Finally, scientists have succeeded to complete a long-mysterious dinosaur skeleton, revealing a form much more unusual than they had predicted.

Paleontologists exposed some fearsome Dino arms about 50 years ago. At 2.4 meters long, they held the record for the longest forelimbs of any two-legged animal. However, these remains belonged to the dinosaur species known as Deinocheirus, which didn’t reveal much information as paleontologists only discovered a few ribs and some pieces of vertebrae.

Though, these idiosyncratic remains were enough to differentiate the skeleton from other, previously known species. But the pieces weren’t complete enough to paint an accurate picture of the creature they had once belonged to.

Recently, the researchers claimed in a new Nature paper, the hunt for the Deinocheirus is complete. After finding two more partial skeletons in 2006 and 2009 (and then tracking down the missing pieces from each dig that had already been poached and sold into private collections when researchers arrived), Deinocheirus is complete enough to find its place in the tree of life.

Deinocheirus mirificus, (meaning “unusual horrible hand”) is certainly a ornithomimosaurs member, which is a group of dinosaurs that hazily resembled modern ostriches, as was theorized when its arms were discovered. However, it was by far the largest with host of features that haven’t been seen in its cousins.

The dinosaur that lived around Mongolia about 70 million years ago, had a large, toothless muzzle that flared out like a duck’s bill. Its curved spine probably formed a sail-like fin, and its feet were strangely broad. These flat-bottomed toes may have helped the dinosaur forage for food in aquatic areas by keeping it from sinking into mud. Since its bill seems similar to an herbivore’s and its stomach contents appears to contain fossilized fish, the researchers believe that Deinocheirus mirificus was omnivorous.

The Deinocheirus’s surprising figure should serve as a reminder that incomplete skeletons can be very deceptive, researchers said.

The authors of the study stated, “Around half a century ago, the discovery of the original specimen 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, even for animals in which the relationships are known.”