''Crassostrea ingens'' is a species of fossil

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...

, a marine

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Ostreidae The Ostreidae, the true oysters, include most species of molluscs commonly consumed as oysters. Pearl oysters are not true oysters, and belong to the order Pteriida. Like scallops, true oysters have a central adductor muscle, which means the s ...

, the oyster. This species lived during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Wairarapa The Wairarapa (; ), a geographical region of New Zealand, lies in the south-eastern corner of the North Island, east of metropolitan Wellington and south-west of the Hawke's Bay Region. It is lightly populated, having several rural service t ...

Whanganui Whanganui, also spelt Wanganui, is a city in the Manawatū-Whanganui region of New Zealand. The city is located on the west coast of the North Island at the mouth of the Whanganui River, New Zealand's longest navigable waterway. Whanganui is ...

basin, Gisborne district,

North Canterbury Canterbury () is a region of New Zealand, located in the central-eastern South Island. The region covers an area of , making it the largest region in the country by area. It is home to a population of The region in its current form was estab ...

, and

Hawke's Bay Hawke's Bay () is a region on the east coast of New Zealand's North Island. The region is named for Hawke Bay, which was named in honour of Edward Hawke. The region's main centres are the cities of Napier and Hastings, while the more rural ...

(especially in the Te Aute limestone).

Description

''Crassostrea ingens'' is a giant fossil oyster. It has a shell reaching a height of to over . This shell is biconvex. The left valve is thick and deep, with inflation of to over ; interior cavity depth to over . The right valve is almost flat, to thick. Most specimens curve slightly to the left. The adductor scar area in most Pliocene specimens retains a purplish red colour. Beu and Raine (2009) note that: "This is the sole giant oyster in New Zealand Late Miocene–Pliocene rocks, and there has never been any confusion over the identity of ''C. ingens''."A.G. BEU and J.I. RAINE (2009
REVISED DESCRIPTIONS OF NEW ZEALAND CENOZOIC MOLLUSCA FROM BEU AND MAXWELL (1990) GNS Science miscellaneous series no. 27.
/ref>

References

Crassostrea Bivalves of New Zealand Extinct animals of New Zealand Molluscs described in 1864 {{Ostreidae-stub