us ▁hol ger i ▁using ▁b one ▁hist ology ▁and ▁demonstrated ▁that ▁the ▁small ▁island ▁species ▁evol ved ▁through ▁a ▁decrease ▁in ▁the ▁growth ▁rate ▁of ▁long ▁b ones ▁as ▁compared ▁to ▁rates ▁of ▁growth ▁in ▁ancest ral ▁species ▁on ▁the ▁main land . ▁Two ▁other ▁possible ▁d war fs ▁are ▁Rap et osa urus , ▁which ▁existed ▁on ▁the ▁island ▁of ▁Mad agas car , ▁an ▁isolated ▁island ▁in ▁the ▁C ret ace ous , ▁and ▁A mp el osa urus , ▁a ▁tit an osa ur ▁that ▁lived ▁on ▁the ▁I ber ian ▁pen ins ula ▁of ▁southern ▁Spain ▁and ▁France . ▁The ▁possible ▁Cet ios aur is cus ▁from ▁Switzerland ▁might ▁also ▁be ▁a ▁d war f , ▁but ▁this ▁has ▁yet ▁to ▁be ▁proven . ▁One ▁of ▁the ▁most ▁extreme ▁cases ▁of ▁island ▁d war f ism ▁is ▁found ▁in ▁Europ as aur us , ▁a ▁relative ▁of ▁the ▁much ▁larger ▁Cam ar as aur us ▁and ▁Bra ch ios aur us : ▁it ▁was ▁only ▁about ▁ ▁long , ▁an ▁ident ifying ▁trait ▁of ▁the ▁species . ▁As ▁for ▁all ▁d war f ▁species , ▁their ▁reduced ▁growth ▁rate ▁led ▁to ▁their ▁small ▁size . ▁ ▁History ▁of ▁discovery ▁The ▁first ▁scra ps ▁of ▁foss il ▁remains ▁now ▁recognized ▁as ▁sau rop ods ▁all ▁came ▁from ▁England ▁and ▁were ▁originally ▁interpreted ▁in ▁a ▁variety ▁of ▁different ▁ways . ▁Their ▁relationship ▁to ▁other ▁din osa urs ▁was ▁not ▁recognized ▁until ▁well ▁after ▁their ▁initial ▁discovery . ▁ ▁The ▁first