broad, breadth slightly exceeds a length. There is a broad area without ornamentation along the posterior margin. A deep, but small pineal pit and antero-laterally situated paired tubercles are present on the visceral surface of the plate. Position of the pineal pit is marked on the outer surface by the pineal elevation or pineal fenestra. The Nu ( Figs 64 E-O; 65N-R) is vaulted ( Lyarskaja & Savvaitova 1974) with an angle between right and left halves slightly larger than 130°, L/B index 68-93, 80 on the average. The anterior division of the lateral margin is concave even in very large specimen, but not straight, as was shown by Lyarskaja for B. pavariensis ( Lyarskaja & Savvaitova 1974: fig. 9), and a little shorter than the posterior division. The shape of the posterior margin is variable, however it always bears the posterior process (mppr). The central sensory line groove is clearly distinct in small individuals, in well-grown specimens sometimes it is present only on one side of the plate (LGI 5/2025: Fig. 65R ), interrupted or very short (LDM 57/14: Fig. 64H ; LDM 57/18: Fig. 64L ; LDM 57/723: Fig. 64J ). In some cases there are short supraoccipital grooves, which terminate little in front of the obtected nuchal area at the rather large external openings for the endolymphatic ducts (d.end). Postorbital crista on the visceral surface is low.

The Pn is of moderate breadth, L/B index 88- 110. The lateral division of the Pn is relatively narrow composing 40-50% of the general breadth of a plate. The Pmg is relatively broad with lateral margins slightly longer than the median margins ( Lyarskaja & Savvaitova 1974). The single Sm (extralateral) ( Figs 64R, S ; 65L, M ), collected by Lukševičs (LDM 57/328) is relatively short with a L/B index about 150. The dorsal margin has a prominent anterodorsal process and posterior attachment area for the skull. The posterior margin is strongly convex, the ventral margin is weakly concave.

The trunk-armour in individuals of moderate size is known from many isolated plates, partial dorsal wall of the trunk-shield prepared from visceral surface consisting of AMD, PMD, left ADL and MxL (LDM 81/58-81/60), and several articulated bones. Plasticine reconstruction was used to describe the features of the trunkarmour.

The trunk-armour was not described by Lyarskaja ( Lyarskaja & Savvaitova 1974) in details. In individuals of moderate size it is relatively broad (B/L index 77), low, with a lateral wall less than three times as long as it is high; in comparison with some other species rather flattened with low dorsal wall. The length of the dorsal wall, probably, reaches more than 200 mm. The ventral wall is not quite flat, but slightly vailted transversely. It is gently arched also in rostrocaudal direction in the posterior division of the armour. The median dorsal ridge is weakly defined, it is present only in the posterior quarter of the PMD. The dorso-lateral and ventro-lateral ridges are well-marked, strongly developed in a posterior part of the armour forming a well-defined crests. Both ridges bear a row of numerous, closely set smooth tubercles, which gradually increase in caudal direction. This feature distinguishes B. ciecere from all the other known Bothriolepis from the Baltics, resembling B. nielseni from Greenland ( Stensiö 1948: text-fig. 308).

The AMD ( Figs 66 ; 67 ) is moderately broad, B/L index about 76-98, 87 on the average. The anterior part of the plate is arched, with right and left laminae forming an angle at the level of lateral corners of about 139°, posterior part is more flattened. The anterior margin is weakly concave or less often fairly straight (in large individuals), moderately broad and 1.1-1.7 time as long as a narrow posterior margin. Overlap areas for the ADL and MxL are normally developed as usually in Bothriolepis , but in LDM 43/5082 and 81/30 the AMD overlaps the MxL by a short anterior part of the posterior division of the lateral margin and in LDM 81/262 sutural connection of the AMD plate with the MxL is of Remigolepis type. The anterior (dlg1) and posterior (dlg2) oblique dorsal sensory line grooves are well-defined only on the plates of individuals of small and moderate size. In many cases there are variations in the course of the dlg2 noticed, as in B. canadensis (Graham-Smith 1978) : the dlg2 is short on the right (LDM 81/252) or left (LDM 81/253) side, as well as on both sides, and terminate in front of the postero-lateral margin (LDM 81/28, 81/29, 81/48, 81/250 A, LGI 5/2021). Sometimes the groove swings round, becoming directed anterolaterally and terminates at the AMD/ADL suture (LDM 81/36, 81/372: Figs 67B ; 66F ). The dlg 2 in 20% of the moderate size individuals are not present.

