These are reptiles in which the body is more or less completely enclosed
by bony plates. This group is first known as fossils from late Triassic
rocks of Europe, and modern representatives of the group include the
turtles and tortoises. Fragmentary remains of turtle shells are among
the most common vertebrate fossils found in the Tertiary. Some of the
late Tertiary land tortoises were 3 to 4 feet long. The earliest known
turtles in Texas have been found in Cretaceous rocks.