# Snow Hill Island Formation

The Snow Hill Island Formation is an Early Maastrichtian geologic formation found on James Ross Island, James Ross Island group, Antarctica. Remains of a paravian theropod Imperobator antarcticus have been recovered from it, as well as the elasmarian ornithopods Trinisaura santamartaensis, "Biscoveosaurus" and Morrosaurus antarcticus, the ankylosaurian Antarctopelta oliveroi, and the shark Notidanodon sp. Alongside these described genera are also the remains of indeterminate elasmosaurids, lithostrotian titanosaurs and an indeterminate pterosaur.
In the Herbert Sound Member of the Snow Hill Island Formation, bivalves, ammonites, and fish were found.

## Fossil content
### Vertebrate

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

#### Plesiosaurs

Plesiosaurs :
| Genus | Species | Presence | Material | Notes | Images |
| Elasmosauridae | Gen. et. sp. indet. | | "MLP 11-II-20-4, one cervical vertebra preserving a partial rib; MLP 86-X-28-3, two cervical vertebrae; MLP 86-X-28-(2–6), 10 posterior cervical vertebrae articulated with three pectoral vertebrae, part of two dorsal vertebrae, ribs, and indeterminate fragments." | | |
| Vegasaurus | V. molyi | Cape Lamb member, Vega Island. | Partial Skeleton (MLP 93-I-5-1). | A plesiosaur. | |

#### Mosasaurs

Mosasaurs :
| Genus | Species | Presence | Material | Notes | Images |
| Taniwhasaurus | T. antarcticus | James Ross Island. | IAA 2000-JR-FSM-1, containing a skull measuring 72 cm (28 in) long, teeth, some vertebrae, and rib fragments. | A tylosaur. | Taniwhasaurus |

#### Dinosaurs

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

##### Ornithischians

Ornithischians of the Snow Hill Island Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Antarctopelta | A. oliveroi | Santa Marta Cove. | A partial skeleton (MLP 86-X-28-1) consists of three isolated teeth, part of the lower jaw with another tooth in situ, some other skull fragments, vertebrae of the neck, back, hips and tail, some shoulder and hip bones (scapula, ilium) a thigh bone (femur), foot and hand bones (five metapodials and two phalanges), and numerous pieces of armor. | A parankylosaur | Antarctopelta_Size_Comparison |
| "Biscoveosaurus" | Indeterminate | Cape Lamb Member. | Dentaries, teeth, a braincase, parts of the maxillae, forelimb elements, assorted vertebrae, and the pectoral girdle. | An ornithopod. | |
| Iguanodontidae | Indeterminate | Cape Lamb Member. | | | |
| Morrosaurus | M. antarcticus | Cape Lamb Member. | Fragmentary right hind limb. | An elasmarian ornithopod. | |
| Trinisaura | T. santamartaensis | Santa Marta Cove, in the lower levels of the formation. | MLP08-III-1-1, disarticulated and partial skeleton that includes one incomplete dorsal vertebra, three sacral centra, seven caudal vertebrae; two incomplete dorsal rib shafts, one proximal haemal arch, incomplete right scapulocoracoid, incomplete right humerus, two metacarpals, both ilia, right pubis, right ischium, right femur, right distal tibia, incomplete metatarsal III, first phalanx of pedal digit III, two phalanges of pedal digit IV, and indeterminate fragments. | An elasmarian ornithopod. | |

##### Saurischians

Saurischians of the Snow Hill Island Formation :
| Genus | Species | Presence | Material | Notes |
| Antarcticavis | A. capelambensis | Cape Lambe Member, Vega Island. | Partial Skeleton (SDSM 78147) consists of two thoracic vertebrae, the sternum keel, the right coracoid and shoulder blade, the sternal part of the left coracoid, the right upper arm, parts of the left upper arm, the proximal right ulna, the proximal left ulna and radius (articulated), the proximal right carpometacarpus, the proximal left carpometacarpus, the distal left carpometacarpus, the synsacrum, the right and left thighs, the proximal right tibiotarsus, the right and left distal tibiotarsus, and the proximal right tarsometatarsus. | |
| Imperobator | I. antarcticus | Cape Lamb Member, Naze Peninsula. | A single specimen that contains skull fragments possibly from the premaxilla, maxilla, and dentary as well as a caudal vertebra, teeth, and pedal elements, UCMP 276000. | A large paravian. |
| Titanosauria | Indeterminate. | Santa Marta Cove. | Partial caudal vertebra. | |

#### Fish

Fish :
| Genus | Species | Presence | Material | Notes |
| Chimaera | C. zangerli | Santa Marta Cove, James Ross Island. | | A chimaera. |
| Chlamydoselachus | C. thompsoni | Santa Marta Cove, James Ross Island. | Complete dentition. | A frilled shark. |
| Edaphodon | E. snowhillensis | Herbert Sound Member. | Complete dentition. | A large species of chimaera. |
| Notidanodon | N. dentatus | Cape Lamb Member, Vega Island. | | A cow shark. |

#### Pterosaur

Pterosaurs :
| Genus | Species | Presence | Material | Notes | Images |
| Pterodactyloidea | gen. et sp. Indet. | Camp Lamb, Vega Island. | MN 7801-V, a wing metacarpal IV. | A pterosaur with an estimated wingspan of 4 to 5 meters. | |

### Invertebrate

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |
Invertebrates :
| Genus | Species | Presence | Material | Notes | Images |
| Fungiacyathus | F. deltoidophorus | Karlsen Cliffs Member. | | | |
| Scleractinia indet. | Unidentifiable | Karlsen Cliffs Member. | | | |