Each other PEFO 34561 and you may PEFO 34269 manage limited 2nd sacral backbone
5.6.4 Sacral vertebrae
Multiple remote sacral centra was amassed (age.g., PEFO 33875 and you will 33819) https://datingranking.net/tr/geek2geek-inceleme/, however the sacral rib and neural arch are broken of. Exactly how many sacral vertebrae is determined getting two centered on: (a) one or two distinct sacral rib scars into ilia of Roentgen. callenderi; (b) a few ankylosed centra (PEFO 36876) which have obvious articulations getting ribs and sensory arches (Numbers 8i–k); and you may (c) there be seemingly merely a few morphologies out of sacral spinal vertebrae certainly the brand new remote specimens. Both ankylosed centra suggests that some specimens out-of R. callenderi may coossify the sacral spinal vertebrae and this that it character try adjustable inside the taxon. Due to the fact the specimens from PFV 297 are regarding equivalent proportions, so it coossification in certain specimens will not be seemingly size related. Rather, as inside ventral look at the horizontal expansions of the centra around brand new ankylosed area aren’t perfectly symmetrical, so it fusion you can expect to represent a pathology and extra specimens are essential to ensure this.
The brand new sacral centra was elongate and mediolaterally wide than simply dorsoventrally high, and the centrum confronts is actually amphicoelous (Numbers 8i–k). The second sacral rib articulates with a lot of of horizontal skin of one’s centrum and you can part of the ventrolateral surface of one’s sensory arc (PEFO 36876). Inside dorsal have a look at, the newest sacral rib of 2nd sacral vertebra grows greatly on an anteroposteriorly elongate articulation towards the ilium (Profile 8l). From inside the horizontal see, this articulation body is cigar-shaped; so it articulates with a lot of of one’s period of this new postacetabular process of your own ilium. The prior portion of the articulation is somewhat convex having a good slight dorsomedial expansion. All of those other articular body try concave. The articular body of your own centrum in addition to 2nd sacral rib try circular in the horizontal consider (Shape 8k). Good transverse ridge distinguishes this new articular facial skin into two fold, a diminished part that suits on the a slot to the horizontal section of the next sacral centrum, and you will a higher area that articulates towards the neural arch. The latest sensory arc is not well-kept in virtually any specimen; the newest prezygapophysis is actually situated sixty° off horizontal together with postzygapophysis is established just ten° out-of horizontal (even though they’ve been somewhat ground).
The level of caudal vertebrae contained in R. callenderi are unfamiliar; not, you can find on 34–36 caudal vertebrae throughout the aetosaurian A great. ferratus (J.B. Desojo, private interaction, 2021), and you will a similar number may have been found in the newest aetosauriform R. callenderi (Profile eight; Nesbitt, 2011 ; ).
5.6.5 Prior and mid-caudal vertebrae
Anterior caudal vertebrae (Shape 8m) keeps hourglass-molded centra for the ventral examine that will be anteroposteriorly longer than mediolaterally wider and you may significantly grooved ventrally (e.grams., PEFO 34561). This groove increases at prior and you will posterior comes to an end and that is marked because of the type of ridges. This new anterior prevent merges with one or two posteriorly inclined confronts, and therefore serve as this new articulation surfaces to your chevrons. Such differ from the newest hook-including chevron components of specific rauisuchids (age.g., UCMP 124890; Much time & Murry, 1995 : fig. 130c). Since anteriormost caudal vertebra isn’t maintained, that isn’t obvious where position the chevrons begin. The new articular faces are round and you may amphicoelous which have evident tires. The newest sensory arch is reasonable, or about half the fresh new top of your centrum articular face. The fresh new prezygapophysis is well-setup developing a great posteroventrally, and you may medially depending flat articular body. Brand new distal margins out of both prezygapophyses combine together with her and tend to be confluent towards prior side of the newest sensory lower back. Brand new spine was anteroposteriorly wider having an even posterior border and you may a keen anteroventrally slanting anterior edge. This new top is not prolonged to your a well-put up back dining table. The newest postzygapophysis is a lot tall (around twice the latest level) as compared to prezygapophysis. Its horizontal margin is nearly upright, as well as the articular body try inclined ventromedially regarding the forty-five° and you can faces some posteriorly.
