Early dinosaurs had rapid growth rates, but so did many of the animals that lived with them, according to a study by Christina Curry Rogers of Macalester College in Minnesota and colleagues published April 3, 2024, in the open-access journal PLOS ONE.
Dinosaurs grew rapidly, a feature that distinguishes them from many animals in their Mesozoic (252 to 66 million years ago) ecosystems. Some researchers have proposed that this high growth rate was key to the dinosaurs' global success, but little is known about the early dinosaurs' growth strategies.
In this study, Rogers and colleagues performed histological analysis, examining patterns of bone tissue development in fossil leg bones of animals from one of the first known Mesozoic ecosystems.
The fossils studied are from the Isigualasto Formation of Argentina and are between 231-229 million years old. Specimen fossils include many of the earliest known dinosaurs and an early relative of many non-dinosaur reptiles and mammals.
The analysis found that most of the species studied had higher growth rates than living reptiles, such as some modern-day mammals and birds. All of the early dinosaurs exhibited particularly rapid growth, but they were not alone, as similar growth rates were observed in non-dinosaur reptiles.
The results show that early dinosaurs were already fast growers, supporting the idea that this trait was important to their later success. But dinosaurs were one of several lineages that evolved with high growth rates during the Triassic period (252-201 million years ago).
The authors note that future studies could expand on these preliminary results by sampling different types of paleoanimals from additional early Mesozoic fossil sites.
The authors add: „Our model suggests that dinosaurs came from when they were infants, limited to relatively small, basic body plans, and evolved into a world full of diverse orders of specialized, non-dinosaur reptiles. We tackled the question of how all these animals evolved, and found that the earliest dinosaurs evolved rapidly, And these rapid growth rates played a significant role in the subsequent rise of dinosaurs within Mesozoic ecosystems; but dinosaurs were not unique—many non-dino lineages shared rapid growth by 230 million years ago.”
Journal Note:
- Curry Rogers K, Martinez RN, Colombi C, Rogers RR, Algober O (2024) Osteohistological insights into the developmental dynamics of early dinosaurs and their contemporaries. PLoS ONE 19(4): e0298242. DOI: 10.1371/journal.pone.0298242