Chelomophrynus bayi, an extinct toad that lived approximately 47 million years ago (Henrici, 1991), is a very close relative of the Mexican Burrowing Toad (Rhinophrynus dorsalis).

Like the Mexican Burrowing Toad, Chelomophrynus bayi bears two spades on each hindfoot that enables it to rapidly burrow into the substrate where it can aestivate to avoid dry, inhospitable (for toads) climatic conditions.

A large sample of this unique fossil anuran was collected by field crews from Carnegie Museum of Natural History during the summers of 1984 and 1986 from the Middle Eocene Wagon Bed Formation of central Wyoming. The collection includes a growth series represented by tadpoles at the metamorphosis stage, postmetamorphic young adults, and adults.

A mass mortality layer of this frog was also discovered, and it was speculated (Henrici and Fiorillo, 1993) that disease was the cause of death.

 

tadpole	young adults
sample of mass mortality layer

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