looks like Tyrannosaurus rex He has one more relative to add to his ever-growing family tree. In 2017, Badlands Dinosaur Museum team member Jack Wilson noticed the remains that turned out to be a new species of tyrannosaur. Daspletosaurus wilsonior d wilsoni. Wilson first saw a small, flat piece of bone protruding from the bottom of a cliff in the Judith River Formation in northeastern Montana. It turned out that the fossil identified by Wilson belonged to the nostril of the dinosaur.
Additional fossils were unearthed between 2017 and 2021, including skeletal fragments of a rib and toe bone, and fragments of a fossilized skull. As detailed in an article published November 25 in the journalism, these lice were enough to identify it as a new species. Paleontology and Evolutionary Science. The remains date back to 76.5 million years ago, during the Cretaceous period, millions of years ago. rex It was crushed during the Late Cretaceous.
[Related: Is T. rex really three royal species? Paleontologists cast doubt over new claims.]
Somebody d wilsoniTheir unique feature is an array of spiked horns around their eyes. It also has a mix of features found in more primitive tyrannosaur species, such as the distinctive set of horns around the eyes. It also has physical characteristics that are more common in later members of this group. rex. One of these more advanced tyrannosaur features is an elongated eye socket and enlarged air pockets inside the skull.
“Like this, d wilsoni Study authors Elías Warshaw, a paleontology student at Montana State University, and Denver Fowler, paleontologist and curator of the Badlands Dinosaur Museum, wrote in a statement that there is a ‘middle point’ or ‘missing link’ between older and younger tyrannosaur species.
The tyrannosaur family is large: it has nine genera that are above the species and below the family in the system that classifies animals and plants. The family includes a genus of hunters called daspletosaurslived in the Late Cretaceous Period, about 79.5 million 74 million years ago. The team believes that d wilsoni an intermediate daspletosaur descended from Daspletosaurus taurusand its predecessor Daspletosaurus horneri. Daspletosaurs It means “terrible lizard” in Greek, and the specimen was named Sisyphus, referring to the legend of the man who was cursed to push a rock up a hill forever. It took a great deal of effort to extract bones from the surrounding rock, including removing about 25 feet of stone from the top of the skeleton.
In North America during the Late Cretaceous, numerous closely related species formed the evolutionary families of dinosaurs. It was previously thought that these species lived at the same time, which would be evidence of what biologists call branching evolution. However, newly discovered specimens like this one and a better understanding of when animals lived have changed the way paleontologists understand dinosaur evolution.
[Related: The T. rex ‘dynasty’ reigned for more than 125,000 generations.]
“We can now see that many of these species diverged very thinly from one another over time, forming successive ladder-like steps in a single evolutionary lineage in which an ancestral species evolved into a direct descendant,” said Warshaw and Fowler.
This process is called anagenesis or linear evolution. This differs from cladogenesis evolution, where successive branching events create many closely related species, not descendants and ancestors, that look similar but are evolutionary “cousins”.
“The new study supports the addition of tyrannosaurs (including horned and duck-billed dinosaurs) to a growing list of dinosaurs for which anagenesis (linear evolution) has been suggested,” said Warshaw and Fowler. This suggests that linear evolution may have been more common in dinosaurs and that branching evolution occurred less frequently than previously thought.
Warshaw is currently conducting more detailed research into the link. rex and Daspletosaurs.