Question

briefly compare and contrast two Cretaceous vertebrates (mammals or dinosaurs) with a mammal that arises during the Paleogene. Consider in your discussion how mammals broadly filled the ecological niches left open by the extinction of the dinosaurs.

Compare:

Aucasaurus and Iguanadon(Cretaceous) to Andrewsarchus(Paleogene)

Answer 1

ANS. Mammals are animals evolved from synapsid reptiles.they feed their young milk and have a unique arrangement of teeth and ear bones.most are covered with fur or atleat have fur on some par of their bodies. except for a few species that could be counted on one hand , all animals give birth to live young.Dinosaures evolved from diapsid reptiles, a group that also contains lizards,snakes, and crocodiles and is related to tortoises. that makes them more closely related modern reptiles than to mammlas. birds are now a divergent group of dinosures.like birds,dinosaures laid eggs and many of them probably have feathers. there are two things will tell you if an animal is mammal or not. all mammals make milk to feed their young.only mammlas do this.

The cretaceous-paleogene extiction event alsoknown as the cretaceous -tertiary(K-T)extinction, was a mass extinction of some three quarters of plants and animal species on the earth that occured over a geologicaly short period of time.the cause of mass extinction that makes the end of the cretaceous and the begining of the paleogene is a sceintific mystery.