‘Bold theory’ that T-Rex was 3 species refuted – ‘Tyrannosaurus Rex is still the only true king of dinosaurs’

T. Rex Model Ultimate Predator

As part of the museum’s temporary exhibition T. rex: The Ultimate Predator, on display from 2019 to 2021, visitors encountered an enormous life-size model of a T. rex with flecks of feathers – the most scientifically accurate representation of a T. rex to date. Credit: Dr. Venin / © AMNH

Paleontologists find insufficient evidence that the iconic Tyrannosaurus Rex must be reclassified.

The bold confirmation was made earlier this year that the fossils identified as belonging to a dinosaur Tyrannosaurus Rex They really represent three distinct species that have been debunked by new research. The appeal finds that the previous proposal lacks sufficient evidence to divide famous genres. The study was published today (25 July 2022) in the journal evolutionary biology It is led by paleontologists at the American Museum of Natural History and Carthage College.

Tyrannosaurus Rex Study co-author Steve Brusatte, a paleontologist at the University of Edinburgh who did his Ph. Work in the museum. Recently, a bold theory was announced in great fanfare: what we call T-Rex They were actually many types. It is true that the fossils we have are somewhat variable in size and shape, but as we show in our new study, this difference is slight and cannot be used to accurately separate fossils into easily defined groups. Based on all the fossil evidence we currently have, T-Rex It stands alone as the only giant predator from the end of the age of the dinosaurs in North America.”

In March 2022, the authors of the controversial study made this case T-Rex It should be reclassified into three types: Standard T-Rexthe huge “T. Emperor“and the leanest”T. Regina. The study also published in the journal evolutionary biologyon the analysis of leg bones and teeth 38 T-Rex samples.

feeding tyrannosaurus rex

Illustration of feeding a T. rex. Credit: © Mark Witton 2022

In the new paper, the scientists revised the data presented in the previous study and also added data points from 112 living dinosaur species — birds — and from four non-avian dinosaurs. According to their findings, the multispecies argument was based on a limited comparison sample, non-comparable measurements, and inappropriate statistical techniques.

Their study claimed that the difference in T-Rex “The specimens were so high that they were probably from multiple species of giant carnivorous dinosaurs,” said James Napoli, co-lead author of the stabbing study and a graduate doctoral student at the museum’s Richard Gilder Graduate School of Education. But this claim was based on a very small comparison sample. When comparing it with data from hundreds of live birds, we actually found that T-Rex Less variable than most living theropod dinosaurs. This evidence for the proposed multiple species does not hold.”

Tyrannosaurus Rex He remains the only real king of the dinosaurs.” – Steve Brusatte

“Identifying differences in long-extinct animals is a major challenge for paleontologists,” said co-lead author Thomas Carr of Carthage College. “Our study shows that accurate statistical analyzes based on our knowledge of living animals are the best way to clarify the boundaries of extinct species. In practice, the three species model is so poorly defined that many excellent specimens cannot be identified. This is a clear warning sign for a hypothesis that does not match The real world “.

The discrepancy in the size of the second tooth in the lower jaw, as well as the durability of the femur, indicates the presence of multiple types according to the original paper. However, the authors of the new study were unable to replicate the dental findings, and they retrieved different results from their own measurements of the same samples. Additionally, in the new study, the scientists discussed how to statistically determine the “breakpoints” of each species using these traits. Because the statistical analysis in the original study limited the number of groups before the test was taken, it’s not useful for hypothesis testing, according to the new study’s authors. In the last paper, a different statistical technique was used to determine the number of groups present within the data without any advanced assumptions, and to discover that it is best to consider them as one group – in other words, one type –T-Rex.

“The boundaries of even living species are hard to define: zoologists, for example, disagree on the number of living species of giraffe,” said co-author Thomas Holtz, of the University of Maryland and the National Museum of Natural History. “It becomes more difficult when the species in question is old and known only from a relatively small number of samples. Other sources of variance—changes with growth, region, sex, good old individual differences—must be rejected before the hypothesis that two sets of samples are in Reality is two separate species. In our opinion, this hypothesis is not yet the best explanation.”

T-Rex “There is still a good chance that there will be more than one species .” said co-author David Hoon of Queen Mary University of London dinosaur There is, but we need solid evidence to make that kind of decision.”

Reference: ‘Insufficient Evidence for Multiple Tyrannosaurus Species in Latest’

The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic era. It ended with the Cretaceous and Paleogene extinction event.

“data-gt-translate-attributes=”[{” attribute=””>Cretaceous of North America: A Comment on “The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus”’ by Thomas D. Carr, James G. Napoli, Stephen L. Brusatte, Thomas R. Holtz Jr., David W. E. Hone, Thomas E. Williamson and Lindsay E. Zanno, 25 July 2022, Evolutionary Biology.
DOI: 10.1007/s11692-022-09573-1

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