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Rhadinosteus parvusgroup is extinct

Containing group: Rhinophrynidae


Rhadinosteus parvus is known from the Late Jurassic Morrison Formation, Rainbow Park Microsite, Utah. This small species is known from partial skeletons and isolated elements.  The fossils do not appear to be adult, but rather represent newly metamorphosed developmental stages.

Being from the Late Jurassic, Rhadinosteus is the oldest rhinophrynid, as well as the oldest pipoid, and is an important calibration point for estimating times of divergence in early frogs.


Some obvious features indicate that this species belongs to the clade Pipoidea:  an azygous frontoparietal and parasphenoid that lacks lateral alae.  Like most rhinophrynids, it also has ectochordal vertebrae.

Although most other rhinophrynids have obvious osteological specializations for fossorliality, Rhadinosteus does not.  Thus, it appears to be a relatively plesiomorphic member of Rhinophrynidae, which is consistent with its Jurassic age.


Henrici, A. C. 1998. A new pipoid anuran from the Late Jurassic Morrison Formation at Dinosaur National Monument, Utah. J. Vert. Paleo. 18(2):321-332.

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Tree of Life Web Project. 2008. Rhadinosteus parvus. Version 29 November 2008 (under construction). http://tolweb.org/Rhadinosteus_parvus/106174/2008.11.29 in The Tree of Life Web Project, http://tolweb.org/

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