Tyrannosaurus rex rex is arguably the most famous of all the dinosaur metal money , with starring roles in reasonably much everydino movieever made . However , scientist have identified a newfangled subspecies of Tyrannosaur , Tyrannosaurus mcraeensis , older and more primitive but still the same size as a treble - decker bus . This young metal money also serve researcher realize whereT. rexand other Tyrannosaurs might have originated from , a inquiry that has amaze palaeontologists .
The new metal money was discover when the team take a closer look at a museum specimen of a 71 - 73 million - twelvemonth - one-time fond skull . The skull was discovered in the Hall Lake Formation , New Mexico , USA in the eighties and is currently on display at theNew Mexico Museum of Natural History & Science(NMMNHS ) .
“ [ The ] skull / jaw was originally described and assigned toT. rexin 1986,“Dr Spencer Lucas , one of the authors of the new newspaper and Curator of Paleontology at NMMNHS , distinguish IFLScience . " decennium later , much has been learned aboutT. rexthrough new discovered fossil . The anatomic dispute between the McRae fogey and otherT. rexnow stand up out as likely systematic difference , hence the indigence for reinvestigation ”
Reconstruction of what Tyrannosaurus mcraeensis might have looked like.Image credit: Sergei Krasinski
close-fitting analysis of the skull revealed that not only was it not aTyrannosaurus rexskull , but it represented a whole Modern specie , now namedTyrannosaurus mcraeensis , thought to have lived 71 - 73 million years ago – around 6 - 7 million year beforeT. rexwas roaming about . It also sheds visible light on the idea that tyrannosaurus were living in North America millions of long time earlier than palaeolontologists antecedently intend .
“ New Mexicans have always known our state is special , now we hump that New Mexico has been a special office for X of zillion of years , ” Dr Anthony Fiorillo , Executive Director of NMMNHS , said in a command seen by IFLScience .
Given thatT. rexis so notable , this helped the team key out key caption differences between the bones within the skull of aT. rexand the skull of the newfangled species .
While it might not look like it, these jaws are shallower and longer than a T.Rex, suggesting a mouth with less bite force.Image credit: Nick Longrich
“ The differences are subtle , but that ’s typically the case in closely related species . Evolution slowly causes mutations to build up over millions of years , causing specie to look subtly different over clock time , ” said Dr Nick Longrich , a atomic number 27 - source from the Milner Centre for Evolution at the University of Bath , UK .
Dr Lucas tell IFLScience that the longer and shallow jaw in the new species suggest that it “ probably had less bite strength than in aT. rex . ” Regardless it was still an imposingly expectant dinosaur , roughly the same size as aT. male monarch , which mensurate up to 12 meters ( 40 feet ) from head to buns and 3.6 meters ( 12 feet ) marvelous . Given the dates of the dodo , it shows that tyrannosaurs spring up to a elephantine sizing near the end of the Campanian ( toward the end of theCretaceous full stop ) . Like its more well - bonk first cousin , both species would have consumed a largely meat - found diet .
Phylogenetic analysis also suggests that the species could be a sister metal money to theT. rexmaking it the nighest known congener . According to Dr Lucas , it could even be a “ plausible ancestor ” , though the composition note not a direct one . The discovery suggest thatTyrannosaursmay have evolved in the south of an island continent holler Laramidia that exist between 100 and 66 million year ago . This island was extremely large and would have stretched from what is now Alaska to Mexico . Towards the ending of the Cretaceous period , the squad posit , Tyrannosaurusstarted spread out northward , alongside other giant species likeTriceratops .
The paper is published inScientific Reports .
