Ancient life, layer by layer

1. Quaternary2.6–0 Ma
   • Woolly mammothAn Ice Age elephant of the far north
   • Blue whaleThe largest animal ever to live
2. Neogene23–2.6 Ma
   • MegalodonThe largest shark that ever lived · Debated
3. Paleogene66–23 Ma
   • DorudonAn early whale that lived wholly in the sea
   • PakicetusOne of the first whales, with four legs
4. Cretaceous143.1–66 Ma

   213 dinosaurs from this period are in the dinosaur encyclopaedia.

5. Jurassic201.4–143.1 Ma
   • IchthyosaurusA dolphin-shaped sea reptile · Found in Britain
   • AmmonitesCoiled-shell relatives of the nautilus · Found in Britain

   82 dinosaurs from this period are in the dinosaur encyclopaedia.

6. Triassic251.9–201.4 Ma
   • MorganucodonA tiny early mammal named after Glamorgan · Found in Britain
   • BrasilodonPossibly the oldest mammal, or one of its closest relatives · Debated

   26 dinosaurs from this period are in the dinosaur encyclopaedia.

7. Permian298.9–251.9 Ma
   • DimetrodonA sail-backed hunter on our side of the family tree
8. Carboniferous358.9–298.9 Ma
   • ArthropleuraA giant millipede, the largest arthropod known · Found in Britain
9. Devonian419.6–358.9 Ma
   • Tiktaalik roseaeA fish on the way to becoming a four-legged animal
10. Silurian443.1–419.6 Ma
    • CooksoniaOne of the first plants with pipes for water · Found in Britain
    • Sea scorpionsArmoured hunters, some longer than a person · Found in Britain
11. Ordovician486.9–443.1 Ma
    • GraptolitesFloating colonies that look like pencil marks on rock · Found in Britain
12. Cambrian538.8–486.9 Ma
    • WiwaxiaA small, spiny, scaly animal from the Burgess Shale
    • AnomalocarisA Cambrian predator with huge compound eyes
    • TrilobitesArmoured sea arthropods that lasted for more than 250 million years · Found in Britain
13. Ediacaran635–538.8 Ma
    • Auroralumina attenboroughiiDescribed by its finders as the earliest known animal predator · Found in Britain
    • CharniaA frond-shaped living thing from the Ediacaran sea floor · Found in Britain

Periods and their colours from the International Chronostratigraphic Chart. Each entry lists its own sources. Groups: Early animals, Life in the sea, Onto the land, Mammals and their kin.