Imagine a creature the size of a double-decker bus looking like a cross between an ostrich, a duck and a camel.
By any stretch of the imagination, Deinocheirus mirificus was one thoroughly mixed-up dinosaur.
Scientists had wondered about the oddball dino for almost 50 years after discovering two of its huge arms.
Now a pair of new skeletons unearthed in Mongolia have allowed them to assemble the missing pieces of the puzzle.
The picture that emerged was peculiar indeed.
Deinocheirus mirificus was the largest member of the ornithomimosaurs, a dinosaur family bearing a resemblance to modern ostriches.
But it had a number of unique features not seen in its relatives - including an elongated, duck-like snout and a humped back.
The creature may have used its "bill" to forage for food at the bottom of streams in the river systems where it lived.
Scientists believe it was an omnivore, eating both plants and animal prey. Fossilised fish remains were found in what appeared to be the stomach contents of one of the skeletons.
Of the two specimens, the largest would have measured 36 feet (11 metres) and weighed more than six tonnes when alive during the Cretaceous era 70m years ago.
A description of the dinosaur from an international team led by Dr Yuong-Nam Lee, from the Korea Institute of Geoscience, appears in the journal Nature.
The scientists wrote: "The discovery of the original specimen almost half a century ago suggested that this was an unusual dinosaur, but did not prepare us for how distinctive Deinocheirus is - a true cautionary tale in predicting body forms from partial skeletons."
