▁distinct ive ▁an atom ical ▁features ▁that ▁are ▁unique ▁to ▁a ▁given ▁organ ism ▁or ▁group . ▁ ▁The ▁cla de ▁Di pl od oc idae ▁is ▁distinguished ▁based ▁on ▁the ▁following ▁characteristics : ▁ ▁n ares : ▁the ▁external ▁n ares ▁face ▁d ors ally ; ▁and ▁the ▁intern arial ▁bar ▁is ▁absent ▁ ▁jug al : ▁the ▁jug al ▁forms ▁a ▁substantial ▁part ▁of ▁the ▁ca ud ov ent ral ▁margin ▁of ▁the ▁ant orb ital ▁fen estra ▁ ▁quadr ato j ug al ▁processes : ▁the ▁angle ▁between ▁the ▁ro str al ▁quadr ato j ug al ▁process ▁and ▁the ▁d ors al ▁quadr ato j ug al ▁process ▁is ▁approximately ▁ 1 3 0 ° ▁ ▁par oc cip ital ▁process : ▁the ▁dist al ▁end ▁of ▁the ▁par oc cip ital ▁process ▁is ▁rounded ▁and ▁tongue - like ▁in ▁shape ▁ ▁par as phen oid : ▁the ▁par as phen oid ▁ro str um ▁is ▁a ▁later ally ▁com pressed , ▁thin ▁sp ike ▁and ▁is ▁lack ing ▁the ▁longitud inal ▁d ors al ▁gro ove ▁ ▁p tery go id : ▁the ▁e ct opter y go id ▁process ▁of ▁the ▁p tery go id ▁is ▁located ▁below ▁the ▁ant orb ital ▁fen estra , ▁and ▁is ▁reduced , ▁such ▁that ▁it ▁is ▁not ▁visible ▁below ▁the ▁vent ral ▁margin ▁of ▁the ▁sk ull ▁when ▁exam ined ▁in ▁later al ▁view ; ▁also ▁the ▁bread th ▁of ▁the ▁main ▁body ▁of ▁the ▁p tery go id ▁at