A NEWLY discovered giant dinosaur species may be the closest known relative of Tyrannosaurus rex.
Remains of the mighty carnivore, which lived in North America around five million years before T.rex, were examined by paleontologists.
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Sebastian Dalman and colleagues identified the new species – which they have named Tyrannosaurus mcraeensis.
They examined a fossilised partial skull, which was previously discovered at the Hall Lake Formation in New Mexico, and described it in the journal Scientific Reports.
The remains were initially assigned to T. rex and are comparable in size to those of T. rex, which was up to 12 metres (40 feet) long.
But the research team say that they belong to a new species due to the presence of multiple “subtle” differences in the shape of, and joins between, the skull bones of the specimen and T. rex.
Based on the locations of the remains in relation to rocks and other dinosaur fossils that have been previously dated to between 66 and 75 million years ago, the researchers suggest that T. mcraeensis may have lived between 71 and 73 million years ago.
That’s between five and seven million years before T. rex.
Doctoral student Mr Dalman, of the New Mexico Museum of Natural History, said: “Analysis of the relationships between T. mcraeensis and other theropod dinosaur species indicates that T. mcraeensis may have been a sister species to T. rex.
“Making it the closest known relative of T. rex.”
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Lost continent
Based on its discovery in New Mexico and its relationship to T. rex, the research team suggest that the Tyranosaurus lineage, Tyrannosaurini, may have originated in southern Laramidia.
That’s an island continent that existed between 100 and 66 million years ago and stretched from modern-day Alaska to Mexico.
Mr Dalman added: “Tyrannosaurini may have evolved a giant body size by approximately 72 million years ago.
“Alongside other giant dinosaurs from southern Laramidia such as ceratopsians, hadrosaurs, and titanosaurs.”
The research team say that the evolution of giant tyrannosaurins may have been driven by the giant body sizes of herbivores that they preyed on in southern Laramidia.
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