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Gigantic, bird-like dinosaur reported

June 13, 2007
Courtesy Nature
and World Science staff

Re­mains of a co­los­sal, sur­pris­ingly bird-like di­no­saur have been un­cov­ered in In­ner Mon­go­lia, Chi­na, sci­en­tists say. 

The an­i­mal, which lived in the Late Cre­ta­ceous pe­ri­od, about 70 mil­lion years ago, is thought to have weighed about 1,400 kilo­grams (3,000 pounds). That’s sur­pris­ing, pa­le­on­tol­o­gists said, be­cause most the­o­ries sug­gest car­niv­o­rous di­no­saurs got smaller as they evolved to be­come more bird-like. 

Click for larger image

Artist's re­con­struc­tion of Gi­gan­torap­tor with much smaller feath­ered di­no­saurs known as or­ni­tho­mi­mids. (Cour­t­esy Zhao Chu­ang and Xin­g Li­da/IVPP)
The di­no­saur, de­scribed in this week’s is­sue of the re­search jour­nal Na­ture, has been classed as a new spe­cies and ge­nus.

Xin­g Xu of the Chin­ese Acad­e­my of Sci­ences in Bei­jing and col­leagues an­a­lyzed the ske­l­e­ton and grouped the fos­sil with a family that in­clud­ed the beaked, bird-like Ovi­rap­tor, be­cause of its si­m­i­larly avi­an fea­tures. The fa­mily is known as Ovi­rap­tor­o­sau­ria.

But what’s most strik­ing, the re­search­ers said, is that the beast was about 35 times heav­i­er than oth­er si­m­i­lar feath­ered di­no­saurs, which rarely ex­ceeded 40 kilo­grams. Al­so, the “bizarre” shape of cer­tain bones in­di­cates the an­i­mal, dubbed Gi­gan­torap­tor er­lia­nen­sis, was “a highly spe­cial­ized lin­eage,” Xu and col­leagues wrote. 

The au­thors es­ti­mate that the new di­no­saur would have been about eight me­tres (26 feet) long and would have stood, at the shoul­der, twice the height of a ma­n. They sug­gest that a growth rate con­sid­erably faster than large North Amer­i­can tyran­nosaurs con­tri­but­ed to this. The team al­so no­ted lines of ar­rested growth on the fos­sil, in­di­cat­ing that it was still a young adult when it died. That sug­gests the full-sized di­no­saur may have been even larg­er, they argued.

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Remains of a colossal, surprisingly bird-like dinosaur have been uncovered in Inner Mongolia, China, scientists say. The animal, which lived in the Late Cretaceous period, about 70 million years ago, is thought to have weighed about 1,400 kilograms (3,000 pounds). That’s surprising, paleontologists said, because most theories suggest that carnivorous dinosaurs got smaller as they evolved to become more bird-like. The dinosaur, described in this week’s issue of the research journal Nature, has been classed as a new species and genus. Xing Xu of the Chinese Academy of Sciences, Beijing, and colleagues analyzed the skeleton and grouped the fossil with a family that included the beaked, bird-like Oviraptor, because of its similarly avian features. But what’s most striking, the researchers said, is that the beast was about 35 times heavier than other similar feathered dinosaurs, which rarely exceeded 40 kilograms. Also, the “bizarre” shape of certain bones indicates the animal, dubbed Gigantoraptor erlianensis, was “a highly specialized lineage,” Xu and colleagues wrote. The authors estimate that the new dinosaur would have been about eight metres long and would have stood, at the shoulder, twice the height of a man. They suggest that a growth rate considerably faster than large North American tyrannosaurs contributed to this. The team also noticed lines of arrested growth on the fossil, indicating that it was still a young adult when it died, so the full-sized dinosaur may have been even larger than this.