Utegenia shpinari (Laurin 1996) Earliest Permian ~300 mya, ~20cm in length was originally considered a sister to Seymouria, but here Utegenia was derived from Silvanerpeton and the CGH IIIB 21 c. 587 specimen wrongly attributed to Gephyrostegus. Utegenia phylogenetically preceded Doleserpeton and Gerobatrachus in the lineage of frogs. Utegenia also preceded Amphibamus and Adelospondylus in the lineage of caecilians.
Overall much smaller than and distinct from Silvanerpeton, the skull of Utegenia was lower and wider. The skull roof was wider. The rostrum was lower. The interpterygoid space expanded. The parasphenoid and basispenoid were enlarged.
The cervicals are not known. The presacral series included ~26 vertebrae or at least 4 fewer than in Silvanerpeton and they were increasingly longer posteriorly. The caudals are not well known.
The clavicle and interclavicle were wider. The scapula and coracoid were reduced to two unfused discs. The humerus was enlarged proximally, removing any trace of the former L shape. The radius and ulna were more robust. The manus was not documented.
The pelvis was reduced to more or less the size of a femur. The foot is not well preserved.
|
