six.dos Roentgen. callenderi, Revueltosaurus-such as for example taxa, therefore the isolated enamel problem

Considering our data, R

The original three character states reinforce new articulations involving the face facets from the mouth musculature (Schumacher, 1973 ). The location of abducens courage foramen are to begin with hypothesized once the a possible synapomorphy support a beneficial crocodylomorph + aetosaur clade private out-of chat avenue almost every other pseudosuchians (Gower, 2002 ), but new phylogenetic analyses, in addition to ours, strongly recommend which apomorphy evolved at least twice-just after during the aetosauriforms and when when you look at the crocodylomorphs. not quantified within this study, a good dorsoventrally thickened skull roof (we.age., nasals, frontals, and parietals) is even shared from the Roentgen. callenderi, erpetosuchids, and you will aetosaurs.

callenderi and you may aetosaurs share parallels about proportions of the new hindlimb in order to forelimb and you will model of the latest humerus and proximal foot issue, regardless of if people parallels were not unambiguous synapomorphies. Specifically, Roentgen. callenderi and aetosaurs share a shortened radius in line with the fresh new humerus, and you will an excellent concave rear skin of your own calcaneal tuber, even if these apomorphies have a far more prevalent delivery certainly one of Archosauria. R. callenderi and you may aetosaurs display middle trunk area vertebrae having diapophyses and you will parapophyses one to grow laterally where each other articulations originate on a transverse techniques. Highest aetosaurs (e.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert ainsi que al., 2010 ) build these procedures laterally and you may partially or entirely coossify these to the fresh new respective rib to create a standard dorsal body. The fresh expansion of the transverse process into the Roentgen. callenderi or other aetosaurs appears to associate to the visibility off greater osteoderms. Likewise, not quantified regarding phylogenetic analysis, R. callenderi and you can aetosaurs display an excellent hypertrophied 4th trochanter of femur, a nature county in the past sensed unique to aetosaurs (Small, 2002 ).

The new parallels of osteoderms of Roentgen. callenderi, aetosaurs, and A beneficial. geoffreyi provide additional assistance for the the fresh new clade, Aetosauriformes, shown here. callenderi, A great. geoffreyi, and you can aetosaurs show the following carapacial synapomorphies (Profile a dozen): (a) the current presence of horizontal osteoderms at the least in the trunk area (as well as within erpetosuchids); (b) a keen prior bar found on the anterior side of brand new osteoderm (including distributed to E. olseni and you can crocodylomorphs); (c) a beneficial ventral carapace regarding trunk area; and you can (d) presacral dorsal osteoderms that are wider than much time. Wrapped in an entire gang of paramedian, horizontal, and ventral osteoderms, the latest osteoderm plans out-of R. callenderi and you can Good. geoffreyi one another wind up as regarding aetosaurs ( ).

Postcranially, R

Clearly there can be however a giant morphological pit involving the skeletal morphology of R. callenderi which away from aetosaurian members of Aetosauriformes because of the higher service into monophyly of the many other aetosaurs in this studies although some (elizabeth.g., ). Adopting the divergence away from Roentgen. callenderi + Good. geoffreyi and aetosaurs off their well-known ancestor, this new skull, carapace, and you can postcranial skeleton of aetosaurs underwent next evolutionary changes relative to other diapsids. The new skulls away from aetosaurs display modifications of your own anterior percentage of the brand new skull because of the elongating brand new premaxillae to create a keen anteroposteriorly enlarged additional naris; the brand new supratemporal fenestra turned into sideways centered, and also in new mandible this new prior dentition is actually faster and you can turned “slipper-shaped” (Desojo mais aussi al., 2013 ; Reyes et al., 2020 ). The newest carapace regarding aetosaurs became a great deal more comprehensive, coating even the ventral part of the end (Heckert ainsi que al., 2010 ). The latest postcranial bones are subsequent altered to compensate into the heavy carapace having hypertrophied limb aspects (the same as ankylosaur dinosaurs) including the robust humeri and you will tibiae and additionally an effective obvious olecranon procedure for the newest ulna. With a virtually the same armour carapace could it possibly be no wonder these types of exact same facets from inside the Roentgen. callenderi have become comparable inside their amount of robustness.