Amphibians
According to museum curator John Foster, "frogs are known from several sites in the Morrison Formation but are not particularly well represented." The history of Morrison anuran discoveries began with the recovery of remains from Reed's Quarry 9 near Como Bluff Wyoming. The new genus Eobatrachus was erected for some of these remains by O. C. Marsh, but the material was later considered non-diagnostic. Decades later another dubious anuran genus, Comobatrachus was erected for addition fragmentary remains. Despite the erection of multiple new names, scientists only recognize two legitimate frog species from the Morrison, Enneabatrachus hechti and Rhadinosteus parvus.
In addition to formally named taxa, indeterminate anuran remains have been retrieved from Morrison strata in Colorado, Wyoming, and Utah, with the best specimens found in Dinosaur National Monument and Quarry 9. Stratigraphically speaking, indeterminate anurans have been found in stratigraphic zones 2 and 4. Indeterminate anurans with remains diagnostic down to the family level have also been reported from the Morrison. Pelobatids are represented by the illium of an unnamed, indeterminate species. A specimen has been recovered from Quarry 9 of Como Bluff in Wyoming. Pelobatids are present in stratigraphic zones 5 and 6.
Indeterminate salamander remains are present in stratigraphic zones 2, 4, and 5. A distinctive type of salamander known only as Caudata B is present in stratigraphic zone 6.
| Color key |
Notes Uncertain or tentative data are in ; |
| Name | Species | State | Member | Material | Notes |
|---|---|---|---|---|---|
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Comobatrachus |
C. aenigmaticus |
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A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. Along with Eobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. |
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Comonecturoides |
C. marshi |
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Represented by a single femur. |
Considered a nomen dubium because the name is based on non-distinctive remains which cannot be classified in detail. |
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Enneabatrachus |
E. hechti |
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A small discoglossid frog whose live weight would have only been a few grams. |
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Eobatrachus |
E. agilis |
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A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. Along with Comobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. |
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Iridotriton |
I. hechti |
A basal salamandroid closely related to today's advanced salamanders. |
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Rhadinosteus |
R. parvus |
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Known from several slabs of rock which contain multiple partial specimens in association. |
A pipoid and possible rhinophrynid, Rhadinosteus parvus was only about 42 mm (1.6 inches) long in life. |
Read more about this topic: Paleobiota Of The Morrison Formation