Lower Cretaceous Aquatic Reptile And Fish Association

Description: The Choristoderes are a poorly-known group of aquatic reptiles. For over a century, they were only known from two genera from North America and Europe. Over the last 20 years, some 9 additional genera have been referred to the Choristodera. This reptile was initially referred to the Thecodontia by the discoverer R.Endo in 1940. It was later referred to the Choristodera by Ke-qin Gao in 2000 based upon a neotype specimen, since the original holotype was reportedly lost during WWII. Recent years have seen a number of specimens come to light, some with integumentary preservation. Notice that this fine example has portions of the basic outline of the body evident. Some scientists believe the skin was much like the modern-day Chinese Crocodile Lizard Shinisaurus crocodilurus , a semi-aquatic lizard that preys on small fish, amphibians, and invertebrates. It is found here with a fish known as Lycoptera davidi, somewhat different in proportions than the more frequently seen L. sinensis.This genus died out at the end of the Jurassic/beginning of the Cretaceous, leaving no descendants. In all likelihood, a volcanic eruption overcame this pair, quickly burying them in place. The depositional environment was such that they were undisturbed during the sedimentation and fossilization process, affording the fine piece seen here. Like most specimens, there are several repaired matrix cracks. The fragile matrix usually fragments during collection, and is repaired once the specimen is brought in from the field.