Mystery fossils belonged to giant ostrichlike dinosaur

Behemoth bones reveal a fish-eating Cretaceous creature

ostrichlike dinosaur drawing

HEFTY HANDS  At more than 6,000 kilograms, Deinocheirus mirificus (shown in an artist’s reconstruction) is the largest ostrichlike dinosaur yet discovered.


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Almost 50 years after paleontologists in the Mongolian desert dug up mysterious dinosaur fossils taller than most people, scientists have now put a fish-eating face to the bones.

The fossils probably belonged to a gigantic type of ostrichlike dinosaur, named Deinocheirus mirificus, or “unusual horrible hand” for its massive forearms and claws, two recently discovered skeletons suggest.

Because the original fossils were mainly just arms, no one knew exactly where to place Deinocheirus in the dino family tree. The bones resembled those of other ostrich dinosaurs but seemed too big: At 2.4 meters long, about the length of a full-sized sofa, the forelimbs dwarfed known specimens. In fact, Deinocheirus’s burly bones stretched longer than the arms of any other bipedal animal.

The new fossils flesh out Deinocheirus’s skeleton and lifestyle, paleontologist Yuong-Nam Lee of the Korea Institute of Geoscience and Mineral Resources in Daejeon and colleagues report October 22 in Nature. Deinocheirus probably was an ostrichlike dinosaur after all, scientists conclude — just an unusually huge one.

At about 6,000 kilograms, more than twice the weight of a Hummer H2, and taller than a one-story building, Deinocheirus may have acted like a giant vacuum cleaner. Some 70 million years ago, the dino probably slurped fish and flora from the bottom of Cretaceous lakes with its ducklike bill and massive tongue.

WATER WADER  The largest ostrich dinosaur ever discovered, Deinocheirus mirificus, known for decades by only its gargantuan arms, may have waded through ponds and streams on blunt clawed feet that kept it from sinking deeply into mud.
Credit: Y.-N. Lee/KIGAM; produced by Ashley Yeager

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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