Altirhinus is a close cousin of Iguanadon & was regarded as a species of, (I. Orientalis.) Altirhinus differs from Iguanadon only in its greater number of teeth, a flatter wider bill, & the very prominent nose. Altirhinus was recovered from the Khukhtek formation at Mongolia in 1981. This showed it lived between 100-120 million years ago. It would've been 7-8 meters in length & 2 meters tall at the hip, with a foot-long skull.
Altirhinus is stands out from other Iguanadonts in two ways: the large nasal cavity that probably shows a very good sense of smell, & the fact that it may be ancestral to the Hadrosaurs, a group of ornithopods that all have some form of ornamentation on their noses & includes the famed Lambeosaurs, whose hollow bony head crests have been a mystery since they were discovered.
Altirhinus must have looked very similar to the Australian Muttaburrasaurus, another dinosaur with a high nose, the highest part of their head. Muttaburrasaurus & Altirhinus were probably closely related & lived similar lifestyles.