Pelobates praefuscus Khosatzky, 1985
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publication ID |
https://doi.org/10.1186/s13358-024-00332-7 |
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persistent identifier |
https://treatment.plazi.org/id/E86287BF-FFFF-FFEC-BA71-A10EFEB3FD84 |
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treatment provided by |
Felipe |
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scientific name |
Pelobates praefuscus Khosatzky, 1985 |
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Pelobates praefuscus Khosatzky, 1985 View in CoL Pelobates aff. praefuscus
Figures 16 View Fig , 17 View Fig
Material. Spilia 1: two humeri ( UU SP1 1144); Spilia 3: four maxillae ( UU SP3 649– UU SP3 652), one frontoparietal ( UU SP3 658), three sacro-urostylar complexes ( UU SP3 653– UU SP3 655), six humeri ( UU SP3 618, UU SP3 633, and UU SP3 642– UU SP3 645), and three ilia ( UU SP3 646– UU SP3 648); Spilia 4: eight maxillae ( UU SP4 669– UU SP4 674 and UU SP4 736), one nasal ( UU SP4 675), two frontoparietals ( UU SP4 668 and UU SP4 691), one sacro-urostylar complex ( UU SP4 676), and one humerus ( UU SP4 711).
Description.
Tese small maxillae from Spilia are only partially preserved ( Fig. 16a–f View Fig ). Most of them are represented by a fragment of the mid-posterior portion of the bone, but UU SP3 651, UU SP3 652, and UU SP4 670 ( Fig. 16e, f View Fig ) preserve the area of the processus palatinus and UU SP3 649 ( Fig. 16a, b View Fig ) preserves most of the bone except for the anterior end and the tooth row. Te maxillae display a rather narrow (higher anteriorly) lamina horizontalis, which does not originate a processus pterygoideus posteriorly. Te tooth row carries closely-spaced and narrow tooth positions. When the teeth are preserved, these are pleurodont, pedicellated and bicuspid. Te tooth row ends in correspondence with the end of the lamina horizontalis in UU SP4 672, but it extends posterior to it in UU SP3 650 ( Fig. 16c View Fig ) and UU SP4 671. Te processus palatinus of UU SP3 649 ( Fig. 16a, b View Fig ), UU SP3 651, UU SP3 652, and UU SP4 670 ( Fig. 16e, f View Fig ), though highly damaged, is visibly narrow, anterodorsally projected and deeply grooved dorsally. Te margo orbitalis is gently concave. A distinct dermal sculpturing is present on the lateral surface. Te sculpturing is rather sparse [very slightly denser in UU SP4 670 ( Fig. 16f View Fig ) and UU SP4 671] and made up by small tubercles and short ridges.
Te nasal (UU SP4 675) from Spilia 4 is of medium size and wide ( Fig. 16g, h View Fig ). Te dorsal surface bears a rather sparse dermal sculpturing made up by tubercles and short ridges.
UU SP3 658 ( Fig. 16i, j View Fig ) and UU SP4 668 ( Fig. 16k, l View Fig ) are fragments of frontoparietalis, preserving approximately the left and right posterolateral quarter of the bone respectively. Te bone they represent is rather robustly built. On the ventral surface, the posterolateral corner of the incrassatio frontoparietalis is visible: it has a straight lateral margin (slightly sigmoid in the anterior portion in UU SP3 658), whereas the posterior margin has an anteromedial course. Lateral to the incrassatio, there is the rather shallow canalis arteriae orbitonasalis, starting from a wide foramen that is visible in ventral view. Te posterior portion of the canalis is open ventrally. A short, wide and distally rounded processus paraoccipitalis is present at the posterolateral corner of the bone. A low and dorsally flat ridge runs longitudinally on the dorsal surface of the latter process. Medial to the base of the same process, the rather wide foramen arteriae occipitalis is not exposed in dorsal view, being visible only in posterior view. UU SP4 691 is also a fragment of frontoparietal, but it preserves the middle portion of the left side of the bone. Te canalis arteriae occipitalis is visible, as well as the lateral margin of the incrassatio frontoparietalis, which appears slightly sigmoid in this portion of the bone. Te canalis opens ventrally in its posterior part and is moderately deep. Te dorsal surface of all specimens is largely covered by a sparse dermal sculpturing with tubercles and short ridges.
