A saurischian dinosaur braincase from the Middle Jurassic (Bathonian) near Oxford, England: from the theropod Megalosaurus or the sauropod Cetiosaurus?
By: Galton, P.M.
Contributor(s): Knoll, F.
Material type: ArticleDescription: 905 - 921 pp ; Illustration.Subject(s): Systematics | Phylogeny | Sauropod | Jurassic | England In: Geological magazine : Vol. 143 Iss. 1-6 Year. 2006Summary: A dinosaur braincase from the Middle Jurassic (Bathonian) of Oxfordshire (England) is described. The specimen, which has historical significance, has been erratically attributed to either a sauropod or a theropod on the basis of vague phenetic resemblances. It is here re-interpreted in the light of recent cladistic analyses of dinosaurs, allowing the first proper character-based discussion of its affinities. It resembles those of ornithischian and prosauropod dinosaurs in the absence of a prominent, caudolaterally directed bony sheet from either the crista tuberalis (as in all theropods) or the crista prootica (as in all sauropods except juveniles of the eusauropod Shunosaurus). This braincase shows two synapomorphic characters of the Eusauropoda: the region of the cranium is rostrocaudally shortened and the long axis of the supratemporal fenestra is transversely oriented. For these characters, ornithischians, theropods, and prosauropods retain the plesiomorphic condition. It is concluded that the specimen is an important exemplar of a Middle Jurassic sauropod braincase and it is suggested that it could be from the eusauropod Cetiosaurus.Item type | Current location | Collection | Call number | Status | Date due | Barcode |
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Article | Library and Information Centre Periodical Section | Bound Journal Collection | Not for loan | 002538_94 | ||
Serials/Scientific Journal | Library and Information Centre Periodical Section | Bound Journal Collection | 550 GEO (Browse shelf) | Available | 002538 |
A dinosaur braincase from the Middle Jurassic (Bathonian) of Oxfordshire (England) is described. The specimen, which has historical significance, has been erratically attributed to either a sauropod or a theropod on the basis of vague phenetic resemblances. It is here re-interpreted in the light of recent cladistic analyses of dinosaurs, allowing the first proper character-based discussion of its affinities. It resembles those of ornithischian and prosauropod dinosaurs in the absence of a prominent, caudolaterally directed bony sheet from either the crista tuberalis (as in all theropods) or the crista prootica (as in all sauropods except juveniles of the eusauropod Shunosaurus). This braincase shows two synapomorphic characters of the Eusauropoda: the region of the cranium is rostrocaudally shortened and the long axis of the supratemporal fenestra is transversely oriented. For these characters, ornithischians, theropods, and prosauropods retain the plesiomorphic condition. It is concluded that the specimen is an important exemplar of a Middle Jurassic sauropod braincase and it is suggested that it could be from the eusauropod Cetiosaurus.
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