New discoglossid and palaeobatrachid frogs from the Late Cretaceous of Wyoming and Montana, and a review of other frogs from the Lance and Hell Creek formations

Abstract

A review of North American Late Cretaceous frogs demonstrates that Paradiscoglossus americanus n. gen. et sp. (Discoglossidae) and Palaeobatrachus occidentalis n. sp. (Palaeobatrachidae) definitively establish the presence of these families in the Late Cretaceous of North America (Lance Formation, Wyoming). P. occidentalis is also represented in the Late Cretaceous Hell Creek Formation in Montana. Interrelationships of palaeobatrachids are briefly discussed. A critical review of Scotiophryne pustulosa, earlier referred to the bombinid line within the Discoglossidae, establishes that there is a weak but definite case for maintaining this taxon in the Discoglossidae. Material that has been questionably referred to the pelobatid frog Eopelobates may be referred to the genus with some confidence. Familial relationships of Theatonius lancensis remain obscure. The presence of discoglossids and palaeobatrachids in North America during the Cretaceous strengthens the hypothesis of Estes and Reig (1973) that these groups were Holarctic in distribution, although both groups seem to have been primarily Eurasian.