One another PEFO 34561 and PEFO 34269 keep partial 2nd sacral spinal vertebrae

One another PEFO 34561 and PEFO 34269 keep partial 2nd sacral spinal vertebrae

5.six.cuatro Sacral spinal vertebrae

Numerous separated sacral centra was in fact collected (elizabeth.g., PEFO 33875 and you can 33819), nevertheless the sacral rib and you will sensory arch are busted of. Exactly how many sacral spinal vertebrae is set is a couple depending on: (a) one or two collection of sacral rib marks for the ilia out-of R. callenderi; (b) a couple ankylosed centra (PEFO 36876) that have obvious articulations having ribs and you will sensory arches (Numbers 8i–k); and (c) truth be told there appear to be simply several morphologies from sacral spinal vertebrae one of the latest separated specimens. Both ankylosed centra shows that certain specimens from R. callenderi will get coossify their sacral backbone and therefore which character are adjustable inside taxon. As all of the specimens out of PFV 297 is out-of equivalent dimensions, so it coossification in a few specimens will not appear to be proportions associated. As an alternative, once the during the ventral look at the lateral expansions of your centra as much as brand new ankylosed city commonly very well symmetric, this combination you will depict an excellent cystic and additional specimens are required to confirm that it.

New sacral centra is elongate and you will mediolaterally wide than dorsoventrally high, together with centrum confronts try amphicoelous (Figures 8i–k). Another sacral rib articulates with a lot of of your own horizontal surface of centrum and you can area of the ventrolateral epidermis of the sensory arch (PEFO 36876). When you look at the dorsal have a look at, the new sacral rib of 2nd sacral vertebra expands greatly for the a keen anteroposteriorly elongate articulation on the ilium (Profile 8l). Into the lateral take a look at, it articulation surface try cigar-shaped; that it articulates with most of the period of the fresh postacetabular process of your ilium. The fresh anterior portion of the articulation is actually a little convex with a beneficial limited dorsomedial expansion. All of those other articular skin was concave. The new articular facial skin of the centrum and also the 2nd sacral rib try circular inside the horizontal glance at (Figure 8k). A beneficial transverse ridge sets apart the articular skin towards two parts, a lower region that fits to your a position with the lateral area of the next sacral centrum, and a higher region one to articulates on the sensory arch. The newest neural arc is not really-maintained in virtually any sample; the prezygapophysis try centered sixty° of horizontal and postzygapophysis try established merely ten° from horizontal (even in the event they’re a little soil).

The complete number of caudal spinal vertebrae found in Roentgen. callenderi is not familiar; however, you’ll find during the 34–thirty-six caudal spinal vertebrae about aetosaurian A. ferratus (J.B. Desojo, personal communications, 2021), and you may the same number may have been contained in brand new aetosauriform R. callenderi (Profile seven; Nesbitt, 2011 ; ).

5.six.5 Anterior and middle-caudal backbone

Prior caudal vertebrae (Profile 8m) provides hourglass-shaped centra inside ventral take a look at which might be anteroposteriorly more than mediolaterally wider and you may deeply grooved ventrally (age.g., PEFO 34561). That it groove grows during the prior and you will rear stops that is noted by the line of ridges. New prior stop merges with a couple posteriorly inclined face, and that act as new articulation counters to the chevrons. This type of range from new hook-particularly chevron elements of some rauisuchids (elizabeth.g., UCMP 124890; Much time & Murry, 1995 : fig. 130c). As the anteriormost caudal vertebra isn’t maintained, this isn’t clear where position the chevrons begin. The latest articular confronts try bullet and you will amphicoelous having clear tires. New sensory arc is reasonable, or around 1 / 2 of the new top of the centrum articular deal with. The new prezygapophysis is actually better-put up creating good posteroventrally, and you may medially depending apartment articular surface. New distal internet margins regarding one another prezygapophyses blend together and so are confluent toward prior side of brand new sensory spine. The spine is actually anteroposteriorly large which have an even rear boundary and you can an enthusiastic anteroventrally slanting prior boundary. This new apex isn’t extended into the a properly-create back table. Brand new postzygapophysis is significantly tall (roughly twice the brand new height) compared to the prezygapophysis. Its horizontal margin is virtually upright, and articular epidermis are much more likely ventromedially from the forty-five° and faces a little posteriorly.

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