Te sacrourostylar complexes from Spilia 3 ( Fig. 17a, b View Fig ) and Spilia 4 ( Fig. 17c, d View Fig ) are poorly preserved and medium to moderately small sized. Most of the urostylar component is missing, but the fusion of the sacral vertebra with the urostyle is still recognizable. Te centrum is cylindrical, with an anterior cotyle. Te neural canal is dorsoventrally compressed, reniform in anterior view. Te neural arch is dorsally flattened, devoid of any developed structure on its dorsal surface. Te lateral processes are very anteroposteriorly enlarged, but they are almost completely missing.
Te humeri from Spilia preserve only the distal half of the bone ( Fig. 17e, f View Fig ). Te shaft is mostly missing and therefore it is not possible to state whether it was straight or curved. Te eminentia capitata is slightly laterally shifted. Te fossa cubitalis ventralis is moderately deep and opened on the lateral side. Te epicondylus ulnaris is almost double in size than the epicondylus radialis. Te cristae medialis and lateralis are not developed. Te olecranon scar is rather large, but somehow elongated.
Te ilia from Spilia are medium sized ( Fig. 17g –j View Fig ). Tey have no dorsal crest and no dorsal tubercle. Te preacetabular and supraacetabular fossae are also absent. Te shaft is mostly missing in all specimens. Te acetabulum is rather wide and semicircular. Te spiral groove is deep. Te posteromedial surface of the bone displays a low degree of striation.
Remarks. All these remains show combinations of features typical for Pelobates (Bailon, 1999; Roček, 2013). Maxillae, nasal, and frontoparietals have a similar dermal sculpturing, which is coossified with the bone in contrast with that of Latonia ( Roček, 2013; Syromyatnikova et al., 2019b); in the latter genus, the sculpturing is a true exostosis and arises separately from dermal bones in outer layers of the dermis, fusing only secondarily with the dermal bones (see Georgalis et al., 2023c). Te humeri have a shifted eminentia capitata and a laterally-open fossa cubitalis ventralis. Te sacrourostylar complexes display an anterior cotyle and strongly-enlarged lateral processes. Tis sacral morphology is present in Pelodytes Bonaparte, 1838b , as well, but fusion with the urostyle is absent in this taxon (Bailon, 1999). Ilia have no dorsal crest, no dorsal tubercle, a deep spiral groove (Böhme, 2010), and a striated posteromedial surface. Te Spilia Pelobates differs from all extant species of the genus in having a ventrally open posterior portion of the canalis arteriae orbitonasalis (Syromyatnikova, 2019). Considering extinct occurrences, it closely recalls Pelobates aff. praefuscus from the Late Miocene (MN 13) of Solnechnodolsk, Russia, in respect to the frontoparietal characters deemed significant by Syromyatnikova (2019). Similar to the taxon from Solnechnodolsk, the one from Spilia has a pustular sculpturing, a shallow canalis arteriae orbitonasalis (even though this may be slightly deeper at least in UU SP4 691), and the foramen arteriae occipitalis that is both located medial to the processus paraoccipitalis and not visible in dorsal view (even though both these latter features are variable in Pelobates aff. praefuscus from Solnechnodolsk; Syromyatnikova, 2019). It differs from all other Miocene species in the pustular (i.e., not pit-and-ridges) sculpturing of the cranial bones. Pelobates praefuscus has an extremely deep canalis artieriae orbitonasalis (Syromyatnikova, 2019), in contrast with the Spilia taxon. Pelobates sp. from the Early Pliocene (MN 14) of Nizhniy Vodyanoi, Russia (Syromyatnikova, 2019) also shares affinities with the Spilia taxon, but only a few of the frontoparietal features are preserved in elements from this Russian locality. Following Syromyatnikova’s (2019) criteria, it appears thus reasonable to identify this Greek pelobatid as Pelobates aff. praefuscus , in the same way as the Solnechnodolsk occurrence.
| UU |
University of Uppsala |
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