The visceral surface of the AMD shows a slightly lengthened levator fossa (f.retr), which is limited by the low postlevator thickenings (alr). The anterior ventral pit (pt1) and the median ventral ridge (mvr) are low in individuals of small and moderate size, in some specimens the median ventral ridge is very weakly defined. In quite large individuals and especially on the plates, occurring from Ketleri site, on the contrary, the anterior ventral pit is deep and median ventral ridge is rather high. The median ventral groove (grm) is short and usually terminates anteriorly to the posterior margin. The AMD from the Ketleri locality differ a little from specimens, found at Ciecere River, by greater thickness.

The PMD ( Figs 68 A-C; 69) is narrow with the B/L index about 80-91, 86 on the average. It is almost flat in the anterior part and arched in the posterior part. The width of a narrow anterior margin varies between 37-44% of total breadth of the plate (Lyarskaja incorrectly mentioned that the anterior margin is 3-3.5 times shorter than the posterior margin). Specimen LGI 5/2023 ( Fig. 69A ) shows the abnormally developed overlap area for the MxL, probably arisen as a result of damage of a living animal bone.

The ADL ( Figs 68 D-H; 70) is slightly shorter than the MxL in articulated armour. The dorsal lamina is relatively narrow and long, and its breadth a little exceeds height of the lateral lamina ( Lyarskaja & Savvaitova 1974). The dorsal and lateral laminae of the plate enclosing an angle of 120-125°. Specimen LDM 81/421 shows the dorsal overlap area partly overlaping the AMD.

The MxL ( Figs 71 A-G; 72) is moderately long. The dorsal lamina of the plate is less than twice (1.8 on the average) as long as it is broad. Dorsal and lateral laminae enclosing an angle about 111°, but not 135° as claimed Lyarskaja ( Lyarskaja & Savvaitova 1974). The lateral lamina is moderately high, 2.9 times as long as it is broad. The posterior oblique sensory line groove (dlg2) is not present almost in a half of specimens. In specimens LDM 81/211 ( Fig. 72H ) and 81/406, there is an additional branch of the posterior oblique dorsal sensory line groove dlg2’, which is parallel to dlg2. The dorso-lateral ridge bears tubercles even in small individuals. The overlap area for the AMD is often restricted to half the length of the anterodorsal margin (LDM 81/422, 81/423), as in Remigolepis ( Stensiö, 1931) , or to the most part of this margin (LDM 81/424).

The AVL ( Figs 73 A-D; 74) is of moderate breadth, the ventral lamina is 1.7-2.2 times as long as it is broad. The subcephalic division comprises 17-23% of total length of the ventral lamina. The ventral lamina 2-2.5 times as broad as the lateral lamina high. The lateral lamina is low, 3-3.5 times as long as it is high. Both the right and left AVL could overlap the opposite AVL. The axillary foramen (f.ax) is rather large, slightly elongated and rounded in shape ( Lyarskaja & Savvaitova 1974). The visceral surface of the AVL shows the high transverse anterior crista (cit1) running antero-mesially parallel to the low and broad transverse thickening (cit2).

The PVL ( Figs 75 ; 76 ) has similar proportions to the AVL, as in most Bothriolepis species. The ventral lamina is 2-2.6 times as long as it is broad. The subanal division is relatively broad, it occupies about one fifth (18-22%) of the total PVL length. The lateral lamina is high, 1.8- 2.4 times long as it is high. The ventral lamina only 1.1 time as broad as the lateral lamina high. The lateral lamina rather steep, the angle between laminae is about 101°, but in no case 130° as indicated by Lyarskaja ( Lyarskaja & Savvaitova 1974). Both the right and left PVL could overlap the opposite PVL. The ventrolateral ridge (vlr) is strongly developed and projects from the plate as a sharp serrated keel along the subanal division. The MV with the L/B index about 1.3 ( Fig. 71H ).

The pectoral fin ( Figs 73 E-G; 74E) is represent- ed by many disarticulated bones, and seven specimens showing articulated plates of the proximal segment. There are two examples of the distal segments. Both segments bear prominent lateral and mesial spines. On the proximal segment the spines are large and closely setting. The proximal segment is not as broad as was claimed by Lyarskaja ( Lyarskaja & Savvaitova 1974: L/B index about 2), but is 3.5 times as long as it is broad. The CD1 is with L/B index varying from 2.6 to 3.1 (2.9 on the average). The shape and proportions of the other individual plates of the pectoral appendage are shown in Fig. 73 .

