I. anglicus , described by Friedrich Holl in 1829 , is the original type species of Iguanodon , but , as discussed above , was replaced by I. bernissartensis . In the past , it have been spelled as I. angelicus ( Lessem and Glut , 1993 ) and I. anglicum ( Holl , 1829 emend . Bronn , 1850 ) . It is known from teeth from the middle Valanginian @-@ age Lower Cretaceous Grinstead Clay Formation ) of Cuckfield , West Sussex , England . It is currently classified in the genus Therosaurus as T. anglicus .