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six.dos Roentgen. callenderi, Revueltosaurus-such as for example taxa, together with separated tooth problem

six.dos Roentgen. callenderi, Revueltosaurus-such as for example taxa, together with separated tooth problem

According to our studies, R

The first three profile says bolster brand new articulations between the face issues for the jaw musculature (Schumacher, 1973 ). The spot of one’s abducens bravery foramen is actually in the first place hypothesized since a possible synapomorphy supporting a good crocodylomorph + aetosaur clade personal away from almost every other pseudosuchians (Gower, 2002 ), but new phylogenetic analyses, and additionally ours, recommend so it apomorphy progressed at least twice-immediately following into the aetosauriforms as soon as from inside the crocodylomorphs. But not quantified within data, an excellent dorsoventrally thickened skull rooftop (we.elizabeth., nasals, frontals, and parietals) is also mutual by R. callenderi, erpetosuchids, and you may aetosaurs.

callenderi and you can aetosaurs share similarities on size of this new hindlimb to help you forelimb and you will model of brand new humerus and you will proximal foot issues, though men and women parallels weren’t unambiguous synapomorphies. Particularly, R. callenderi and you may aetosaurs show a reduced radius in accordance with the fresh humerus, and you can a good concave posterior body of the calcaneal tuber, in the event such apomorphies have a very extensive shipment one of Archosauria. R. callenderi and you can aetosaurs share middle trunk area backbone having diapophyses and you can parapophyses one to build sideways in which both articulations originate to your good transverse techniques. Highest aetosaurs (elizabeth.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert ainsi que al., 2010 ) grow these procedures sideways and you may partially otherwise totally coossify them to the brand new respective rib to make an over-all dorsal skin. New expansion of one’s transverse processes within the Roentgen. callenderi or other aetosaurs appears to correlate on visibility out-of wider osteoderms. On top of that, but not quantified on the phylogenetic analysis, R. callenderi and you may aetosaurs express a good hypertrophied fourth trochanter of femur, a characteristics condition in the past noticed novel in order to aetosaurs (Small, 2002 ).

The new similarities of osteoderms of R. callenderi, aetosaurs, and you will A. geoffreyi bring even more assistance towards the newest clade, Aetosauriformes, displayed here. callenderi, A good. geoffreyi, and you may aetosaurs express the next carapacial synapomorphies (Profile a dozen): (a) the clear presence of horizontal osteoderms at least regarding trunk area part (also contained in erpetosuchids); (b) a keen anterior pub located on the prior edge of the osteoderm (as well as shared with E. olseni and you may crocodylomorphs); (c) good ventral carapace on trunk area; and you may (d) presacral dorsal osteoderms that will be broad than much time. Wrapped in an entire selection of paramedian, lateral, and you may ventral osteoderms, the osteoderm preparations from R. callenderi and you can A great. geoffreyi one another end up like that aetosaurs ( ).

Postcranially, R

Clearly discover nonetheless an enormous morphological gap within skeletal morphology off Roentgen. callenderi and this off aetosaurian people in Aetosauriformes considering the higher service to your monophyly of all of the most other aetosaurs in this analysis while some (elizabeth.g., ). Adopting the divergence away from Roentgen. callenderi + A beneficial. geoffreyi and aetosaurs off their popular predecessor, the latest skull, carapace, and you can postcranial bones away from aetosaurs underwent next evolutionary changes prior to most other diapsids. The skulls out-of aetosaurs display variations of your anterior portion of the latest head by elongating the premaxillae to create an anteroposteriorly enlarged exterior naris; the new supratemporal fenestra turned sideways oriented, and also in brand new mandible the prior dentition are shorter and you will turned “slipper-shaped” (Desojo ainsi que al., 2013 ; Reyes mais aussi al., 2020 ). The brand new carapace from aetosaurs turned into so much more detailed, coating probably the ventral part of the tail (Heckert mais aussi al., 2010 ). New postcranial bones try further altered to compensate on the big carapace that have hypertrophied limb issue (like ankylosaur dinosaurs) like the sturdy humeri and tibiae together with a great pronounced olecranon procedure of the ulna. Which have a very nearly the same armor carapace can it be no surprise these types of same issues inside the R. callenderi are particularly comparable inside their standard of robustness.

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