The world’s most famous dinosaur is going through an identity crisis.
In February, a team of scientists hypothesized that Tyrannosaurus Rex was actually three different species. Rather than having only one “tyrant lizard king”, their paper made the case for a royal family of massive predators. Joining the king in the genus Tyrannosaurus would be the oldest and oldest emperor, T.
The proposed reclassification of T. rex shocked the paleontology community like an asteroid, sparking passionate debates. On Monday, another team of paleontologists published their first peer-reviewed counterattack.
“The evidence was not convincing and had to be answered because T-Rex research goes well beyond science and into the public domain,” said Thomas Carr, a paleontologist at Carthage College in Wisconsin and author of the new book. “It was unreasonable to let the public think that the multi-species hypothesis was true.”
The previous team of researchers expected this appeal, which was published in the journal Evolutionary Biology. Gregory Poole, one of the authors of the original study, is working on another paper and says many of the stabbing allegations are outlandish.
“I don’t like flat Earth because the evidence is against it,” said Mr. Ball, an independent researcher and influential old artist. “It’s the same here: the evidence strongly suggests that there are multiple types.”
It seems that this great taxonomic debate is destined to rage through the ages. Which isn’t surprising given how difficult it is for researchers to distinguish prehistoric species. Without dinos’ DNA, the lines between one fossil and another are chaotic. So paleontologists measure various features, such as the size and shape of a particular bone. However, fossils can be misleading, as spending eons buried underground can disfigure the bones. And that’s before thinking about how sexual differences, injuries, disease, and natural diversity sculpt bones during an animal’s life.
In live ensembles, distorted traits are counterbalanced by large data sets. But sample sizes for even well-known dinosaurs like T. rex are very small according to Philip Curie, a paleontologist at the University of Alberta who was not an author on either study. “The main problem is that although a rough estimate of 100 known specimens of tyrannosaurs may seem like a lot, it is not enough,” Dr. Corey said.
With paleontologists forced to decipher these fragmented mysteries, the field is littered with misidentities and names of defunct species. And even myths aren’t immune – T-Rex’s fossil nemesis, Triceratops, experienced its own naming drama in 1996 when scientists divided the three-horned herbivore into two species.
But perhaps no scientific name is as sacred as Tyrannosaurus Rex. Since it was named in 1905, the world’s most studied dinosaur has kept its nickname. But the latest study by Mr. Paul and his colleagues threatened to send shock waves through museum halls by renaming their attractions as stars.
Many scholars immediately had their doubts. The initial study focused on the large tyrannosaur bones and the presence of two sets of incisive teeth emerging from the lower jaw of the predator.
In the rebuttal study, Dr. Carr claimed that there was no distinguishing feature of any of the purported tyrannosaur species. “Features purported to be different between the three species were in fact overlapping,” said Dr. Carr, who published a rigorous study examining traits in more than 40 specimens of T. rex in 2020. The different species – we should have a higher level than that.” He adds that many well-preserved specimens of tyrannosaurus fail to fall into any suggested species based on their teeth and the heaviness of their bones.
It is also intended to puncture the statistical analyzes used in the original paper. According to James Napoli, a paleontologist at the American Museum of Natural History in New York and co-author of the appeal, the statistics used were misleading because the authors specified how many species they expected before conducting the tests. “It’s a great test if you’re trying to predict which individuals belong to which group and you know how many groups you have in your data,” said Dr. Napoli. But using it to find distinct groups is less useful because it “will always collect data in the number of groups you tell it to.”
In the original paper, the researchers compared the contrast between individual tyrannosaurus specimens with that found between several allosaurus skeletons. However, the challenge claims that comparing apex predators is misleading because allosaurs descended from a single bony bottom in Utah while tyrannosaurus fossils came from scattering sites over a longer period of time. Therefore, they say, greater amounts of regional and temporal variation should be expected in the tyrannosaur data set.
The challenge team also looked at the diversity of Tyrannosaurus rex’s living relatives – birds. After examining the bones of 112 living bird species, the team concluded that the differences between the bones of T. rex femurs were relatively unremarkable.
But Mr. Poole thinks there is another feature that could make this difference more noticeable. In a forthcoming study, it is hypothesized that the pattern of the horns adorning the skull of tyrannosaurs differed for each species, such as the contrasting crests that characterize the tyrannosaur species. Says the brow of T. Paul said, “That should seal the deal.”
Dr.. Naples is not convinced. Like the armor of modern crocodiles, these bone spurs are likely covered with keratin, which protects the bones that are constantly growing beneath them. It is believed that the shape of the T. rex horns likely changed with the animal’s age.
One thing both teams of researchers agree on is the need for more tyrannosaurus specimens. “When more skeletons are found, they are added to the data set, and eventually one way or another, the statistical support will be too strong for logical scientists to disagree,” said W. Scott Pearsons, a paleontologist at the College of Charleston. and co-author with Mr. Paul on the previous paper.
While neither side is willing to give in, Peter Makovicki, a University of Minnesota paleontologist who was not involved in either studies, believes that Tyrannosaurus Rex’s constant back-and-forth identity is good for paleontology because it allows the public to experience the finer details that define the discipline.
“It gives the layman an idea of why we care so much about identifying new species in the fossil record,” said Dr. Makovicki, who is setting himself up in the single-species camp. “It would be very hard to convince someone of that if it was an arcuate stump, but T. rex takes it to another level.”