How were fossil tracks made by Early Triassic swimming reptiles so well preserved?

That swim tracks made by tetrapods occur in high numbers in deposits from the Early Triassic is well known. What is less clear is why the tracks are so abundant and well preserved. Paleontologists have now determined that a unique combination of factors in Early Triassic delta systems resulted in the production and unusually widespread preservation of the swim tracks: delayed ecologic recovery, depositional environments, and tetrapod swimming behavior. ...read more