A little ridge toward posterodorsal margin of your dorsal procedure articulates when you look at the a slot towards anteroventral osal. Posterior compared to that you will find a low fossa that’s overlapped from the anterolateral edge of the quadrate. The fresh new ventral tip of your own fossa is the prior edging from the newest quadrate foramen. The new posteroventral part of quadratojugal versions a continuous epidermis which have the new horizontal part of the quadrate, fitted towards the an effective fossa for the horizontal margin of second ability. New quadratojugal forms brand new posteroventral area of the horizontal temporary fenestra in the Roentgen. callenderi.
Anteriorly, brand new tapering rear procedure for the latest jugal inserts into a triangular slot on lateral surface of your own quadratojugal (Profile 4o). This kind of articulation is also found in P. kirkpatricki (TTU P-9002; Weinbaum, 2011 : fig. 13). A similar articulation build occurs in A good. ferratus and you will Paratypothorax andressorum (SMNS 19003; Schoch & Desojo, 2016 ), where a sub-triangular rear process of the latest jugal inserts with the a keen embayment into the the new anteroventral margin of your quadratojugal ventral into the horizontal temporary fenestra. Within these taxa, a little anteroventral process of the fresh new quadratojugal underlaps the brand new jugal (Schoch, 2007 ). An identical articulation along with occurs in brand new doswelliid archosauriform Rugarhychos sixmilensis (Wynd ainsi que al., 2020 ) recommending that it reputation state is generally plesiomorphic.
Brand new postorbital try a beneficial triradiate bone with an ornamented lateral body and about three line of procedure (Figures 4q, r). The anterodorsal processes has actually a definite horizontal position one receives the ventral and you may rear part of the postfrontal, the brand new posterodorsal techniques articulates toward anterodorsal osal, and the ventral processes matches to your a position on the prior and you can medial facial skin of your own posterodorsal procedure for the jugal. This new dorsal margin is broadly rounded and it has a distinct ridge that versions the new anterolateral margin of your own supratemporal fenestra. The newest curved anterior margin possess a weakened ridge, building the fresh posterodorsal margin of your own orbit. The brand new good dorsal ridge, and that extends posteriorly onto the squamosal, is not found in aetosaurs (age.g., Desmatosuchus smalli, TTU P9024-; T. coccinarum, PEFO 38001). It is very probably missing in the A good. geoffreyi (UCMP 156046), which does not maintain this new postorbital, but has new squamosal and you may lacks so it ridge. D. grallator possess the same dorsal ridge with the postorbital and you may squamosal (Sues et al., 2003 ).
The new anteroventral portion of the squamosal and posterodorsal procedure of the brand new jugal almost matches along side posteroventral side of brand new postorbital, nearly leaving out so it element regarding contribution regarding the horizontal temporal fenestra (Profile 3b). It near exclusion isn’t unique so you’re able to R. callenderi as it together with happens in P. kirkpatricki (Weinbaum, 2011 ), therefore the contribution may be very minimal during the aetosaurs (elizabeth.g., An effective. ferratus) together with crocodylomorph D. grallator (Nesbitt, 2011 ; Schoch, 2007 ).
The fresh new triangular function in the first place translated as lacrimal by the Parker ainsi que al. ( 2005 : fig. 2) is actually a remote postorbital retrieved with the skull out-of PEFO 33787. The fresh new anterior part of the leftover squamosal within the Parker ainsi que al. ( 2005 : fig. 2b) is largely a keen articulated postorbital.
The fresh quadrate is actually maintained for the PEFO 34561 (Profile 4s, t), therefore the quadrates is actually blurred during the PEFO 38609 (Data 3c, d). This new quadrate body’s a good, dorsoventrally high bones one to lacks fenestration and you can slopes posteroventrally, varying on symptom in shuvosaurids and you can aetosaurs where in actuality the quadrate mountains anteroventrally (Nesbitt, 2007 ).
A deep dorsoventrally based fossa is present posterolateral towards horizontal flange (Shape 4s). New pterygoid flange isn’t really-kept inside the PEFO 34561, nevertheless the thickened foot of the flange happens off to the right ability merely dorsal for the medial condyle over the medial border of your own quadrate.