21. These are both brachiopods (not clams). Without knowing anything about the biology of brachiopods, choose the fossil that is preserved as original shell material. What is your evidence (you should ...

Pterotrigonia wasn't just any clam; it was part of a family of mollusks known for their ribbed shells, something that made them stand out both during their time on the planet and in the fossil ...

These included brachiopods, which lived in shells resembling those of clams or cockles ... which left a huge number of fossils. Trilobites had flattened, segmented, plated bodies that helped ...