Goniopholis sp. - fossil crocodilian jawbone from the Jurassic of Utah, USA. (DNM 3047, Dinosaur National Monument, Utah, USA)

The crocodylomorphs have been around since the Triassic (early Mesozoic). Some fossil crocodylomorphs reached such immense sizes that they preyed on dinosaurs. Another fossil group of reptiles, the phytosaurs (<a href="http://upload.wikimedia.org/wikipedia/commons/d/d2/Rutiodon_BW.jpg" rel="noreferrer nofollow">upload.wikimedia.org/wikipedia/commons/d/d2/Rutiodon_BW.jpg</a>), closely resemble crocodylomorphs, but are unrelated (phytosaurs are crurotarsan archosaurs).

All modern and fossil crocodylomorphs have the same overall skeletal structure, although some fossils forms did depart somewhat from the stereotypical crocodile body plan (quadrupedal, dorso-ventrally compressed bodies, elongated skull & snout with eyes atop the head). So, the crocodylomorphs are, in relative terms, evolutionarily conservative.

Living crocodilians are tropical to temperate, predatory semiaquatic reptiles, but fossil representatives include fully marine forms and inferred terrestrial forms.

Classification: Animalia, Chordata, Vertebrata, Reptilia, Crocodylomorpha, Crocodyliformes, Neosuchia, Goniopholididae

Stratigraphy: unrecorded/undisclosed member in the Morrison Formation (possibly the Carnegie Quarry Sandstone of the Brushy Basin Member), Kimmeridgian Stage, Upper Jurassic, ~150 to 156 Ma

Locality: unrecorded/undisclosed site in Dinosaur National Monument (possibly the Carnegie Quarry), northern Uintah County, northeastern Utah, USA

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