For four decades, an often contentious debate has raged in paleontological circles over the proper taxonomy of a handful of rare fossil specimens. One faction insisted that the fossils were young. Tyrannosaurus rex; another argued that they represented a new species, called Nanotyranus lanceolata. Now paleontologists believe they have settled the debate once and for all, thanks to a new analysis of a well-preserved fossil.
Verdict: This is indeed a new species, according to a new paper published in the journal Nature. The authors also reclassified one more specimen as a second new species, distinct from N. lanceolate. To sum it up, Nanotyrant is a valid taxon and contains two species.
“This fossil doesn't just settle disputes,” Lindsay Zanno saidpaleontologist at North Carolina State University and director of paleontology at the North Carolina Museum of Natural Sciences. “This is turning over decades T. rex research upside down.” This is because paleontologists relied on such fossils to model growth and behavior T. rex. The new findings suggest that there may have been multiple species of tyrannosaurs and that paleontologists have underestimated the diversity of dinosaurs from this period.
Our story begins in 1942, when a fossilized skull nanotyrant nicknamed Chomper, was excavated in Montana by an expedition from the Cleveland Museum of Natural History. Initially, paleontologists believed that it belonged to GorgosaurusBut paper 1965 disputed this identification and stated that the skull belonged to a minor T. rex. Only in 1988 scientists have suggested that the skull actually belonged to a new species, Nanotyrant. It was constant movement back and forth since then.
More recently, in 2020, very influential newspaper claimed that Nanotyrant was definitely underage T. rex. However, a significant number of paleontologists still believed that it should be classified as a separate species. A Document for January 2024for example, fell firmly on Nanotyrant side of the discussion. Co-authors Nicholas Longrich from the University of Bath and Evan Saitta from the University of Chicago measured tree rings in Nanotyrant bones and came to the conclusion that the animals were almost grown.
Dueling dinosaurs
Moreover, no evidence has been found of hybrid fossils combining features of both species. Nanotyrant And T. rexwhich would be expected if the former were a child's version of the latter. Longrich and Saitta also discovered a skull bone kept in a San Francisco museum that belonged to a teenager. T. rexand they were able to make anatomical comparisons. They claimed that Nanotyrant had a lighter build, longer limbs and larger hands than T. rex and was probably smaller, faster and more maneuverable.
