One another PEFO 34561 and PEFO 34269 keep limited 2nd sacral backbone

One another PEFO 34561 and PEFO 34269 keep limited 2nd sacral backbone

5.6.cuatro Sacral spinal vertebrae

Multiple remote sacral centra was in fact gathered (elizabeth.grams., PEFO 33875 and 33819), however the sacral rib and sensory arc was damaged off. The amount of sacral backbone is set is one or two created on: (a) a couple of distinct sacral rib marks to your ilia of R. callenderi; (b) two ankylosed centra (PEFO 36876) that have obvious articulations to have ribs and you may sensory arches (Data 8i–k); and you will (c) there be seemingly merely a couple of morphologies out-of sacral vertebrae one of this new remote specimens. The two ankylosed centra demonstrates that certain specimens of R. callenderi may coossify the sacral spinal vertebrae and that which reputation is varying for the taxon. Because every specimens from PFV 297 try out-of equivalent proportions, it coossification in some specimens doesn’t appear to be dimensions relevant. Rather, since the into the ventral view the horizontal expansions of centra to brand new ankylosed urban area are not well symmetrical, it combo you certainly will depict a beneficial cystic and additional specimens are required to confirm this.

The sacral centra are elongate and you may mediolaterally broad than dorsoventrally extreme, and the centrum confronts was amphicoelous (Numbers 8i–k). Next sacral rib articulates with most of the lateral surface of one’s centrum and you will the main ventrolateral facial skin of the sensory arc (PEFO 36876). In dorsal take a look at, this new sacral rib of your second sacral vertebra increases greatly to the a keen anteroposteriorly elongate articulation towards the ilium (Figure 8l). For the horizontal consider, which articulation epidermis was cigar-shaped; which articulates with a lot of of one’s period of the fresh new postacetabular procedure of your ilium. The newest prior portion of the articulation are some convex that have a slight dorsomedial extension. All of those other articular facial skin is actually concave. The latest articular facial skin of centrum plus the 2nd sacral rib was round in horizontal evaluate (Figure 8k). A great transverse ridge distinguishes new articular surface to your two parts, less region that meets on a position on horizontal area of the second sacral centrum, and you can a higher part that articulates for the neural arch. The fresh neural arc is not better-kept in just about any specimen; the prezygapophysis try centered 60° out of lateral and the postzygapophysis are dependent just ten° from horizontal (regardless if they are a bit ground).

The amount of caudal spinal vertebrae present in R. callenderi are not familiar; although not, there are at the 34–thirty-six caudal spinal vertebrae regarding the aetosaurian A good. ferratus (J.B. Desojo, personal interaction, 2021), and you may a similar amount might have been within the fresh aetosauriform R. callenderi (Shape seven; Nesbitt, 2011 ; ).

5.6.5 Prior and mid-caudal spinal vertebrae

Prior caudal vertebrae (Contour 8m) possess hourglass-formed centra from inside the ventral look at that are anteroposteriorly more than mediolaterally large and you may seriously grooved ventrally (age.g., PEFO 34561). So it groove develops on prior and rear ends up and is marked from the distinct ridges. This new anterior end merges having a couple posteriorly inclined face, which act as the brand new articulation surfaces with the chevrons. These types of range from the fresh link-including chevron areas of certain rauisuchids (age.grams., UCMP 124890; Enough time & Murry, 1995 : fig. 130c). Given that anteriormost caudal vertebra is not kept, this isn’t obvious from which place the chevrons start. The fresh articular face is actually bullet and amphicoelous having sharp tires. The fresh new neural arc try lowest, or about 1 / 2 of this new height of the centrum articular deal with. The fresh prezygapophysis try really-put up developing an effective posteroventrally, and you can medially centered apartment articular skin. The distal margins out-of both prezygapophyses mix with her consequently they are confluent with the anterior side of the latest sensory spine. The new lower back is anteroposteriorly wide which have a much rear line and you can a keen anteroventrally inclining anterior line. The apex isn’t longer into the a properly-setup spine table. This new postzygapophysis is much large (around twice the newest peak) compared to the prezygapophysis. Their lateral margin is close to straight, while the articular facial skin was more inclined ventromedially from the forty five° and you may face quite posteriorly.