The closest known relative of the infamous Tyrannosaurus rex has been unearthed by paleontologists in New Mexico.
The newly discovered Tyrannosaurus mcraeensis was found in New Mexico's Hall Lake Formation by paleontologist Sebastian Dalman and his colleagues. A part of the fossilized skull was analyzed to find out more about the species, according to a paper in the journal Scientific Reports.
At first, researchers thought the remains belonged to T. rex itself, given the similarities, but closer observation found this was not the case. There were several subtle differences between these remains and those of a T. rex, including a slightly different jawbone structure.
It also appears that this species thrived in a different period, compared with T. rex. It is estimated that the T. mcraeensis lived around 71 million to 73 million years ago, about 5 million to 7 million years before T. rex.
The predator was around the same size as the T. rex, which was approximately 40 feet long and 12 feet tall.
"[This discovery] was not a surprise in the sense that the theory of evolution tells us T. rex had earlier and more primitive relatives—lots of them," Nick Longrich, a co-author of the paper who is with the Milner Center for Evolution at the U.K.'s University of Bath, told Newsweek. "But in paleontology, the problem is finding these things. You spend a lot of time looking and not finding, so it's something of a surprise when you do find it."
He continued: "It was a bit surprising in that we'd assumed this animal was late Maastrichtian [a geologic period] and T. rex, and then when we looked at the evidence. Neither [was] true. It wasn't late Maastrichtian and wasn't T. rex. This animal was right in front of us—it was on display in the museum in Albuquerque—and we didn't recognize what it was for more than 30 years."
Paleontologists do not believe the new species is a direct ancestor of T. rex. It is more likely a sister species, which means it is the closest known relative to the predator ever found.
"Once again, the extent and scientific importance of New Mexico's dinosaur fossils becomes clear—many new dinosaurs remain to be discovered in the state, both in the rocks and in museum drawers," Spencer Lucas, paleontology curator at the New Mexico Museum of Natural History and Science, said in a summary of the paper's findings.
The discovery sheds light on the origins of T. rex and indicates that more tyrannosaur species have yet to be discovered.
"There's a lot of tyrannosaur fossils waiting to be studied and restudied. I'm currently looking at tyrannosaurs in Mexico, and it seems they have different species," Longrich said.
The most notable finding is that these huge, apex predators lived in this area earlier than originally thought.
Researchers also now believe that the Tyrannosaurus lineage may have begun in what was then southern Laramidia, an island that once stretched from modern-day Alaska to Mexico.
Although this discovery answers a lot of questions, it raises others that are still puzzling paleontologists. It seems that larger dinosaurs evolved only in southern regions, including Tyrannosaurus. The species then spread north at the end of the Cretaceous period, the reason still being a mystery to scientists.
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Robyn White is a Newsweek Nature Reporter based in London, UK. Her focus is reporting on wildlife, science and the ... Read more
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