Earlier this yeara study made headlines after claiming that Tyrannosaurus rex may actually be made up of three species, including T. regina, or the “queen of the dinosaurs”.
Now scientists at the American Museum of Natural History have refuted those claims, saying they lack sufficient evidence to split the iconic species.
“Tyrannosaurus rex remains the only true king of the dinosaurs,” said study co-author Steve Brusatte.
Scientists from the American Museum of Natural of History have refuted claims that the T.rex was actually three species and say they lack sufficient evidence to separate the iconic species.
Earlier this year, a study made headlines after claiming that Tyrannosaurus rex could actually be three species. Shown here: A) Tyrannosaurus rex; B) Tyrannosaurus rex?; C) Tyrannosaurus regina; D) Tyrannosaurus regina’ E) Tyrannosaurus imperator; F Tyrannosaurus incertae sedis
THREE PROPOSED TYRANNOSAURUS SPECIES
– tyrannosaurus rex
– Imperator Tyrannosaurus
– tyrannosaurus regina
– Currently, Tyrannosaurus rex is the only recognized species of the genus Tyrannosaurus.
In February, researchers in Baltimore reanalyzed nearly 40 fossilized Tyrannosaurus skeletons, including “Sue,” a complete Tyrannosaurus skeleton currently at the Field Museum of Natural History in Chicago, and “AMNH 5027,” famously found at Big Dry Creek, Montana, in 1908.
They noted physical differences in the femur, or femur, as well as dental structures and other bones across the specimens — clues they said pointed to three different species of Tyrannosaurus.
The researchers have suggested that the larger specimens are attributed to a new species called Tyrannosaurus imperator (emperor lizard tyrant).
Meanwhile, the smaller, thinner specimens should be attributed to a species called Tyrannosaurus regina (tyrant lizard queen), they said.
“Recently, a bold theory was announced with great fanfare: what we call T. rex was actually made up of multiple species,” Brusatte said.
It is true that the fossils we have are somewhat variable in size and shape, but as we show in our new study, this variation is minor and cannot be used to cleanly separate the fossils into easily defined clusters.
“Based on all the fossil evidence we currently have, T. rex is the only giant predator of the late dinosaur era in North America.”
In the new study, the researchers revisited the data presented in the previous study and also studied data from 112 species of birds and four other dinosaurs.
Analysis suggests argument for three T.rex species was based on ‘inappropriate’ techniques and measurements
WHAT IS THE T-REX?
Tyrannosaurs rex was a species of bird-like carnivorous dinosaur.
It lived 68 to 66 million years ago in what is now the western part of North America.
They could grow up to 40 feet (12 meters) long and 12 feet (4 meters) high.
Over 50 fossilized specimens of T. rex have been collected to date.
The monstrous animal had one of the strongest bites in the animal kingdom.
Artist’s impression of the T.Rex
Their analysis suggests that the argument for three T.rex species was based on “inappropriate” techniques and measurements.
“Their study claimed that the variation in T. rex specimens was so high that they likely came from several closely related species of giant meat-eating dinosaurs,” said James Napoli, co-lead author of the new study.
“But that claim was based on a very small comparative sample.
“Compared to data from hundreds of living birds, we actually found that T. rex is less variable than most living theropod dinosaurs. This line of evidence for the proposed multiple species does not hold.
One of the main cases for several species in the original study was the observed variation in the size of the second tooth in the lower jaw.
However, in the new study, the researchers were unable to replicate the results and even found different results when they took their own measurements of the same specimens.
The researchers also wonder how the “breaking points” for each new species using these traits were determined.
In the original study, the number of groups was defined before running the test.
But when the researchers used a different technique to determine the number of groups from the data, they found that they were best considered as one group – T.rex.
“Species boundaries, even living ones, are very difficult to define: for example, zoologists disagree on how many living species of giraffe there are,” 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 old and only known from a fairly small number of specimens.
“Other sources of variation—changes with growth, with region, with sex, and with good old-fashioned individual differences—must be discarded before accepting the hypothesis that two sets of specimens are in fact distinct species. In our opinion, this hypothesis is not yet the best explanation.
As what is arguably the most iconic dinosaur species, T.rex is important for communicating science to the public, researchers say.
David Hone, co-author of the study, concluded: “It is important that we get it right.
“There’s still a good chance there’s more than one species of Tyrannosaurus, but we need solid evidence to make that kind of decision.”
HOW THE DINOSAURS WERE EXTINCT ABOUT 66 MILLION YEARS AGO
Dinosaurs ruled and dominated the Earth around 66 million years ago, before suddenly disappearing.
The Cretaceous-Tertiary extinction event is the name given to this mass extinction.
It was believed for many years that climate change was destroying the food chain of huge reptiles.
In the 1980s, paleontologists discovered a layer of iridium.
It is a rare element on Earth but found in large quantities in space.
When this was dated, it coincided precisely with when the dinosaurs disappeared from the fossil record.
A decade later, scientists discovered the massive Chicxulub crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question.
The scientific consensus now says that these two factors are linked and that they were both likely caused by a huge asteroid crashing into Earth.
With the projected impact size and velocity, the collision would have caused a huge shock wave and likely triggered seismic activity.
The fallout would have created ash plumes that likely covered the entire planet and made it impossible for the dinosaurs to survive.
Other animal and plant species had a shorter time interval between generations, which allowed them to survive.
There are several other theories about what caused the famous animals to disappear.
One early theory was that small mammals ate dinosaur eggs and another proposes that poisonous angiosperms (flowering plants) killed them.