Which are the dinosaur teeth?

TEETH450

Clockwise from top: Tyrannosaurus rex tooth (Late Cretaceous, western US), tyrannosaur tooth (Late Cretaceous, Judith River, MT), rugose coral (Middle Devonian, Falls of the Ohio, Clarksville, Indiana), rugose coral (Paleozoic, locality unknown), ornithomimid toe claw (Late Cretaceous, western US), rugose coral (Paleozoic, locality unknown), tyrannosaur tooth (Late Cretaceous, Judith River, MT), rugose coral (Paleozoic, locality unknown), theropod tooth (Late Cretaceous, Ojo Alamo, NM), tyrannosaur toe claw (Late Cretaceous, western US). 

All are fossils except, technically, the T. rex tooth, which is actually a cast of a real tooth. The rugose corals (also known as solitary or horn corals) are very often mistaken for dinosaur teeth but are older than the oldest dinosaurs, having gone extinct around 250 million years ago (the oldest known dinosaurs are around 230 million years old).