An illustrated coastline from above at golden hour, a shallow blue-green sea lapping pale sandbars, dense forest inland with rivers threading out to the sea, mountains in the distance.

What did Earth look like when dinosaurs lived?

Not one way, because their time was long enough for the map to change under them. By 200 million years ago, when the first dinosaurs had already appeared, almost all the land was joined in one enormous mass. By 100 million years ago the world was warmer, wetter, and had far more shallow sea than today.

AI reconstruction — not a photograph · Shutterstock AI/Shutterstock.com · Shutterstock Standard License

Three periods and two moments

The TriassicTwo maps across one period, and between them the biggest fall in sea of any two maps on this site.
200 million years agoThe land gathered into one mass with a single ocean wrapped around it, and the least water of any map here.
The JurassicThe one period on this site where the water came back, told through the maps at either end of it.
100 million years agoWarmer and wetter, with much of the sea lying shallow across the middle of continents instead of out in the deep ocean.
The CretaceousThe period that ended with the extinction that finished the dinosaurs, and whose shallow seas left chalk under southern England.

Real photograph · AI reconstruction — not a photograph: 301131261/Shutterstock.com · Tatiana Diuvbanova/Shutterstock.com · ArtEvent ET/Shutterstock.com · Shutterstock AI/Shutterstock.com · Sven Hansche/Shutterstock.com · Shutterstock Standard (free image collection, API) License · Shutterstock Standard License

How to read the five

The three period pages each carry their own start and end dates, from a source, and this page does not repeat them. The two moment pages each show a single map instead of a pair.

Read them in order and one number keeps moving: the share of the world below sea level. It falls across the Triassic and comes back in the Jurassic. The Triassic page is plain that it will not say why, because a reason would be a claim that no source here makes.

Where these answers come from

The maps on the pages above: PALEOMAP Paleodigital Elevation Models (PaleoDEMS) for the Phanerozoic, version 2. Scotese, C. R., & Wright, N. M. (2018). PALEOMAP Paleodigital Elevation Models (PaleoDEMS) for the Phanerozoic (Version 2) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.5460860 Licensed CC BY 4.0, read on 1 September 2026.
How sure is this?: Each of those maps is one model’s reconstruction — an estimate built from evidence, not a photograph. 1° cells — roughly 111 km at the equator. Nothing at the scale of a town can be read from this grid.

Where next

For the seas themselves, with names where a source gives one, go to What oceans existed during the dinosaurs? For what the animals drank in that world, start at What did dinosaurs drink? And for how a map of a world nobody saw can be trusted at all, read How do we know?