MuyInteresante: dinosaurs 250M years earlier

Dinosaurs are one of those subjects that feel settled until they suddenly aren’t. The bones we can point to with confidence still cluster around 230 million years ago. But a new paper from Chase Doran Brownstein and Christopher Thomas Griffin argues the dinosaur family itself likely started earlier — between 250 and 240 million years ago. That matters because it changes the shape of the story: dinosaurs may not have popped into view late and abruptly. They may have been around for a while before the fossil record really starts catching them. ### What actually changed? The new study landed in *Proceedings of the Royal Society B* on April 22, 2026. Instead of announcing a newly dug-up “first dinosaur,” the authors re-ran the timing problem with statistical methods that combine anatomy, evolutionary relationships, and fossil ages. Their estimate puts the origin of Dinosauria at 250 to 240 million years ago, about 10 million years before the oldest unambiguous dinosaur fossils. ### Why doesn’t the fossil record already show that? Because fossils are patchy, and the earliest members of a group are often rare, local, and easy to miss. The oldest clear dinosaur fossils still sit in the early Late Triassic, around 230 million years ago. That has long created an awkward gap: major dinosaur branches already look distinct by the time they appear, which hints they must have been evolving earlier somewhere else, or in rocks we haven’t found or sampled well. ### What is Bayesian tip-dating here? Basically, it is a way of estimating when lineages split by using fossils as actual dated endpoints — not just as labels on a family tree. The team ran nine different morphological datasets, meaning matrices of skeletal traits across early dinosaurs and close relatives. If several differently built datasets keep pointing to the same earlier window, that makes the argument harder to dismiss as one quirky tree. ### Why nine datasets matter? Early dinosaur relationships are notoriously messy. Small changes in which bones count, or how species are grouped, can reshuffle the base of the dinosaur family tree. The paper’s point is not that one perfect dataset solved the mystery. It is that across nine separate datasets, the same broad timing signal kept showing up — an origin before the first unquestioned fossils. ### Did the paper only move the date back? No — it also argues for a burst of skeletal evolution soon after dinosaurs originated. The authors say the main dinosaur lineages appeared and diversified rapidly, with morphological evolution peaking in the early Late Triassic. So the update is not just “dinosaurs started earlier.” It is “they started earlier, then changed fast.” ### How does this fit with last year’s debate? Pretty neatly, turns out. A 2025 UCL-led study argued that the earliest dinosaurs likely originated earlier than the fossil record suggests, probably in low-latitude Gondwana — parts of what are now South America and Africa. That paper leaned on biogeographic modeling and fossil before their clean fossil debut. ### So were there dinosaurs 250 million years ago? Maybe at the early end of that range, but not in the way people picture classic dinosaurs ruling the planet. Around 252 million years ago, Earth had just come out of the Permian-Triassic mass extinction, and the Triassic world was still rebuilding. If dinosaurs originated around 250 to 240 million years ago, the first ones were likely small members of a broader archosaur world, not immediate top predators. ### What is the real bottom line? This is not a dramatic rewrite where *T. rex* suddenly gets 20 million extra years. It is a cleaner explanation for a long-standing mismatch between family trees and fossils. The bones still matter most. But the gap before the first obvious dinosaur fossils now looks less like a contradiction and more like exactly the kind of blind spot paleontology should expect.