A Sauropod from Down Under Bristol

Thecodontosaurus antiquus skeletonThecodontosaurus antiquus, a sauropodomorphan from the Durdham Down region of Bristol, England, is a rather ordinary sauropodomorphan. It’s not that there’s not anything special about it — for there are quite a few — but that it seems so … ordinary. It didn’t have some peculiar nose like the “plateosaurids,” it didn’t have particularly curved teeth, nor did it seem to have special feet or hands. It was just … ordinary.When recovered in the early 1800s, it was thought to be some form of large lizard, and its name was given due to the very peculiar and deep sockets into which the tall, “lanceoltate” teeth were rooted. (Typically, lizards today and even in the past have only acrodont or pleurodont dentition, teeth not rooted within a socket but rather in a shallow depression and appressed to the inner side or along the top of the jaw ramus. Thus, the presence of deep sockets was peculiar.) The Durdham Down region produced a quarry in which several individuals have been recovered, but of these only fragmentary, associated or separated, remains exist. Originally, the taxon was named without a full binomen: Riley & Stutchbury (1836) only applied the name Thecodontosaurus to it, and as this left the name an ambiguous mess it was up to Morris (1843), seven years later, to provide the full name: Thecodontosaurus antiquus. But what is most interesting about Thecodontosaurus antiquus (the ancient socket-toothed lizard) is what happened after it was discovered.

At one point, a block from what is assumed to have been Durdham Down was extracted and found its way to Australia. From there, it returned to England but this time with the auspice from “having arrived from Australia.” Comparable to Massospondylus from Africa and Thecodontosaurus from England, the material was identified as Agrosaurus macgillivrayi (Seeley, 1891). However, as early as the early 1900s, researchers had suspected the material was astonishingly similar to the British material and even equated the sediment in which the material was extracted to the peculiar beds of the Downs. Von Huene (1908) suggested congeneric identity, naming the material Thecodontosaurus macgillivrayi, but this wasn’t followed for half a decade. It wouldn’t be until Vickers-Rich et al. (1999) would examine the auspice of the specimen that they assumed the material must have come from Thecodontosaurus, and question the provenance of Australia. So as it stands, Agrosaurus macgillivrayi is a name applied to some probably Durdham Down sauropodomorphan material that took quite a journey to get back to its origin.

But not long after von Huene suggested the “Australian” sauropodomorphan wasn’t Australian, WWII happened, and the material that had been illustrated, including the original jaw which had been assumed the type specimen, was destroyed during the Bristol Blitz of 1940. But, not all material was lost, and what remained included nearly identicla mandibles, casts of the holotype, and affirmation that all of the Durdham Down material was consistently the same taxon. Thecodontosaurus antiquus was safe, and a neotype was designated.

Across the Bristol Channel, north of Swansea in Wales, a new quarry near the town of Pantyffynnon unearthed remains of an animal very, very similar to the Durdham Down specimens, but these were substantially better preserved. They included partial, articulated and associated skeletons in multiple age classes. When originally identified, they were found to be very similar to Thecodontosaurus antiquus and were provisionally associated with the name. However, subtle details and an assumption at one point that the type material of Thecodontosaurus antiquus was not diagnostic resulted in defining the species as a new one, Thecodontosaurus caducus (Yates, 2003). The distinction from antiquus was then widened when caducus was referred to a new container, and thus dubbed Pantydraco (Galton et al. 2007) and thus much tittering began.

Not all British dinosaurs have a storied past, but some have more interesting stories than others. Some, such as the Scottish Scleromochlus taylori of Lossiemouth, are just unusual in their own right. But when you have an ordinary dinosaur, it is often ordinary only in perspective.

This skeletal reconstruction is Open Access, CC-BY. You are free to distribute, copy, download, even modify the work. You don’t need to get my permission to copy it, but if you do present this skeletal anywhere, I do request you include my name in the form of “Produced by Jaime A. Headden,” or some similar token. The skeleton was produced for a forthcoming book on English dinosaurs.

Galton, P. M., Yates, A. M. & Kermack, D. 2007. Pantydraco n. gen. for Thecodontosaurus caducus Yates, 2003, a basal sauropodomorph dinosaur from the Upper Triassic or Lower Jurassic of South Wales, UK. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 243: 119-125.
Morris, J. 1843. A Catalogue of British Fossils. (British Museum, London,)
Riley, H. & S. Stutchbury, S. 1836. A description of various fossil remains of three distinct saurian animals discovered in the autumn of 1834, in the Magnesian Conglomerate on Durdham Down, near Bristol. Proceedings of the Geological Society of London 2: 397-399.
Seeley, H. G., 1891. On Agrosaurus macgillivrayi, a saurischian reptile from the northeast coast of Australia. Quarterly Journal of the Geological Society of London 47: 164–165.
Vickers-Rich, P., Rich, T. H., McNamara, G. C. & Milner, A. 1999. Agrosaurus: Australia’s oldest dinosaur? Records of the Western Australian Museum Supplement 57: 191-200.
von Huene, F. 1908. On phytosaurian remains from the Magnesian Conglomerate of Bristol (Rileya platyodon). Annals and Magazine of Natural History (ser. 8) 1: 228-230.
Yates, A. M. 2003. A new species of the primitive dinosaur Thecodontosaurus (Saurischia: Sauropodomorpha) and its implications for the systematics of early dinosaurs. Journal of Systematic Palaeontology 1 (1): 1-42.

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5 Responses to A Sauropod from Down Under Bristol

  1. “Not all British dinosaurs have a storied past, but some have more interesting stories than others. Some, such as the Scottish Scleromochlus taylori of Lossiemouth…”

    Which isn’t a dinosaur. But more on topic…

    “It’s not that there’s not anything special about it — for there are quite a few — but that it seems so … ordinary. It didn’t have some peculiar nose like the “plateosaurids,” it didn’t have particularly curved teeth, nor did it seem to have special feet or hands. It was just … ordinary.”

    Well, we don’t have its nose. Or its feet, or its hands, at least for described material. Note the stereotypical Thecodontosaurus hypodigm (e.g. Benton et al., 2000) is a lot of isolated elements, plus the type and matching dentaries, plus the pectoral girdle and arm of Asylosaurus. There are at least three taxa in there (Galton, 2007), so if your reconstruction is Durdham Down, it’s likely a chimaera. Yates’ more complete coding of Thecodontosaurus is based on the Tytherington Quarry material, which has not yet been described.

    • There is a lot of Pantyrdraco caducus in this animal, and given their closeness in phylogenetic context it felt useful to use it as a strong basis. I drew the skull as a projected model of the larger Panty skull but aged a big and made more plateosaur-ish in appearance. It is likely the skull was not a triangular skull normally, and that the skulls of Ammosaurus and Pantydraco that are preserved are not merely subadults but that projections of growth would presume a more square skull in aspect.

      As for the taxic assemblage of sauropodomorphans from Durdham Down, I am a little skeptical of distinctions using a single specimen to provide any systematic value, much less a fair basis for nomenclature. It is enough that there is often an urge to oversplit taxa from jumbled, disarticulated, damaged and otherwise mixed up remains, as the Greensands pterosaurs attest, as there is in assuming the complex is both autochthonous and monotaxic. This skeletal represents not all material referrable to Thecodontosaurus antiquus, but what the full skeleton might have looked like.

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