Bavarioboa Szyndlar and Schleich, 1993

Ivanov, Martin, 2002, The oldest known Miocene snake fauna from Central Europe: Merkur-North locality, Czech Republic, Acta Palaeontologica Polonica 47 (3), pp. 513-534 : 513-514

Genus Bavarioboa Szyndlar and Schleich, 1993 Bavarioboa sp.

Type species: Bavarioboa hermi Szyndlar and Schleich, 1993 .

Material.—Fourtrunkvertebrae( SGDB 7408/MI−1–4),2cervical vertebrae ( SGDB Ah−1, 2), 7 trunk vertebrae ( SGDB Ah−3–9), 1 cloacal vertebra ( SGDB Ah−10).

Cervical vertebrae ( Fig. 2A 1 –A 4 ).—Fragmentary vertebrae with hypapophyses broken off at their base are typified by a vaulted neural arch. The neural canal is approximately circular with small lateral sinuses. The neural spine is restricted to the posterior half of the vertebral length, its cranial margin is directed posteriorly as is the caudal margin. The paradiapophyses are indistinctly divided and the parapophyseal processes are very short and obtuse. The prezygapophyseal articular facets are oval to subtriangular and the prezygapophyseal processes are very short and hardly visible from above. In dorsal view, the cranial margin of the zygosphene bears the distinct lateral lobes and a blunt median lobe.

Trunk vertebrae ( Fig. 2B 1 –B 5 ).—In lateral view, the neural spine is about as long as high. The cranial margin of the neural spine overhangs anteriorly and the caudal margin overhangs posteriorly. The dorsal border of the neural spine is markedly thickened. Relatively sharp interzygapophyseal ridges are well developed. Small lateral foramina are visible and are not situated in depressions. Subcentral ridges are marked, relatively short and dorsally arched. The haemal keel is distinct. The paradiapophyses are not distinctly divided and the parapophyses are short and rounded at the ventral margin. Postzygapophyses are tilted upward as seen in caudal view. In dorsal view, the cranial margin of the zygosphene has distinct lateral lobes and a wide median lobe. The neural spine rises just at the base of zygosphene and occupies less than half of the vertebral length. The neural spine is thickened dorsally, sometimes with an indistinct bifurcation at its caudal margin. The prezygapophyseal articular facets are subtriangular; the prezygapophyseal processes are very short and hardly visible in dorsal view. Epizygapophyseal ridges are obsolete. In ventral view, the distinct haemal keel is wide at the base but relatively sharp at its ventral margin and sometimes has a small tubercle developed on its cranial margin. The subcentral ridges and grooves are better developed in the cranial portion of the vertebrae. The subcentral foramina are obvious and in one vertebra the right subcentral foramen is doubled. The postzygapophyseal articular facets are either suborbicular or irregularly shaped. In cranial view, the neural arch is slightly flattened dorso−ventrally and the neural canal is approximately circular with small lateral sinuses. The zygosphenal lip is straight or slightly concave. The prezygapophyses are strongly tilted upward. The paracotylar foramina are missing. Measurementsareasfollows(n=6):cl:or= 2.64–4.56mm;naw:or= 3.14–5.47 mm; cl/naw: or = 0.83–1.05, mean 0.90±0.08.

Cloacal vertebra.—The cranial margin of the dorsally thickened neural spine overhangs anteriorly and the caudal margin overhangs posteriorly. The haemal keel is sharp at its caudal part, resembling a small hypapophysis. The pleurapophyses are broken off at their bases.

