Paleontology. Biggest extinction hit land and sea.
Kerr
R A
RA
D000818:Animals; D017753:Ecosystem; D005618:Fresh Water; D019015:Geologic Sediments; D009792:Oceans and Seas; D010163:Paleontology; D010944:Plants; D012623:Seawater; D018707:Volcanic Eruptions