▁have ▁been ▁true ▁end oth erm s , ▁the ▁larger ▁forms ▁could ▁have ▁been ▁in ert ial ▁home oth erm s , ▁or ▁many ▁din osa urs ▁could ▁have ▁had ▁intermediate ▁met abol ic ▁rates . ▁ ▁New ▁theories ▁on ▁din osa ur ▁behaviour ▁ ▁The ▁late ▁ 1 9 6 0 s ▁ ▁also ▁saw ▁several ▁new ▁theories ▁on ▁the ▁way ▁din osa urs ▁behav ed , ▁often ▁involving ▁s oph istic ated ▁social ▁behaviour . ▁ ▁On ▁the ▁basis ▁of ▁track ways , ▁Bak ker ▁argued ▁that ▁sau rop od ▁din osa urs ▁moved ▁in ▁struct ured ▁her ds , ▁with ▁the ▁adult s ▁surrounding ▁the ▁ju ven iles ▁in ▁a ▁protect ive ▁ring . ▁However , ▁shortly ▁afterwards ▁this ▁particular ▁interpretation ▁was ▁challeng ed ▁by ▁Ost rom ▁among ▁others , ▁although ▁the ▁v ener able ▁din osa ur ▁track ▁expert ▁Roland ▁T . ▁Bird ▁apparently ▁agreed ▁with ▁Bak ker . ▁ ▁The ▁first ▁rig orous ▁study ▁of ▁din osa ur ▁nest ing ▁behaviour ▁came ▁in ▁the ▁late ▁ 1 9 7 0 s , ▁when ▁p ala e ont ologist ▁Jack ▁Hor ner ▁showed ▁that ▁the ▁du ck bil led ▁din osa ur ▁Mai asa ura ▁c ared ▁for ▁its ▁young . ▁ ▁Ch anging ▁port ray al ▁of ▁din osa urs ▁ ▁The ▁din osa ur ▁r ena issance ▁changed ▁not ▁only ▁scientific ▁ideas ▁about ▁din osa urs , ▁but ▁also ▁their ▁port ray al ▁by ▁artists . ▁Bak ker , ▁himself ▁a ▁tal ented ▁artist , ▁often ▁illustrated