As part of the museum’s temporary exhibition, T. rex: The Ultimate Predator, on display from 2019-2021, visitors encountered a large, life-size T. rex model with feathers that are the most scientifically accurate representation of T. rex. you give. Credit: D. Finnin/ ©AMNH
Paleontologists find scant evidence that the iconic Tyrannosaurus rex should be reclassified.
a bold claim done earlier this year fossils identified as dinosaurs Tyrannosaurus rex it really represents three different species, refuted by new research. The rebuttal finds that the previous proposal lacked sufficient evidence to separate the iconic species. The study was published today (July 25, 2022) in the journalism. Evolutionary Biology and led by paleontologists at the American Museum of Natural History (AMNH) and the College of Carthage.
“Tyrannosaurus rex remains the only true king of the dinosaurs,” said research co-author Steve Brusatte. University of Edinburgh Who did his doctorate? work in the museum. “Recently, a bold theory was unveiled with great fanfare: T. rex It was actually more than one species. It is true that the fossils we have are somewhat variable in size and shape, but as we have shown in our new study, this variation is small and cannot be used to separate fossils into easily identifiable clusters. Based on all the fossil evidence we currently have, T. rex It stands alone as the only giant apex predator from the end of the Age of Dinosaurs in North America.”
The authors of the controversial study in March 2022, T. rex should be reclassified into three types: standard T. rexmore voluminous”T. emperor“and thinner”T. regina“The work is also published in the magazine Evolutionary BiologyIt was based on analysis of the leg bones and teeth of 38 people. T. rex examples.
An example of a T. rex feed. Credit: © Mark Witton 2022
In the new paper, the scientists reviewed the data presented in the previous study and also added data points from 112 living dinosaur species (birds) and four non-avian theropod dinosaurs. According to their findings, the multi-species argument relied on a limited comparative sample, incomparable measurements, and inappropriate statistical techniques.
“Their studies show that variation T. rex The samples were so numerous that they were probably from multiple closely related species of giant meat-eating dinosaurs,” said James Napoli, co-author of the rebuttal study and a graduate doctoral student at the Museum’s Richard Gilder Graduate School. “But that claim is too small for a comparative sample. was based. Compared to data from hundreds of live birds, we actually found: T. rex less variable than most living theropod dinosaurs. This set of evidence is not valid for the proposed multiple species.”
“Tyrannosaurus rex remains the only true king of the dinosaurs.” – Steve Brusatte
“Detecting variation in extinct animals is a major challenge for paleontologists,” said co-author Thomas Carr of Carthage College. “Our work shows that rigorous statistical analysis based on our knowledge of living animals is the best way to clarify the boundaries of extinct species. In practical terms, the three species models are so poorly defined that many perfect examples cannot be identified. This is a clear warning of a hypothesis that does not match the real world. sign.”
The change in the size of the second tooth in the lower jaw, in addition to the robustness of the femur, indicated the presence of more than one species, according to the original paper. However, the authors of the new study were unable to replicate the dental findings and obtained different results from their own measurements of the same samples. Additionally, the scientists in the new study were interested in how “breakpoints” were statistically determined for each species that used these traits. Because the statistical analysis in the original study defined the number of groups before the test was run, it is not useful for testing the hypothesis, according to the authors of the new study. The most recent paper used a different statistical technique to determine how many clusters were present in the data without any advanced assumptions, and found that they were best considered as a single group, a single species.T. rex.
“Even the boundaries of living species are very difficult to define: zoologists, for example, cannot agree on the number of living giraffe species,” said co-author Thomas Holtz of the University of Maryland and the National Museum of Natural History. “It becomes much more difficult when the species involved are ancient and known only from relatively few specimens. Other sources of variation—changes by growth, region, sex, and old-fashioned individual differences—must be rejected before accepting the hypothesis that the two sample sets are in fact separate species. In our view, , this hypothesis is not yet the best explanation.”
“T. rex “It’s an iconic species and incredibly important for both paleontological research and communicating with the public about science, so it’s important we get it right,” said co-author David Hone, of Queen Mary University of London. there is luck. Tyrannosaurus but we need strong evidence to make that kind of decision.”
Reference: ‘Insufficient Evidence for Multiple Species of Tyrannosaurus in the Recent Period'[{” 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
