Pelobates sp.
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publication ID |
https://doi.org/ 10.26879/772 |
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persistent identifier |
https://treatment.plazi.org/id/03FD514F-EC59-FFF5-FE06-FEEE15DF2E47 |
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treatment provided by |
Felipe |
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scientific name |
Pelobates sp. |
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Figure 3.1 View FIGURE 3 -11
Material. Volchaya Balka locality: two frontoparietals (GIN 1143-223, 224); six maxillae (GIN 1143- 225–230); one presacral vertebra (GIN 1143-231), one sacral vertebra (GIN 1143-232). Gaverdovsky locality: two maxillae (GIN 1144-200), one sacral vertebra (GIN 1144-201).
Description. The frontoparietals ( Figure 3.1-2 View FIGURE 3 ) are represented by the two posterolateral fragments of the bone. Dorsally, the bone is covered by a sculpture consisting of prominent isolated tubercles (= pustular sculpture sensu Roček et al., 2014), which is characteristic of the Pliocene–Recent Pelobates . The posterolateral part of the frontoparietal extends to the well-developed paraoccipital process, which is pointed distally. Dorsally, the process bears two sharp ridges. Anteriorly to the paraoccipital process, the dorsal sculptured surface of the bone extends laterally above the paraoccipital process which indicates the presence of the well-developed tectum supraorbitale. The foramen arteriae occipitalis is located medially to the base of the paraoccipital process and hidden in dorsal view by the base of the medially placed sharp ridge on the paraoccipital process. There is no additional foramen on the paraoccipital process, which is known in P. sanchizi ( Venczel, 2004; Böhme and Vasilyan, 2014).
The maxilla ( Figure 3.3 View FIGURE 3 -6) is represented by several posterior parts. As in the case of the frontoparietal, all the specimens are fully covered by sculpture consisting of prominent isolated tubercles (= pustular sculpture). The zygomaticomaxillar process and pterygoid process are not preserved. The margo orbitalis is deeply concave. The lamina horizontalis greatly projects lingually and widens near the middle part of the bone.
The single vertebra ( Figure 3.7 View FIGURE 3 -9) is represented by the posterior presacral vertebra. Its centrum is procoelous and elongated. On the left side, it bears a long, cylindrical, and anteriorly directed transverse process. The neural arch in dorsal view is concave anteriorly and forms a pointed median process posteriorly, which seems to be longer than those of Eopelobates aff. E. bayeri (see above). In the lateral view, the neural arch lacks the spinal foramen on both sides.
The sacral vertebra ( Figure 3.10 View FIGURE 3 -11) is seriously damaged, but it is clear that it was completely fused to the urostyle. The cotyle of the sacral vertebra is deep and circular. The neural canal is wide and dorsoventrally compressed. The transverse processes are broken off at their bases. Dorsally, the sacral vertebra and preserved portion of the urostyle are smooth, without a neural spine. The urostyle bears longitudinal lateral laminae which are confluent with sacral wings.
Comments. Pelobates remains from Volchaya Balka and Gaverdovsky can be assigned to the group of the Pliocene–Recent Pelobates species (sensu Venczel, 2004) based on the sculpturing of the frontoparietal and maxilla with prominent isolated tubercles (= pustular pattern). In Miocene Pelobates the sculpturing is a pit-and-ridge type (Oligo-Miocene forms) or transitional between those pit-and-ridge and pustular patterns (in some Miocene forms) ( Venczel, 2004; Roček et al., 2014). Pelobates from Volchaya Balka differs from the Oligocene-Miocene Pelobates and Eopelobates in having the presacral vertebrae without spinal foramina and sacral vertebra fused to urostyle. These two characters are the same as in Pliocene- Recent Pelobates . Within this species group, the urostyle is fused to the sacrum in P. fuscus and P. syriacus , whereas in P. cultripes and P. varaldi these two elements are frequently free ( Bailon, 1991, 1999). The position of the foramen arteriae occipitalis in Pelobates from Volchaya Balka is consistent with that of P. cultripes , P. syriacus , and P. sanchizi , where this foramen is visible only in posterior view ( Bailon, 1999; Venczel, 2004). The described Pelobates remains are too fragmentary and are not diagnostic at the species level. This is why we refer it to Pelobates sp.
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