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Anatomy of the Basal Sauropodomorph Pantydraco caducus from the Upper Triassic of the UK

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Galton, P. M., and D. Kermack. 2010. The anatomy of Pantydraco caducus, a very basal sauropodomorph dinosaur from the Rhaetian (Upper Triassic) of South Wales, UK. Revue de Paléobiologie, Genève 29 (2) : 341-404.

Abstract - Apart from characters of the dentary (proportional shortness, also Saturnalia tupiniquim) and vertebrae of proximal third of tail (posterior position of antero-posteriorly short neural spine on arch, absence of ventral furrowing on centra ; both also Efraasia minor), the bones of very basal sauropodomorphs from the Rhaetian (Upper Triassic) fissure fill in Clifton near Bristol (including holotypes of Thecodontosaurus antiquus, Asylosaurus yalensis ; taxon with robust humerus) share no diagnostic characters with those of Pantydraco caducus from the Rhaetian of South Wales. This taxon is diagnosed by four autapomorphies : median fusion of the nasals, prominent medial tubercle from posterior part of surangular, epipophyses of cervical vertebrae 3-5 form flat plates that overhang the posterior margins of the postzygapophyseal facets but do not form raised ridges on the dorsal surface of the postzygapophysis, and the fossae, possibly pneumatic, prominent on the neurocentral suture of cervical vertebrae 6-8 and shallow on the lateral part of centrum 9. The dentary is deep and short, with maximum height of more than 20 % of length (also Saturnalia tupiniquim, Thecodontosaurus antiquus), occupying less than 40 % of total mandibular length (also Saturnalia tupiniquim). The ilium is tall with a long anterior process (also Anchisaurus polyzelus) and a short postacetabular process with the plesiomorphic absence of a brevis shelf. Other plesiomorphic characters include the lack of a buccal emargination on the dentary (also Saturnalia tupiniquim); teeth all recurved in lateral view; neck short with mid-cervical centra less than three times as long as wide (also Riojasaurus incertus, “Gyposaurussinensis) ; and humerus with a uniquely small tubercle medial to head and an antero-posteriorly low (also Asylosaurus yalensis) asymmetrical deltopectoral crest with the apex at 40 % of humeral length. At least three different sized individuals are preserved and the new skeletal reconstruction, with the posterior region scaled up to match the larger holotype, indicates a more bipedal animal than the more quadrupedal pose based on the incorrect premise that the two main blocks represent one individual. The specimens represent juveniles as indicated by the proportionally large skull with large orbits and short, high snout, slender postorbital bone, separation of most of bones of braincase, large metotic fissure and fenestra ovalis, low maxillary and dentary tooth counts, open neurocentral sutures of cervical vertebrae, and incomplete ossification of distal ends of the femur and metatarsals. The diversity of basal sauropodomorphs from the Rhaetian of Wales and England adjacent to the Severn Estuary is high with five taxa (Pantydraco caducus, three from Clifton, large basal sauropod Camelotia borealis from Somerset).

6 comments:

  1. The questions is: why? Adam Yates very comprehensively monographed this exact specimen only eight year ago -- did it really need a comprehensive redescription when there are so many sauropodomorphs out there that have never been adequately described?

    REFERENCE

    Yates, Adam 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. doi:10.1017/S1477201903001007

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  2. Pantydraco? Are you kidding me?

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  3. Here's the link to the new paper: http://www.ville-ge.ch/mhng/paleo/paleo-pdf/29-2/pal_29_2_04.pdf

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  4. It's true there are taxa in more need of redescription (*cough* Ruehleia *cough* anything from China), but this is a much more detailed description than Yates', with extensive illustrations to boot. I know with Yates' description there were several times I was coding Pantydraco and thought "the cranial reconstruction suggests this coding, but is that visible in the material or just hypothesized?" I don't think that will be much of an issue with the new paper. Not that there was anything wrong with Yates' work, but more is always better.

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  5. To Mike Taylor:

    Why not? Galton specializes in British taxa and ornithischians. And he's Peter fricken Galton.

    To "Anonymous":

    From the Welsh locality of Pant-y-ffynnon (or Pantyffynnon), and pronounced "pant-uh-fee-nahn."

    It does not mean "panty dragon," but "Pantyffynnon dragon."

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  6. "Pant" is a common component of Welsh place names (there are several Welsh towns called Pant), and means hollow or valley.

    As pointed out above, Pantydraco is from Pantyffynnon, which approximately means "well in the hollow" ("ffynnon" is well).

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