Prehistoric mammal

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Prehistoric mammals are various groups of mammals that lived before humans developed writing. 164 million years ago, in the Jurassic period, Castorocauda lutrasimilis, a mammal-like (mammaliaform) animal weighing about 500 grams (1.1 lb), had a full mammalian pelt, with guard hairs and under fur, webbed feet, and scales on the tail like a modern beaver. They had teeth specialised for catching fish.

Later, about 130 million years ago in the Cretaceous, there were larger mammals, including Repenomamus giganticus and Repenomamus robustus. Fossils up to one meter (3¼ ft) long have been found, with dinosaur remains in their stomach contents.

The lineages of many varieties continued through the Tertiary period where some reached very large sizes. Most of the very large mammals became extinct in the last ice age, but have smaller descendants.

[edit] List of Prehistoric Mammals

Main article: List of prehistoric mammals

Prehistoric mammals include:

• American Zebra
• Basilosaurus
• Brontotherium
• Castorocauda lutrasimilis[1]
• Cave Bear
• Cave Lion
• Dire Wolf
• Giant Beaver
• Glyptodon
• Hyracotherium
• Indricotherium
• Irish Elk
• Macrauchenia
• Mammoths
  • Columbian Mammoth
  • Woolly Mammoth
• Mastodons
• Megatherium
• North American Camel
• North American Lion
• North American Llama
• Repenomamus giganticus and r.robustus[2]
• Saber-toothed cats
  • Smilodon
• Uintatherium
• Woolly rhinoceros