The ornamentation is reticulate, anastomosing ridges are broken into shorter ridges on the anterior part of the La and Prm and in large specimens also on the Nu and Pp. The ornament on the Sm consists of short ridges and tubercles, on the trunk-armour it is typically reticulate in general. In large specimens, the reticulate ornament retained only on the central part of plates, whereas on the marginal parts of bones the anastomoses between ridges reduse. On the AMD the ornament may consist of ridges parallel to the margins of the plate, but on the MxL and PVL there are short ridges perpendicular to the dorso-lateral or ventro-lateral ridge. The ornamentation of the pectoral appendage is reticulate in general, radially arranged on the CD1. The network ridges bear weak elevations in the points of anastomoses on the ML2 and CV1.

REMARKS

Lyarskaja ( Lyarskaja & Savvaitova 1974) described two species: Bothriolepis ciecere and B. pavariensis on a base of material collected in 1971 from the Pavāri locality. She claimed that B. pavariensis differs from B. ciecere in its 1) larger size; 2) the broader Prm; 3) the shape of Pp; 4) the size and position of the external openings for the endolymphatic ducts; 5) the position and shape of a branches of the posterior oblique sensory line groove; 6) the shape of the AMD ( Lyarskaja & Savvaitova 1974). The description of B. pavariensis was based on three poorly preserved specimens: part of head-shield LDM 43/337, AMD 43-5082, and ADL 43-5095. In 1978, Lyarskaja collected additional material; the author collections from the type locality, gathered in 1989, 1991, and 1995, and material from the Ketleri locality, collected in 1984, 1995, and 1999, largely expanded Bothriolepis materials from the Ketleri Formation. The revision of all material allowed Lukševičs (1991) to suggest that only one species occurs in the Ketleri Formation. Mostly bones are from well-grown individuals of moderate size, but there are also some quite large specimens. All specimen described by Lyarskaja as B. pavariensis fit well within the variation row of B. ciecere , and there are no gaps in between these two forms neither in the shape and proportions of individual plates, nor in the position of the sensory line grooves. The above mentioned distinctions between B. pavariensis and B. ciecere could be explained mostly by changes that take place during growth in Bothriolepis : size of the plates, shape of the Prm, Pp, AMD; or by considerable intraspecific variation characteristic for B. ciecere : the position and shape of the posterior oblique sensory line groove. The following short description is the first full treatment in English, following Lukševičs (1991) and considerably adding details to the description provided by Lyarskaja ( Lyarskaja & Savvaitova 1974).

DISCUSSION

Bothriolepis ciecere can be distinguished readily from B. leptocheira curonica and B. jani

(Lukševičs 1986), other Famennian Bothriolepis representatives from the Main Devonian field, and resembles B. ornata by some features. B. ciecere differs from B. ornata in its 1) smaller size; 2) shape and proportions of the Pn and Prm; 3) situation of the lateral pit on the La and postero-lateral corner of otico-occipital depression on the Pn; 4) development of the attachment area for the Sm on the La; 5) broader anterior margin of the AMD; 6) shape of the PMD; 7) strongly developed dorso-lateral and ventro-lateral ridges.

There are no species of Bothriolepis from Scotland ( Miles 1968) similar to B. ciecere . B. laverocklochensis Miles, 1968 from the Rosebrae Beds differs from B. ciecere in the shape of PMD, absence of the crest on the dorso-lateral ridge and presence of sharply defined dorsal median ridge. B. wilsoni Miles, 1968 has well-defined dorso-lateral ridge, however clearly differs from B. ciecere in proportions of a head-shield bones, AMD and presence of well-developed dorsal median ridge on AMD, as well as ornament.

