▁Stage ▁of ▁the ▁Late ▁Tri ass ic . ▁ ▁Fa una ▁and ▁habitat ▁▁▁ ▁In ▁the ▁I sch ig ual asto ▁Form ation , ▁din osa urs ▁constit uted ▁only ▁about ▁ 6 % ▁of ▁the ▁total ▁number ▁of ▁foss ils , ▁but ▁by ▁the ▁end ▁of ▁the ▁Tri ass ic ▁Period , ▁din osa urs ▁were ▁becoming ▁the ▁dominant ▁large ▁land ▁animals , ▁and ▁the ▁other ▁arch osa urs ▁and ▁syn aps ids ▁decl ined ▁in ▁variety ▁and ▁number . ▁ ▁Studies ▁suggest ▁that ▁the ▁pale o environment ▁of ▁the ▁I sch ig ual asto ▁Form ation ▁was ▁a ▁vol can ically ▁active ▁flo od plain ▁covered ▁by ▁for ests ▁and ▁subject ▁to ▁strong ▁season al ▁ra inf alls . ▁The ▁climate ▁was ▁mo ist ▁and ▁warm , ▁though ▁subject ▁to ▁season al ▁variations . ▁Veg et ation ▁consisted ▁of ▁f ern s ▁( C lad oph le bis ), ▁hor set ails , ▁and ▁giant ▁con if ers ▁( Pro to j uni per ox yl on ). ▁These ▁plants ▁formed ▁high land ▁for ests ▁along ▁the ▁banks ▁of ▁rivers . ▁San ju ans aur us ▁lived ▁in ▁the ▁j ung les ▁of ▁Late ▁Tri ass ic ▁South ▁America ▁alongside ▁early ▁din osa urs , ▁E or apt or , ▁Her rer as aur us , ▁Ch rom og is aur us , ▁and ▁Pan ph ag ia , ▁as ▁well ▁as ▁Sau ros uch us , ▁a ▁giant ▁land - l iving ▁ra uis uch ian ▁( a ▁quad ru