HERBIVOROUS DINOSAURS 



223 



duck-billed, wading dinosaurs {Trachodon), with stalking limbs 

 and elevated bodies. Third, there are more fully aquatic, free- 

 swimming forms with crested skulls iCorytliosaiirus). The 



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Fig. ioi. Adaptive Radiation of the Iguanodont Dinosaurs into Three Groups. 



(Upper.) Three characteristic types: A, Typical "duck-bill" Trachodon; B, Corytho- 

 saitrus, the hooded "duck-bill," with a head like a cassowary, probably aquatic; C, 

 Kritosaiirus, the crested "duck-bill " dinosaur. Restorations by Brown and Deckert. 



(Lower.) Mounted skeleton of Corythosaurus in the American Museum of Natural His- 

 tory, recently discovered in the Upper Cretaceous of Alberta, Canada, with the integ- 

 ument impressions and body lines preserved. 



anatomy and habits of all these forms have been made known 

 recently by American Museum explorations in Alberta, Canada, 

 under Barnum Brown (Fig. loi). 



The partly armored dinosaurs known as stegosaurs are 

 related to the iguanodonts and belong to the bird-pelvis group 