The species B. ciecere and B. nielseni from Greenland are clearly very close morphologically. They are similar in the 1) general proportions of the trunk-armour; 2) development of the dorso-lateral ridge; 3) shape and proportions of individual plates of the trunk-armour; 4) reticulate ornament. Unfortunately, B. nielseni is represented only by the holotype which consists of a crushed and flattened trunkarmour and badly preserved parts of the headshield and pectoral fin ( Stensiö 1948). Absence of the description of the head-shield and the poor preservation of the type specimen does not allow to compare both species with sufficient detail. The distinctions between them are insignificant and consist in that in B. nielseni 1) the dorsal wall of the trunk-armour is relatively broader; 2) the posterior margin of the AMD is longer; 3) the proximal segment of the pectoral fin is more slender; 4) the ventro-lateral ridge is not bearing the row of tubercles. It seems likely that B. ciecere and B. nielseni are phylogenetically very close. There is good evidence of a relationship between B. ciecere and B. nielseni : affinity of their stratigraphical situation, as well as fact, that both B. ciecere and B. nielseni are the youngest species, the last representatives of Bothriolepis in Baltic and Greenland respectively.

Figures

FIG. 63. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A-C, head-shields in dorsal (A) and visceral (B, C) views; A, B, LDM 81/545; C, LDM 81/407; E-J, Pi in dorsal (E, G, I) and visceral (F, H, J) views; E, F, LDM 57/10; G, H, LDM 57/13; I, J, LDM 57/12; K-N, Prl in dorsal (K-M) and visceral (N) views; K, LDM 57/732; L, LDM 57/910; M, N, LDM 57/7; O, P, Prm LDM 57/2 in dorsal and visceral views; R-Z, La in dorsal (R, T, Z) and visceral (S, U, V) views; R, S, LDM 81/602; T, U, LDM 57/5; V, Z, LDM 81/410. A-C, R, S, V, Z, Ciecere River near Pavāri hamlet, Latvia; E-P, T, U, Venta River near Ketleri hamlet, Latvia.Ketleri Formation. Abbreviations: La, lateral plate; Pi, pineal plate; Prl, prelateral plate; Prm, premedian plate. Scale bar: 10 mm.

FIG. 64. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A-D, La in dorsal (A, C) and visceral (B, D) views; A, B, LDM 81/629; C, D, LDM 81/628; E-O, Nu in dorsal (E, G, H, J, L, N) and visceral (F, I, K, M, O) views; E, F, LDM 81/698; G, LDM 81/811; H, I, LDM 57/14; J, K, LDM 57/723; L, M, LDM 57/18; N, O, LDM 57/909; P, articulated Nu and Pp 81/412 in dorsal view; R, S, Sm LDM 57/328 in dorsal and visceral views; T, U, Pn 57/721 in dorsal and visceral views. A-G, P, Ciecere River near Pavāri hamlet, Latvia. H-O, R-U, Venta River near Ketleri hamlet, Latvia. Ketleri Formation. Abbreviations: La, lateral plate; Nu, nuchal plate; Pn, paranuchal plate; Pp, postpineal plate; Sm, submarginal plate. Scale bar: 10 mm.

FIG. 65. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A, B, head-shields in dorsal view; A, LDM 81/25; B, LDM 81/545; C, D, Prm; C, LGI 5/2034; D, LDM 57/2; E-G, La; E, F, LDM 57/5 in dorsal and visceral views;G, LGI 5/2044; H-J, left-side Prl; H, I, LDM 57/7 in dorsal and visceral views;J, LDM 57/732 in dorsal view; K, Pi LDM 57/10;L, M, Sm LDM 57/328 in dorsal and visceral views;N-R, Nu in dorsal (N, O, R) and visceral (P) views;N, LGI 5/2029;O, P, LDM 57/18;R, LGI 5/2025;S, Pn LDM 57/721 in visceral view. A, B, Ciecere River near Pavāri hamlet,Latvia.C-S,Venta River near Ketleri hamlet, Latvia.Ketleri Formation. Abbreviations:La, lateral plate;Nu, nuchal plate;Pmg, postmarginal plate;Pn, paranuchal plate;Pp, postpineal plate;Prl, prelateral plate; Prm, premedian plate; Sm, submarginal plate; ad1, 2, anterior and posterior articular processes; a.Prl, attachment area for Prl; a2Sm, posterior attachment area for Sm; cir, semicircular pit-line groove; cr.o, median occipital crista; cr.pm, paramarginal crista;cr.tv, transverse nuchal crista; csl, central sensory line groove;d.end, opening of canal for endolymphatic duct;fe.orb, orbital fenestra;ifc1, principal section of infraorbital sensory line;ifc2, branch of infraorbital sensory line diverging on La; nm, obtected nuchal area; nprl, prelateral notch;ood, oticooccipital depression; p, lateral pit of head-shield; prh, preorbital recess; pr.po, antero-lateral corner of otico-occipital depression; soc, anterior section of the supraorbital sensory line; sot, supraotic thickening;tlg, transverse lateral groove.Scale bar:10 mm.

