Bivalves
Bivalves are animals that live in water. Their name is derived from bi + valva (Latin) meaning two folding doors. These refer to the two hinged shells that bivalves have.
Bivalves are the common sea shells that we find on the beach (see left). Bivalves look like brachiopods, with pairs of shells, but bivalve shells are usually lop-sided rather than symmetrical, and both shells tend to look the same.
The state fossil of Virginia is Chesapecten jeffersonius, a bivalve.
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Size: 14mm
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Timescale: Bivalves have been around for a long time, over 540 million years ago. There are still bivalves alive today.
Different types of fossil bivalves have been called 'Osses 'Eds (horses' heads) and bulls' hearts.
The bivalve below is called Gryphaea. The top one came from Oxford Clay in Peterborough. The common name is Devil's toenails, perhaps because the Devil has goat's feet and they look like horns, or perhaps the Devil needs a pedicure! They were used to cure pains in the joints. They can be found at Scunthorpe, Yorkshire, and two Gryphaea bivalves can be found on Scunthorpe's shield (left).
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From Oxford Clay in Peterborough: Size: 45mm
Unknown location: Size: 35mm
From Penarth beach, near Cardiff: Size: 50mm
From Llantwit Major beach, near Cardiff: Size: 35mm and 30mm
Like modern sea shells, bivalves can be many shapes.
Size: 40mm
Size of stone: 40mm
Size of biggest fossil: 31mm
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This rock is rather fun. From one side it looks like a simple nodule of flint. However, when you turn it over, you realise there is a fossil bivalve. Size: 40mm
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These fossil mussel shells were collected on Portland Bill, Dorset, from the limestone. Both have size: 32mm
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This was collected at Whitby, Yorkshire, from the Blue Lias (top and bottom).
Size: 28mm
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You don't just collect modern shells on a beach! This is the imprint of a fossil cockle (Cardiiae) on flint, about 80 million years old. It was collected on Hastings beach, in Sussex.
Size of stone: 26mm
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These fossil shells were collected from Bracklesham Bay (near Chichester). They are Cardita shells. The Bracklesham beds are clay, just off the coast, although some are exposed at low tide, and they are full of Eocene fossils which can be hard to distinguish from modern shells.
The size of these shells vary from 30mm to 65mm across
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More bivalves from Bracklesham
Size of shells: around 25mm
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© Jo Edkins 2007 - Return to Fossils index