Nature
PUBLISHED
Humans love to categorize things. Why else would we have founded the headache-inducing craft of taxonomy? It enables us to separate living things into species, but it’s not a perfect science.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.We see blurry areas emerge in the fossil record. Just look at the line between dinosauriforms – dinosaur-like animals that came before the dinosaurs – and dinosaurs, which can be a hard line to establish. That’s why the oldest dinosaur fossil ever found has a few potential candidates.
For one of the undisputed champions, we can look to Brazil. In 2024, palaeontologists realized that heavy rains had done their work for them. A deluge sped up the process of erosion next to a reservoir in Rio Grande do Sul dating back to the Triassic, and here they found one of the oldest dinosaurs ever discovered.
It was an apex predator from the Herrerasauridae, a family of carnivorous dinosaurs that walked on two legs. It represented the most complete of its kind ever found and at ~233 million years old is one of the oldest “true” dinosaur fossils ever found.
A 2022 paper reported similarly old dinosaur remains from Zimbabwe. Representing Africa’s oldest definitive dinosaurs, the finds included a nearly complete skeleton of the sauropodomorph Mbiresaurus raathi thought to be around 230 million years old. But can we go back any further? Well, possibly.
Nyasasaurus parringtoni may take the crown as the oldest dinosaur fossil known to science. It lived during the Middle Triassic around 243 million years ago, and left behind remains that predate other dinosaur fossils by around 10 to 15 million years.
“For 150 years, people have been suggesting that there should be Middle Triassic dinosaurs, but all the evidence is ambiguous,” said lead author of the 2012 paper Sterling Nesbitt of the University of Washington in a release. “Some scientists used fossilized footprints, but we now know that other animals from that time have a very similar foot. Other scientists pointed to a single dinosaur-like characteristic in a single bone, but that can be misleading because some characteristics evolved in a number of reptile groups and are not a result of a shared ancestry.”
Nyasasaurus is a tricky case because it's only known from fragmentary fossil evidence. That makes taxonomy all the more difficult as we have limited evidence with which to decide if something is a dinosaur or earlier dinosauriform.
Then there’s the rock these fossil fragments come from. If it dates back to the Anisian as was originally thought, then the fossils predate other dinosaurs by around 15 million years. However, it’s been debated if the rocks are actually Carnian in age, which could weaken Nyasasaurus’s lead.
“If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far," said Nesbitt.
It’s possible that there may be dinosaur fossils on Earth that are even older than those already mentioned, but we just can’t get to them. In 2025, a team of palaeontologists suggested that finding them might be so difficult because the areas they first evolved in are hard to explore.
“Our modelling suggests that the earliest dinosaurs might have originated in western, low-latitude Gondwana,” said University College London PhD student Joel Heath to IFLScience. “This is a hotter and drier environment than previously thought, made up of desert- and savannah-like areas.”
They include the Amazon rainforest and Sahara Desert. I’m no field expert, but logistically you can imagine they don’t provide the ideal access and working conditions for establishing dig sites. Perhaps if Percy Fawcett hadn’t been so tied up searching for The Lost City Of Z, he might have realized something more precious than gold was lurking beneath the Amazonian soil…
