To make it in a tough world, the first dinosaurs had to grow up fast according to a study published in the open-access PLOS ONE journal.
Fossils analysed in this study came from the Ischigualasto Formation in northwestern Argentina. The rocks in the geological formation date between 231 million and 229 million years old.
It is about this time that the first dinosaurs emerged. Over the course of millions of years, dinosaurs became the dominant life on land. Their size and adaptability saw them occupy every ecological niche and they ruled for more than 150 million years.
Having rapid growth rates likely gave dinosaurs an edge later in their rule in competing with other animals, including early mammals and crocodilians. Now it is clear that this is a strategy that was in action from the earliest dinosaurs during the Triassic period (252–201 million years ago).
“Our sample comes from a time in which dinosaurs were the new kids on the block, restricted to relatively small, basic body plans, and evolving within a world rich with a diverse array of more specialized, non-dinosaur reptiles,” the authors write.
Alongside the dinosaur bones were the remains of several non-dinosaur reptiles and one early relative of mammals. The palaeontologists were able to estimate the growth rates of the different animals using their femurs – much like tracking the growth of trees using their rings.
The results show that the earliest dinosaurs already had fast growth rates.
But it wasn’t only the dinosaurs who grew up fast in the Triassic. Multiple lineages 230 million years ago grew just as fast.
“We tackled the question of how all of these animals grew, and found that the earliest dinosaurs grew quickly, and that these rapid growth rates probably played a significant role in dinosaurs’ subsequent ascent within Mesozoic ecosystems,” say the authors. “But dinosaurs weren’t unique – many of their non-dino sidekicks shared rapid growth 230 million years ago.”
