Andrewsarchus A huge flesh-eating mammal from the Eocene Epoch. It was four metres long and had a skull nearly one metre long. It may have been more of a scavenger than a hunter. Andrewsarchus was the largest known flesh-eating land mammal.

Eocene Epoch The span of time in Earth’s history from 56 to 34 million years ago. During this time, the climate was warm and tropical rainforest was widespread, even at the poles.

Eohippus A 60-centimetre-long (2-foot) prehistoric horse from the Eocene Epoch.

Gastornis A 2-metre-tall (6.5-foot) "terror bird" from the Eocene Epoch. It could not fly and was probably a herbivore. Another name for Gastornis, or possibly a close relative) was Diatryma. 

Gigantopithecus A 3-metre-tall (10-foot) ape that lived in the forests of the Pleistocene.

Glyptodon A large armoured mammal from the Pleistocene Epoch. It looked a lot like a modern armadillo.

Holocene Epoch The span of time in Earth’s history that started 11,500 years ago and continues to this day.

Hyaenodon A flesh-eating, cat-like predator from the Eocene. It measured up to 3 metres (10 feet) long and had strong jaws with sharp, knife-like teeth.

Ice ages A period when the Earth’s temperature drops significantly and ice sheets spread out from the poles. It is not quite certain what causes this to happen. The last ice age occurred in the Pleistocene Epoch, reaching its greatest extent about 22,000 years ago.

Interglacial A period between two ice ages when the Earth’s climate warms up.

Mammoth A large, elephant-like animal from the Pleistocene Epoch. They only ate grass. Some species of mammoth roamed the Earth until about 11,500 years ago (although some woolly mammoths lived on a remote Siberian island until just 3700 years ago). They died out either because of climate change after the last ice age, or because humans hunted them to extinction. The woolly mammoth was a species from the far north with a shaggy coat and long, curved tusks

Mastodon A mammal with tusks, trunks and thick hair. Mastodons roamed the Earth from the Oligocene to the Pleistocene. They were slightly smaller than mammoths, and had teeth adapted to eating leaves.

Megatherium A 6-metre-long (20-foot) sloth from the Pleistocene Epoch. It probably moved about the ground on all fours.

Miocene Epoch The span of time in Earth’s history from 23 to 5 million years ago. During this period, vast areas of grassland started to appear, leading to the evolution of horses and antelopes, as well as dogs, cats and hyenas to prey on them.

Neogene Period A period of Earth’s history from 23 to 2.6 million years ago, comprising the Miocene and Pliocene epochs.

Oligocene Epoch The span of time in Earth’s history from 34 to 23 million years ago. During this time, the climate began to cool. Ice caps formed at the poles and forests were replaced by more open woodland.

Palaeocene Epoch The span of time in Earth’s history from 66 to 56 million years ago. Most animals from this period were forest-dwellers. During this period, mammals replaced reptiles as the dominant group of animals.

Palaeogene Period A period of Earth’s history from 66 to 23 million years ago, comprising the Palaeocene, Eocene and Oligocene epochs. During this period, mammals replaced reptiles as the dominant group of animals.

Paraceratherium A massive plant-eater that lived in Asia during the Eocene and Oligocene epochs. Paraceratherium measured 5 metres (16 feet) high at the shoulder, making it the largest land mammal ever. It used its flexible lips and tusk-like teeth to strip leaves from trees.

Pleistocene Epoch The span of time in Earth’s history from 2.6 million years ago to 12,000 years ago. It was a time of many ice ages.

Quaternary Period A period of Earth’s history from 2.6 million years ago to the present. It followed the Neogene Period and includes the Pleistocene and Holocene epochs.

Sabre-toothed cats Several species of cats from the Eocene and Pleistocene epochs. They had huge canine teeth at the front of their mouths and probably hunted in packs.

Tertiary Period The period of Earth’s history from 66 to 2.6 million years ago. It has now been divided into the Palaeogene Period and the Neogene Period.

Warm-blooded Warm-blooded animals are kept warm by energy taken from food. They can maintain their temperature regardless of their surroundings.

Woolly rhinoceros A large, woolly, rhinoceros-like animal from the Pleistocene Epoch.

Consultant: Chris Jarvis