FIG. 66. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, AMD in dorsal (A, C-F) and visceral (B) views; A, B, LDM 57/25; C, holotype LDM 43/303; D, LDM 81/725; E, LDM 81/533; F, LDM 81/372. C-F, Ciecere River near Pavāri hamlet, Latvia. A, B, Venta River near Ketleri hamlet, Latvia. Ketleri Formation. Abbreviation: AMD, anterior median dorsal plate. Scale bars: 10 mm.

FIG. 67. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, AMD in dorsal (A-D) and visceral (E, F) views; A, LDM 81/251; B, LDM 81/36; C, LDM 81/28; D, E, LGI 5/2020; F, LDM 57/25. A-C, Ciecere River near Pavāri hamlet, Latvia. D-F, Venta River near Ketleri hamlet, Latvia. Ketleri Formation. Abbreviations: ADL, anterior dorso-lateral plate; MxL, mixilateral plate; PMD, posterior median dorsal plate; alr, postlevator thickening; cf.ADL, area overlapping ADL; cf.MxL, area overlapping MxL; dlg2, posterior oblique dorsal sensory line groove; dma, tergal angle; f.retr, levator fossa; grm, ventral median groove; lc, lateral corner; mvr, median ventral ridge; npn, postnuchal notch; oa.MxL, area overlapped by MxL; oa.PMD, area overlapped by PMD; pr.pl, external postlevator process; pt1, anterior ventral pit; sna, supranuchal area. Scale bar: 10 mm.

FIG. 68. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, PMD; A, B, LDM 57/722 in dorsal and visceral views; C, LGI 5/2023, in dorsal view; D-H, ADL in dorsal view; D, LDM 81/708; E, LDM 43/306; F, LDM 81/709; G, LDM 81/371; H, LDM 81/556. D-H, Ciecere River near Pavāri hamlet, Latvia. A-C, Venta River near Ketleri hamlet, Latvia. Ketleri Formation. Abbreviations: ADL, anterior dorso-lateral plate; PMD, posterior median dorsal plate. Scale bars: 10 mm.

FIG. 69. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, PMD; A, B, LGI 5/2023 in dorsal and visceral views; C, D, LDM 57/722, in dorsal and visceral views; E, 81/704 in dorsal view. A-D, Venta River near Ketleri hamlet, Latvia. E, Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviations: AMD, anterior median dorsal plate; MxL, mixilateral plate; PMD, posterior median dorsal plate; cf.AMD, area overlapping AMD; cf.MxL, area overlapping MxL; cr.tp, crista transversalis interna posterior; dmr, dorsal median ridge; grm, ventral median groove; l, lateral corner; oa.MxL, area overlapped by MxL; pa, posterior corner; plc, postero-lateral corner; pma, posterior marginal area; pt2, posterior ventral pit. Scale bar: 10 mm.

FIG. 70. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, ADL; A, LDM 81/62; B, LDM 81/245. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviations: ADL, anterior dorso-lateral plate; AMD, anterior median dorsal plate; dlm, dorsal lamina; dlr, dorso-lateral ridge; lcg, main lateral line groove; n.prpl, notch in dorsal margin of ADL for external postlevator process of AMD; oa.AMD, area overlapped by AMD; pnoa, postnuchal ornamented corner; pro, processus obstans. Scale bar: 10 mm.

FIG. 71. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A-G, MxL; A, LDM 81/424; B, LDM 81/423; C, LDM 81/193; D, LDM 81/429; E, 81/540; F, LDM 81/712; G, LDM 81/424; H, MV LDM 81/722; I, J, articulated ADL, AVL, CD1 and CV1 LDM 81/434, in ventral and lateral views; K, AVL LDM 81/630 in visceral view. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation.Abbreviations:ADL, anterior dorso-lateral plate; AVL, anterior ventro-lateral plate; CD1, central dorsal plate 1; CV1, ventral central plate 1; MV, median ventral plate; MxL, mixilateral plate. Scale bars: 10 mm.

