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2183 Views 11 Replies Last post: Feb 17, 2013 10:04 PM by MikeHardman RSS
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Feb 10, 2013 12:32 AM

Fossil Starfish or some other Echinoid?

Hi, I'm looking for help in identifying this fossil. I found it around 20 years ago on Brighton beach. I'm keen to know what it is and how old. I think it's in flint and almost translucent in appearance. I absolutely love it and its by far my favourite fossil. Just keen to know more about it.

 

Thanks

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    Feb 10, 2013 8:41 AM (in response to SimonM)
    Re: Fossil Starfish or some other Echinoid?

    Simon,

     

    Well you're in the right ball park - the phylum Echinodermata.

     

    Some startfish fossils do have a sort of hub in the middle, as in this one -

    http://www.thefossilstore.com/fossils/echinoids/palaeocoma-egertoni-brittle-star-11ins-28cm.html

    But you'll see it is fairly flat (you can zoom in).

     

    However, yours is a sea urchin - an Echinoid.

    It has been very well abraded by surf and feet on the beach, but when it came out of the rock, it would have been a bit more recognizable, like this one -

    http://www.discoveringfossils.co.uk/peacehaven.htm

    (CTRL-F search for the third occurrence of 'Echinocorys')

     

    The local rock, ignoring superficial deposits, is Upper Cretaceous chalk, which includes the Meeching Beds, which are known for some interesting Echinocorys species. Echincorys occurs in the chalk as well. That is the most likely genus for your specimen. If it does come from those rocks, it is about 80 million years old.

     

    If Fiona takes a look at your question, she may be able to share her opinion.

     

    Here's a collection of flint echinoids, amongst which yours would not look out of place -

    http://www.discoveringfossils.co.uk/roy_shepherd.htm

    (part-way down on the right)

     

    Refs:

    - Brighton geology - http://www.brighton-hove.gov.uk/index.cfm?request=c1114481

    - Geology Conservation Review, Newhaven to Brighton - http://jncc.defra.gov.uk/pdf/gcrdb/GCRsiteaccount216.pdf

    - Echinocorys in 'The Echinoid Directory' - http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/taxa/taxon.jsp?id=175

    - Upper Cretaceous chronostratigraphy - http://en.wikipedia.org/wiki/Late_Cretaceous

    - Brighton area geological map - http://www.shop.ordnancesurveyleisure.co.uk/products/paper-maps/paper-maps-british-geological-survey/paper-maps-british-geological-survey-50000-geological-maps/brighton-and-worthing-bedrock-and-superficial-geology-map/pid-9780751834567

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    Feb 11, 2013 7:55 AM (in response to SimonM)
    Re: Fossil Starfish or some other Echinoid?

    Hi Simon - hmmmmmm, an interesting specimen - definitely from the phylum Echinodermata. I will need to ponder on this one for a while and get back to you. Bye for now, Fiona

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    • Hi Simon - I had some doubts about it being Echinocorys due to the overall shape andconfigurations. I consulted Dr. Steve K. Donovan - this is response:

      Dear Fiona,

       

      Definitely not Echinocorys! Figures 4A, B in the attached paper Donovan & Lewis show a true flint steinkern of Echinocorys. Most flint steinkerns of echinoids are Echinocorys, though (see attached paper by Donovan), making this specimen particularly interesting.

       

      The specimen appears to be a flint steinkern of an echinoid. Presumably out of the Chalk and Upper Cretaceous, which I know you’d already worked out – Brighton beach is a classic site for flint cobbles. (Apparently it was sandy until the Victorians stopped longshore transport of sand with multitudinous groynes.) The specimen is a bit battered, but I think it must be the internal mould of a regular echinoid, although one ambulacrum (bottom right) is poorly preserved. It could be irregular, but I suspect not. I just scanned through the plates of parts 1-4 of Smith & Wright on the Chalk echinoids, but no matches. But John Jagt’s monograph (Scripta Geologica, 2000, #121) has an oblique view of a Goniopygus (see pl. 8, fig. 7, on p. 331) that has depressed interambulacra like this specimen. So, tentatively, it may be a steinkern of Goniopygus – fascinating! I’ve never seen such a thing.

