Donnez votre avis sur cette ammonite

() : thank you. ( 05/07/2003 à 08:24 )
Hello.I engoy a lot from your beautiful ammonites.Thank you very much.But I have aquestion .How you can distinguish between the 2 Ammonites that are similar to eachother.For example this one and Parkinsonia Are very similar.I like to know more about them.2 Pictures of each ammonite from different sides are useful to recognize them. thank you.
Hervé : () ( 05/07/2003 à 09:44 )
Hello. Thanks for your message.
There are lots of differences between this ammonite and a Parkinsonia that may not be obvious on a single picture :
- the whorl section of this ammonite is strongly rounded and depressed, while Parkinsonia are flatened and compressed ammonites ; I'll publish a ventral view in the next future ; before, you can look at my Stephanoceras to see a quite similar venter
- for the same reason, the umbilicus is much deeper
- ribs are not interrupted on venter ; on Parkinsonia, they are
- there is a difference that you can't see in the suture line that characterizes Stephanocerataceae
- furthermore, these ammonites are older (Late Lower Bajocian) than Parkinsonia (Late Upper Bajocian) and so are not found in the same layers
Hervé : Update ( 09/07/2003 à 20:43 )
Here are the new pictures! Sorry, my Stephanoceras had no more ventral view :-/.

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