Rhadinosteus parvus

About Rhadinosteus parvus:

Rhadinosteus is a small Jurassic frog with a body length of about half an inch. Its name means "small slender bone." It was found in pond deposits and was probably aquatic. Like all modern frogs, it was a carnivore and probably fed on small insects.

Rhadinosteus - small and delicate frog fossil
This small and delicate frog fossil can be difficult to see at first. The head is the largest black spot in the center of the rock. If you follow the backbone, you will see two hind legs that continue to almost the edge. The original contains multiple frog skeletons overlapping, but this cast has been painted to show a single specimen for easier viewing. Scale bar is 1 inch.

Why is Rhadinosteus parvus a superstar?

Rhadinosteus has only ever been found at Dinosaur. It is the only complete frog from the Morrison and one of few complete frogs from anywhere in the Jurassic. Usually only fragments of frog bone are found as fossils. However, a slab that was found at Dinosaur contains over a dozen skeletons.Although it can be challenging to see the individual frogs' shapes in the slab, close inspection reveals mostly complete specimens.


Jurassic Fact: Because they all died as they were metamorphosing, the Rhadinosteus skeletons do not have fully adult anatomy.

For more information: Visit the Quarry Exhibit Hall where a cast is on display. A cast of the Rhadinosteus slab is also on display at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.

Last updated: February 24, 2015

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