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six.dos R. callenderi, Revueltosaurus-such as for instance taxa, as well as the isolated tooth state

six.dos R. callenderi, Revueltosaurus-such as for instance taxa, as well as the isolated tooth state

Centered on the studies, Roentgen

The first about three character states bolster the articulations between your face facets of the jaw musculature (Schumacher, 1973 ). The location of your abducens bravery foramen try in the first place hypothesized due to the fact a potential synapomorphy help an effective crocodylomorph + aetosaur clade personal out-of most other pseudosuchians (Gower, 2002 ), however, more recent phylogenetic analyses, along with ours, suggest so it apomorphy advanced at least twice-after in aetosauriforms and once when you look at the crocodylomorphs. Yet not quantified in this study, an excellent dorsoventrally thickened skull rooftop (we.age., nasals, frontals, and you may parietals) is also shared of the Roentgen. callenderi, erpetosuchids, and aetosaurs.

callenderi and you may aetosaurs share parallels on size of brand new hindlimb so you can forelimb and model of the latest humerus and you can proximal foot elements, in the event those parallels just weren’t unambiguous synapomorphies. Particularly, R. callenderi and you can aetosaurs express a shortened distance prior to new humerus, and you will an excellent concave rear surface of your own calcaneal tuber, even when these types of apomorphies possess a prevalent distribution certainly one of Archosauria. R. callenderi and you can aetosaurs show center trunk area vertebrae having diapophyses and you can parapophyses one develop laterally in which each other articulations originate with the a transverse processes. Large aetosaurs (e.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert et al., 2010 ) expand these processes sideways and you may partially otherwise entirely coossify them to this new particular rib to make a standard dorsal epidermis. The newest expansion of one’s transverse processes inside the R. callenderi or other aetosaurs seems to correlate to the exposure off greater osteoderms. Simultaneously, but not quantified regarding phylogenetic studies, R. callenderi and you will aetosaurs express a great hypertrophied last trochanter of the femur, a character condition previously felt unique to aetosaurs (Brief, 2002 ).

The parallels of your own osteoderms out of Roentgen. callenderi, aetosaurs, and you can A great. geoffreyi give additional support towards the the newest clade, Aetosauriformes, exhibited right here. callenderi, An excellent. geoffreyi, and you can aetosaurs display another carapacial synapomorphies (Profile several): (a) the current presence of horizontal osteoderms at least in the trunk area part (as well as found in erpetosuchids); (b) a keen prior bar found on the prior side of the brand new osteoderm (in addition to distributed to Age. olseni site köprüsü and you will crocodylomorphs); (c) a beneficial ventral carapace regarding the trunk area; and (d) presacral dorsal osteoderms that are large than enough time. Covered with a full band of paramedian, horizontal, and you may ventral osteoderms, new osteoderm plans of R. callenderi and you will Good. geoffreyi one another resemble that of aetosaurs ( ).

Postcranially, R

Demonstrably you will find nevertheless a massive morphological gap within skeletal morphology off R. callenderi which out-of aetosaurian members of Aetosauriformes because of the higher support on monophyly of the many most other aetosaurs inside data while some (elizabeth.grams., ). Following the divergence off R. callenderi + A great. geoffreyi and you can aetosaurs from their prominent ancestor, the brand new head, carapace, and postcranial skeleton regarding aetosaurs undergone then evolutionary transformations prior to other diapsids. Brand new skulls from aetosaurs showcase adjustment of one’s anterior portion of the fresh skull by elongating the fresh premaxillae in order to create an enthusiastic anteroposteriorly expanded additional naris; the newest supratemporal fenestra became sideways centered, plus the mandible this new anterior dentition is faster and you will turned “slipper-shaped” (Desojo mais aussi al., 2013 ; Reyes mais aussi al., 2020 ). The fresh carapace away from aetosaurs became a lot more detailed, level even the ventral portion of the tail (Heckert et al., 2010 ). The new postcranial skeleton are after that altered to pay on the heavy carapace that have hypertrophied limb factors (the same as ankylosaur dinosaurs) like the robust humeri and you may tibiae and additionally an effective pronounced olecranon process of the newest ulna. Having an around similar armour carapace is-it no wonder these same points inside R. callenderi have become equivalent within level of robustness.

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