The 'Large Thief' that defied dinosaur classification for decades

Nature · Published 20 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: For years, scientists struggled to place Megaraptor on the tree of life. Was it a giant dromaeosaur, a cousin to the spinosaur, or a relative of the tyrannosaur? This 8-meter predator's unique anatomy—including massive hand claws and a specialized jaw—suggests a complex evolutionary history that still puzzles paleontologists.

Discovered in the Patagonian Portezuelo Formation roughly 90–88 million years ago, Megaraptor (meaning 'large thief') was initially misidentified. In 1998, paleontologist Fernando E. Novas named the genus based on a large claw he believed belonged to the foot. This led to early depictions of the animal as a giant dromaeosaurid, similar to the 'raptors' of popular culture. However, subsequent discoveries in 2004 revealed that the massive claw actually belonged to the hand, prompting a complete reassessment of its lineage.

The animal's evolutionary position has been a moving target. In 2004, researchers suggested it might predate the split between allosauroids and coelurosaurs. By 2008, some proposed it was a cousin of the spinosaurids. Later, it was grouped with carcharodontosaurs. Most recently, analysis of a juvenile skull in 2014 has placed it primarily within Coelurosauria, potentially as a close relative of the Tyrannosauroidea. This shifting classification highlights how fragmentary remains can lead to vastly different interpretations of prehistoric biology.

Megaraptor's physical build suggests a unique hunting strategy. While it possessed a relatively gracile skull, it featured very large deltopectoral crests on its upper arm bones, indicating powerful forelimbs. Its hand claws were exceptionally long—the first finger claw reaching 35 cm (14 in)—and were likely covered in keratin sheaths. Rather than relying solely on its jaws, Megaraptor may have used these massive claws to grab prey and pull it toward its chest to be dispatched by its heterodont teeth, which featured short conical teeth at the front and longer, curved teeth at the back.

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