six.dos R. callenderi, Revueltosaurus-like taxa, in addition to remote tooth situation

six.dos R. callenderi, Revueltosaurus-like taxa, in addition to remote tooth situation

Based on our analysis, Roentgen

The original three character says reinforce the latest articulations amongst the facial elements associated with mouth musculature (Schumacher, 1973 ). The spot of abducens guts foramen try originally hypothesized since the a potential synapomorphy help a good crocodylomorph + aetosaur clade exclusive regarding most other pseudosuchians (Gower, 2002 ), however, newer phylogenetic analyses, and ours, highly recommend so it apomorphy changed at least twice-immediately after in aetosauriforms and once in crocodylomorphs. Although not quantified inside investigation, a great dorsoventrally thickened skull rooftop (we.age., nasals, frontals, and parietals) is also shared because of the R. callenderi, erpetosuchids, and you can aetosaurs.

callenderi and you will aetosaurs express similarities on the dimensions of the latest hindlimb in order to forelimb and you can model of the fresh new humerus and you can proximal ankle aspects, even when those people similarities weren’t unambiguous synapomorphies. Especially, Roentgen. callenderi and you will aetosaurs show a reduced radius in accordance with new humerus, and you may a great concave posterior facial skin of your own calcaneal tuber, although these types of apomorphies possess a very widespread shipping certainly Archosauria. R. callenderi and you will aetosaurs express center trunk backbone having diapophyses and you can parapophyses you to definitely build laterally in which both articulations originate on the a beneficial transverse techniques. High aetosaurs (age.grams., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert ainsi que al., 2010 ) grow these methods laterally and you will partly or entirely coossify them to the fresh new respective rib to create a standard dorsal epidermis. The fresh new extension of one’s transverse processes inside R. callenderi and other aetosaurs seems to associate with the presence of broad osteoderms. Simultaneously, although not quantified regarding phylogenetic data, Roentgen. callenderi and you can aetosaurs display a hypertrophied next trochanter of femur, a characteristics condition before noticed unique in order to aetosaurs (Quick, 2002 ).

The parallels of osteoderms out of R. callenderi, aetosaurs, and you can A. geoffreyi promote even more assistance on this new clade, Aetosauriformes, shown right here. callenderi, A beneficial. geoffreyi, and aetosaurs show the following carapacial synapomorphies (Figure twelve): (a) the existence of horizontal osteoderms at the least from the trunk area (and contained in erpetosuchids); (b) a keen anterior club located on the anterior edge of new osteoderm (as well as distributed to E. olseni and crocodylomorphs); (c) a great ventral carapace about trunk; and (d) presacral dorsal osteoderms that are greater than enough time. Wrapped in a full band of paramedian, lateral, and you may ventral osteoderms, the newest osteoderm arrangements from Roentgen. callenderi and you will A. geoffreyi both end up like that of aetosaurs ( ).

Postcranially, R

Certainly there can be still a huge morphological pit between the skeletal morphology out-of Roentgen. callenderi which out of aetosaurian members of Aetosauriformes because of the large help for the monophyly of the many other aetosaurs within analysis and others (elizabeth.grams., ). Following the divergence out-of Roentgen. callenderi + A great. geoffreyi and you can aetosaurs off their prominent ancestor, the fresh skull, carapace, and you can postcranial bones of aetosaurs underwent next evolutionary changes relative to most other diapsids. The newest skulls from aetosaurs display improvement of your prior percentage of the head from the elongating the premaxillae to create an anteroposteriorly enlarged additional naris; brand new supratemporal fenestra turned sideways established, plus in brand new mandible the new prior dentition is faster and you can turned “slipper-shaped” (Desojo ainsi que al., 2013 ; Reyes ainsi que al., 2020 ). The new carapace regarding aetosaurs turned into significantly more detailed, covering perhaps the ventral portion of the tail (Heckert ainsi que al., 2010 ). Brand new postcranial bones is next changed to compensate to the big carapace having hypertrophied limb factors (the same as ankylosaur dinosaurs) like the sturdy humeri and you will tibiae including a great pronounced olecranon procedure for the fresh ulna. Which have an around identical armour carapace is it not surprising these types of exact same issues for the R. callenderi are similar inside their degree of robustness.

Leave a Reply

Your email address will not be published. Required fields are marked *