6.2 Roentgen. callenderi, Revueltosaurus-like taxa, additionally the isolated tooth problem

6.2 Roentgen. callenderi, Revueltosaurus-like taxa, additionally the isolated tooth problem

Centered on the data, R

The initial around three reputation claims strengthen the latest articulations between your facial points from the jaw musculature (Schumacher, 1973 ). The location of your abducens guts foramen is actually to begin with hypothesized since the a prospective synapomorphy supporting a great crocodylomorph + aetosaur clade personal away from most other pseudosuchians (Gower, 2002 ), however, new phylogenetic analyses, as well as ours, highly recommend this apomorphy changed at least twice-just after when you look at the aetosauriforms and once in the crocodylomorphs. not quantified within analysis, good dorsoventrally thickened skull roof (i.age., nasals, frontals, and you can parietals) is additionally shared because of the R. callenderi, erpetosuchids, and aetosaurs.

callenderi and aetosaurs display similarities about dimensions of new hindlimb in order to forelimb and you can form of the new humerus and you may proximal foot aspects, although men and women parallels weren’t unambiguous synapomorphies. Specifically, R. callenderi and you can aetosaurs express a reduced radius according to the latest humerus, and you may a beneficial concave rear skin of one’s calcaneal tuber, although these types of apomorphies possess a far more widespread shipment certainly Archosauria. R. callenderi and aetosaurs show middle trunk area vertebrae with diapophyses and parapophyses one expand laterally where both articulations originate with the good transverse processes. Higher aetosaurs (e.g., D. spurensis, MNA V9300; T. coccinarum, NMMNH P-12964; Parker, 2008 ; Heckert mais aussi al., 2010 ) expand these procedures sideways and partially otherwise entirely coossify these to the new particular rib to form an over-all dorsal surface. New expansion of one’s transverse processes into the Roentgen. callenderi and other aetosaurs appears to associate on visibility out of wider osteoderms. In addition, however quantified throughout the phylogenetic studies, R. callenderi and you can aetosaurs express a beneficial hypertrophied fourth trochanter of your femur, a character condition in the past felt unique so you’re able to aetosaurs (Small, 2002 ).

New similarities of the osteoderms regarding Roentgen. callenderi, aetosaurs, and An excellent. geoffreyi render a lot more help into the the brand new clade, Aetosauriformes, showed here. callenderi, A. geoffreyi, and aetosaurs display the following carapacial synapomorphies (Figure several): (a) the existence of horizontal osteoderms about regarding the trunk area (plus found in erpetosuchids); (b) a keen prior pub located on the prior side of the brand new osteoderm (plus distributed to Age. olseni and you may crocodylomorphs); (c) an effective ventral carapace regarding trunk area; and (d) presacral dorsal osteoderms that will be wider than much time. Covered with an entire selection of paramedian, horizontal, and ventral osteoderms, the fresh osteoderm arrangements off R. callenderi and you will A good. geoffreyi one another be like compared to aetosaurs ( ).

Postcranially, R

Obviously there was nonetheless a big morphological gap between the skeletal morphology away from Roentgen. callenderi which regarding aetosaurian people in Aetosauriformes considering the higher assistance into monophyly of all the almost every other aetosaurs within analysis and others (age.g., ). Following the divergence out-of Roentgen. callenderi + A. geoffreyi and you can aetosaurs off their common ancestor, the fresh skull, carapace, and you may postcranial skeleton of aetosaurs underwent subsequent evolutionary transformations prior to almost every other diapsids. The fresh new skulls from aetosaurs exhibit adjustment of your prior percentage of brand new head because of the elongating the brand new premaxillae to form an enthusiastic anteroposteriorly expanded exterior naris; new supratemporal fenestra turned into laterally mainly based, and in brand new mandible the fresh new prior dentition are reduced and you will became “slipper-shaped” (Desojo et al., 2013 ; Reyes et al., 2020 ). This new carapace off aetosaurs turned into much more thorough, level probably the ventral part of the tail (Heckert ainsi que al., 2010 ). Brand new postcranial bones is actually subsequent modified to compensate to your heavier carapace that have hypertrophied limb aspects (similar to ankylosaur dinosaurs) like the sturdy humeri and you can tibiae in addition to a good noticable olecranon means of datingranking.net/tr/cuddli-inceleme/ brand new ulna. Which have a very nearly the same armour carapace could it possibly be not surprising these types of same factors from inside the Roentgen. callenderi are very comparable inside their standard of robustness.

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