Up-to-date measurements of a large fossil found in Saskatchewan almost 30 years ago confirm it as the largest known fossil in the world. Tyrannosaurus rex skeleton. Remarkably, the new paper suggests T. rex and other dinosaurs grew to a size larger than typically enjoyed.
New research published last week in The Anatomical Record describes "Scotty," a T. rex skeleton also known as RSM specimen P2523.8. Scotty is now officially the largest and oldest T. rex already discovered, and the most gigantic of any known two-legged carnivorous dinosaur known as theropod.
With an estimated 8,870 kg, it is also the largest dinosaur ever discovered in Canada. The new study was conducted by paleontologist Scott Persons of the University of Alberta.
Scotty's skeleton was discovered near Eastend, Saskatchewan in 1991, but work to remove it from the ground did not begin completely until 1994. Paleontologists took nearly a decade to excavate the fossil because it was encased in compact, cement-like sandstone . The extra effort to dig the bones beyond the sample size resulted in more delays.
That said, paleontologists were able to recover about 65 percent of the T. rex specimen, which terrorized the Cretaceous of Canada some 66 million years ago.
The first attempts to characterize the skeleton between 2008 and 2014 were marked by inaccuracies due to the fact that the fossil was not fully prepared for analysis. Consequently, as pointed out in the new study, Scotty "was never formally described and its skeletal proportions were scientifically quantified." The new study is now the first to provide detailed and accurate skeletal measurements, including a comparative analysis with other researchers. known T. rex fossils.
The measurements of Scotty's legs, hips and shoulders point to a T. rex of enormous size. People and their colleagues relied on an equation developed by other researchers to infer their body mass, using the circumference of the femur, or thigh bone, to collect the amount of weight the legs could support. In this case, Scotty's femur suggested a weight of 8,870 kg, which is equivalent to almost 20 tons. At 13 meters long, Scotty may not have been the largest or the largest T. rex who has lived – but certainly was great in terms of mass.
Analysis of growth patterns in Scotty's bones suggests that the dinosaur died in the early 30s, becoming the oldest T. rex skeleton already discovered. Extensive wounds were detected throughout the body, pointing to a particularly brutal life. Scotty had broken ribs, an infected jaw and bite marks on the tail, the latter of which seemed to be inflicted by an opponent T. rex, suggests the new study.
People and their colleagues compared Scotty's skeleton to other 11 well preserved T. rex skeletons, including Sue – a specimen also known as FMNH PR 2081. Sue's bones were found in 1990, and was once considered the largest T. rex skeleton, a title that now belongs to Scotty. Sue weighed 18,651 pounds (8,460 kg), which is about 5% lighter than Scotty.
"I've been waiting a long time for the description of this incredible T. rex fossils like many paleontologists, "Steven Brusatte, a paleontologist at the University of Edinburgh, told Gizmodo. "It is one of the largest and oldest Rexes out there and gives us a glimpse of just how big T. rex during these last years of his life ".
Brusatte said the new study provides good evidence that a 7-to-8-ton body plane, 13 meters long, was "as big as the King, but very large," adding that T. rex it is still the "largest pure meat eater that ever lived on earth as far as we know it today."
In fact, other large species of theropod, such as Spinosaurus aegyptiacus, Giganotosaurus caroliniiand Tyrannotitan Chubutensis, may have been greater than T. rex, but more fossil evidence is needed for paleontologists. For now, T. rex remains king.
As an interesting aside, paleontologists have noted substantial size variations between T. rex fossils. Some scientists have proposed a classification scheme based on two forms: "gracile" Rexes with long and thin skeletons and "robust" Rexes with more robust constructions and greater volume. Other paleontologists say that such discrepancies in size can be explained by individual variation or age. Another possibility is sexual dimorphism, in which females are larger than males. The reason for the hypothetical older woman Rexes could have something to do with the increased physical demands of having to lay and protect eggs.
A fascinating conclusion reached in the new study is that the sizes of T. rex and other dinosaurs are being underestimated by paleontologists. The reason, according to the authors, is that few dinosaurs survived to full maturity. Consequently, there are more fossils of smaller and smaller dinosaurs than larger and older dinosaurs, resulting in a sort of selection bias. Looking at Scotty's skeleton, with its wide display of wounds, life as a dinosaur was clearly difficult – even when you are a T. rex.
John Hutchinson, professor of evolutionary biomechanics at the Royal Veterinary College of the University of London and specialist in T. rex physiology, was a little blasé about the new study.
"If you read between the lines in previous studies and this new one, the Scotty specimen is not noticeably larger than other known specimens – at best, maybe 5% larger, and that's with a wide margin of error," said Hutchinson to Gizmodo. .
What is fair; the margin of error for the weight estimates presented in the study is 25% more. In addition, "some bones are smaller than known skeletons, while others are larger," Hutchinson said, so that "we did not learn something really important, unambiguous, and new about the size of the known skeletons." T. rex of this specimen. "
Palaeontologist Thomas Carr of Carthage University, also not affiliated with the new study, said that the absolute difference in size between Scotty, Sue and others may not be large, but Scotty's specimen increases the ceiling to the maximum size of T. rex, which is now larger than previously thought.
"This changes our image of what is within the range of possibility for these large animals and expands our understanding of the biology of the great theropods at that end of the size range," Carr told Gizmodo. "Without Scotty, our estimate of the ceiling of maximum size would be inaccurate – Scotty sharpens that image."
[The Anatomical Record]