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413 Views 6 Replies Last post: Jun 29, 2014 2:08 PM by kate RSS
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Jun 27, 2014 4:28 PM

what are these Airshire fossils

Fossil's Airshire 005.JPGthis has got to be cropolite from something large and seed eating?Is Fossil's Airshire 077.JPGIs this a headless trilobite, emerging from or burrowing into the mud?Fossil's Airshire 071.JPGFossil's Airshire 004.JPGI think these may be squashed bivalves

Fossil's Airshire 085.JPGMaggot fossil ??

Fossil's Airshire 088.JPGFossil's Airshire 089.JPGthis is eather a bit of a tooth or claw??

Fossil's Airshire 037.JPGFossil's Airshire 038.JPGback and front view of what i think is a trace fossil?

These fossils were all found on the Airshire Coast in Scotland, Thanks

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    Jun 28, 2014 6:46 AM (in response to kate)
    Re: what are these Airshire fossils

    Kate,

     

    1. Coprolite?... I can't say, but that depression in the middle of the larger depression looks like that of a crinoid ossicle

     

    2&3. Productus (or similar) bivalve. They have that sort of shape and ridging

    http://2.bp.blogspot.com/-5fBGwxFeiIc/UTRBGaB5RqI/AAAAAAAAADw/9L05TZsf89k/s320/Productus1445.jpg

    http://www.theglasgowstory.com/image.php?inum=TGSE00580

     

    4. Could be one of the flatter valves from a Productus. If so, we're seeing them from the inside, since they are unridged. Aptychi are also a possibility, but less likely IMO.

     

    5. Maggot fossil? - no - It is the stem of a crinoid (called sea lily, though it is actually animal not vegetable)

     

    6&7. Can't tell; may not be fossil, could be part of a trace fossil; various possibilities.

     

    8. Not fossil. I'm pretty sure it is just a lump of ferruginous siltstone with various fracture patterns, and orange colouration due to weathering of the iron.

     

    Mike

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        Jun 28, 2014 10:20 AM (in response to kate)
        Re: what are these Airshire fossils

        Kate,

         

        That's a good question to ask.

         

        Part of what we learn from fossils comes from the fossils themselves, but some also comes from their context.

         

        You should record:

         

        - Size.

          Measure it and write it down.

          If you are taking photos, it is always a good idea to include a scale. A small ruler can be used, but there is usually a problem because it will give a false indication unless your photo is square-on to the ruler. A coin or lens cap of known diameter, laid parallel with the fossil (assuming it is flattish) gets over that problem because although it may appear as an ellipse in the photo (due to being seen somewhat sideways), the greatest diameter will be the true diameter. Also, the ratio of the greatest to least diameters gives the forshortening for the subject as a whole, allowing you to distort the image (in an image editor) to show it in its true proportions.

         

        - Description

        Less important if you are collecting the specimen, or photographing it. But there's always a chance that you will notice something in the field that you forget later.

         

        - In situ or ex situ.

          That is, whether the fossil was loose (in gravel, on the beach, in soil, etc. - 'ex situ') or in the rock ('in situ').

         

        - Description of the soil/gravel/etc or rock in which it was found.

        If ex situ, the soil or the greater mass of gravel may give a clue where it all came from. It could have come from only a short distance away (eg. if in the talus at the foot of a cliff; or it could have travelled a good distance if brought-in by glaciers, perhaps).

        If in situ, that would help you understand the depositional environment, which can cut down the list of possibilities when trying to make an ID. It can also help you indentify the particular stratum, by reference to published works - in association with the next point...

         

        - Exact location

          If in situ, that can help determine the particular stratum of origin (assuming you have a good geological map), which would give a good idea about its age and the environment in which it lived. The environment and age can both be useful when trying to make an ID. For instance, you don't find corals in deep-sea sediments, and you don't find trilobites in the Miocene.

        If in situ or ex situ, the location may enable you to find other people's records of what has been collected there - giving you a list of possibilities for you own fossil.

        Location can be recorded in different ways: description, grid reference, GPS...

         

        - Orientation

        This is often not significant, but sometimes it can be. If in situ, sometimes it is relevant to record which way was up. That's because some fossils include geopetal indicators. Some hollow fossils include a small amount of sediment, which tends to settle to the bottom, and can therefore indicate which way was up at the time of fossilization.

        Orientation in terms of compass bearing is unlikely to be significant as regards fossils. It is most relevant when doing structural mapping.

         

        - What other fossils you saw nearby.

        These can also be an indicator of the depositional environment and age.

         

        In recording all that, you'll need a numbering system.

        You can devise your own; many people do.

        It is common practice to put a little dab of white paint on the specimen (in a non-critical spot), then write a reference number on it once it is dry.

        A notebook (these days it can be a file on a smart phone or tablet) then keeps all the data together, including names of image files, URLs for ID discussions, etc.

         

        Mike

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            Jun 28, 2014 12:56 PM (in response to kate)
            Re: what are these Airshire fossils

            Kate,

             

            It is up to you how you record things; it all depends what your subsequent use of the records might be...

             

            However, unless you find the fossils actually in an outcrop of bedrock, they should be considered ex-situ. Spoil from mine workings are definitely ex situ - the rock they came from may be at the same location on a map, but could be a long way underground - where the geology could be very different to that at the surface. Other than that, it is not vital to pigeon-hole specimens into categories; your description serves well enough.

            Also, it is often the case that an ex situ specimen containing a fossil will include some of the host rock. That can be useful in determining the depositional environment, and maybe the stratum that the specimen came from - though it is not as reliable and useful as the host rock in outcrop.

             

            Good for you for taking advantage of the time window to collect in.

             

            Mike

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