Heaviest ornithopod

The heaviest ornithopod ("bird-footed") dinosaur was Magnapaulia laticaudus, formally described in 1981 but rehoused in its own genus in 2012. A member of the hadrosaur or duck-billed dinosaur taxonomic family of ornithopods, this huge herbivorous species is estimated to have weighed as much as 23 tonnes, and is estimated to have been 12.5–16.5 m long. It is also notable for its extremely tall tail. It existed approximately 73 million years ago during the late Cretaceous in Baja California, northwestern Mexico.

Hadrosaurs earn their duck-billed alternative name to their dorsoventrally flattened jaws, which resembled the beak of a duck (and were used to clip off leaves, twigs and other portions of foliage). Unlike the latter bird's beak, however, the back of the jaws of hadrosaurs contained numerous tiny teeth, which were used to grind up food before swallowing it.