The original about three profile claims strengthen the fresh articulations between the facial aspects associated with mouth musculature (Schumacher, 1973 ). The spot of one's abducens nerve foramen try in the first place hypothesized as the a prospective synapomorphy help a good crocodylomorph + aetosaur clade personal from most other pseudosuchians (Gower, 2002 ), but newer phylogenetic analyses, as well as ours, highly recommend it apomorphy changed at least twice-shortly after into the aetosauriforms and once within the crocodylomorphs. However quantified within investigation, a good dorsoventrally thickened skull rooftop (i.e., nasals, frontals, and you may parietals) is even common by Roentgen. callenderi, erpetosuchids, and aetosaurs.
callenderi and you will aetosaurs show similarities on the dimensions of the fresh new hindlimb so you can forelimb and you can model of the newest humerus and you may proximal ankle elements, though men and women similarities just weren't unambiguous synapomorphies. Especially, R. callenderi and you can aetosaurs share a shortened distance in line with the fresh new humerus, and you will an effective concave posterior epidermis of your calcaneal tuber, even when these apomorphies enjoys a far more prevalent delivery certainly Archosauria. Roentgen. callenderi and you will aetosaurs express middle trunk area spinal vertebrae having diapophyses and you will parapophyses that grow laterally where each other articulations originate into the an effective transverse process. Higher aetosaurs (age.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert mais aussi al., 2010 ) grow these procedures laterally and you may partly or completely coossify them to the newest particular rib to form a standard dorsal facial skin. The fresh new expansion of the transverse techniques within the Roentgen. callenderi or any other aetosaurs generally seems to associate with the presence from large osteoderms. As well, however quantified regarding the phylogenetic investigation, R. callenderi and you may aetosaurs show a hypertrophied next trochanter of your femur, a character state in the past felt unique in order chatroulette ekЕџi to aetosaurs (Short, 2002 ).
The parallels of osteoderms of Roentgen. callenderi, aetosaurs, and you may An excellent. geoffreyi provide additional support towards the this new clade, Aetosauriformes, demonstrated right here. callenderi, An excellent. geoffreyi, and you may aetosaurs share the following carapacial synapomorphies (Shape several): (a) the presence of horizontal osteoderms no less than from the trunk area (including found in erpetosuchids); (b) an enthusiastic anterior club on the anterior side of new osteoderm (together with shared with Elizabeth. olseni and you will crocodylomorphs); (c) a great ventral carapace on the trunk area; and (d) presacral dorsal osteoderms that are wider than much time. Wrapped in a full gang of paramedian, horizontal, and ventral osteoderms, the osteoderm agreements out of R. callenderi and you will A. geoffreyi each other be like regarding aetosaurs ( ).
Clearly there's nonetheless a big morphological pit within skeletal morphology from Roentgen. callenderi and that regarding aetosaurian people in Aetosauriformes considering the large help for the monophyly of all the almost every other aetosaurs within this studies although some (age.grams., ). Following the divergence off Roentgen. callenderi + A good. geoffreyi and you may aetosaurs off their popular predecessor, the newest skull, carapace, and you will postcranial bones away from aetosaurs undergone after that evolutionary transformations relative to most other diapsids. Brand new skulls from aetosaurs display changes of your anterior portion of this new head because of the elongating this new premaxillae in order to create an enthusiastic anteroposteriorly enlarged exterior naris; this new supratemporal fenestra became sideways situated, plus the fresh new mandible the fresh new prior dentition is actually quicker and you will turned “slipper-shaped” (Desojo et al., 2013 ; Reyes et al., 2020 ). The latest carapace away from aetosaurs turned into significantly more thorough, coating probably the ventral portion of the tail (Heckert mais aussi al., 2010 ). This new postcranial bones was further modified to compensate towards heavier carapace that have hypertrophied limb issue (exactly like ankylosaur dinosaurs) like the powerful humeri and you will tibiae and good obvious olecranon procedure for the brand new ulna. With a practically the same armor carapace would it be not surprising that this type of exact same issue into the Roentgen. callenderi are extremely similar within degree of robustness.