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JamieLynn

Odd find from Oxford Clay in Dorset England - Crinoid Calyx ?

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JamieLynn

Hi All! Just got back from a lovely trip to England and had a great hunt in Weymouth. Found this odd thing that I thought was a crinoid Calyx, but I am really not sure. I will eventually clean out the center, but was wondering if anyone might be able to tell me for sure what it is. Any help is appreciated! Thanks! 

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caldigger

Brooksella?

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JamieLynn

I thought that too but can't seen to find any info of them being found anywhere but Alabama and Georgia. 

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daves64

Ammonite chamber?

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Ludwigia
7 hours ago, caldigger said:

Brooksella?

Could very well be, although ammonite chamber is another possibility. There are records of Brooksella family members ranging up into the Devonian of which according to the geological map of Weymouth there are outcrops.

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TqB

I think it's a sponge, probably from the Cretaceous Greensand - perhaps Hallirhoa sp. (I don't believe there are any sponges in the Oxford Clay, although there are in other Callovian deposits.)

 

59 minutes ago, Ludwigia said:

...the Devonian of which according to the geological map of Weymouth there are outcrops.

Roger, I was a bit mystified by that! - maybe you're looking at this Wikipedia map? 

https://en.wikipedia.org/wiki/Geology_of_Dorset#/media/File:Dorset_Geology.png 

The bits that look Devonian brown coloured are all Jurassic, the practically identical brown of the Kimmeridge Clay

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JamieLynn

so we were kind of on the right track with Brooksella....I think sponge is probably accurate. It definitely does not have the same features of any kind of ammonite chamber I've seen, even water worn. So perhaps this washed up from another formation in that location.

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TqB
2 hours ago, JamieLynn said:

so we were kind of on the right track with Brooksella....

Yes, it looks very similar, though Brooksella (or some of them) may not actually be a sponge...:wacko:

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Ludwigia
5 hours ago, TqB said:

Roger, I was a bit mystified by that! - maybe you're looking at this Wikipedia map? 

https://en.wikipedia.org/wiki/Geology_of_Dorset#/media/File:Dorset_Geology.png 

The bits that look Devonian brown coloured are all Jurassic, the practically identical brown of the Kimmeridge Clay

Oops!You're right about that. I mistook the Kimmeridge Clay for the Devonian. Well, Brooksella may not be right, but I think that sponge is the right idea.

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JamieLynn

could it be polypothecia? 

Image result for polypothecia

 

or porifera Tetralithistida8e366e7ca10052e734794d82baf75a20.jpg

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Mark Kmiecik

Would Alcyonite be a possibility?

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JamieLynn

I just don't know!! Nothing seems to fit just right.....

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TqB

Sponge identification is usually a matter for a specialist, with microscopic work and looking at spicules. Overall form is highly variable so not necessarily that diagnostic.

 

Polypothecia hasn't been properly described and there are a number of possible synonyms that should take precedence, including Hallirhoa. See:

https://www.academia.edu/36777066/Where_is_Polypothecia_Benett_1831

 

Tetralithistida isn't a genus but an order, a very large group that contains many sponge genera. Hallirhoa is one of them and is what your illustration shows (as the old label says!).

 

So I still reckon Hallirhoa? is a reasonable ID until you take it to a sponge specialist. :)

 

(I think Alcyonite is an archaic term not in modern use that includes a lot of sponges.)

 

 

 

 

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JamieLynn

thank you for taking the time to explain! As you can tell, i have no experience with sponges- and yes, I did see the Hallirhoa tag on that one so was curious about that. I will just go with Halirhoa! 

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TqB
17 hours ago, JamieLynn said:

thank you for taking the time to explain! As you can tell, i have no experience with sponges- and yes, I did see the Hallirhoa tag on that one so was curious about that. I will just go with Halirhoa! 

A pleasure! I'm very much an amateur on sponges. They're an enormous and endlessly fascinating group - in the academic sponge world, each specialist can only concentrate on a particular area within them. I've had a lot of help from @Spongy Joe who hasn't been seen on here for a while...

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Mark Kmiecik
On 9/19/2019 at 1:52 AM, TqB said:

(I think Alcyonite is an archaic term not in modern use that includes a lot of sponges.)

It happens in your late sixties. I'm 68, therefore I am. Archaic that is. :D

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TqB
11 minutes ago, Mark Kmiecik said:

It happens in your late sixties. I'm 68, therefore I am. Archaic that is. :D

:D

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