The Erased World Hiding Inside Every Mouth on Earth

Three hundred million years ago, in the Permian, the land belonged to somebody else — and they left their teeth in your mouth. This world built you. Long before the dinosaurs existed, almost every continent had collided into one supercontinent, Pangaea. The ice age ended, the coal swamps broke up, and the interior of the largest landmass the planet has ever assembled turned into a desert on a scale Earth has never repeated since. The animals that ruled that world were not reptiles and they were not dinosaurs. They were synapsids — the branch of the family tree that leads to every mammal alive, and to you. Dimetrodon, with the great sail on its back, was the top predator of the early Permian, and it is a closer relative of yours than of any dinosaur that would ever live. Later come the dicynodonts, tusked plant-eaters with beaks like a tortoise's, and the gorgonopsids, sabre-toothed hunters built like long-legged dogs. This film walks five places in their world. A river floodplain in what is now Texas, where Edaphosaurus grazes, the amphibian Eryops waits in the shallows, and a griffinfly with the wingspan of a small hawk goes past. The dune sea at the heart of the supercontinent, where a trackway is still pressed into the red sandstone of New Mexico. A reef that stands today as a mountain face in west Texas, with the last of the trilobites on the sea floor beneath it. The Glossopteris forests of the cooler south. And a burrow in the South African Karoo, with an animal curled up asleep at the bottom of it. It is a tour of the world that drafted your body. Teeth of different shapes for different jobs. A fang at each corner of the mouth. Two small bones that once worked the hinge of a jaw and now sit inside your ear — which is how every word of this film reaches you. Then, 252 million years ago, it very nearly all came to nothing. ━━━━━━━━━━━━━━━━━━━━ WHAT IS SOLID, AND WHAT IS INFERRED Every image here is a painted reconstruction, not a photograph. Nobody has photographed this world and nobody ever will. The bones, the burrows and the footprints are real, measured and published. Colour, sound, movement and behaviour are inferred or invented, and the narration says so where it matters. The diagrams were drawn by us rather than generated, and every word on screen was written and checked by a human being. Where researchers genuinely disagree — what the sail was for, how warm these animals ran — the film says they disagree instead of choosing for you. If we got something wrong, tell us in the comments. There is a Corrections playlist on this channel and it exists because we expect to use it. ━━━━━━━━━━━━━━━━━━━━ CHAPTERS 0:00 A mouth built from different tools 0:38 The Permian: Pangaea, the melting ice, the drying world 1:50 What would actually kill you on a Permian floodplain 3:07 Dimetrodon, and the mystery of the sail 4:35 The desert at the heart of the supercontinent 5:42 The Permian reef and the last of the trilobites 6:51 Glossopteris forests, dicynodonts and gorgonopsids 8:29 The burrows, and animals that may have run warm 9:24 Synapsids: the family that leads to mammals 10:08 The Great Dying, and what survived it ━━━━━━━━━━━━━━━━━━━━ Every episode:    • When Earth Was Alien — Every Episode   Four billion years of alien worlds. All of them were here. Handle spelled in letters, not numerals: @fourbillionsummers Business enquiries: fourbillionsummers@outlook.com #Permian #DeepTime #EarthHistory #Paleontology