Restoration of Tyrannosaurus mcraeensis. Credit: Sergei Krasinski, editedNewly found Tyrannosaurus mcraeensis, possibly T. rexs closest relative, lived 71-73 million years earlier in southern Laramidia, showing the early development of giant tyrannosaurs.A brand-new types of tyrannosaur from southern North America that might the closest recognized relative of Tyrannosaurus rex is explained in a research study published in Scientific Reports.Sebastian Dalman and associates determined the brand-new types– which they have actually named Tyrannosaurus mcraeensis– by examining a fossilized partial skull, which was previously found in the Hall Lake Formation, New Mexico, USA.Jaw of Tyrannosaurus mcraeensis at the New Mexico Museum of Natural History and Science. Keep in mind the big scar towards the back of the jaw, which the authors hypothesize might have resulted from a battle with another Tyrannosaurus. Credit: Nick LongrichAlthough these remains were initially assigned to T. rex and are comparable in size to those of T. rex (which was up to 12 meters/ 39 feet long), the authors propose that they come from a brand-new species due to the existence of several 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 stays that have been previously dated to between 66 and 75 million years back, the authors recommend that T. mcraeensis might have lived in between 71 and 73 million years back– between 5 and seven million years before T. rex. Teeth of Tyrannosaurus mcraeensis. Credit: Nick LongrichAnalysis of the relationships between T. mcraeensis and other theropod dinosaur species indicates that T. mcraeensis may have been a sibling species to T. rex, making it the closest recognized relative of T. rex.Based on its discovery in New Mexico and its relationship to T. rex, the authors recommend that the Tyranosaurus family tree, Tyrannosaurini, might have come from in southern Laramidia– an island continent that existed between 100 and 66 million years earlier and stretched from modern-day Alaska to Mexico.Kettle Top Butte in southeastern New Mexico. This fossilized jaw from Tyrannosaurus mcraeensis was discovered near the base of the butte. Credit: Dr. Spencer Lucas, NM Museum of Natural History & & Science. Credit NM Department of Cultural AffairsAdditionally, they propose that Tyrannosaurini might have progressed a huge body size by around 72 million years earlier, alongside other huge dinosaurs from southern Laramidia such as ceratopsians, hadrosaurs, and titanosaurs.The authors hypothesize that the advancement of giant tyrannosaurins may have been driven by the huge body sizes of herbivores that they victimized in southern Laramidia.For more on this discovery, see New Fossil Sheds Light on Tyrannosaurus Rexs Earliest Known Relative.Reference: “A giant tyrannosaur from the Campanian– Maastrichtian of southern North America and the advancement of tyrannosaurid gigantism” by Sebastian G. Dalman, Mark A. Loewen, R. Alexander Pyron, Steven E. Jasinski, D. Edward Malinzak, Spencer G. Lucas, Anthony R. Fiorillo, Philip J. Currie and Nicholas R. Longrich, 11 January 2024, Scientific Reports.DOI: 10.1038/ s41598-023-47011-0.
