T. rex Took Four Decades to Reach Full Size, Study Finds
A groundbreaking new study has revealed that the mighty Tyrannosaurus rex did not reach its full adult size until around age 40. This finding extends the previous growth timeline by about 15 years, offering fresh insights into the life of Earth's most famous predator.
Examining Bone Tissue for Clues
Researchers analyzed the bone tissue microstructure in leg bones from 17 different T. rex specimens. Many of these fossils are housed at the Museum of the Rockies in Montana. The team used polarized light to identify previously unseen growth marks in the bones.
"This growth trajectory is more gradual than expected," said paleohistologist Holly Woodward of Oklahoma State University Centre for Health Sciences, who led the study. "Rather than T. rex ratcheting up to adult size quickly, it spent a lot of its life at juvenile to subadult sizes."
Flexible Growth Patterns
The scientists examined annual growth rings in the dinosaur bones, similar to those found in tree trunks. They discovered that growth-ring spacing varied significantly between individual T. rex specimens.
"We also found that growth-ring spacing in individual T. rex was variable," Woodward explained. "T. rex had a flexible growth pattern. Some years it didn't grow much, while other years it grew a lot."
This flexibility likely depended on food availability and environmental conditions. When resources were scarce, the dinosaur conserved energy rather than growing. During favorable periods, it could achieve substantial growth spurts.
Survival Advantages
This adaptable growth strategy may have given T. rex significant survival advantages. The extended juvenile period allowed younger individuals to pursue different food strategies than their larger adult counterparts.
"This flexibility allowed it to survive harsh times while growing larger than other carnivores, so it could outcompete others for resources," Woodward noted. "Ultimately, T. rex was only competing against other T. rex for food."
Revised Lifespan Estimates
Previous research suggested T. rex lived about 30 years. The new study points to a significantly longer lifespan of 45 to 50 years.
Paleontologist Jack Horner of Chapman University in California, a co-author of the study, commented on the revised estimates. "We don't know for certain which of these estimates are more accurate since we don't have living T. rexes to measure, but these new estimates make more sense logically and statistically, considering the size these dinosaurs attain."
Research Methodology
This investigation involved more T. rex specimens than any previous study of the species' life history. The researchers employed a novel statistical approach that considered growth records from different specimens across all life stages.
The comprehensive analysis produced conclusions that differ significantly from earlier work. The study was published this week in the peer-reviewed journal PeerJ.
T. rex in Its World
Tyrannosaurus rex prowled western North America during the Cretaceous Period, just before an asteroid struck Earth 66 million years ago. This catastrophic event ended the age of dinosaurs and wiped out three-quarters of Earth's species.
The massive predator reached lengths exceeding 40 feet (12.3 meters) and possessed tremendous bite strength. It walked on two powerful legs and had distinctive small arms with just two fingers.
Diet and Hunting Strategies
T. rex preyed on various plant-eating dinosaurs including:
- Duckbilled dinosaurs like Edmontosaurus
- Horned dinosaurs like Triceratops
- In southern regions, the enormous long-necked Alamosaurus
Horner suggested that older adult T. rex individuals may have been more opportunistic scavengers than their younger counterparts. "The extended growth period would provide a longer period of time for the younger individuals to possibly acquire more live prey," he added.
This new research fundamentally changes our understanding of how the most famous dinosaur grew and survived in its prehistoric world.