Comments.—The described vertebrae, originally identified as belonging to Boidae A( Ivanov 1997a: 39, fig. 20), un − doubtedly belong to the family Boidae , which is shown by the low ratio cl/naw. Based on morphology and measurements, Bavarioboa sp. resembles Bavarioboa hermi Szyndlar and Schleich, 1993 , the only known species of this genus. This species was described ( Szyndlar and Schleich 1993) from the west Bohemian Early Miocene (MN 4) locality at Dolnice (originally identified by Szyndlar 1987, from this site as a possible member of the recent Asiatic erycine genus Gongylophis , cf. Gongylophis sp. ). One cannot exclude the fact that some morphotypes of the family Boidae from the Bavarian localities at Ehrenstein 7 (Late Oligocene) and Rothenstein 13 (Middle Miocene) also belong to the genus Bavarioboa ( Szyndlar and Schleich 1993) . Bavarioboa sp. from Merkur−North shares several features with the representatives of Bavarioboa hermi reported from the Bavarian type locality at Petersbuch 2, MN 4 ( Szyndlar and Schleich 1993) and the differences are only minimal as follows: 1) the cranial margin of the neural spine of Bavarioboa sp. overhangs anteriorly in lateral view, while in Bavarioboa hermi this cranial margin is vertical or inclined posteriorly; 2) in dorsal view, the thickened dorsal border of the neural spine has the same width along its entire length, while in Bavarioboa hermi this border is anteriorly narrow and becomes wider posteriorly; 3) in cranial view, the zygosphenal lip is not always concave in Bavarioboa sp. , unlike the species Bavarioboa hermi .

Figures

Fig. 2. Bavarioboa sp. from the Early Miocene (MN 3a) of Merkur−North; A1–A4. Cervical vertebra (SGDB Ah−2). B1–B5. Mid−trunk vertebra (SGDB 7408/MI−1). In lateral (A1, B1), dorsal (A2, B2), ventral (A3, B3), cranial (A4, B4), and caudal (B5) views. Scale bar 2 mm.

Fig. 1. The distribution of some Early and Middle Miocene ophidian localities in the areas of Germany, Czech Republic, Slovak Republic, Poland and Austria. 1, Weisenau (MN 1); 2, Hessler (MN 1); 3, Ulm−Westtangente (MN 2); 4, Stubersheim 3 (MN 3); 5, Merkur−North (MN 3a); 6, Dolnice (MN 4); 7, Petersbuch 2 (MN 4); 8, Langenau (MN 4); 9, Oberdorf (MN 4); 10, Randecker Maar (MN 5); 11, Eichstätt (MN 4–6); 12, Ivančice (MN?4–6); 13, Oggenhausen (MN 5/6); 14, Przeworno (MN 5–6); 15, Devínska Nová Ves (MN 6); 16, Vösendorf; 17, Sandelzhausen (MN 6); 18, Rothenstein 13 (MN 6); 19, Opole (MN 7); 20, Öhningen (MN 7+8); 21, Steinheim am Albuch (MN 7+8).

Fig. 4. Coluber suevicus (Fraas, 1870) from the Early Miocene (MN 3a) of Merkur−North. A. Right quadrate (SGDB−Ah−33). B1–B3. Cervical vertebra (SGDB−Ah−36). C1–C5. Trunk vertebra (SGDB 7408/MI−26). In postero−lateral (A), lateral (B1, C1), dorsal (B2, C2), ventral (B3, C3), cranial (C4), and caudal (C5) views. Scale bar 2 mm.

Fig. 5. Coluber caspioides Szyndlar and Schleich, 1993 from the Early Miocene (MN 3a) of Merkur−North. A1, A2. Left frontal (SGDB Ah−44). B. Right palatine (SGDB Ah−46). C1, C2. Right pterygoid (SGDB Ah−45). D. Right quadrate (SGDB Ah−l 1). E. Left dentary (SGDB Ah−48). F1, F2. Right compound bone (SGDB Ah−49). G1–G5. Cervical vertebra (SGDB Ah−51). H1, H2. Mid−trunk vertebra (SGDB Ah−615). I1–I5. Posterior trunk vertebra (SGDB 7408/MI−37). In dorsal (A1, C1, G2, H2, I2), ventral (A2, B, C2, G3, I3), postero−lateral (D), labial (E, F1), lingual (F2), lateral (G1, H1, I1), cranial (G4, I4), and caudal (G5, I5) views. Scale bar 2 mm.