Gerobatrachus

Gerobatrachus is an extinct genus of amphibamid temnospondyl (represented by the type species Gerobatrachus hottoni) that lived in the Early Permian, approximately 290 million years ago (Ma), in the area that is now Baylor County, Texas. When it was first described in 2008, Gerobatrachus was announced to be the closest relative of Batrachia, the group that includes modern frogs and salamanders. It possesses a mixture of characteristics from both groups, including a large frog-like head and a salamander-like tail. These features have led to it being dubbed a frogamander by the press. Some more recent studies place Gerobatrachus as the closest relative of Lissamphibia, the group that contains all modern amphibians including frogs, salamanders, and caecilians, or place modern amphibians far from Gerobatrachus within a group called Lepospondyli.

==Description== The only known specimen of Gerobatrachus is a nearly complete skeleton (USNM 489135) about long, that is articulated, preserved in ventral view, missing only the stylopodia, zeugopodia, and ventral portions of the skull and pectoral girdle. It is preserved in red siltstone with only its underside exposed. Like other amphibolid temnospondyls, Gerobatrachus has a rounded and flattened head, well-developed limbs, and a small tail. Its vertebral column is somewhat shorter than those of related amphibolids. The large, round head and shortened vertebral column are features Gerobatrachus shares in common with frogs and the early salamander Karaurus. Gerobatrachus also has a large embayment at the back of the skull called an optic notch, which is seen other amphibolids and in frogs and supports the tympanum, an eardrum-like structure used in hearing.