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Sponges?


Wrangellian

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I posted some of these in the 'Collections' section, but I still don't know for sure if they are sponges. The preservation is not what I would want, but I can't expect much from our local shale, it's not exactly Burgess Shale and the sponge may have been delicate in life. The fine crosshatched pattern reminds me of a Hexactinellid (Glass) sponge. One guy I showed it to was skeptical and thought it was just a plant, but I want a 2nd opinion. I only showed him specimen #2 below, and I failed to point out to him that all the plant material from this site (which is plentiful) contains carbon (coal), visible even as a black film in a leaf, for example, while these have none (and these aren't weathered either - I broke them fresh out of the rock myself.)

Does this structure jump out screaming 'sponge' to anyone?

I realize I might get better answers when I start taking better pics, but this is what I've got now!

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post-4372-051160700 1289631679_thumb.jpg

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it does actually, im not sure what species but im pretty sure its sponge.

-Shamus

The Ordovician enthusiast.

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looks like fossil burlap :P

cool fossil, could it be a bryzoan or coral?

It looks like fossil cheesecloth to me!

I thought of bryozoan, and I can't rule that out, but I always thought bryozoans looked more like interlocking tubes whereas this stuff looks like fine mesh as in sponge spicules. No idea really. I doubt it's coral for similar reasons.. It looks like a flimsy material that tended to get twisted and squashed easily during preservation.

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this peice resembles yours, and its bryozoan

http://www.kgs.ku.edu/Extension/fossils/jpegs/Septopora.jpg

Interesting.. it does resemble.. what age is that one? Mine is U. Cretaceous, but bryozoans are still around today so that's not outside the realm of possibility is it? Incidentally I read that the Cretaceous was the most diverse time for sponges, so I would think they should be everywhere, it just depends on the preservation. (I wonder which is more delicate, the sponge or the bryo. I know the Glass sponges have silica spicules, while the other types are calcareous or spongin or whatever, so I would think the glass ones would be more likely to preserve. I don't know what bryos are made of..)

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im sorry i dont know what age, i got the picture off of google ;)

-Shamus

The Ordovician enthusiast.

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Wrangee

Nice finds, yes they resemble sponge or fenestrate bryozoans!!

I haven't seen any from our Cretaceous sites before!!

Cephalopods rule!!

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Wrangee

Nice finds, yes they resemble sponge or fenestrate bryozoans!!

I haven't seen any from our Cretaceous sites before!!

I know, I don't think there have been any sponges or bryos yet found in our Cretaceous.. I'm hoping if I get this confirmed I'll have discovered something new! -going to try to get some more of the VicPS guys to look at them at the meeting this Wed.

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Wrangellian , you should send some photos to Dr Paul Taylor at the Natural History Museum , London. He will be able to tell you if this is a fossil bryozoan

Cephalopods rule!!

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  • 3 weeks later...

Hi wrangellian, it looks to me like a meshwork of skeletal needles from a hexactinellid sponge. This type of sponges sometimes does have this regular nearly square meshwork consisting of siliceous spicules. Compare your find to Diagonella spec. or Protospongia spec., both from middle and upper cambrium.

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Thanks guys, that's what I was thinking. I did hear back from Dr Paul Taylor the Bryozoan expert and he doesnt think they are Bryozoans, apparently there aren't Bryos like this in the Cretaceous. But the only reference I can find do sponges with this pattern are Paleozoic too, like the ones you mentioned! Of course my sources are limited.

Can anybody show me pics of Cretaceous sponges with this netlike pattern?

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Quadratic mesh patterns in recent and fossil sponges are quite prolific. A quick perusal of the sponge atlas volume of the treatise indicates numerous types from the Paleozoic forward. I've attached a image of two Cretaceous quadrate examples that also preserve their coloration.

From The Treatise on Invertebrate Paleontology Part E - Porifera Revised Vol.2

quadrule (n). Square mesh with sides formed by tangential rays of four hexactines, pentactines, or stauractines, whose centers are located at the corners, or produced by subdivision of such a square by smaller spicules within it (Hex).

post-4301-034282000 1291676606_thumb.jpg

image.png.a84de26dad44fb03836a743755df237c.png

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I see that, but I figure if Dr Paul Taylor says fairly confidently that it's not a bryozoan then I'll take his word for it.

The thing that has me wondering with both the bryos and sponges I've seen so far is that they all seem to have thickness to them, as if they were made up of interlocked tubes, while mine looks thin like it was made of cheesecloth. I don't know if that's just a difference in the preservation, but I'd still like to see examples more similar to mine to be confident. In any case I don't think it's a plant like one of our local experts suggested on the basis of one specimen, so I'm still looking for answers.

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I was leaning towards sponge, but went back to look at some bryos - This Ptilopora striata interested me... :)

Coincidental sponge mimicry is a worthy topic - TFF is a clearinghouse for "What is it - Sponge Coral Bryo?" threads. The debate is always a interesting one. Here is Receptaculites - the quintessential sponge mimic. So good in fact that it escaped proper classification for many years. Although it was removed from Porifera and placed as a algal form the treatise nonetheless still pays tribute with a special category of 'Genera Incorrectly Assigned to Porifera But Belonging To Other Taxa'. Among 39 disallowed taxa 12 were receptaculitids outnumbering all others. Bryozoans are well represented with 6 for a 2nd place ranking among exiled sponge imposters.

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Wrangellian,

For a definitive opinion on the sponge hypothesis, you should contact Dr. J. Keith Rigby, the preeminent authority on all things spongy. He is an emeritus faculty member at the Brigham Young Dept of Geology, and you can find a link to his email at the bottom of this page.

Don

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I see that, but I figure if Dr Paul Taylor says fairly confidently that it's not a bryozoan then I'll take his word for it.

The thing that has me wondering with both the bryos and sponges I've seen so far is that they all seem to have thickness to them, as if they were made up of interlocked tubes, while mine looks thin like it was made of cheesecloth. I don't know if that's just a difference in the preservation, but I'd still like to see examples more similar to mine to be confident. In any case I don't think it's a plant like one of our local experts suggested on the basis of one specimen, so I'm still looking for answers.

The Cambrian sponges that come to mind are generally preserved flat like a cheesecloth. Isn't this more or less just to be expected given the age and typical characteristics of preservation? I don't mean to oversimplify the premise other than to say many Cambrian faunas yield flat fossils.

I'll post photos here of various flattened Paleozoic - Cenozoic sponges for you to evaluate in comparison with your specimens.

image.png.a84de26dad44fb03836a743755df237c.png

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The following images represent a variety of hexactinellid sponge fossils from the Ediacaran to the Pliocene-Holocene boundary. The focus was to showcase the forms that best exhibit a net-like spicular mesh preserved as flat impression fossils. One example was discovered from Class Demospongea and happily included with the others. It's been a great exercise to compile and research this fascinating group of sponges. Enjoy! ;)

Palaeophragmodictya - Ediacaran

Wapkia - Cambrian

Leptomitus - Cambrian

Leptomitella - Cambrian

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