       

      This is about as far as I can get on one photograph. If the specimen could be left with you, I’ll be in London for the Palaeontographical Society AGM in April and might be able to shed a little more light. Alternately, I’ve copied this reply to one David Lewis who wrote that fine article in Geology Today on fossils in flint a few years ago. Any ideas, David?

       

      All the best,

       

      Steve

       

      If you would like to see the papers Steve sent me as attachments, please email me at IAS2@nhm.ac.uk. Another possibility that it is a Phymatosomatid echinoid which can also be seen in in one of the papers I can send you  (see p. 111 Fig. 3. Geological Society 2012, v.59; p109-113).

       

      Thank you for sending in such a fascinating fossil. Thanks also to Mike for providing such useful websites.

      All the best,

      Fiona

       


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      • Simon glad to hear you are inspired to get back into fossils by all this.

         

        Hi Mike, Fiona, Steve & Simon.

         

        This sort of find is something that interests me as well & so i felt compelled to air my non expert opinions about this find.

         

        I also agree with this being a flint internal mould of a regular echinoid as both sides seem to show  typical looking regular echinoid ambulacra & interambulacras so that for me says its not likely to be one of the irregulars however i don't say thats conclusive proof as Conulus is still one slim possibility so i would really like to see the fossils side on view please, the profile/shape could still offer some valuable information that could be missing..

         

          As already said,, its flint, so its safe to say it must be from the near by upper Chalk.

        Because its so worn its not possible to make a formal I.D. but with that said i think judging the way it looks with the deep interambulacrals also its size & the appearance & difference of the two sides its most likely to be a species of Salenia.

         

        No #disrespect intended Steve but from what i can find in my reference books it looks like#

        Goniopygus is not a species thats found in the U.K. Chalk, so that will obviously include flint. Going by A.B. Smiths 1993 monograph, British Cretaceous Echinoids part 3, it looks like the only known U.K. specimens are from the Farringdon Sponge Gravels & from the Upper Greensand of Devon (described as internal moulds preserved in a coarse cherty sandstone).

        Also it seems this is a small species,  that doesn't seem to compare with Simon's find that i have guessed is around 30mm?. .

         

        Am i missing something here? to me Goniopygus is really not looking like a possible candidate.

         

         

        Hope this is some help

        Keith

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    Feb 12, 2013 11:48 AM (in response to SimonM)
    Re: Fossil Starfish or some other Echinoid?

    Hi Simon,

    I have just had a response from our specialist Dave . N. Lewis, this is what he says:

     

    "From what I can see of the specimen, it does seem to be the internal cast of a regular echinoid, probably one that I would have called a  "phymosomatid" during my day. There are of course other regulars, but this shape used to crop up occasionally. I can't remember if I figured it in that "Fossils Explained" paper to which you refer, Steve. Anyway, the complete enquiries label as would have been written by one D. N. Lewis in his heyday is as follows:-

     

    Internal cast in flint of a phymosomatid (regular echinoid)

    Cretaceous, derived from the Chalk; ca. 85 million years old."

     

    I hope this has been useful to you - thank you so much for providing such an interesting find.

    Kind regards,

    Fiona

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    Feb 12, 2013 11:58 AM (in response to SimonM)
    Re: Fossil Starfish or some other Echinoid?

    Great stuff !

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    Feb 16, 2013 11:31 PM (in response to SimonM)
    Re: Fossil Starfish or some other Echinoid?

    Hi Simon

    I have attached a few images of some of my Chalk echinoid finds, all in the family Phymosomatidae.

    Just thought you would like to see how yours may have looked when fresh from the Chalk, also a few photos might help others when they read this thread. I'm sure there must be a few echinoid fans that also might like to see them.

     

    1st photo is a Phymosoma koenigi  test size is 3.5cm. Quite a rare find with associated spines. oral view

     

    2nd is also Phymosoma koenigi   large bare test, size 4.5cm.oral view

     

    3rd is  Gauthieria spatulifera   a smaller species up to around 3cm. This one is 1.7cm, preserved on a flint nodule with a few spines & jaw parts scattered around the test. aboral view

     

    Cheers

    Keith

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