Skip to main content
Dryad

An early burst of skeletal evolution at the origin of dinosaurs

Brownstein, Chase1; Griffin, Christopher2

Published Mar 03, 2026 on Dryad. https://doi.org/10.5061/dryad.w9ghx3g33

Data files

Mar 03, 2026 version files 44.71 GB

Click names to download individual files Select up to 11 GB of files for zip download

Abstract

Over 230 million years of Earth history, dinosaurs became a major terrestrial animal clade and produced one of the most species-rich living tetrapod lineages, birds. Yet, largely because of uncertainty surrounding the phylogeny and geographic origins of dinosaurs, the tempo and mode of their emergence and initial radiation remain poorly constrained. Here, we reconstruct the initial diversification of dinosaurs through Bayesian tip-dating analyses. Using seven morphological datasets to account for uncertainty, we suggest that dinosaurs emerged between 250 and 240 Ma, 10 million years before the earliest unambiguous dinosaur fossils. The emergence of the dinosaurs was followed by the rapid appearances and diversification of all major lineages, coinciding with a burst of morphological evolution that peaked in the early Late Triassic. The patterns we infer are consistent with the expectations under a scenario of evolutionary radiation, in which ecologically disparate lineages rapidly diversify from a single common ancestor. In turn, our results provide a biological explanation for the instability surrounding early dinosaur phylogeny and suggest that the diversity of dinosaurs, including birds, has been sculpted by multiple adaptive radiations following successive mass extinctions in deep time.