Pelobates sanchizi Venczel, 2004
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publication ID |
https://dx.doi.org/10.3897/fr.25.83781 |
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publication LSID |
lsid:zoobank.org:pub:7A16698D-4F18-48D2-9D96-51A6E0CC15AC |
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persistent identifier |
https://treatment.plazi.org/id/38E0BE8B-7F1D-57B2-8D83-CAC184CF274C |
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treatment provided by |
by Pensoft |
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scientific name |
Pelobates sanchizi Venczel, 2004 |
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Pelobates sanchizi Venczel, 2004
Fig. 7 View Figure 7
Material.
Four frontoparietals HLMD-Ez 2107-2110, 13 squamosals HLMD-Ez 2104-2106, one premaxilla HLMD-Ez 2098, 48 maxillae HLMD-Ez 2095-2097, 38 fragments of skull bones HLMD-Ez 2103, three presacral HLMD-Ez 2098, 2099, 2102 and two sacral vertebrae HLMD-Ez 2100, 2101, 11 ilia HLMD-Ez 2111-2115.
Description.
Frontoparietals: Fragmentarily preserved remains are covered dorsally with the characteristic pit-and-ridge style sculpture as well as low spines (Fig. 7A, H View Figure 7 ). The tectum supraorbitale is moderately broad. In dorsal view, the lateral superior process is longer than broad. The articulation surface with the squamosal is well-developed, concave and oriented fully laterally (Fig. 7A View Figure 7 ). Neither incrassation frontoparietalis nor the margins are preserved/observable in the remains. The paroccipital process is reduced, but its dorsal surface possesses a distinct crest. The medial base of the paroccipital process is pierced by the occipital arterial foramen, which is covered dorsally by the posterior margin of the frontoparietal and, thus, not visible in dorsal view (Fig. 7E View Figure 7 ). The fragmentarily preserved parts of the inferior superior process suggest that it was not longer than the lateral superior process. However, its lateral and slightly ventrally bending can be assumed. The arteria orbitonasalis opens ventrally on the supraorbital tectum (Fig. 7F View Figure 7 ).
Squamosals: The dorsal surface is covered by a similar to frontoparietal pit-and-ridge sculpture. The bone remains are fragmentarily preserved. Only in HLMD-Ez 2105 (Fig. 7H, I View Figure 7 ), an intact posterodorsal process lamina is present, and shows rounded posterior margin. The dorsal and zygomatic processes are broken. However, considering the presence of intact and concave bone margins between the preserved bases of these processes, we can suggest that they were delimited from each other. In ventral view, lamellar structures at the base of the posterolateral processes are observable (Fig. 7I, K View Figure 7 ). However, they are incomplete for any further description.
Maxillae: The labial surface of the bone is covered by a dense network of moderately deep to deep pits-and-ridge sculpture. The distinct zygomatic process extends posterodorsally and has a rounded posterior tip (Fig. 5L View Figure 5 ). The posterior process projects backwards. It is separated clearly from the zygomatic process by a deep concavity and projects much posteriorly. The orbital margin is concave. In lingual view, the pterygoid process projects posteromedially (Fig. 7M, O View Figure 7 ). Anteriorly, it is connected with the dorsally oriented lamella above the horizontal lamina.
Premaxilla: In anterior view, the pars dentalis is low but broad. Its surface is covered by rugose structures (Fig. 7P View Figure 7 ), which recalls the pit-and-ridge sculpture of, e.g., frontoparietal and maxilla. The pars facialis is broken, but its preserved base suggests a L-shaped form. Medially from this process, another shorter and posteromedially oriented process is present. The lateral crest (sensu Venczel 2004) is moderately developed. The dental crest possesses 15 tooth pedicles (Fig. 7Q View Figure 7 ).
Vertebrae: three presacral and two sacral vertebrae are present. The vertebra centrum is procoelous (four vertebrae, HLMD-Ez 2098, 2100-2102) or amphicoelous (one vertebra, HLMD-Ez 2099, Fig. 7R View Figure 7 ). The HLMD-Ez 2099 represents a small-sized individual that, most probably, does not have fully ossified joints. In presacral vertebrae, the neural arch is high; and the neural canal is large. The foramina for the spinal nerve are present slightly above the posterior bases of the neural arch. In presacral vertebrae, they are visible in lateral view, whereas in sacral ones - in posterior views (Fig. 7T View Figure 7 ). The sacral vertebrae have a broad and flattened transverse process.
Ilium: Though all ilia are very fragmentarily preserved, the following characters can be observed on the material: the acetabular region triangular; the acetabulum itself has round outline; the dorsal prominence low and covered by rare irregular structures; the dorsal protuberance absent; the moderately deep spiral groove extends from ventrolateral to dorsomedial direction in the region of the fusion of iliac shaft and acetabulum (Fig. 7W View Figure 7 -AA); in medial view, the ilioischiatic juncture is covered by elongated striae (Fig. 7Z View Figure 7 ); the dorsal acetabular expansion larger than the ventral one.
Remarks.
The described remains can be assigned to the genus Pelobates based on the following combination of characters: 1) azygous frontoparietals articulating with the squamosals; 2) well-pronounced pit-and-ridge style sculpture with pustular structures on frontoparietal, squamosal and maxillae; 3) the presence of the spinal nerve foramina in vertebrae; 4) the presence of the moderately deep spiral groove on ilium, etc. (e.g., Venczel 2004; Roček et al. 2014). The fossil material of Pelobates can be allocated to the species P. sanchizi considering: 1) the presence of moderately broad tectum supraorbitale; 2) the occipital arterial foramen not visible in dorsal view; 3) the arteria orbitonasalis opening ventrally on the supraorbital tectum; 4) delimited posterior and posterodorsal processes of squamosal ( Venczel 2004)
Comparison of our material with other fossil species of Pelobates ( Böhme et al. 1982; Khozatskiy 1985; Böhme 2010; Roček et al. 2014) allowed to suggest further diagnostic features for P. sanchizi such as: 1) the lateral superior process of the frontoparietal is longer than broad; 2) articulation surface on frontoparieals with squamosal well-developed, concave and oriented fully laterally.
The single premaxilla from Echzell shows a remarkable feature: ornamented on the anterior surface of the bone, recalling the pit-and-ridge sculpture of, e.g., frontoparietal and squamosal. Comparable ornamentation has not been ever described for the genus Pelobates and in P. sanchizi from other Miocene localities. Only for Eopelobates deani ( Roček et al. 2014), a moderated rugose outer surface has been mentioned.
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