Eopelobates sp.
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https://doi.org/ 10.4202/app.2011.0063 |
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persistent identifier |
https://treatment.plazi.org/id/03D287C7-8358-FFDE-BF3D-C11FFDB4FDA1 |
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Felipe |
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Eopelobates sp. |
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Fig. 6 View Fig .
Material.—GU/RSR/VAS 5201 ( Fig. 6 View Fig ), a nearly complete right ilium.
Description.—Only the proximal (= anterior) part of the shaft and the ventral extremity of the pars descendens are missing. In medial and dorsal views, a partial dorsal crest extends onto the anterior half of the bone. There is no tuber superius, but a thin ridge bordered by two shallow spiral grooves extends posterolaterally−anteromedially. The junction between the acetabular area and the shaft is not constricted. There is no fossa around the acetabulum. The angle between the pars ascendens and the shaft is close to 180°. The pars ascendens is short. The pars descendens is broken but was likely flared. The acetabulum is oval and its border is very well marked. The angle between the shaft and the pars descendens is close to 90°. In medial view, an interiliac tubercle is well developed. Below this latter, a striated scar indicates that the contact between the two ilia was extensive (see Table 1).
Discussion.—The morphology of this ilium is reminiscent of Pelobatidae . This family includes only the living genus Pelobates and the fossil genera Elkobatrachus (middle Eocene, Elko Formation, Nevada, USA; Henrici and Haynes 2006) and Eopelobates (see distribution below). Pelobatid ilia are characterized by the absence of the dorsal crest, the tuber superius and the subacetabular and supraacetabular fossae ( Rage and Hossini 2000) and by the presence of an oblique spiral groove on the middle surface ( Evans and Milner 1993). All these characters are visible in the Vastan specimen. The Miocene specimens of Pelobates and Eopelobates have a small interiliac tubercle whereas the Recent specimens of Pelobates do not ( Rage and Hossini 2000). Moreover, following Rage and Hossini (2000), the presence of striated scars on the postero−mesial border of the ilia is indicative of the genus Pelobates . However, striated scars are also present in Eopelobates (personal observation on specimens of E. wagneri, SMF Me−11262a and 2795). In addition, there is a partial dorsal crest extending on the anterior half of the bone, which is only known in the genus Eopelobates . For these reasons, the ilium GU/RSR/VAS 5201 from Vastan is here attributed to the genus Eopelobates . The type species of the latter genus, E. anthracinus from the latest Oligocene of Rott (MP30), Germany, differs from all the other Eopelobates species by being about half the size of the other species ( Roček and Rage 2000). Following Rage and Roček (2003), three other species are recognized in the genus. Two species are known from the middle Eocene of Germany, E. wagneri from Messel (MP11) and E. hinschei from Geiseltal (MP13), the latter possibly a synonym of E. wagneri ( Roček and Rage 2000) . The third species is E. bayeri from the late Oligocene of Bechlejovice, Czech Republic, which is smaller than E. wagneri ( Roček and Rage 2000) and bigger than E. anthracinus ( Estes 1970) .
The identification of the different species of Eopelobates is based on cranial characters, especially the frontoparietal; whereas ilia of Eopelobates are not diagnostic enough for determination below the genus level ( Evans and Milner 1993; Rage and Roček 2003). Nevertheless, the single ilium from Vastan was compared with IRSNB A 2 (field number BE 2−126), an exceptionally well preserved specimen of Eopelobates wagneri from the middle Eocene of Messel, which preserves the two ilia in dorsomedial view ( Fig. 6A View Fig ). The ilia of both the Indian and German specimens are very close in size and morphology ( Fig. 6A View Fig 2 View Fig , B). They share a similar aceta−
http://dx.doi.org/10.4202/app.2011.0063
bular area, the presence of a thin ridge instead of the tuber superius, a dorsal crest extending on the anterior half of the bone, and a well−developed interiliac tubercle. Comparisons with other specimens attributed to Eopelobates wagneri (HLMD−Be−171 and SMF Me−11262a, SMF Me−2795, SMF Me−2562, SMF Me−189) confirm these observations. The vertebrae, cranial bones and other skeletal elements of this Indian taxon are unknown. It is therefore not possible to give a more precise identification of the Vastan pelobatid frog until a revision of Eopelobates is undertaken.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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