Based on our data, R
The original around three character claims bolster the latest articulations between the face issues with the chin musculature (Schumacher, 1973 ). The location of your own abducens bravery foramen is to begin with hypothesized while the a possible synapomorphy supporting good crocodylomorph + aetosaur clade private regarding almost every other pseudosuchians (Gower, 2002 ), however, newer phylogenetic analyses, plus ours, suggest this apomorphy advanced at least twice-once when you look at the aetosauriforms and once when you look at the crocodylomorphs. Yet not quantified in this studies, good dorsoventrally thickened skull rooftop (we.elizabeth., nasals, frontals, and you will parietals) is even shared because of the R. callenderi, erpetosuchids, and you can aetosaurs.
callenderi and aetosaurs share parallels regarding size of the fresh hindlimb so you can forelimb and you can form of the latest humerus and you will proximal ankle factors, even if those people similarities weren’t unambiguous synapomorphies. Specifically, R. callenderi and aetosaurs express a shortened distance according to the fresh new humerus, and you will a good concave posterior body of your own calcaneal tuber, even if this type of apomorphies features a far more widespread distribution certainly Archosauria. Roentgen. callenderi and you may aetosaurs display center trunk spinal vertebrae which have diapophyses and you can parapophyses that grow laterally where one another articulations originate towards the a beneficial transverse process. Higher aetosaurs (elizabeth.grams., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert et al., 2010 ) grow these methods sideways and you will partly otherwise completely coossify these to the latest particular rib to make a standard dorsal epidermis. The newest extension of the transverse techniques in the Roentgen. callenderi and other aetosaurs appears to correlate towards blackdatingforfree.com visibility of large osteoderms. At the same time, however quantified on the phylogenetic data, Roentgen. callenderi and aetosaurs show a great hypertrophied next trochanter of femur, a character condition in earlier times thought book in order to aetosaurs (Quick, 2002 ).
The new parallels of your own osteoderms out-of R. callenderi, aetosaurs, and you may A. geoffreyi offer a lot more service to the this new clade, Aetosauriformes, demonstrated right here. callenderi, A good. geoffreyi, and aetosaurs express next carapacial synapomorphies (Shape twelve): (a) the clear presence of lateral osteoderms at the very least regarding the trunk part (plus present in erpetosuchids); (b) a keen anterior bar found on the prior side of the fresh new osteoderm (together with distributed to E. olseni and crocodylomorphs); (c) a great ventral carapace regarding trunk area; and you will (d) presacral dorsal osteoderms which might be broad than simply much time. Wrapped in a complete gang of paramedian, lateral, and ventral osteoderms, the newest osteoderm arrangements out-of R. callenderi and A great. geoffreyi one another resemble regarding aetosaurs ( ).
Obviously there is certainly nevertheless a giant morphological gap within skeletal morphology from R. callenderi hence regarding aetosaurian people in Aetosauriformes given the highest support towards monophyly of all most other aetosaurs contained in this study while some (elizabeth.grams., ). Adopting the divergence from Roentgen. callenderi + An effective. geoffreyi and aetosaurs using their preferred predecessor, the latest skull, carapace, and you can postcranial skeleton away from aetosaurs underwent subsequent evolutionary changes according to most other diapsids. The new skulls out-of aetosaurs exhibit variations of your anterior portion of the head by the elongating the new premaxillae to create a keen anteroposteriorly expanded additional naris; this new supratemporal fenestra turned laterally mainly based, and in the new mandible new prior dentition is smaller and you will turned into “slipper-shaped” (Desojo ainsi que al., 2013 ; Reyes ainsi que al., 2020 ). The fresh carapace away from aetosaurs turned more comprehensive, level possibly the ventral part of the tail (Heckert et al., 2010 ). New postcranial skeleton is further changed to pay to the big carapace with hypertrophied limb aspects (exactly like ankylosaur dinosaurs) for instance the powerful humeri and you may tibiae including a great pronounced olecranon process of this new ulna. That have a very nearly identical armor carapace is-it no wonder these types of same elements when you look at the R. callenderi are particularly equivalent within degree of robustness.