Lowering of the iguana’s dewlap (its skin flap beneath its chin). More signs of aggression or danger may include: Hissing.

An illustration shows what Duonychus tsogtbaatari might have looked like. Unlike its therizinosaur brethren, the new species ...

Turtles use hand signals for a number of reasons. This turtle is laying a smackdown, and it could be aggression or flirtation ...

Fossils of Duonychus unearthed in Gobi Desert of Mongolia It had two fingers on each hand, with large curved claws It is a member of the therizinosaur dinosaur group March 25 (Reuters ...