urs ▁was ▁champion ed ▁by ▁John ▁Ost rom , ▁who ▁argued ▁that ▁birds ▁evol ved ▁from ▁co el u ros aur ian ▁din osa urs , ▁and ▁particularly ▁Robert ▁Bak ker ▁who ▁argued ▁passion ately ▁that ▁din osa urs ▁were ▁warm - blo oded ▁in ▁a ▁way ▁similar ▁to ▁modern ▁m amm als ▁and ▁birds . ▁Bak ker ▁frequently ▁port rayed ▁his ▁ideas ▁as ▁a ▁r ena issance ▁of ▁those ▁popular ▁in ▁the ▁late ▁nin ete enth ▁century , ▁referring ▁to ▁the ▁period ▁in ▁between ▁the ▁Din osa ur ▁Wars ▁and ▁the ▁din osa ur ▁r ena issance ▁as ▁" the ▁din osa ur ▁d old rum s ". ▁ ▁The ▁din osa ur ▁r ena issance ▁led ▁to ▁a ▁prof ound ▁shift ▁in ▁thinking ▁on ▁nearly ▁all ▁aspects ▁of ▁din osa ur ▁bi ology , ▁including ▁phys i ology , ▁evolution , ▁behaviour , ▁e col ogy ▁and ▁ext inction . ▁It ▁also ▁led ▁to ▁many ▁dep ict ions ▁of ▁din osa urs ▁in ▁popular ▁culture . ▁ ▁Din osa urs ▁and ▁the ▁origin ▁of ▁birds ▁▁ ▁In ▁the ▁mid ▁and ▁latter ▁parts ▁of ▁the ▁nin ete enth ▁century , ▁many ▁scient ists ▁thought ▁there ▁was ▁a ▁close ▁relationship ▁between ▁birds ▁and ▁din osa urs — and ▁that ▁din osa urs ▁represented ▁an ▁intermediate ▁stage ▁between ▁" re pt iles " ▁and ▁birds . ▁ ▁Short ly ▁after ▁the ▁ 1 8 5 9 ▁publication ▁of ▁Charles ▁Dar win ' s ▁The ▁Origin ▁of ▁Species , ▁British ▁bi ologist ▁and ▁evolution -