Name: Karatau Location: South Kazakhstan Age: Jurassic

Taphonomy

Some of the more delicate fossils such as the insects and the plants could not survive in turbulent water, as they would be destroyed. They also could not survive being transported over great distances as again, they would have been destroyed or at least extremely damaged by this process.

The rocks in which the fossils are found are very fine grained, which indicates that the lake contained quiet water. The fine-grained sediments have also allowed detailed impressions of plant material to be formed, so although the actual leaf itself has long since vanished; the impression has been preserved.

The fact that many of the vertebrate skeletons are nearly complete, if not complete, also suggests very still aquatic conditions as the skeletons would have been disarticulated if there had been much turbulence in the lake waters. The pterosaurs are particularly well preserved and the wing membranes and soft tissues can be observed, as can some internal structures. 'Hair-like' structures can also be seen on the head and body of some specimens. Other vertebrate fossils show evidence of soft tissue preservation too.

In the case of the crocodile (Karatausuchus sharovi), it seems likely that this was washed into lake Karatau from a river as crocodiles will only live in certain habitats and it is believed that the lake may not have been suitable for them. Although it may have been transported some distance, it is still nearly intact and there have been suggestions that if transport of a carcass occurs just before or after death, then the animal may not become disarticulated.