Fossil Oysters 2

Fossil Oysters - Deltoideum delta from Dorset's jurassic Coast

This is the second in a series of Postings about fossil oysters. In this Post there are detailed photographs, taken from all angles, of a fossil oyster found with the two halves still in position, on the beach at Ringstead Bay, Dorset, UK. It’s a specimen of Deltoideum delta, and in common with many species of present day oysters such as Ostrea edulis, the shells of this extinct species can exhibit a wide variety of variations – in shape, size, and many other characteristics.  The most noticeable feature of this particular specimen is the attachment of six other oyster shells – four to the outer surface of the left valve and two to the exterior of the right valve.

The left or lower valve would have been the original surface of attachment for the spat oyster as it settled after a brief larval life. Old oyster shells are a preferred settlement substrate. It is not possible to say whether the oyster shells on which it settled were empty or still occupied by the living animals. Eventually the oyster would have overgrown and incorporated the other oyster shells as it developed.

On the other hand, the oyster shells attached to the outer surface of the right or uppermost valve would have settled on it only when the oyster had itself reached maturity.

Additionally, the ligament – which is the horny proteinaceous (conchyiolin) structure that connects the two halves of the oyster at the dorsal margins of the shells in life – seems to have been fossilised along with the calcareous shell valves. The shells have a brittle texture and an almost porcelain-like appearance. There are multiple cracks and fractures, as is common with the oyster fossils from this locality, and a certain flattening of the valves seems to have occurred so that there is now very little space indeed between the the two halves of the oyster.

[At the bottom of this posting is a slide show of the oyster shells photographed with a reference scale to indicate size. These pictures have a minimum of labelling. If anyone should want more information about these fossil oysters, please do not hesitate to get in touch.]

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

Fossil Oysters - Deltoideum delta

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About winderjssc

Jessica Winder has a background in ecological studies in both the museum and the research laboratory. She is passionate about the natural world right on our doorsteps. She is enthusiastic about capturing what she sees through photography and wants to open the eyes of everyone to the beauty and fascination of nature. She is author of 'Jessica's Nature Blog' at http://natureinfocus.wordpress.com. Jessica has also extensively researched macroscopic variations in oyster and other edible marine mollusc shells from archaeological excavations as a means of understanding past exploitation of marine shellfish resources. She is an archaeo-malacological consultant through Oysters etc. and is publishing summaries of her shell research work on the WordPress Blog called 'Oysters etc.' at https://oystersetcetera.wordpress.com 'Photographic Salmagundi' at http://photosalmagundi.wordpress.com is a showcase of photographs and digital art on all sorts of subjects - not just natural history.
This entry was posted in FOSSIL OYSTER SHELLS, Nature, OYSTER SHELL VARIATIONS, PALAEONTOLOGY and tagged , , , , , , , , , , , , , , , , , , . Bookmark the permalink.

3 Responses to Fossil Oysters 2

  1. Pingback: Fossil Oysters 3 | Oysters etc.

  2. Joey says:

    Hello, my name is Joseph Fines. I am from Stafford county, Virginia. I was walking along a favorite area along the river and found a oyster that is HUGE. I would have to say, that I have done some research and think it is the biggest oyster ever found in this area. It is the whole oyster and is petrified into a rock. I would have to say it wieghts about five pounds and is bigger than the palm of your hand. If you are interested please email at jc2011antiques@gmail.com.
    Thank you , Joseph Fines.

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