 The genus was named in 1825 by English geologist Gideon Mantell , based on fossil specimens that are now assigned to Therosaurus and Mantellodon . Iguanodon was the second type of dinosaur formally named based on fossil specimens , after Megalosaurus . Together with Megalosaurus and Hylaeosaurus , it was one of the three genera originally used to define Dinosauria . The genus Iguanodon belongs to the larger group Iguanodontia , along with the duck @-@ billed hadrosaurs . The taxonomy of this genus continues to be a topic of study as new species are named or long @-@ standing ones reassigned to other genera . 
 The genus was named in 1825 by English geologist Gideon Mantell , based on fossil specimens <a href='null_relcl' title='1'><mark>that</mark></a>are now assigned to Therosaurus and Mantellodon . Iguanodon was the second type of dinosaur formally named based on fossil specimens , after Megalosaurus . Together with Megalosaurus and Hylaeosaurus , it was one of the three genera originally used to define Dinosauria . The genus Iguanodon <a href='uninflect' title='2'><mark>belongs</mark></a> to the larger group Iguanodontia , along with the duck @-@ billed hadrosaurs . The taxonomy of this genus <a href='uninflect' title='3'><mark>continues</mark></a> to be a topic of study as new species are named or long @-@ standing ones reassigned to other genera . 
Da genus was named in 1825 by English geologist Gideon Mantell , based on fossil specimens r now assigned to Therosaurus and Mantellodon . Iguanodon was the second type of dinosaur formally named based on fossil specimens , after Megalosaurus . Together with Megalosaurus and Hylaeosaurus , it was one of tdathree genera originally used to define Dinosauria . Thdaenus Iguanodon belong to the larger group Iguanodontia , along wid the duck @-@ billed hadrosaurs . Thedaxonomy of dis genus continue to be a topic of study as new species arramed or long @-@ standing ones reassigned to other genera .