FIG. 72. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974, MxL in dorsal (A-C, E-H) and lateral (D) views; A, LDM 81/191; B, LDM 81/232; C, D, LDM 81/196; E, LDM 81/190; F, LDM 81/7; G, LDM 81/210; H, LDM 81/211. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation.Abbreviations:ADL, anterior dorso-lateral plate;MxL, mixilateral plate; PMD, posterior median dorsal plate; PVL, posterior ventro lateral plate; cu, postero-ventral ornamented corner; d, dorsal corner; dlg2, posterior oblique dorsal sensory line groove; dlg2’, additional branch of posterior oblique dorsal sensory line groove; dlr, dorso-lateral ridge; lcg, main lateral line groove;oa.ADL, area overlapped by ADL;oa.PMD, area overlapped by PMD;oa.PVL, area overlapped by PVL.Scale bar:10 mm.

FIG. 73. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A, articulated AVL and proximal segments of pectoral fin LDM 81/716 in ventral view; B, articulated AVL LDM 81/318 and 81/319 in ventral view; C, AVL LDM 81/631 in ventral view; D, AVL in visceral view with articulated proximal segment of pectoral fin, Nu and Pp in dorsal view, LDM 81/435; E, proximal segment of pectoral fin LDM 81/724 in dorsal view; F, G, proximal segment of pectoral fin LDM 81/723 in ventral and dorsal view; H, I, CV1 in ventral view; H, LDM 81/338; I, LDM 81/339; J-K, ML2 in dorsal view; J, LDM 81/634; K, LDM 81/334; L-P, CD1 in dorsal view; L, LDM 81/345; M, LDM 81/341; N, LDM 81/575; O, LDM 81/325; P, LDM 81/336. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviations: AVL, anterior ventro-lateral plate; CD1, central dorsal plate 1; CV1, ventral central plate 1; ML2, lateral marginal plate 2; Nu, nuchal plate; Pp, postpineal plate. Scale bar: 10 mm.

FIG. 74.— Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova,1974,AVL in ventral (A-D, F), visceral (E) and lateral (G) views;A, LDM 81/3; B, LDM 81/4; C, LDM 81/70; D, LDM 81/631; E, AVL with articulated proximal segment of pectoral fin LDM 81/435; F, G, LDM 81/718. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviations: ADL, anterior dorso-lateral plate; AVL, anterior ventro-lateral plate; MV, median ventral plate; PVL, posterior ventro lateral plate; a.un, unornamented area beneath fossa articularis pectoralis; c.al, antero-lateral corner of subcephalic division; CD1, dorsal central plate 1; CD2, dorsal central plate 2; cf.ADL, area overlapping ADL; cf.AVL, area overlapping AVL; cf.MV, area overlapping MV; cf.PVL, area overlapping PVL; cit1, crista transversalis interna anterior;cit2, transverse thickening;f.ax, axillary foramen;f.mp, protractor area of processus brachialis;fp, funnel pit of processus brachialis; ML2, lateral marginal plate 2; m.lim, margo limitans; MM2, mesial marginal plate 2; oa.AVL, area overlapped by AVL; p.br, processus brachialis;pe, pars pedalis of processus brachialis;prc, prepectoral corner;vlr, ventro-lateral ridge.Scale bars:10 mm.

FIG. 75. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A-F, PVL in ventral view; A, LDM 81/567; B, LDM 81/445; C, LDM 81/562; D, LDM 81/566; E, LDM 81/77; F, LDM 81/73; G, H, PVL LDM 81/721 in ventral and lateral views. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviation: PVL, posterior ventro-lateral plate. Scale bars: 10 mm.

FIG. 76. — Bothriolepis ciecere Lyarskaja in Lyarskaja & Savvaitova, 1974; A-C, left-side PVL and D-H, right-side PVL in ventral (A-G) and lateral (H) views; A, LDM 81/73; B, LDM 81/77; C, LDM 81/76; D, LDM 81/300; E, LDM 81/75; F, LDM 81/302; G, H, LDM 81/78. Ciecere River near Pavāri hamlet, Latvia. Ketleri Formation. Abbreviations: AVL, anterior ventro-lateral plate; PVL, posterior ventro-lateral plate; dc, dorsal corner of lateral lamina; oa.AVL, area overlapped by AVL; oa.PVL, area overlapped by PVL; vlr, ventrolateral ridge. Scale bar: 10 mm.