One another PEFO 34561 and you will PEFO 34269 uphold limited next sacral backbone
5.6.cuatro Sacral spinal vertebrae
Multiple isolated sacral centra was in fact obtained (elizabeth.grams., PEFO 33875 and you can 33819), although sacral rib and you will neural arc are damaged away from. Just how many sacral vertebrae is set getting two created on: (a) a few collection of sacral rib marks on the ilia from Roentgen. callenderi; (b) one or two ankylosed centra (PEFO 36876) having clear articulations to possess ribs and you may neural arches (Rates 8i–k); and you may (c) there be seemingly merely one or two morphologies away from sacral vertebrae certainly one of the newest remote specimens. The 2 ankylosed centra implies that certain specimens of R. callenderi may coossify their sacral vertebrae which it reputation is changeable when you look at the taxon. Since all of the specimens out-of PFV 297 is out of equivalent proportions, this coossification in a number of specimens doesn’t seem to be size associated. As an alternative, once the in the ventral view the horizontal expansions of your centra doing the fresh ankylosed city are not very well shaped, that it combo you may represent an effective cystic and extra specimens are required to ensure this.
The latest sacral centra try elongate and you can mediolaterally broad than simply dorsoventrally high, and also the centrum faces are amphicoelous (Rates 8i–k). The second sacral rib articulates with many of the lateral surface of one’s centrum and you will part of the ventrolateral body of your own neural arc (PEFO 36876). In dorsal take a look at, brand new sacral rib of your 2nd sacral vertebra increases greatly on the an anteroposteriorly elongate articulation towards ilium (Figure 8l). When you look at the lateral examine, this articulation body are cigar-shaped; this articulates with most of amount of brand new postacetabular processes of your own ilium. The brand new anterior portion of the articulation try some convex which have a great moderate dorsomedial extension. Other articular epidermis are concave. The newest articular skin of the centrum while the second sacral rib try circular inside horizontal examine (Figure 8k). Good transverse ridge separates the new articular surface with the two parts, a diminished region that suits towards a slot to the lateral region of the 2nd sacral centrum, and you may a top region you to definitely articulates towards sensory arc. The newest neural arc isn’t better-kept in almost any specimen; the latest prezygapophysis was depending sixty° of lateral therefore the postzygapophysis is built only 10° away from horizontal (even though they truly are a bit ground).
The full level of caudal backbone present in R. callenderi try unfamiliar; not, you’ll find at the 34–36 caudal backbone in the aetosaurian A beneficial. ferratus (J.B. Desojo, private communication, 2021), and you will an equivalent number might have been found in the new aetosauriform R. callenderi (Contour seven; Nesbitt, 2011 ; ).
5.six.5 Prior and you may mid-caudal backbone
Anterior caudal vertebrae (Profile 8m) have hourglass-formed centra during the ventral take a look at that are anteroposteriorly more than mediolaterally wider and you will seriously grooved ventrally (age.g., PEFO 34561). Which groove develops from the prior and you can posterior stops and that is noted from the line of ridges. Brand new anterior prevent merges having two posteriorly inclined confronts, and therefore act as the new articulation surfaces to your chevrons. This type of range from the newest hook up-such as for example chevron facets of specific rauisuchids (e.g. cybermen indir, UCMP 124890; Much time & Murry, 1995 : fig. 130c). As the anteriormost caudal vertebra isn’t kept, this isn’t obvious of which position the chevrons initiate. New articular confronts was bullet and you may amphicoelous which have sharp tires. The newest sensory arc was low, or about half of the new top of your own centrum articular deal with. This new prezygapophysis was really-put up forming a beneficial posteroventrally, and medially created apartment articular skin. Brand new distal margins away from both prezygapophyses combine along with her and they are confluent on the anterior side of new sensory lower back. The fresh lower back is anteroposteriorly broad which have an even rear border and an enthusiastic anteroventrally slanting prior edge. The fresh top isn’t stretched into the a proper-set-up spine desk. The fresh postzygapophysis is much tall (approximately double brand new level) versus prezygapophysis. Its horizontal margin is close to upright, and articular facial skin was inclined ventromedially from the forty-five° and you can confronts slightly posteriorly.