Scientists have made significant strides in resolving a long-standing debate regarding the origins of a mysterious dinosaur first excavated in the 1940s. Previously, researchers struggled to determine whether the dinosaur was a juvenile Tyrannosaurus rex or a different species entirely. Initial findings were limited to a solitary tyrannosaur skull, which left many questions unanswered. Over the years, additional discoveries, including another skull and skeleton nicknamed Jane, added to the confusion, but did not provide a definitive answer.
Recent research, however, offers clarity. A complete skeleton unearthed in Montana’s Hell Creek Formation in 2006 has led a team of scientists to conclude that this dinosaur represents a distinct species rather than a young T. rex. The findings, published in the journal Nature, suggest that this new dinosaur is a relative of T. rex known as Nanotyrannus lancensis. Study co-author Lindsay Zanno, affiliated with the North Carolina Museum of Natural Sciences and North Carolina State University, remarked that the discovery “rewrites decades of research on Earth’s most famous predator.”
New Discoveries Transform Understanding of Dinosaur Evolution
The research team utilized growth rings found in the bones of the Montana specimen to determine that it was an adult, approximately half the size of a mature T. rex. Additionally, comparisons of its skeletal structure with other reptiles, including crocodiles, revealed that the anatomical differences between the mystery dinosaur’s skull and that of an adult T. rex—such as variations in bone structure, nerve patterns, and sinuses—are not merely the result of differences in age or puberty.
The implications of this discovery are significant. Holly Woodward, a fossil bone expert from Oklahoma State University who was not involved in the study, noted that there is now “more support and evidence than there ever has been” that this T. rex relative could exist. Yet, she remains cautious, stating that she is not yet convinced that specimens like Jane represent something entirely new.
Other experts in the field also maintain that the debate surrounding the identity of these dinosaurs is ongoing. Thomas Carr, a vertebrate paleontologist at Carthage College, acknowledged that while the new skeleton is indeed an adult, it could represent a sister species to T. rex rather than a distant relative. He pointed out the similarities between the skull shapes of T. rex and the newly identified specimens, suggesting that the issue is far from settled.
Resolving the question of mistaken identity is crucial for understanding how T. rex and its kin evolved. Co-author James Napoli, from Stony Brook University, emphasized that another vital question is whether T. rex was the dominant predator at the end of the dinosaur age, around 67 million years ago, or if a smaller yet formidable predator, such as Nanotyrannus, also roamed the land. Napoli speculated, “I suspect that these two species would have occasionally come into conflict, as predators tend to do, but the long legs of Nanotyrannus, and its small size, suggest that it mostly hunted smaller, faster prey than Tyrannosaurus.”
The new skeleton, dubbed the “Dueling Dinosaurs,” was discovered entangled with the bones of a Triceratops and is currently on display at the North Carolina Museum of Natural Sciences. This study coincides with recent research indicating that dinosaur populations were thriving in North America prior to the catastrophic asteroid event that led to their extinction.
On a related note, in June, scientists identified a new tyrannosauroid named Khankhuuluu mongoliensis, a smaller-bodied ancestor of T. rex that previously roamed the plains of Mongolia. This discovery adds further context to the evolutionary lineage, as researchers suggest that apex predators like T. rex eventually descended from these smaller tyrannosauroids.
As the scientific community continues to investigate the lineage of these ancient creatures, the findings surrounding Nanotyrannus lancensis open new avenues for understanding the complexity of dinosaur evolution and the ecological dynamics of their time.
