A trematosauroid temnospondyl from the Middle Triassic of Jordan

Phylogenetic hypotheses, biogeographic dispersal models, and evolutionary scenarios are difficult to form but easy to reject: a single fossil may be sufficient. Previously neglected or inaccessible regions bear high potential for the discovery of such fossils, because they shed light on new faunas with unorthodox combinations of taxa, and sometimes reveal representatives of clades that were not expected in such a place and time. In the Triassic, many tetrapods reached a worldwide distribution – or at least the fossil record is good enough to document such a distribution. Still, there are regions where the record is poor, with the Middle East ranking among those. Here I report evidence for a Middle Triassic tetrapod from a region that may have been crucial for dispersal of shallow water taxa but hitherto yielded very little material: Jordan. During the Triassic, the Tethys covered vast areas of northern Gondwana, among them northern Africa and the Middle East. In deposits formed under epicontinental, shallow marine conditions, aquatic reptiles (placodonts, nothosaurs, pachypleurosaurs, thalattosaurs) are usually abundant, and a few finds have been reported from the Middle East (Rieppel et al. 1997, 1999). However, the specimen reported here stems from a temnospondyl, representing a clade of early tetrapods (stem-amphibians) believed to have inhabited a vast range of water bodies from rivers and lakes over brackish marshes to epicontinental shallow marine habitats (Schoch & Milner 2000; Laurin & Soler-Gij n 2001). The objective of the present study is to describe the find and elucidate its phylogenetic position among the temnospondyls.