Ammonite ID help

[distant_smile]

Hi all. Both ammonites found in Bristol, UK, BS31, as we're the shells and coral. Not much else to say but would be nice to get a bit more info from the pros?

[Ludwigia]

Since the ammonite bits are only partials, it would be necessary to know the precise stratigraphy, since many different ammonite species have similar structures. However if the finds were made in the Early Jurassic (Lias), then I could hazard the guess that the first one could be part of the outer whorls of an Arietites. It could also help in identifying the coral, and although I'm no expert on that subject, I do know that these are more difficult to id and often a very close examination of the internal structure is necessary, sometimes even by sectioning. The bivalve is poorly preserved and difficult for me to determine, although maybe someone more familiar with this area has an idea?

[distant_smile]

Thank-you Ludwigia your comments are very much appreciated. I hoped the size of the large ammonite may narrow it down as in the past I've only found small ones...but I think I also knew it was a long shot due to the degredation

[Aman]

Hi, I'm quite familiar with the fossils that are commonly found on the Somerset coast, which I believe to be the same formation (blue lias), and therefore of similar age, as the Jurassic rocks that underly parts of Bristol and the surrounding areas.

     The first ammonite that you have could only be either a Coroniceras (also known as Arietites) or a Paracoroniceras because of its size, however it's difficult to narrow it down past that because of how little there is of it. I've attached a picture of a complete, but poorly preserved, Coroniceras that I found recently. It was about 25 cm across, but I have found several specimens that are much larger (several over 40 cm, a few over 50 cm, one much, much larger than that) and much better preserved than this one.

     Unfortunately the second ammonite is too poorly preserved to give a definitive ID, but due to its size I would hazard a guess that it might be a piece of one of the two types of large ammonite that I mentioned before.

     The coral looks like it is from the genus Isastrea, though the specific species I cannot say. As for the bivalves, it is difficult to say what they are exactly as these are once again not very well preserved; they appear to be some sort of clam from what I can see, possibly small examples of Plagiostoma, which is a large bivalve quite common in the blue lias, though it is difficult to know for sure.

I hope this has cleared some things up for you.

[distant_smile]

Thanks! My own, albeit amateur, research lead me to coroniceras and paracoroniceras due to the size so its great to hear you say that. And thanks for the educated guesses on the others...at least I now know what general area they may be in and it gives me a bit more knowledge for identifying in the future. Much appreciated.

 

[Mark Kmiecik]

On 4/15/2024 at 11:42 AM, distant_smile said:

as we're the shells and coral.

 

I'm pretty sure you are not.

[distant_smile]

Sorry Mark I dont quite understand the comment?  

[distant_smile]

Lol sorry just re-read it. Yes Mark we are not the shells *were. Nice catch

Edited April 16 by distant_smile