Guides
Short, data-led articles on reading dinosaur fossil ranges. Every number in them is calculated from the same 3,628 Paleobiology Database records as the rest of the site.
How to read a dinosaur fossil range
What the two numbers mean, how they are calculated and why so many ranges look the same.
Which dinosaurs lived at the same time?
Overlapping ranges, pairs found in the same fossil collections, and same-age genera that never met.
The longest and shortest dinosaur fossil ranges
Ten longest, eight shortest, and what actually drives the length of a range.
Triassic, Jurassic and Cretaceous dinosaurs in numbers
Genera per period and per stage, which groups dominate when, and why the Triassic looks empty.
How far apart in time were famous dinosaurs?
Stegosaurus and T. rex, nine other famous pairs, and the widest gap on the site.
Using the Who lived when tool
Picking a moment, why answers change in steps, and the three results of a comparison.
Written by Sophie Taylor. For the calculations behind them see Data & method; to explore the data directly use Who lived when.