Help! Ammonite ID required.

Phil

Colossal Squid
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#1
Hi all,

Can anyone help to identify this ammonite for me please? A work colleague picked it up in a second hand shop for £6 and wondered if I knew which species it was. It certainly is not local.

The specimen measures 1 1/2 inches in diameter and has a very thin profile with a slight raised keel. I will do some research, but I thought I'd let you chaps have a stab at it first.

Phil

(nice to be back!)
 

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neuropteris

GPO
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#2
Hi Phil - nice to see you are back in operation again.

No idea on the ammonite but the matrix looks like an oolite so it could be from the Inferior oolite around the Burton Bradstock area of Dorset if its from the UK. The inferior oolite is highly fossiliferous with a diverse ammonite fauna and is Middle Jurassic if thats any help in pinning it down - if its not from the UK all that could be wrong though.

All the best

Andy
 

Phil

Colossal Squid
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#3
Thanks Andy. Unfortunately we don't know where it came from, but perhaps you are right. I'll pass it on.

I am leaning towards an Early Jurassic Oxynoticeras ID, or something very similar to that. Anyone agree/disagree?
 

Architeuthoceras

Architeuthis
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#4
There are a number of Hildoceratids with a compressed whorl section, falcoid ribs and a keel, it could be any one, or even a homeomorph. Really need locality or age info.

Sorry Phil, this don't help much :sad:
 

spartacus

Haliphron Atlanticus
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#5
from what I'm pulling up, it looks French & therefore early Jurassic, any sign of spines on the keel or smell of garlic ?
will consult my guide & brb

Keef
 

Phil

Colossal Squid
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#6
Thanks Kevin. Here's another picture though I don't think it'll be of much help. The flash reflecting off the varnish tends to mask some of the detail. I'll try another without the flash on in the daylight in the next day or two. (I'm sure you'd like your fossil back Neale!)

No spines or other Gallic wierdness, Spartacus. I think any money put on early Jurassic date is onto a winner though.
 

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Phil

Colossal Squid
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#8
Kevin,

Thank you very much, I think you may have got it, the specimen resembles the image provided in your link to Dorsetensia to a remarkable extent, including the profile. I will pass the details onto Neale tomorrow.

I've had a Google search on Dorsetensia which was interesting as not only had I had never even heard of it before, but I did not realise there were beds of these beasts in Somerset in SW England preserved in oolite. Also thanks to Andy too here for the oolite suggestion.

Interesting details here, from a Somerset City Council Report from 1997;

Miller‘s Hill is located 650 metres west of the hamlet of Milborne Wick,approximately 5 kilometres north-east of Sherborne. The site comprises rockexposures in the lane sides, the adjacent field north of the lane and land around acovered reservoir to the south of the lane.Miller‘s Hill is an important and historically famous locality for studies of MiddleJurassic (Bajocian) stratigraphy and palaeontology. In ascending order, the sectionexposes the Corton Denham Beds, the Miller‘s Hill Beds and the Sherborne BuildingStone of the Inferior Oolite; this site is also the type locality for the Miller‘s HillBeds.

The complete section is over 6 metres thick and ranges from the Laeviuscula toSubfurcatum zones, but particular interest rests on the so-called 'Astarte spissa' Bed.This level yields abundant well preserved fossil brachiopods and molluscs including arich ammonite fauna of Humphresianum Zone, Cycloides Subzone age. This fauna includes macro- and microconchs of Sphaeroceras, Poecilomorphus, Oppelia,Dorsetensia, Teloceras and Stephanoceras. No other site in Britain yields as rich afauna of this age.Miller‘s Hill is a famous site of national significance, well known for its exposures of Inferior Oolite sediments and their associated fossils. The ammonite fossils from the Cycloides Subzone are of international significance for correlation and represent themost diverse faunas of this age known in Britain.
I knew I could rely on you chaps to come up trumps!
 

Architeuthoceras

Architeuthis
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Moderator
#10
And alotta books :wink:

And Google :wink:

There are a few more it could possibly be but I cant find anything on the web. Try Darellella and Reynesella, they look comparable. Amaltheus has a similar shape and ribs, but the keel is serrated.:smile:
 

Phil

Colossal Squid
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#12
Thanks again Kevin.

I'm afraid I have been unable to find any images of Darellella and Reynesella to compare. They are not listed in any of my books, on my copy of Paleobase or register any hits on the net. The keel, as you say, is smooth, so it cannot be Amaltheus. Still, the rock seems to be oolite as Andy has pointed out, and it looks so close to the link you kindly provided to Dorsetensia that I'm sure that be the beast in question, especially considering that the type of rock is very similar or identical to the Somerset beds.

Thanks again!
 
#13
Definately not Amaltheus so my moneys on Dorsetensia aswell :smile:

The ammonite fauna in the inferior oolite really is spectacular - I went to a dig at the Burton Bradstock caravan park a few years ago and it was amazing - didn't get much as most of what was there had already been spoken for but there were ammonites (mainly Parkinsonia) as big and bigger than dinner plates lying around together with huge Stephanoceras, Breydia, Leioceras and nautilus - dead ceph paradise! Did get one nice Parkinisonia (pic attached). The land owners were digging out hard standing for new caravans so this stuff was just being dumped as waste but the local collectors get wind of new exposures and get in there first. Still - it was nice to see.

Andy
 

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