The Late Cretaceous frog Gobiates from Central Asia: its evolutionary status and possible phylogenetic relationships

The fossil record of the Late Cretaceous anuran Gobiates is reviewed, and an articulated postcranial skeleton is described for the first time. A separate family status for the genera Gobiates Špinar et Tatarinov, 1986, Cretasalia Gubin, 1999, and Gobiatoides Roček et Nessov, 1993 is re-assessed. In principle, the Gobiatidae are characterized by a combination of primitive and derived characters, of which the most important for inferring phylogenetic relationships are: (1) amphicoelous (ectochordal) vertebral centra; (2) eight presacral vertebrae; (3) palatines fused to maxillae (postchoanal process of the vomer absent); and (4) pterygoid process of the maxilla absent. The Gobiatidae share with the Jurassic anurans Prosalirus, Notobatrachus and Vieraella (and also found in other Mesozoic anurans, e.g., Aygroua Jones et al., 2003 and Rhadinosteus Henrici, 1998) the first character; however, gobiatids differ from these taxa in having a complete maxillary arch (including qudratojugal) and a lower number of presacral vertebrae. Gobiatidae differ from discoglossoids and pipoids (the only other Mesozoic anurans) in the shape (opisthocoelous or stegochordal, respectively, in the latter) of vertebrae, implying a different method of vertebral development. In general, the Gobiatidae, in spite of their Late Cretaceous age, retain primitive features of Jurassic frogs, combined with derived features (e.g., low number of presacral vertebrae) that are quite unusual for Late Cretaceous non-pipoid anurans.