Crassigyrinus was a large tetrapod which lived in the Early Carboniferous period. It also lived before the Pennsylvanian period and appear in the Middle Mississippian.Crassigyrinus "Thick Tadpole" was a large tetrapod from the Early carboniferous period
Crassigyrinus in The Land Before Time
It appears in the first movie, incorrectly portrayed with a sail on its back. It appears in the very first frame, where it swims for a while before being pursued by a Metriorhynchus, but escapes. Since it has a sail, it may actually be a Platyhisthrix (Synapsid-like amphibian) that fell into the water. It also resembled a small aquatic Longisquama.