Predicated on our research, R
The initial around three profile claims strengthen the brand new articulations amongst the facial issues from the chin musculature (Schumacher, 1973 ). The spot of your abducens bravery foramen is in the first place hypothesized as a potential synapomorphy support an excellent crocodylomorph + aetosaur clade private from most other pseudosuchians (Gower, 2002 ), however, new phylogenetic analyses, including ours, strongly recommend it apomorphy evolved at least twice-just after during the aetosauriforms and when in crocodylomorphs. But not quantified within analysis, a good dorsoventrally thickened skull rooftop (i.age., nasals, frontals, and you will parietals) is additionally mutual by Roentgen. callenderi, erpetosuchids, and you may aetosaurs.
callenderi and you can aetosaurs express parallels on proportions of new hindlimb so you're able to forelimb and you can form of this new humerus and proximal foot elements, although those individuals similarities weren't unambiguous synapomorphies. Particularly, R. callenderi and you will aetosaurs share a reduced radius according to the brand new humerus, and a good blendr hesap silme concave posterior facial skin of your calcaneal tuber, even if such apomorphies keeps a far more widespread shipping certainly Archosauria. Roentgen. callenderi and you will aetosaurs express center trunk area vertebrae having diapophyses and you can parapophyses you to develop laterally where each other articulations originate toward good transverse procedure. Large aetosaurs (elizabeth.grams., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert mais aussi al., 2010 ) build these procedures sideways and you may partly or totally coossify these to the respective rib in order to create an over-all dorsal skin. The fresh extension of your transverse procedure in R. callenderi or any other aetosaurs appears to associate towards the presence out of wide osteoderms. Likewise, although not quantified from the phylogenetic studies, R. callenderi and aetosaurs display good hypertrophied last trochanter of one's femur, a nature state in the past believed unique to aetosaurs (Short, 2002 ).
The new similarities of your own osteoderms from Roentgen. callenderi, aetosaurs, and you will A. geoffreyi promote most help to your the new clade, Aetosauriformes, exhibited right here. callenderi, Good. geoffreyi, and you may aetosaurs display another carapacial synapomorphies (Shape 12): (a) the presence of horizontal osteoderms about throughout the trunk part (along with found in erpetosuchids); (b) a keen anterior club on the anterior edge of brand new osteoderm (and distributed to Age. olseni and you can crocodylomorphs); (c) a good ventral carapace throughout the trunk area; and you can (d) presacral dorsal osteoderms which can be broad than simply enough time. Covered with the full band of paramedian, horizontal, and you will ventral osteoderms, new osteoderm arrangements from R. callenderi and you may A beneficial. geoffreyi both end up like that of aetosaurs ( ).
Postcranially, Roentgen
Demonstrably you will find nevertheless a massive morphological gap between the skeletal morphology off R. callenderi and that regarding aetosaurian members of Aetosauriformes considering the higher support into monophyly of all of the other aetosaurs inside investigation although some (e.grams., ). Adopting the divergence from Roentgen. callenderi + A good. geoffreyi and you can aetosaurs off their preferred predecessor, the head, carapace, and postcranial skeleton out of aetosaurs undergone after that evolutionary changes according to most other diapsids. The new skulls from aetosaurs display improvement of prior part of brand new head by the elongating the fresh premaxillae to form a keen anteroposteriorly expanded exterior naris; the brand new supratemporal fenestra turned laterally created, plus in the new mandible the prior dentition try less and you may became “slipper-shaped” (Desojo mais aussi al., 2013 ; Reyes et al., 2020 ). The carapace of aetosaurs became much more extensive, coating possibly the ventral portion of the end (Heckert et al., 2010 ). The new postcranial bones is subsequent changed to compensate on hefty carapace with hypertrophied limb aspects (similar to ankylosaur dinosaurs) such as the robust humeri and you may tibiae and additionally a great pronounced olecranon procedure for the new ulna. Having a nearly similar armor carapace could it possibly be no surprise these types of same issue in the Roentgen. callenderi are comparable within their amount of robustness.