▁ ▁The ▁recognition ▁of ▁p neum atic ▁foram ina ▁in ▁Maj ung as aur us , ▁besides ▁providing ▁an ▁understanding ▁of ▁its ▁resp ir atory ▁bi ology , ▁also ▁has ▁larger - scale ▁imp lications ▁for ▁evolution ary ▁bi ology . ▁The ▁split ▁between ▁the ▁cer at osa ur ▁line , ▁which ▁led ▁to ▁Maj ung as aur us , ▁and ▁the ▁t et an ur an ▁line , ▁to ▁which ▁birds ▁belong , ▁occurred ▁very ▁early ▁in ▁the ▁history ▁of ▁ther op ods . ▁The ▁av ian ▁resp ir atory ▁system , ▁present ▁in ▁both ▁lines , ▁must ▁therefore ▁have ▁evol ved ▁before ▁the ▁split , ▁and ▁well ▁before ▁the ▁evolution ▁of ▁birds ▁themselves . ▁This ▁provides ▁further ▁evidence ▁of ▁the ▁din osa ur ian ▁origin ▁of ▁birds . ▁ ▁Bra in ▁and ▁inner ▁ear ▁structure ▁▁ ▁Comput ed ▁tom ography , ▁also ▁known ▁as ▁CT ▁sc anning , ▁of ▁a ▁complete ▁Maj ung as aur us ▁sk ull ▁( FM N H ▁PR ▁ 2 1 0 0 ) ▁allowed ▁a ▁rough ▁reconst ruction ▁of ▁its ▁brain ▁and ▁inner ▁ear ▁structure . ▁Over all , ▁the ▁brain ▁was ▁very ▁small ▁relative ▁to ▁body ▁size , ▁but ▁otherwise ▁similar ▁to ▁many ▁other ▁non - co el u ros aur ian ▁ther op ods , ▁with ▁a ▁very ▁conserv ative ▁form ▁closer ▁to ▁modern ▁cro cod ili ans ▁than ▁to ▁birds . ▁One ▁difference ▁between ▁Maj ung as aur us ▁and ▁other ▁ther op ods ▁was ▁its ▁smaller ▁flo cc ulus , ▁a