He is mighty Tyrannosaurus Rex Really three types of dinosaurs, as a study earlier this year claimed? Says Fuggedaboutit research from a new study.
The veto published online today (25 July) in the magazine evolutionary biology (Opens in a new tab)Shows that the T-Rex The “triple” study does not have the evidence to support its weighty ideas.
“Tyrannosaurus Rex remains the only true king of dinosaursStudy co-author Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland, said in a statement released today by the American Museum of Natural History (AMNH) in New York City.
However, the lead author of the original study, Gregory Poole, an independent paleontologist, is not convinced by the new findings. “[It] Not a proper scientific study,” Paul told Live Science in an email. It appears as old propaganda that seems to be organized to defend T-Rexrather than seriously exploring the possibilities that fossil specimens of the genus could have dinosaur It contained more than one kind of what sex certainly did.”
Related: T. rex and its relatives were warm-blooded like modern birds
The controversial study by Paul and his co-authors, published in March 2022, is also in the journal evolutionary biology (Opens in a new tab)suggest it T-Rex They were three separate types, which were identified as the standard T-Rexthe biggest T. Emperorand less T. Regina. The authors based their findings on an analysis of the femurs (femurs) and teeth from 38 T-Rex individually.
However, their study faced opposition even before it was published. The authors did not definitively specify one for each sample they analyzed—even those with well-preserved residues. As a result, Philip Curie, a well-known paleontologist at the University of Alberta in Canada, removed his name from the study before it appeared, New York times I mentioned at the time.
Despite this controversy, Paul, who does not have a degree in the field but has contributed to a long stack of published studies, defended the paper. “I realize there may be a lot of people out there who wouldn’t be happy with this,” Paul previously told the New York Times. “And my answer to them is to publish a refutation.”
Now, a group of researchers experienced with theropods – a group of bipedal, largely carnivorous dinosaurs that included T-Rex And his close relatives – they did just that.
Recently, a bold theory was announced in great fanfare: what we call T-Rex “It was actually multiple species,” Brusatte said in the statement. 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 easily separate fossils into specific 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 the new study, the researchers examined data from the Mars study, as well as data points from 112 species of birds — which are living dinosaurs — and four non-lobian theropods, including Tarbosaurus batar And the sarcophagus of petrosaurus. Their analysis revealed that the “three types” proposal was based on a limited comparison sample, non-comparable measurements, and inappropriate statistical techniques, according to an AMNH statement.
Their study claimed that the difference in T-Rex The samples were so high that they may have been from multiple species closely related to giant carnivorous dinosaurs,” study co-author James Naples, a graduate doctoral candidate at AMNH’s Richard Gilder Graduate School of Studies, said. 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 line of evidence for the proposed multiple species does not hold.”
Related: Are birds dinosaurs?
Study co-author Thomas Carr, a vertebrate paleontologist and assistant professor of biology at Carthage College in Wisconsin, said it can be difficult to pinpoint species-identifying differences in long-extinct animals. That’s why the authors of the new study looked at living dinosaurs, as well as extinct dinosaurs.
“Our study shows that accurate statistical analyzes based on our knowledge of living animals are the best way to clarify the limits of extinct species,” Carr said in the statement. “In practice, the model of the three species 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 March study suggested that when researchers looked at several T-Rex Specimens, changes in size in the second tooth on the lower jaw and in the durability of the femur, revealed that the iconic dinosaur was, in fact, three species. However, the researchers in the new study were unable to replicate the tooth discovery. They even obtained different results when taking simple measurements of dental samples.
Furthermore, the researchers in the new study disagreed with how the original paper statistically identified the three species. In the original study, the authors of the new study said that statistical analysis identified the three groups before the test was actually taken, so they couldn’t blindly test the “threesome” hypothesis. In the new study, the researchers used a different statistical technique to find out how many groups there are within the data without any presuppositions. Their results showed that T-Rex It is better to consider them as a single group – that is, as one species.
“It’s hard to determine the boundaries of even living species: For example, zoologists disagree about the number of living species of giraffe,” said study co-author Thomas Holtz, a vertebrate paleontologist at the University of Maryland and Smithsonian National Museum. Natural History in Washington, D.C., he said in the statement. “It becomes more difficult when the species in question are old and known only from a relatively small number of samples. Other sources of variance—changes with growth, region, sex, old-fashioned individual differences—must have been rejected before the hypothesis that two groups of The two samples are actually two separate species. In our opinion, this hypothesis is not the best explanation yet.”
But Paul disagreed with the assessment from the new study, calling it a “significantly flawed work that fails to refute the data and analyzes provided by Paul et al. (2022), and has errors of its own,” Ball told Live Science in his long-listed email. One of the differences he had with the new publication.
Ball also objected to the fact that the original study “took decades to produce,” while the new study “was produced within a few weeks, was reviewed and published in just months, and shows the opposite results.”
T-Rex Famous in the world of dinosaurs and popular culture, “so it’s important to get this right,” said co-author David Hawn, a senior lecturer in zoology at Queen Mary University of London. “There is still a good chance that there will be more than one species dinosaur There is, but we need solid evidence to make that kind of decision.”
Originally published on Live Science.