Additional Pleistocene Amphibians and Reptiles from the Seymour Formation, Texas

Abstract

A recent collection of amphibian and reptile fossils from the Gilliland local fauna (early Pleistocene: Irvingtonian: Burnett Quarry site) of the Seymour Formation of Knox County, Texas, contains two frogs, two turtles, one lizard, and at least seven snakes. Ten taxa (2 frogs, 1 lizard, 7 snakes) are herein reported as new to the herpetofauna of the Gilliland local fauna. With the exception of Geochelone and Eumeces cf. E. fasciatus, all the fossils represent extant forms that live in north-central Texas today. An ilium referred to Bufo w. woodhousii is distinctly thicker than those of Recent specimens suggesting that this subspecies of toad was more robust and moderately larger in Irvingtonian time than it is today. The presence of Geochelone indicates warmer winter conditions, and Eumeces cf. E. fasciatus implies moister habitat. Matrix recently collected from a site, the Burnett Quarry (Dalquest and Carpenter, 1986), in the Seymour Formation of Knox County, Texas, has yielded a small but noteworthy assemblage of amphibian and reptile bones that add new information on the early Pleistocene paleoherpetofauna of north-central Texas. The location of the fossil-bearing sediments is stratigraphical- ly below a deposit of Type O Pearlette vol- canic ash, indicating an age greater than 600,000 years BP, and the mammalian fau- na suggests referral to the Irvingtonian Land Mammal Age (Dalquest and Carpen- ter, 1986). The herpetofauna discovered in the Bur- nett Quarry is included in the Gilliland local fauna (contemporary with Cudahay- type local faunas), and is older than the Vera local fauna of the Seymour Forma- tion. Continued separation of the two local faunas is suggested by W. Dalquest (pers. comm.). A taxonomic list of the amphibi- ans and reptiles known from the Vera and Gilliland local faunas, to include those re- ported herein, is given in Table 1. This report provides the first account of small amphibians and reptiles from the Gilliland