5.6.cuatro Sacral backbone
Numerous separated sacral centra was basically collected (age.g., PEFO 33875 and you can 33819), however the sacral rib and you may sensory arch is damaged from. The number of sacral backbone is decided is one or two dependent on: (a) a few distinctive line of sacral rib markings for the ilia out-of Roentgen. callenderi; (b) a few ankylosed centra (PEFO 36876) which have obvious articulations to possess ribs and neural arches (Figures 8i–k); and you will (c) indeed there be seemingly simply one or two morphologies off sacral vertebrae one of the fresh new remote specimens. Both ankylosed centra demonstrates that particular specimens of R. callenderi can get coossify the sacral backbone and that which profile try variable from inside the taxon. Since all the specimens out-of PFV 297 are off comparable size, this coossification in certain specimens doesn’t seem to be proportions associated. Instead, since when you look at the ventral look at the lateral expansions of your centra up to the fresh new ankylosed area aren’t really well symmetric, so it combination you can expect to show an effective cystic and extra specimens are essential to ensure that it.
This new sacral centra was elongate and you will mediolaterally broad than just dorsoventrally tall, and centrum face is amphicoelous (Numbers 8i–k). The next sacral rib articulates with many of your own lateral skin of centrum and you may area of the ventrolateral skin of one’s sensory arc (PEFO 36876). During the dorsal take a look at, the newest sacral rib of one’s next sacral vertebra expands considerably on the an enthusiastic anteroposteriorly elongate articulation into ilium (Profile 8l). Within the horizontal consider, so it articulation epidermis was cigar-shaped; so it articulates with a lot of of your own period of the brand new postacetabular procedure of ilium. The newest anterior part of the articulation was a little convex with an excellent slight dorsomedial extension. The rest of the articular surface was concave. The alua nedir new articular facial skin of centrum while the second sacral rib was game during the lateral examine (Profile 8k). A beneficial transverse ridge distinguishes brand new articular body towards two parts, less region that meets for the a slot to the horizontal side of the next sacral centrum, and a higher part that articulates to the sensory arc. The fresh new sensory arch is not better-managed in every specimen; new prezygapophysis are built sixty° out-of lateral and postzygapophysis is oriented just 10° regarding lateral (regardless of if these include some crushed).
The total level of caudal backbone present in R. callenderi is actually unknown; however, there are at the 34–thirty six caudal spinal vertebrae throughout the aetosaurian A beneficial. ferratus (J.B. Desojo, private correspondence, 2021), and you can an identical amount might have been found in the brand new aetosauriform Roentgen. callenderi (Figure eight; Nesbitt, 2011 ; ).
5.six.5 Prior and you can mid-caudal backbone
Prior caudal vertebrae (Shape 8m) have hourglass-designed centra inside the ventral see which might be anteroposteriorly more than mediolaterally wider and deeply grooved ventrally (age.g., PEFO 34561). It groove increases on anterior and you can posterior ends that’s noted because of the type of ridges. The fresh prior end merges which have a couple of posteriorly more inclined confronts, and this serve as the fresh new articulation counters on the chevrons. These differ from the latest connect-such as for example chevron elements of particular rauisuchids (elizabeth.grams., UCMP 124890; Enough time & Murry, 1995 : fig. 130c). While the anteriormost caudal vertebra isn’t maintained, that isn’t obvious at which position the chevrons begin. The new articular confronts was bullet and you may amphicoelous with clear rims. The new sensory arch try lowest, or just around half the fresh top of your centrum articular deal with. Brand new prezygapophysis is really-set-up building an excellent posteroventrally, and medially established flat articular skin. Brand new distal margins out-of one another prezygapophyses combine along with her and they are confluent into anterior edge of the fresh sensory spine. Brand new back is actually anteroposteriorly wide which have a much posterior line and a keen anteroventrally inclining prior border. The latest apex is not extended on a properly-set up spine dining table. The brand new postzygapophysis is significantly tall (approximately double this new top) as compared to prezygapophysis. Their horizontal margin is practically upright, as well as the articular surface is more inclined ventromedially about forty five° and you can faces a little posteriorly.