| Scunthorpe Mudstone | |
| Type: | Formation |
| Age: | Rhaetian-Hettangian ~ |
| Period: | Sinemurian |
| Prilithology: | Mudstone |
| Otherlithology: | Limestone, Siltstone |
| Namedfor: | Scunthorpe |
| Region: | England |
| Coordinates: | 52.9°N -1°W |
| Paleocoordinates: | 38°N 1.3°W |
| Unitof: | Lias Group |
| Subunits: | Barnstone Member |
| Underlies: | Charmouth Mudstone Formation |
| Overlies: | Lilstock Formation |
| Thickness: | Up to 128 m |
| Extent: | East Midlands Shelf Leicester to Market Weighton |
| Location Ts: | Blyborough Borehole, Blyborough, Lincolnshire |
The Scunthorpe Mudstone is a geologic formation in England. It preserves plesiosaur fossils dating back to the Late Triassic (Rhaetian) to Early Jurassic (Hettangian) period.[1] It predominantly consists of grey mudstone with thin beds of argillaceous limestone and calcareous siltstone.[2] The Ichthyosaur Wahlisaurus is known from the formation.[3] As is the holotype specimen of the dinosaur Sarcosaurus.[4]