6.2 Roentgen. callenderi, Revueltosaurus-instance taxa, and also the remote enamel situation

6.2 Roentgen. callenderi, Revueltosaurus-instance taxa, and also the remote enamel situation

Predicated on our data, Roentgen

The original three character says strengthen the articulations involving the face facets regarding the chin musculature (Schumacher, 1973 ). The spot of your abducens bravery foramen was to begin with hypothesized as a possible synapomorphy help an effective crocodylomorph + aetosaur clade personal out of other pseudosuchians (Gower, 2002 ), but newer phylogenetic analyses, along with ours, highly recommend which apomorphy developed at least twice-after inside aetosauriforms as soon as into the crocodylomorphs. Although not quantified in this data, a good dorsoventrally thickened skull rooftop (i.elizabeth., nasals, frontals, and parietals) is additionally mutual of the Roentgen. callenderi, erpetosuchids, and aetosaurs.

callenderi and aetosaurs share parallels from the dimensions of the new hindlimb to forelimb and you can shape of the humerus and proximal ankle points, in the event those individuals similarities were not unambiguous synapomorphies. Particularly, Roentgen. callenderi and you will aetosaurs express a reduced distance according to the fresh humerus, and you may an excellent concave rear skin of your own calcaneal tuber, though these apomorphies possess a far more prevalent shipping among Archosauria. Roentgen. callenderi and you can aetosaurs express middle trunk backbone having diapophyses and you can parapophyses that expand laterally where one another articulations originate on the good transverse processes. High aetosaurs (age.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert et al., 2010 ) grow these processes laterally and you may partially otherwise totally coossify them to this new particular rib to create a general dorsal skin. This new expansion of one’s transverse process when you look at the Roentgen. callenderi or other aetosaurs generally seems to associate into the exposure off greater osteoderms. On top of that, yet babel y??kle not quantified on the phylogenetic study, Roentgen. callenderi and you will aetosaurs display a beneficial hypertrophied next trochanter of femur, a character state in the past sensed novel in order to aetosaurs (Brief, 2002 ).

The fresh similarities of your own osteoderms out of Roentgen. callenderi, aetosaurs, and you may A great. geoffreyi bring additional support for the the fresh new clade, Aetosauriformes, demonstrated here. callenderi, A beneficial. geoffreyi, and you can aetosaurs display the following carapacial synapomorphies (Contour a dozen): (a) the presence of lateral osteoderms about regarding the trunk area (including present in erpetosuchids); (b) an prior club located on the anterior edge of the brand new osteoderm (in addition to distributed to Elizabeth. olseni and you may crocodylomorphs); (c) a beneficial ventral carapace throughout the trunk area; and you can (d) presacral dorsal osteoderms that are wider than simply much time. Wrapped in a complete selection of paramedian, lateral, and you can ventral osteoderms, the newest osteoderm plans away from R. callenderi and you may An excellent. geoffreyi both wind up as regarding aetosaurs ( ).

Postcranially, R

Demonstrably you will find nonetheless a big morphological pit involving the skeletal morphology away from R. callenderi which out-of aetosaurian people in Aetosauriformes given the higher help on monophyly of all almost every other aetosaurs contained in this data while others (elizabeth.grams., ). After the divergence away from R. callenderi + An effective. geoffreyi and you may aetosaurs off their prominent predecessor, brand new head, carapace, and you can postcranial bones out-of aetosaurs undergone after that evolutionary transformations prior to other diapsids. The brand new skulls out-of aetosaurs exhibit variations of the anterior portion of brand new skull of the elongating the fresh premaxillae in order to create an anteroposteriorly increased exterior naris; new supratemporal fenestra became sideways mainly based, plus brand new mandible the fresh new prior dentition are shorter and turned into “slipper-shaped” (Desojo ainsi que al., 2013 ; Reyes mais aussi al., 2020 ). The new carapace out-of aetosaurs turned into way more thorough, layer probably the ventral portion of the end (Heckert ainsi que al., 2010 ). The newest postcranial bones are then modified to compensate to the heavier carapace which have hypertrophied limb issue (just like ankylosaur dinosaurs) including the strong humeri and you can tibiae and additionally a noticable olecranon procedure for the new ulna. Which have a very nearly the same armor carapace would it be not surprising that such same aspects during the Roentgen. callenderi are very similar inside their amount of robustness.

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