5.six.4 Sacral spinal vertebrae

Multiple separated sacral centra was basically gathered (age.grams., PEFO 33875 and you will 33819), however the sacral rib and you can sensory arch try busted out-of. How many sacral spinal vertebrae is decided to get one or two situated on: (a) a few distinct sacral rib marks to the ilia away from Roentgen. callenderi; (b) several ankylosed centra (PEFO 36876) which have obvious articulations for ribs and you will sensory arches (Data 8i–k); and you will (c) there appear to be simply a few morphologies from sacral vertebrae one of the fresh separated specimens. The 2 ankylosed centra implies that some specimens from Roentgen. callenderi can get coossify their sacral spinal vertebrae and that which reputation is varying inside the taxon. Due to the fact every specimens away from PFV 297 are regarding similar size, so it coossification in a few specimens cannot seem to be proportions associated. As an alternative, once the for the ventral look at the horizontal expansions of centra doing the fresh new ankylosed urban area aren’t really well symmetrical, it blend you will definitely portray a good pathology and additional specimens are essential to confirm this.

The latest sacral centra was elongate and you may mediolaterally broad than dorsoventrally tall, plus the centrum face was amphicoelous (Numbers 8i–k). Next sacral rib articulates with many of one’s lateral body of one’s centrum and you will part of the ventrolateral facial skin of sensory arch (PEFO 36876). Within the dorsal have a look at, the fresh new sacral rib of second sacral vertebra develops greatly on the an anteroposteriorly elongate articulation with the ilium (Profile 8l). When you look at the lateral check, this articulation surface is cigar-shaped; it articulates with most of amount of the new postacetabular procedure of ilium. The brand new anterior part of the articulation was a bit convex which have a slight dorsomedial extension. The rest of the articular epidermis is concave. New articular skin of the centrum and the next sacral rib are rounded inside the lateral take a look at (Contour 8k). An effective transverse ridge separates the newest articular skin with the two-fold, a lowered area that meets towards the a position toward horizontal section of the 2nd sacral centrum, and you can a top region that articulates toward neural arch. The sensory arch is not well-maintained in virtually any sample; the newest prezygapophysis are oriented sixty° regarding horizontal in addition to postzygapophysis is actually mainly based simply ten° from horizontal (even when they’re a little floor).

The entire level of caudal spinal vertebrae present in R. callenderi is actually unknown; however, you’ll find during the 34–36 caudal backbone about aetosaurian Good. ferratus (J.B. Desojo, private telecommunications, 2021), and you may a comparable amount was present in brand new aetosauriform Roentgen. callenderi (Profile seven; Nesbitt, 2011 ; ).

5.6.5 Anterior and you will mid-caudal spinal vertebrae

Prior caudal vertebrae (Contour 8m) keeps hourglass-designed centra into the blackplanet hile ventral take a look at that are anteroposteriorly longer than mediolaterally wider and you can significantly grooved ventrally (e.g., PEFO 34561). That it groove develops on anterior and you may posterior ends which can be designated because of the collection of ridges. The fresh prior stop merges that have one or two posteriorly more likely faces, and this serve as new articulation counters on the chevrons. Such differ from brand new hook up-for example chevron areas of particular rauisuchids (age.g., UCMP 124890; A lot of time & Murry, 1995 : fig. 130c). Given that anteriormost caudal vertebra isn’t kept, this isn’t clear of which position the chevrons start. The fresh articular face try round and you may amphicoelous that have clear wheels. The fresh neural arc is actually reduced, or about 50 % of the brand new level of one’s centrum articular deal with. The latest prezygapophysis was really-put up developing good posteroventrally, and you will medially oriented apartment articular surface. The latest distal margins out of one another prezygapophyses combine together and are also confluent towards prior edge of the fresh sensory back. Brand new lower back is anteroposteriorly large having an even posterior edge and you may an enthusiastic anteroventrally slanting prior edge. The fresh new top is not offered for the a well-setup lower back table. The postzygapophysis is much high (roughly double brand new peak) compared to the prezygapophysis. Their horizontal margin is almost upright, together with articular epidermis was more inclined ventromedially about forty five° and you will confronts somewhat posteriorly.