 I. gracilis , named by Lydekker in 1888 as the type species of Sphenospondylus and assigned to Iguanodon in 1969 by Rodney Steel , has been tossed of as a synonym of Mantellisaurus atherfieldensis , but is dubious nowadays . 
 I. gracilis , named by Lydekker in 1888 as the type species of Sphenospondylus and assigned to Iguanodon in 1969 by Rodney Steel , <a href='been_done' title='1'><mark>has</mark></a> been tossed of as a synonym of Mantellisaurus atherfieldensis , but <a href='drop_aux' title='2'><mark>is</mark></a>dubious nowadays . 
I. gracilis , named by Lydekker in 1888 as the type species of Sphenospondylus and assigned to Iguanodon in 1969 by Rodney Steel , done been tossed of as a synonym of Mantellisaurus atherfieldensis , but dubious nowadays .