Stegosaur vert (Dacentrurus) or marine?

[FF7_Yuffie]

Hi

 

Any thoughts on this? Sold as uk stegosaur (Dacentrurus?) 14 x 11 x 6.

 

From Abingdon, Kimmerisge Clay. I think it is actually a marine vert, but figured Id post in case im wrong.

 

Thanks for the help

[pachy-pleuro-whatnot-odon]

I don't know, Jack, but this doesn't look like your typical, run-of-the-mill pl(es)iosaur vertebra to me. Although it would've been great if the clay would've been cleaned from the base of the vertebra, so that we could check for subventral foramina and exclude a plesiosaurian origin, and it's proven difficult to find usable reference material for stegosaur vertebrae, there are still enough features that set this vertebra apart:

 

1. The thick bevels outlining the edge of the vertebral centrum both anteriorly and posteriorly.
2. The projection/bevel at the base of the neural canal.
3. The narrow dorsal struts of bone that connect the neural arch to the lateral rib facets.

The vendor also mentions the large vascular cells visible on the top part of the centrum central to the first photograph, but I don't quite agree with that. I've seen ichthyosaur vertebrae with similarly large vascular cells (see image below):

 

 

On the whole, I don't think this is a marine reptile bone (maybe @paulgdls or @DE&i can confirm), but wouldn't quite be able to attribute this to a stegosaur either (unless may be a cervical close to the pectoral region). But may be @Troodon would be able to help... In any case, here are a couple of images for comparison:

 

 

Kentrosaurus sp. at the Paläontologische Sammlung MUT Tübingen

 

Caudal section of Stegosaurus mjosi from the Morrison Formation at Howe Ranch, Bighorn Mountains, Wyoming

 

Stegosaurian remains from the quarry near Chipping Norton, Oxfordshire, from Lomax and Tamura (2014)'s "Dinosaurs of the British Isles".

 

Another stegosaurian vertebra from the quarry near Chipping Norton (ibid.)

 

Vertebrae from Loricatosaurus priscus (figure 198, ibid.)

 

Vertebrae from Dacentrurus armatus (figure 223, ibid,)

 

[Troodon]

I dont get a Stego vibe on this one.   Really need to see a side view.

 

A great paper to see its vertebrae is this paper.

The Postcranial Skeleton of an Exceptionally Complete Individual of the Plated Dinosaur
Stegosaurus stenops (Dinosauria: Thyreophora) from the Upper Jurassic Morrison Formation of Wyoming, U.S.A.
Susannah Catherine Rose Maidment, Charlotte Brassey, Paul Michael Barret

 

Stego verts are much wider than this view

 

[pachy-pleuro-whatnot-odon]

2 hours ago, Troodon said:

I dont get a Stego vibe on this one.

 

Stego verts are much wider than this view

 

I agree, I also doubt this is a stegosaur vertebra (though I would've expected you to say that their vertebrae should be taller ). But it doesn't feel like marine reptile to me either... An odd one...

Edited May 28, 2021 by pachy-pleuro-whatnot-odon

[Troodon]

5 minutes ago, pachy-pleuro-whatnot-odon said:

 

I agree, I also doubt this is a stegosaur vertebra (though I would've expected you to say that their vertebrae should be taller ). But it doesn't feel like marine reptile to me either... An odd one...

 

Anytime you're just dealing with a centrum it can be very difficult to diagnose.  My initial gut when I first looked at it was marine but nothing beyond that.

[FF7_Yuffie]

Hmmm, interesting. I was expecting, like 99% of other verts from Abingdon it to be clear-cut marine fossil. I almsot dismissed this as being a common marine and not getting it ID'd on here--but it did intrigue me. The fact there's a bit of doubt here is a surprise.

 

I'll see about getting some extra photos--one from the side, see if that will help.

 

 

Thanks for taking a look--appreciated.

 

 

[pachy-pleuro-whatnot-odon]

9 hours ago, Troodon said:

My initial gut when I first looked at it was marine but nothing beyond that.

 

These days, whenever Jack posts a vertebra, I'm finding it increasingly more difficult to outright say it's marine, as the easy signs aren't always present any more (which, I guess, goes to show how much closer he's getting to actually finding himself those elusive dinosaur vertebrae ). I have been fooled before

 

Anyway, when I first saw this piece, I believe it struck me as "probably another plesiosaur"-vertebra, but "what a weird one". The closer a look I took, the less it seemed like a plesiosaur vertebra to me. Obviously the typical tell-tale signs of the subventral foramina are still covered by clay, and so may a mamilla, if present at the centre of the centrum. But while Tarlo (1960) describes of a broad spectrum of morphological features for pliosaur vertebrae - such as ventral keel, ventral lipping (esp. Liopleurodon spp. and P. brachyspondylus), marginal bevelling (esp. Pliosaurus), double rib facets (e.g. Pliosaurus and Stretosaurus/Pliosaurus), and peripheral grooving (e.g. P. brachydeirus and L. ferox) - dorsal lipping, to my knowledge, isn't mentioned. nor would the neural arch be so short compared to the full length of the vertebra. And while I'm admittedly less certain about this, I don't think plesiosaurian vertebra would have such struts running from the rib facets to the neural arch. These look rather gracile, whereas in plesiosaurs I'd expect them to be more robust and thus either connect to the base of the neural arch for rib facets at the height as in this specimen, or have the rib facets located higher up for those that would connect to the neural arch more directly. Anyway, that's just my thoughts on the matter