Because of the fragile nature of their bodies, birds are seldom found as
fossils. In spite of this, however, some interesting and important
fossil bird remains have been discovered.
The oldest known bird was found in Upper Jurassic rocks exposed in
Germany. This primitive bird, named _Archaeopteryx_, is little more than
a reptile with feathers. _Archaeopteryx_ was a pigeon-sized creature
which had scales as well as feathers, a lizard-like tail, a toothed
beak, and other definitely reptilian characteristics.
During late Cretaceous time the birds underwent changes that resulted in
forms similar to those that are living today, and most of the
present-day birds had developed by the end of the Tertiary.
Although not commonly found, fossil birds have been recorded from
certain of the Cenozoic rocks of Texas.