# Magnesian Conglomerate

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 dates back to the Rhaetian stage of the Late Triassic, although it may be as old as the Norian stage of the Late Triassic and as young as the Hettangian stage of the Early Jurassic.
The Magnesian Conglomerate was first discovered in autumn 1834 and was studied in 1836 by Henry Riley and Samuel Stutchbury.
The Avon Fissure Fill is often paired with the Magnesian Conglomerate.

## Vertebrate paleofauna

| Taxon | Species | Presence | Notes |
| Actinopteri | Indeterminate | Geographically present in Durdham Down. | A tooth. |
| Agnosphitys | A. cromhallensis | Geographically present in Avon, England (now Bristol). | Its remains include a left ilium (holotype) and a left maxilla, astragalus and humerus (referred specimen). |
| Agrosaurus | A. macgillivrayi | Geographically 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. |
| Archosauria | Indeterminate | Geographically present in Durdham Down. | Five specimens, including jaw fragments, caudals, and a scapulocoracoid. |
| Archosauromorpha | Indeterminate | Geographically present in Durdham Down. | A fragment of a small tooth. |
| Asylosaurus | A. yalensis | Geographically present in Avon, England (now Bristol). | 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. |
| Chimaeriformes | Indeterminate | Geographically present in Bristol. | Indeterminate remains. |
| Clevosaurus | C. hudsoni | Geographically present in Gloucestershire. | Partial cranial and post-cranial skeleton (holotype). |
| Crinoidea | Indeterminate | Geographically present in Bristol. | Reworked from older Carboniferous sediments (Friars Point Limestone Formation). |
| Cryptovaranoides | C. microlanius | Geographically present in Slickstones Quarry. | Holotype (partial skeleton) and referred isolated remains. |
| Diphydontosaurus | D. avonensis | Geographically present in Bristol. | Complete to near-complete specimens. |
| Herrerasauria? | Indeterminate | Geographically present in Durdham Down. | 3 indeterminate specimens. |
| Hwiccewyrm | H. trispiculum | Geographically present in Slickstones Quarry. | Several specimens comprising a partial skeleton. Discovered during the 1970s and listed as cf. Hypsognathus by Whiteside et al. (2016). |
| Hybodontiformes? | Indeterminate | Geographically present in Bristol. | Indeterminate remains. |
| Gyrolepis | Indeterminate | Geographically present in Bristol. | Indeterminate remains. |
| Kuehneosauridae | Indeterminate | Geographically present in Durdham Down. | Rib that may instead be an ulna belonging to Terrestrisuchus. |
| Lissodus | L. minimus | Geographically present in Bristol. | Teeth. |
| Ornithischia | Indeterminate | Geographically present in Durdham Down. | Indeterminate specimen. |
| Palaeosaurus | P. cylindrodon | Geographically present in Avon, England (now Bristol) and Bristol. | Two teeth (one destroyed in 1940). |
| Phytosauria | Indeterminate | Geographically present in Durdham Down. | Two teeth previously assigned to Mystriosuchinae. |
| Planocephalosaurus | P. robinsonae | Geographically present in Bristol. | Skull (holotype) and a tooth. |
| Plateosauria | Indeterminate | Geographically present in Durdham Down. | 22 partial specimens. |
| Rhomphaiodon | R. minor | Geographically present in Bristol. | Teeth, including the subsidiary cusp of one tooth. |
| Rileyasuchus | R. bristolensis | Geographically present in Bristol. | Two vertebrae and a humerus. |
| Sauropodomorpha | Indeterminate | Geographically present in Durdham Down. | Indeterminate remains. |
| Sphenosuchia | Indeterminate | Geographically present in Durdham Down. | A right femur initially named as Thecodontosaurus costa. |
| Terrestrisuchus | T. gracilis and indeterminate | Geographically present in Bristol and South Wales. | Indeterminate and partial remains. |
| Theropoda | Indeterminate | Geographically present in Avon, England (now Bristol) and Bristol. | A tooth, and a tibia that was once allied with Thecodontosaurus. Possibly similar to Pendraig milnerae. |
| Thecodontosaurus | T. antiquus | Geographically present in Avon, England (now Bristol) and Bristol. | Partial cranial and postcranial remains (holotype is a lower jaw). |