As part of the museum’s 2019-2021 temporary exhibition, T. Rex: The Ultimate Predator, visitors were treated to a life-size massive model of a T. rex with feather patches – the most scientifically accurate representation of a T. rex. till today. Credit: D. Finnin/ ©AMNH
Paleontologists find insufficient evidence to reclassify the iconic Tyrannosaurus rex.
A bold claim made earlier this year fossils were found to belong to dinosaurs Tyrannosaurus rex is refuted by new research that actually three different species are represented. The refutation finds that the previous proposition lacks sufficient evidence to divide the symbolic species. The study was published today (July 25, 2022) in the journal Evolutionary biology and managed by paleontologists at the American Museum of Natural History (AMNH) and Carthage College.
“Tyrannosaurus rex remains the only true king of the dinosaurs,” said study co-author Steve Brusatte, a paleontologist. University of Edinburgh He works at the Museum, where he is doing his PhD thesis. “Recently, a bold theory has caused a lot of buzz: what we call T. rex in fact it was of many kinds. It is true that the fossils we have are somewhat variable in size and shape, but as we show in our new study, this variability is small and cannot be used to neatly separate fossils into easily identifiable groups. Based on all the fossil evidence we currently have, T. rex In North America, it has stood alone as a single giant apex predator since the end of the Dinosaur Age.
In March 2022, the authors of a controversial study claimed this T. rex should be reclassified as three types: standard T. rexbigger”T. the emperor,” and more subtle “T. regina.” Research, that was it has been published in the magazine Evolutionary biologyIt was based on analysis of the leg bones and teeth of 38 T. rex samples.
Illustration of T. rex feeding. Credit: © Mark Witton 2022
In the new paper, the scientists re-examined the data presented in the previous study and also added data points from 112 species of living avian dinosaurs and four non-avian theropod dinosaurs. According to their findings, the multiple species argument was based on a limited comparative sample, noncomparable measurements, and improper statistical methods.
“Their study argued that diversity exists T. rex The specimens were so high that they were likely from several closely related species of giant meat-eating dinosaur,” said James Napoli, co-author of the rebuttal study and a graduate student at the museum’s Richard Gilder Graduate School. “However, this claim was based on a very small comparative sample. Comparing data from hundreds of live birds, we actually found that T. rex less variable than most living theropod dinosaurs. This line of evidence does not hold up for the many species proposed.
“Tyrannosaurus rex remains the only true king of the dinosaurs.” — Steve Brusatte
“Determining variation in long-extinct animals is a major challenge for paleontologists,” said co-author Thomas Carr of Carthage College. “Our study 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 types of models are so poorly defined that many perfect examples cannot be identified. This is a clear warning sign of an assumption that does not fit the real world.”
Variation in the size of the second tooth in the mandible, in addition to the robustness of the femur, indicated the presence of multiple 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 specimens. In addition, the scientists in the new study raised the issue of how the “breakpoints” were statistically determined for each species using these traits. According to the authors of the new study, since the statistical analysis in the original study determined the number of groups before the test, it is not useful for testing the hypothesis. A more recent paper used a different technique to determine how many groupings existed in the data without any advanced statistical assumptions, and found that they were best treated as a group, in other words, a species.T. rex.
“Even delimiting living species is very difficult: for example, zoologists disagree about the number of living species of the giraffe,” said co-author Thomas Holtz of the University of Maryland and the National Museum of Natural History. “It is more difficult when the species involved are ancient and known only from a relatively small number of specimens. Other sources of variation—variation by growth, region, sex, and good old-fashioned individual differences—must be rejected before accepting the hypothesis that two sets of specimens are actually separate species. In our opinion, this hypothesis is still not the best explanation.”
“T. rex is an iconic species and incredibly important for both palaeontological research and public awareness of science, so it’s important that we get it right,” said co-author David Hone from Queen Mary University of London. “There is still a good chance that there will be more than one species tyrannosaurus but we need strong evidence to make such a decision.”
Reference: “Insufficient evidence for multiple species of Tyrannosaurus in recent times”[{” 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
