The Magnesian Conglomerate is a geological formation in Clifton, Bristol in England (originally Avon), Gloucestershire and southern Wales, present in Tytherington, Durdham Down, Slickstones Quarry and Cromhall Quarry.
It is traditionally considered to date back to the Rhaetian stage of the Late Triassic,Magnesian Conglomerate in the Paleobiology DatabaseWeishampel et al., 2004, pp. 521–525 although it may be as old as the Carnian stage of the Late Triassic, having formed during the Carnian pluvial episode.
The Magnesian Conglomerate was first discovered in autumn 1834 and was studied in 1836 by Henry Riley and Samuel Stutchbury.Riley & Stutchbury, 1836
The Avon Fissure Fill is often paired with the Magnesian Conglomerate.
Vertebrate paleofauna +TaxonSpeciesPresenceNotesImagesActinopteriIndeterminateGeographically present in Durdham Down.A tooth.AgnosphitysNicholas C. Fraser, Kevin Padian, Gordon M. Walkden and A. L. M. Davis, 2002. Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. Palaeontology. 45(1), 79-95.A. cromhallensisGeographically present in Avon, England (now Bristol).Its remains include a left ilium (holotype) and a left maxilla, astragalus and humerus (referred specimen). AgrosaurusA. macgillivrayiH. G. Seeley. (1891). On Agrosaurus macgillivrayi (Seeley), a saurischian reptile from the N.E. coast of Australia. Quarterly Journal of the Geological Society of London 47:164-165Geographically present in Avon, England (now Bristol). Originally believed to have been found in Cape York Peninsula, Queensland (Australia).A tibia, a claw and some other fragments. ArchosauriaIndeterminateGeographically present in Durdham Down.Five specimens, including jaw fragments, caudals, and a scapulocoracoid.ArchosauromorphaIndeterminateGeographically present in Durdham Down.A fragment of a small tooth.AsylosaurusA. yalensisGeographically present in Avon, England (now Bristol).Riley H and Stutchbury S (1836a) "A description of various remains of three distinct saurian animals discovered in the autumn of 1834, in the Magnesian Conglomerate on Durdham Down, near Bristol". Geological Society of London, Proceedings, 2 (45): 397-399.Dorsal vertebrae, ribs, gastralia, a shoulder girdle, humeri, a partial forearm, and a hand; additional bones from the neck, tail, pelvis, arm and legs that may represent the same individual.ChimaeriformesIndeterminateGeographically present in Bristol.Indeterminate remains.ClevosaurusW. E. Swinton. (1939). A new Triassic rhynchocephalian from Gloucestershire. Annals and Magazine of Natural History: Zoology, Botany, and Geology 4:591-59C. hudsoniGeographically present in Gloucestershire.Partial cranial and post-cranial skeleton (holotype).CrinoideaIndeterminateGeographically present in Bristol.Reworked from older Carboniferous sediments (Friars Point Limestone Formation).CryptovaranoidesC. microlaniusGeographically present in Slickstones Quarry.Holotype (partial skeleton) and referred isolated remains.DiphydontosaurusD. avonensisGeographically present in Bristol.Complete to near-complete specimens.Herrerasauria?IndeterminateGeographically present in Durdham Down.3 indeterminate specimens.HwiccewyrmH. trispiculumGeographically present in Slickstones Quarry.Several specimens comprising a partial skeleton. Discovered during the 1970s and listed as cf. Hypsognathus by Whiteside et al. (2016).Whiteside, D. I., Duffin, C. J., Gill, P. G., Marshall, J. E. A., & Benton, M. J. (2016). The Late Triassic and Early Jurassic fissure faunas from Bristol and South Wales: Stratigraphy and setting. Palaeontologia Polonica, 67, 257–287.Hybodontiformes?IndeterminateGeographically present in Bristol.Indeterminate remains.GyrolepisIndeterminateGeographically present in Bristol.Indeterminate remains.KuehneosauridaeIndeterminateGeographically present in Durdham Down.Rib that may instead be an ulna belonging to Terrestrisuchus.LissodusL. minimusGeographically present in Bristol.Teeth.OrnithischiaIndeterminateGeographically present in Durdham Down.Indeterminate specimen.PalaeosaurusGalton, Peter (2007). "Notes on the remains of archosaurian reptiles, mostly basal sauropodomorph dinosaurs, from the 1834 fissure fill (Rhaetian, Upper Triassic) at Clifton in Bristol, southwest England". Revue de Paléobiologie. 26 (2): 505–591.P. cylindrodonGeographically present in Avon, England (now Bristol) and Bristol. Two teeth (one destroyed in 1940).PhytosauriaIndeterminateGeographically present in Durdham Down.Two teeth previously assigned to Mystriosuchinae.PlanocephalosaurusP. robinsonaeGeographically present in Bristol.Skull (holotype) and a tooth.PlateosauriaP. Galton. (2005). Basal sauropodomorph dinosaur taxa Thecodontosaurus Riley & Stutchbury, 1836, T. antiquus Morris, 1843 and T. caducus Yates, 2003: their status re: humeral morphs from the 1834 fissure fill (Upper Triassic) in Clifton, Bristol, UK. Journal of Vertebrate Paleontology 25(3, suppl.):61AIndeterminateGeographically present in Durdham Down.22 partial specimens.RhomphaiodonR. minorGeographically present in Bristol.Teeth, including the subsidiary cusp of one tooth.Rileyasuchusvon Huene, F. (1902). Überischt über die Reptilien der Trias. Geologische und Paläontologie Abhandlungen, Neu Folge 8:97-156. [German]R. bristolensisKuhn, O. (1961). Die Familien der rezenten und fossilen Amphibien und Reptilien. Meisenbach:Bamberg, 79 p.Geographically present in Bristol.Two vertebrae and a humerus. SauropodomorphaIndeterminateGeographically present in Durdham Down.Indeterminate remains.SphenosuchiaIndeterminateGeographically present in Durdham Down.A right femur initially named as Thecodontosaurus costa.TerrestrisuchusT. gracilis and indeterminateGeographically present in Bristol and South Wales.Indeterminate and partial remains.TheropodaIndeterminateGeographically present in Avon, England (now Bristol) and Bristol. A tooth, and a tibia that was once allied with Thecodontosaurus. Possibly similar to Pendraig milnerae.ThecodontosaurusT. antiquusGeographically present in Avon, England (now Bristol) and Bristol.Partial cranial and postcranial remains (holotype is a lower jaw).
See also List of dinosaur-bearing rock formations List of fossiliferous stratigraphic units in England
References
Bibliography
Further reading
Riley, H. and Stutchbury, S. 1840. A description of various fossil remains of three distinct saurian animals recently discovered in the Magnesian Conglomerate near Bristol Transactions of the Geological Society of London 5, 349–357 W. Buckland. 1824. Reliquiæ Diluvianæ; or, Observations on the Organic Remains Contained in Caves, Fissures, and Diluvial Gravel, and on Other Geological Phenomena, Attesting the Action of a Universal Deluge. Second Edition. John Murray, London 1-303
External links British Geological Survey Lexicon of Named Rock Units