Mystery! Are any of these shallow-water exclusive?

[eternal_flow]

Hello!  

 

I'm wondering if any of these shells are known to ONLY be found in shallow water.  If so, which one?  And how shallow are we talking-- 10 meters?  100 meters?

 

Found near the Azores, depth unknown.  Some forams can be used for scale.

 

Any help will be greatly appreciated.  Thank you!

 

Edited May 16, 2018 by eternal_flow

[Jazfossilator]

Interesting question, what made you wonder that? It may be helpful for people to identify the shells if you take clear pictures of them individually. 

[Raggedy Man]

These look like foraminifera to me and that all I know. We have a few experts who seems to only collect these. Hopefully they'll chime in and will be able to answer your questions.

[Cowboy Paleontologist]

I see a number of foraminiferans, a couple of ostracods, and maybe a couple of bivalves?  I can't say more without better pictures.  I've only found these types of organisms in shallow water.  That being said, I have never looked in deep water  

 

I would imagine though, that even if the organisms only live in shallow water, it would not be out of the question for them to settle to the bottom, however deep that may be.  Perhaps @Peat Burns could be of some more assistance.

 

[Spongy Joe]

Of these, ostracodes may be the key group to look at, since they're often used in ecology/palaeoecology to understand water depth changes. I haven't got a clue on the modern species, but yours look like they include some distinctive ones. You could start somewhere like this, and see where you get to...:

http://www.nhm.ac.uk/research-curation/scientific-resources/biodiversity/global-biodiversity/atlantic-ostracods/atlas/index.html

 

p.s. is that a terebratulid brachiopod in the last image?

[doushantuo]

Most ostracods have a rather wide bathymetric distribution.

 

 

[Spongy Joe]

19 minutes ago, doushantuo said:

Most ostracods have a rather wide bathymetric distribution.

 

 

True - but that's the same in any group, once you go below the intertidal-specialist zone of the shallowest shelf. For this sort of study you do need a bit of luck to find the most useful species.

 

Of course, the best way to narrow down the sample origin is to find overlapping ranges - some with shallower limits, and some with deeper, and see over what range they coincide (allowing for offshore transport, of course...).

 

One thing worth noting is probably the agglutinated tubes (annelid or foram?) made of fine sand grains. These don't tend to travel long distances intact, and suggest a sandy substrate - so, maybe shallower rather than deeper... but we really need someone who actually knows these specific faunas to chime in!

[doushantuo]

Here's what I think: the poster SEEMS to want to know if there's some surefire bathymetric indicator(relevant to the usual ecological zonations,I presume) among the microfossils he found.

I was simply trying to say that a single ostracod valve (carapace) has limited value.

Left/right valve ratios,abrasion,fungal boring(etc),mixing of ontogenetic stages,perhaps male/female ratios are more productive avenues,but I'd like to be proven wrong.

image from Schroder(JFR,1988) et al:

some forams* use specific particles in the agglutination process(mineralogically/granulometrically speaking)(*Eggerelloides,Textularia)

 

 

Some foram taphonomical literature that MIGHT be useful:

 

BeyESRtaphonforams.pdf

(about 1,8 Mb)

outtake:

[Spongy Joe]

I've got no argument with any of that, Ben!

 

There may be something in those few photos that actually gives a definite answer on its own, but you're absolutely right that in general this sort of question takes a lot of answering. If you're in the extreme shallows, it's generally a lot easier to find a smoking foram (guns are no use in depth zonation, after all), but for the mid to outer shelf range it's not easy. Multiple species with overlapping ranges are good, and taphonomic aspects can be really useful as well - if you have an unbiased sample to work from. In this case, I suspect we're stuck with what we've got; but at least there seem to be several species of ostracode in those images, so it's something to have a go at...

[doushantuo]

the ostracod seems to have suffered little abrasion,so perhap "intertidal" is out of the question

Most/A lot  of the installments of the "Stereo atlas of ostracods" is available online,BTW,via Biodiversity Heritage Library

I can recommend:

[Tidgy's Dad]

17 hours ago, Spongy Joe said:

Of these, ostracodes may be the key group to look at, since they're often used in ecology/palaeoecology to understand water depth changes. I haven't got a clue on the modern species, but yours look like they include some distinctive ones. You could start somewhere like this, and see where you get to...:

http://www.nhm.ac.uk/research-curation/scientific-resources/biodiversity/global-biodiversity/atlantic-ostracods/atlas/index.html

 

p.s. is that a terebratulid brachiopod in the last image?

Not a brachiopod, sadly, some forams have that sort of shape, I think it's one of them.