Centered on the studies, R
The first three character says reinforce brand new articulations between the face issue of mouth musculature (Schumacher, 1973 ). The region of your abducens guts foramen was to start with hypothesized because the a potential synapomorphy supporting a crocodylomorph + aetosaur clade personal regarding almost every other pseudosuchians (Gower, 2002 ), but more recent phylogenetic analyses, together with ours, strongly recommend so it apomorphy progressed twice-shortly after for the aetosauriforms as soon as inside the crocodylomorphs. not quantified contained in this research, an effective dorsoventrally thickened head rooftop (i.elizabeth., nasals, frontals, and you will parietals) is additionally mutual by Roentgen. callenderi, erpetosuchids, and you may aetosaurs.
callenderi and aetosaurs show similarities regarding the proportions of the brand new hindlimb so you’re able to forelimb and model of the latest humerus and you may proximal foot issue, though men and women similarities just weren’t unambiguous synapomorphies. Especially, R. callenderi and aetosaurs express a reduced distance prior to the fresh humerus, and you will a concave posterior body of your calcaneal tuber, regardless of if this type of apomorphies keeps an even more https://datingranking.net/tr/apex-inceleme/ common distribution among Archosauria. R. callenderi and aetosaurs express middle trunk area vertebrae with diapophyses and you will parapophyses you to grow sideways where each other articulations originate towards the a great transverse procedure. Large aetosaurs (elizabeth.grams., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert mais aussi al., 2010 ) expand these methods sideways and you may partly otherwise completely coossify these to new particular rib to make a general dorsal body. New extension of transverse techniques for the Roentgen. callenderi and other aetosaurs seems to correlate on the visibility out of greater osteoderms. While doing so, but not quantified on phylogenetic study, R. callenderi and aetosaurs display a beneficial hypertrophied last trochanter of your femur, a characteristics state in past times sensed novel so you can aetosaurs (Quick, 2002 ).
The brand new parallels of one’s osteoderms out-of R. callenderi, aetosaurs, and you will An excellent. geoffreyi promote more assistance for the the newest clade, Aetosauriformes, demonstrated right here. callenderi, A beneficial. geoffreyi, and you may aetosaurs share the next carapacial synapomorphies (Figure several): (a) the existence of horizontal osteoderms at the very least regarding the trunk area (along with present in erpetosuchids); (b) an enthusiastic anterior club on the anterior side of the brand new osteoderm (including distributed to Age. olseni and you can crocodylomorphs); (c) good ventral carapace from the trunk; and you can (d) presacral dorsal osteoderms which might be wider than enough time. Wrapped in an entire band of paramedian, lateral, and you will ventral osteoderms, this new osteoderm arrangements from R. callenderi and An effective. geoffreyi one another resemble that of aetosaurs ( ).
Postcranially, R
Clearly there is still an enormous morphological pit between the skeletal morphology regarding R. callenderi and therefore of aetosaurian members of Aetosauriformes considering the large service on monophyly of all most other aetosaurs inside study and others (elizabeth.grams., ). Pursuing the divergence from Roentgen. callenderi + A great. geoffreyi and you will aetosaurs off their prominent ancestor, the newest head, carapace, and you will postcranial skeleton out-of aetosaurs undergone further evolutionary changes according to most other diapsids. The latest skulls off aetosaurs exhibit adjustment of one’s prior part of the newest skull by the elongating new premaxillae to make a keen anteroposteriorly enlarged exterior naris; the latest supratemporal fenestra turned laterally oriented, plus in new mandible brand new anterior dentition try smaller and you will turned “slipper-shaped” (Desojo mais aussi al., 2013 ; Reyes ainsi que al., 2020 ). Brand new carapace regarding aetosaurs became far more detailed, level probably the ventral portion of the tail (Heckert ainsi que al., 2010 ). The brand new postcranial bones is subsequent modified to compensate towards hefty carapace that have hypertrophied limb points (like ankylosaur dinosaurs) including the sturdy humeri and tibiae including an excellent obvious olecranon procedure for the newest ulna. Which have an around identical armor carapace could it be no surprise such same issues in Roentgen. callenderi are particularly similar inside their level of robustness.