5.six.cuatro Sacral spinal vertebrae
Numerous separated sacral centra have been amassed (age.grams., PEFO 33875 and you may 33819), although sacral rib and you may neural arc was broken regarding. Just how many sacral backbone is set to get a few depending on: (a) a couple collection of sacral rib marks into ilia out-of R. callenderi; (b) two ankylosed centra (PEFO 36876) with obvious articulations to have ribs and you will sensory arches (Figures 8i–k); and you will (c) truth be told there seem to be only one or two morphologies of sacral spinal vertebrae certainly the new separated specimens. Both ankylosed centra shows that specific specimens from R. callenderi can get coossify the sacral spinal vertebrae and therefore that it profile try variable inside the taxon. Given that every specimens of PFV 297 is actually out-of comparable dimensions, this coossification in some specimens does not be seemingly size associated. As an alternative, as the during the ventral look at the horizontal expansions of your centra around the ankylosed area are not very well symmetrical, so it fusion you certainly will depict good pathology and extra specimens are required to ensure that it.
The sacral centra was elongate and you will mediolaterally large than dorsoventrally extreme, while the centrum faces try amphicoelous (Rates 8i–k). The next sacral rib articulates with many of your lateral surface of one’s centrum and you will the main ventrolateral body of one’s neural arc (PEFO 36876). Inside dorsal consider, the fresh new sacral rib of one’s next sacral vertebra grows significantly to your an anteroposteriorly elongate articulation to your ilium (Figure 8l). Into the lateral have a look at, cybermen premium apk so it articulation facial skin is cigar-shaped; which articulates with many of your own duration of the postacetabular process of ilium. New anterior portion of the articulation is actually somewhat convex which have a good slight dorsomedial expansion. The rest of the articular epidermis is actually concave. The fresh new articular body of centrum plus the 2nd sacral rib is circular in horizontal view (Profile 8k). A beneficial transverse ridge sets apart the fresh new articular surface on two-fold, a diminished area that fits towards the a slot into lateral section of the second sacral centrum, and a top region you to articulates on sensory arc. The brand new neural arc is not well-maintained in just about any specimen; the fresh new prezygapophysis is depending 60° away from lateral and also the postzygapophysis is actually dependent merely ten° away from lateral (whether or not they truly are quite soil).
The total level of caudal vertebrae found in R. callenderi are unknown; although not, there are within 34–thirty six caudal spinal vertebrae in the aetosaurian A beneficial. ferratus (J.B. Desojo, individual communications, 2021), and the same number may have been contained in the fresh new aetosauriform Roentgen. callenderi (Figure seven; Nesbitt, 2011 ; ).
5.six.5 Prior and you may middle-caudal backbone
Prior caudal spinal vertebrae (Contour 8m) provides hourglass-formed centra for the ventral view which can be anteroposteriorly longer than mediolaterally broad and you can seriously grooved ventrally (elizabeth.grams., PEFO 34561). That it groove increases at the prior and posterior closes which will be designated by line of ridges. Brand new prior avoid merges with a few posteriorly more likely face, and therefore serve as the articulation surfaces into chevrons. Such range from brand new hook-like chevron areas of certain rauisuchids (e.grams., UCMP 124890; Much time & Murry, 1995 : fig. 130c). As the anteriormost caudal vertebra is not preserved, it is not clear of which put the chevrons start. The new articular face is round and you may amphicoelous having sharp rims. The latest neural arch was reasonable, or just around half the new level of one’s centrum articular deal with. The brand new prezygapophysis are well-setup developing a posteroventrally, and medially situated apartment articular skin. The fresh new distal margins out-of each other prezygapophyses blend together and are usually confluent with the prior edge of the latest neural lower back. The fresh new spine was anteroposteriorly large with an even posterior border and you will a keen anteroventrally slanting prior edge. New top is not expanded towards a proper-establish spine dining table. The new postzygapophysis is a lot tall (roughly twice brand new level) compared to the prezygapophysis. The horizontal margin is virtually straight, plus the articular surface try inclined ventromedially throughout the forty-five° and you will face somewhat posteriorly.