▁the ▁level ▁of ▁the ▁fourth ▁tro chan ter ▁ ▁Disc overy ▁▁▁ ▁San ju ans aur us ▁was ▁named ▁and ▁described ▁in ▁ 2 0 1 0 ▁by ▁Oscar ▁Al co ber ▁and ▁Ric ardo ▁Mart ine z . ▁The ▁type ▁species ▁was ▁named ▁S . ▁g ord illo i ▁after ▁Ra ul ▁G ord illo , ▁the ▁head ▁foss il ▁prepar ator ▁and ▁artist ▁of ▁the ▁San ▁Juan ▁Museum . ▁ ▁It ▁is ▁known ▁from ▁and ▁based ▁on ▁an ▁associated ▁and ▁partially ▁art ic ulated ▁partial ▁ske leton ▁( P VS J   6 0 5 ) ▁consisting ▁of ▁a ▁j aw ▁fragment , ▁most ▁of ▁the ▁verte br al ▁column ▁from ▁the ▁axis ▁to ▁the ▁anterior ▁tail , ▁the ▁shoulder ▁bl ades , ▁an ▁ul na , ▁part ▁of ▁the ▁pel vis , ▁most ▁of ▁the ▁long ▁b ones ▁of ▁the ▁legs , ▁and ▁a ▁few ▁other ▁b ones . ▁ ▁Pale o ec ology ▁ ▁Pro ven ance ▁and ▁occurrence ▁ ▁San ju ans aur us ▁hol ot ype ▁spec imen ▁P VS J   6 0 5 ▁was ▁discovered ▁in ▁ 1 9 9 4 , ▁in ▁gray - green ▁sand stone ▁of ▁the ▁Can cha ▁de ▁B oc as ▁Member ▁near ▁the ▁base ▁of ▁the ▁I sch ig ual asto ▁Form ation , ▁in ▁I sch ig ual asto ▁Provin cial ▁Park ▁in ▁San ▁Juan , ▁Argentina . ▁This ▁horizon ▁dates ▁to ▁approximately ▁ 2 3 1 . 4   Ma , ▁during ▁the ▁late ▁Car n ian