Bavarioboa cf. hermi Szyndlar & Schleich, 1993

Ivanov, Martin, Čerňanský, Andrej, Bonilla-Salomón, Isaac & Luján, Àngel Hernández, 2020, Early Miocene squamate assemblage from the Mokrá-Western Quarry (Czech Republic) and its palaeobiogeographical and palaeoenvironmental implications, Geodiversitas 42 (20), pp. 343-376 : 356-357

Bavarioboa cf. hermi Szyndlar & Schleich, 1993 ( Fig. 7 )

Bavarioboa cf. hermi – Ivanov & Musil 2004: 228, 229, fig. 3C, D. — Ivanov et al. 2006: 229, table 2.

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 1/2001 Turtle Joint: One posterior trunk vertebra (Pal. 1448).

DESCRIPTION

Trunk vertebra

The only preserved trunk vertebra is almost complete with partial damage to the large paradiapophyses, the cranial margin of the zygosphene and the caudal margin of the condyle. In lateral view, the neural spine rises at about the level of the zygosphenal base. The cranial margin of the neural spine is inclined caudally with a rounded anterodorsal margin. The articular surfaces of the zygosphene are widely oval. The short interzygapophyseal ridges are rather sharp. The small lateral foramina, situated close below the interzygapophyseal ridges, do not sit within depressions. The short and dorsally bent subcentral ridges are well-developed, especially in the anterior half of the centrum. In dorsal view, the partially damaged prezygapophyseal articular facets were originally broadly subtriangular to oval in outline. The prezygapophyseal processes are rather short (about a quarter of the prezygapophyseal facets length). The zygosphene was almost straight with small lateral lobes; however, the medial part of the zygosphenal lip is rather damaged in the preserved specimen. The dorsal margin of the neural spine becomes thick towards its caudal margin. The caudal margin of the neural arch forms a relatively shallow notch. In ventral view, the haemal keel is laterally wide with a rounded ventral surface. The subcentral foramina are rather small and developed on either side of the haemal keel base. The subcentral grooves are wide and deep. The postzygapophyseal articular facets are subrectangular in shape. In cranial view, the prezygapophyses are tilted slightly dorsally. Prezygapophyseal articular facets are situated high above the neural canal base roughly at the level of the dorsal margin of the lateral sinuses. The cranial margin of the zygosphene is slightly concave with strongly build lateral sinuses and a rather thin central part. The neural arch is vaulted. The neural canal is rounded with rather wide and shallow lateral sinuses. Depressions are developed on either side of the slightly dorsoventrally depressed cotyle. The paracotylar foramina are absent. In caudal view, the zygantrum is wide. The condyle is slightly depressed dorsoventrally. The vertebral dimensions are as follows (Pal. 1448): cl: = 5.19 mm; naw = 6.73 mm; cl/naw = 0.77.

REMARKS

The massive structure of vertebra, the cl/naw ratio <1, the relatively large dimensions, and the absence of paracotylar foramina as well as the relatively slender structure of the zygosphenal rim support the assignment to the subfamily Boinae . The single preserved vertebra resembles that of the genus Bavarioboa by the almost straight cranial margin of the zygosphenal lip in dorsal view, as well as the dorsally thickened neural spine that is typical for the posterior trunk vertebrae of Bavarioboa hermi (see Szyndlar & Rage 2003). B. ultima Szyndlar & Rage, 2003 from the German late early Miocene Rothenstein 13 locality (late Burdigalian, MN 5), originally assigned to B. hermi by Szyndlar & Schleich (1993), differs mainly by the lower neural spine as well as longer prezygapophyseal processes ( Szyndlar & Rage 2003).

Figures

FIG. 7. — Bavarioboa cf. hermi from the early Miocene (MN 4) of MWQ. Posterior trunk vertebra Pal. 1448 (1/2001 Turtle Joint) in left lateral (A), dorsal (B), ventral (C), cranial (D) and caudal (E) views. Abbreviations: ct, cotyle; hk, haemal keel; ir, interzygapophyseal ridge; na, neural arch; nc, neural canal; ns, neural spine; pd, paradiapophysis; pof, postzygapophyseal articular facet; prf, prezygapophyseal articular facet; prp, prezygapophyseal process; scf, subcentral foramen; scg, subcentral groove; scr, subcentral ridge; zy, zygosphene; zyg, zygantrum. Scale bar: 2 mm.