Researchers led by Dr. Kristina Curry Rogers of Macalester College, Minnesota, have shed light on the growth patterns of early dinosaurs and their contemporaries.
Fast growth rates have long been considered a hallmark of dinosaurs, potentially contributing to their dominance during the Mesozoic Era (252 to 66 million years ago). However, this study reveals a surprising twist – many other animals living alongside these early dinosaurs also exhibited rapid growth.
The research team employed histological analysis, a technique that examines bone tissue microstructure, to investigate growth patterns in fossilized leg bones. Their focus was on a diverse range of creatures from the Ischigualasto Formation in Argentina, dating back 231-229 million years ago. The fossil collection included some of the earliest known dinosaurs, various non-dinosaur reptiles, and even an early mammal relative.
The analysis yielded intriguing results. Most of the examined species, including the early dinosaurs, displayed growth rates more akin to modern mammals and birds than to present-day reptiles. This finding aligns with the established notion of fast growth in dinosaurs. However, the surprise lies in the fact that several non-dinosaur reptiles also exhibited similar growth patterns.
“Our sample comes from a time in which dinosaurs were the new kids on the block,” explain the study’s authors. Back then, dinosaurs were relatively small and lacked the diversity of later periods. They coexisted with a rich tapestry of specialized non-dinosaur reptiles.
The key takeaway from this study is twofold. Firstly, it confirms that rapid growth was a characteristic of the earliest dinosaurs, potentially laying the groundwork for their future success. Secondly, and more importantly, it reveals that this growth strategy wasn’t unique to dinosaurs. Many of their contemporaries also possessed this ability.
“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; but dinosaurs weren’t unique—many of their non-dino sidekicks shared rapid growth 230 million years ago,” summarize the authors.
This discovery compels us to re-evaluate factors that contributed to dinosaur dominance. Fast growth may have been just one piece of the puzzle, alongside other adaptations that remain to be fully understood. The study also highlights the importance of examining a broader range of species to paint a more complete picture of life in the Triassic period. Future research incorporating a wider variety of fossils from additional sites holds the potential to further refine our understanding of this fascinating era.
The study is published in PLOS ONE.
Source: Public Library of Science