Paleontology. Paring down the big five mass extinctions.
Kerr
R A
RA
D000818:Animals; D005075:Biological Evolution; D025061:Dinosaurs; D017753:Ecosystem; D005580:Fossils; D019015:Geologic Sediments; D008322:Mammals; D010163:Paleontology; D012623:Seawater