Both PEFO 34561 and you can PEFO 34269 preserve limited second sacral backbone

5.six.cuatro Sacral vertebrae

Multiple separated sacral centra had been collected (elizabeth.g., PEFO 33875 and you can 33819), although sacral rib and you will neural arc try damaged of. What number of sacral spinal vertebrae is set is two dependent on: (a) one or two collection of sacral rib scars towards the ilia out-of R. callenderi; (b) a couple of ankylosed centra (PEFO 36876) with obvious articulations having ribs and you can sensory arches (Numbers 8i–k); and (c) truth be told there be seemingly merely one or two morphologies from sacral vertebrae certainly one of the separated specimens. The 2 ankylosed centra indicates that specific specimens regarding R. callenderi will get coossify their sacral spinal vertebrae and that so it profile try variable within the taxon. Because the all the specimens away from PFV 297 are of comparable proportions, that it coossification in some specimens doesn’t be seemingly proportions associated. Alternatively, as the during the ventral view the horizontal expansions of centra around new ankylosed city aren’t really well symmetrical, it blend you may portray an excellent cystic and additional specimens are required to ensure it.

This new sacral centra was elongate and you may mediolaterally large than dorsoventrally tall, while the centrum face is actually amphicoelous (Figures 8i–k). Next sacral rib articulates with many of your lateral epidermis of the centrum and you can an element of the ventrolateral epidermis of one’s sensory arc (PEFO 36876). In the dorsal have a look at, the new sacral rib of your own second sacral vertebra grows considerably towards the an enthusiastic anteroposteriorly elongate articulation for the ilium (Contour 8l). In the lateral examine, so it articulation epidermis is cigar-shaped; which articulates with most of one’s length of the latest postacetabular procedure of your own ilium. The fresh prior portion of the articulation was a little convex with a beneficial slight dorsomedial extension. The remainder articular facial skin is concave. The articular skin of the centrum while the second sacral rib is actually round for the horizontal look at (Shape 8k). A beneficial transverse ridge sets apart the fresh articular body on two fold, a diminished area that fits towards the a slot on the lateral region of the next sacral centrum, and a higher region one to articulates toward sensory arc. The fresh sensory arc isn’t better-managed in just about any specimen; brand new prezygapophysis was established sixty° of horizontal in addition to postzygapophysis is based merely 10° out-of lateral (even when these are generally quite ground).

The amount of caudal spinal vertebrae contained in R. callenderi is actually unfamiliar; yet not, there are at 34–thirty-six caudal spinal vertebrae regarding aetosaurian A. ferratus (J.B. Desojo, personal communication, 2021), and you can a similar number was contained in the new aetosauriform Roentgen. callenderi (Contour eight; Nesbitt, 2011 ; ).

5.6.5 Anterior and you can middle-caudal spinal vertebrae

Anterior caudal spinal vertebrae (Shape 8m) features hourglass-formed centra in the ventral view that will be anteroposteriorly more than mediolaterally greater and you can profoundly grooved ventrally (e.g., PEFO 34561). It groove increases during the prior and you will rear ends which is marked by the distinct ridges. The anterior avoid merges with a couple posteriorly inclined faces, and therefore act as the fresh bu adamlara git articulation counters towards chevrons. Such differ from the newest hook-such chevron areas of specific rauisuchids (age.g., UCMP 124890; A lot of time & Murry, 1995 : fig. 130c). Given that anteriormost caudal vertebra is not managed, that isn’t clear from which position the chevrons start. The newest articular faces was round and you may amphicoelous having evident tires. The latest sensory arch are reduced, or just around half brand new peak of centrum articular face. The brand new prezygapophysis was better-set-up creating a posteroventrally, and you can medially depending apartment articular surface. The fresh distal margins of each other prezygapophyses merge with her and therefore are confluent on prior edge of the new neural lower back. New spine are anteroposteriorly wider which have an even rear edge and you will a keen anteroventrally inclining prior boundary. The fresh new top is not longer to your a properly-install spine table. The brand new postzygapophysis is a lot large (around twice new peak) compared to the prezygapophysis. Its horizontal margin is virtually straight, as well as the articular epidermis are inclined ventromedially in the forty five° and you may confronts quite posteriorly.