Fossil evidence has led to the identification of a new prehistoric mammal with similarities to ... it to efficiently extract food from hard-shelled prey. Ontocetus had four post-canine teeth ...

Land mammals responded in kind ... Squid and other soft-bodied cephalopods replaced their shelled relatives, which once filled the middle rung on the food chain. Sea snails and bivalves that ...

The oceans teemed with the coiled-shelled ammonites ... biggest changes came with the evolution of dinosaurs and the first mammals in the late Triassic, starting around 230 million years ago.