Vertebrate Animals (Part 2)
Birds
• Birds (Aves) are feathered creatures. Most birds fly, but some are flightless. Birds are rare as fossils.
Mammals
• Mammals (Mammalia) are the most advanced vertebrates. They occupy all environments. Their skeletons and teeth are common fossils in geologically younger rocks.
Whale vertebra (Photograph by Parvinder Sethi)
Whale fossils, like this vertebra, are examples of fossilized mammals. Whale fossils are common in the Calvert Formation in Westmoreland County.