Matt’s drawn my attention to a bizarre fact: despite 17 separate posts about Xenoposeidon on this blog (linked from here and here), we’ve never shown a decent scan of Lydekker’s (1893) original illustration of NHMUK PV R2095, the partial mid-to-posterior dorsal vertebra that since Taylor and Naish (2007) has been the holotype specimen of Xenoposeidon proneneukos — and since Taylor (2018) has been known to represent a rebbachisaurid.

Well, here it is at last!

That’s Xeno on the left, of course. On the right, we have one of the various Wealden titanosauriform dorsal vertebrae that were constantly getting referred back and forth between taxa in the late 1800s. I think it might be one of the NPMUK PR R90 vertebrae, perhaps the one that, for disambiguation purposes, I’ve informally named R90a.

Lydekker — or, more likely, an uncredited illustrator — did rather a good job on this, as we can see by juxtaposing the illustration with the now well-known left-lateral photo that’s launched a thousand blog-posts:

The main differences here seem to pertain to how Lydekker and I perceived “lateral”. I think he has the vertebra rotated slightly away from us, so that it’s leaning into the page, and that’s why the centrum appears slightly taller and the arch slightly less tall than in my photo. He seems to have a bit more matrix stuck on the front of the centrum — perhaps because slightly more prep has been done since 1893 — but, worryingly, slightly less bone around the cotyle. I think that can only be illustration error, since that bone is definitely there.

References

• Lydekker, R. 1893. On a sauropodous dinosaurian vertebra from the Wealden of Hastings. Quarterly Journal of the Geological Society, London 49:276-280.
• Taylor, Michael P. 2018. Xenoposeidon is the earliest known rebbachisaurid sauropod dinosaur. PeerJ 6:e5212. doi: 10.7717/peerj.5212
• Taylor, Michael P., and Darren Naish. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50(6):1547-1564. doi: 10.1111/j.1475-4983.2007.00728.x