A recent study has changed our understanding of the Tyrannosaurus rex and its growth timeline. Research published in PeerJ indicates that these dinosaurs reached full size between ages 35 and 40, much later than the previous guess of 25.
Led by professor Holly Woodward from Oklahoma State University, the study used advanced bone analysis to uncover that T. rex spent a significant time in growth stages. This finding challenges old beliefs about their life cycle and ecological role. It suggests that instead of quickly becoming the dominant predator, T. rex had a more gradual and dynamic development process. This could also mean that some fossils thought to belong to the same species might not actually be from T. rex.
One key technique in this study involved examining leg bones from 17 T. rex specimens. Woodward and her team used polarized light microscopy to uncover hidden growth rings that indicate changes over time. Unlike tree rings, these fossilized markers show growth only from the last 10 to 120 years of life.
Interestingly, while past research suggested T. rex gained its full weight of about eight tons by age 25, Woodward’s team found that rapid growth occurred mainly between ages 14 and 29. During this time, a T. rex could gain between 800 and 1,200 pounds each year. However, it continued to grow at a slower pace until as late as 40. Woodward mentioned, “Instead of growing quickly, T. rex spent most of its life in a mid-size range rather than achieving its full length swiftly.”
The researchers employed a new statistical method from mathematician Nathan Myhrvold to create a clearer picture of the dinosaur’s growth. This approach combined data from various specimens, leading to the most comprehensive growth curve for T. rex yet. Each data point came from real fossils, providing a better understanding of the variations in size.
Additionally, the study’s insights have reignited a debate about whether all T. rex fossils belong to the same species. Specifically, two well-known specimens, called “Jane” and “Petey,” showcased different growth patterns. Paleontologist Lindsay Zanno praised the methodology, saying it could lead to crucial discoveries about whether these distinct specimens are a different species, perhaps Nanotyrannus, or just young T. rex.
Another paleontologist, Steve Brusatte, believes that this research suggests there’s more variation within T. rex than previously thought. If future studies confirm these differences, we might see old classifications revised and possibly recognize several species under a broader category.
In light of this new research, our understanding of T. rex is evolving. Scientists are more open to the idea that growth rates, life stages, and possibly species distinctions are much more complex than we once believed.
This changing perspective invites further exploration in paleontology, emphasizing the need for updated methodologies. It shows how interconnected the growth and ecological roles of dinosaurs can be, as they adapted to their surroundings over time.
