Description

Late Triassic

Bull Canyon Formation

Guadalupe County, New Mexico, USA

Excellent 0.15 inch FULLY ROOTED thecodont tooth.

Reptile.

When people are talking about archosaurs, they are talking about a diverse group of reptiles that include dinosaurs, birds, pterosaurs, crocodilians, and certain other extinct groups.  Someone might say, “Wait a minute, why are birds included?”  Birds are included because perhaps the best way to classify organisms is to determine an ancestor and then group it with all its descendants through time.  That makes the group that includes all modern birds and all extinct birds an archosaur group because its ancestor was most likely a dinosaur.