5.six.cuatro Sacral backbone
Multiple isolated sacral centra was indeed built-up (age.g., PEFO 33875 and you will 33819), but the sacral rib and you can sensory arch try broken regarding. The number of sacral backbone is decided is a few created on: (a) one or two https://datingranking.net/tr/antichat-inceleme/ line of sacral rib scars into the ilia regarding Roentgen. callenderi; (b) one or two ankylosed centra (PEFO 36876) with clear articulations having ribs and you may sensory arches (Numbers 8i–k); and you can (c) around seem to be simply a couple of morphologies off sacral backbone among the latest separated specimens. The two ankylosed centra demonstrates that specific specimens off R. callenderi can get coossify their sacral backbone which so it reputation is variable in taxon. Since all the specimens out-of PFV 297 are off equivalent dimensions, that it coossification in a number of specimens doesn’t seem to be proportions related. Alternatively, given that when you look at the ventral look at the lateral expansions of one’s centra to the fresh new ankylosed urban area are not very well symmetric, which mixing you will definitely represent a beneficial pathology and extra specimens are expected to verify that it.
The fresh new sacral centra are elongate and you can mediolaterally wide than dorsoventrally extreme, as well as the centrum face is amphicoelous (Rates 8i–k). The following sacral rib articulates with a lot of of lateral body of centrum and a portion of the ventrolateral body of one’s sensory arc (PEFO 36876). Into the dorsal consider, brand new sacral rib of your 2nd sacral vertebra increases considerably towards a keen anteroposteriorly elongate articulation for the ilium (Figure 8l). Inside lateral take a look at, it articulation surface try cigar-shaped; which articulates with most of one’s length of new postacetabular process of your own ilium. The prior part of the articulation was a bit convex having a great moderate dorsomedial extension. Other articular facial skin is concave. The brand new articular epidermis of the centrum while the next sacral rib are round inside the lateral examine (Figure 8k). A good transverse ridge sets apart this new articular body toward two fold, a lesser area that suits towards the a slot for the horizontal region of the next sacral centrum, and you will a top area one to articulates on sensory arch. The newest neural arc isn’t really-managed in almost any sample; brand new prezygapophysis try dependent 60° out-of lateral and postzygapophysis try established just ten° off horizontal (even when they truly are somewhat floor).
The quantity of caudal vertebrae within R. callenderi was not familiar; not, you can find from the 34–thirty-six caudal spinal vertebrae regarding the aetosaurian An excellent. ferratus (J.B. Desojo, private correspondence, 2021), and you will an equivalent matter was contained in the aetosauriform Roentgen. callenderi (Contour eight; Nesbitt, 2011 ; ).
5.6.5 Anterior and mid-caudal spinal vertebrae
Anterior caudal vertebrae (Profile 8m) enjoys hourglass-designed centra for the ventral glance at that will be anteroposteriorly more than mediolaterally greater and you will profoundly grooved ventrally (e.grams., PEFO 34561). This groove expands at the prior and you can rear concludes that is designated by distinct ridges. Brand new anterior end merges having one or two posteriorly more inclined faces, and therefore act as the newest articulation counters to your chevrons. This type of range from the fresh hook up-including chevron facets of some rauisuchids (elizabeth.g., UCMP 124890; Enough time & Murry, 1995 : fig. 130c). As anteriormost caudal vertebra isn’t maintained, this is simply not clear of which place the chevrons begin. The new articular face are bullet and amphicoelous which have evident wheels. The neural arch are lower, or around 50 % of the latest height of the centrum articular deal with. The newest prezygapophysis is actually really-set-up forming an excellent posteroventrally, and you will medially built flat articular epidermis. The fresh distal margins from one another prezygapophyses blend with her and so are confluent towards prior side of the latest neural spine. The newest back are anteroposteriorly broad which have an even posterior edge and you will a keen anteroventrally slanting prior border. New apex isn’t longer toward a highly-developed back desk. The latest postzygapophysis is significantly large (about twice the fresh new height) as compared to prezygapophysis. Their horizontal margin is virtually upright, and the articular surface are more inclined ventromedially on the forty-five° and you may face slightly posteriorly.
