Using DinoAtlas
Reading the fossil map
5 min read
The short version
The fossil map shows where fossils were dug up, not where dinosaurs lived. Those are very different things: the map is thick in the American West and Mongolia partly because dinosaurs were there, and partly because that is where the right-aged rock is bare and people have been looking for 150 years.
Two maps in one
Modern mode plots each site at today's coordinates. Paleo mode plots it where that patch of crust actually sat at the time, reconstructed from plate motions.
Flip between them on a Late Jurassic search and the Atlantic closes: Portugal's Lourinhã fauna and Colorado's Morrison fauna, strikingly similar in content, move next door to each other.
Collecting bias
Fossils are found where three things coincide: rock of the right age, exposed at the surface, in a country with an active research tradition and permits.
Large parts of Africa, India and Antarctica hold suitable rock but few records. An empty patch on the map is usually an absence of fieldwork, not an absence of dinosaurs.
Common questions
- Why are so many dinosaurs found in the United States?
- Extensive Mesozoic rock exposed in western badlands, plus 150 years of intensive collecting and well-funded museums.
- What does the paleo view on the map show?
- Each site's position on the globe at the time it was deposited, reconstructed from plate tectonic models.
- Were there dinosaurs in Antarctica?
- Yes — Cryolophosaurus and Antarctopelta among others. Antarctica was warmer and forested during the Mesozoic; the ice cap just makes collecting nearly impossible.