Maclurites Living Component

[Bev]

Maclurites were sea snails in the Ordovician and probably beyond.

Does anyone have an idea of what the fleshy, living portion of the creature looked like? Just a slug or perhaps with antennae?

Modern snail

Maclurites crassus

Common Maclurites in matrix

[jpc]

I think there is no reason to believe they looked any different than modern snails....

[Wrangellian]

Hi Bev, Try a google image search for and look at various snails/gastropods (Archeogastropoda?) and see which one you think matches best. I wonder if there are any informed reconstructions out there of Paleozoic snails that you can use as a rough guide at least.

Edited February 18, 2015 by Wrangellian

[Bev]

That's just what I needed! THANK YOU!

http://palaeos.com/metazoa/mollusca/gastropoda/macluritidae.html

[Jeffrey P]

Bev, Those specimens are very impressive. Did you find them?

[Bev]

Bev, Those specimens are very impressive. Did you find them?

Oh yes! I LOVE Maclurites!

[Wrangellian]

Flat side down, sedentary suspension feeders!

[Plantguy]

Nice finds Bev! Regards, Chris

[Bev]

Thanks Chris!

Hey Wrangallian, I read this PDF:

http://www.soest.hawaii.edu/oceanography/courses/OCN621/Spring2011/OCN621_Suspension%20Feeding_website.pdf

How would a snail suspension feed? I just see it crawling around picking up what is at the bottom. The antennae certainly aren't feeding mechanisms, or am I oh so uninformed???!!! :-D

[Wrangellian]

No idea!

[Al Dente]

How would a snail suspension feed? I just see it crawling around picking up what is at the bottom. The antennae certainly aren't feeding mechanisms, or am I oh so uninformed???!!! :-D

There are some modern gastropods that suspension feed. One common one is the slipper shell (sometimes called slipper limpet) Crepidula. This is a common find on our beaches here in North Carolina. The males are able to move around and feed by grazing on algae but the females are pretty much sedentary. The females will use cilia to move water across their gills. Mucus on their gills will trap suspended particles and they will feed on the mucus. Here are several pictures of Crepidula. Males are frequently found stacked up on females.

https://www.google.com/search?q=crepidula&biw=1280&bih=929&source=lnms&tbm=isch&sa=X&ei=RGfsVNiuGY_jsATukoL4Cw&ved=0CAYQ_AUoAQ

[Bev]

Fascinating Al Dente!!! :-D

I found this:

Morphometrics indicates giant Ordovician macluritid gastropods switched life habit during ontogeny

Philip M. Novack-Gottshall and Keoki Burton

Department of Biological Sciences, Benedictine University, 5700 College Road, Lisle, IL, 60532, USA, < pnovack-gottshall@ben.edu>

Abstract

Paleontologists have long speculated that the bizarre, giant Ordovician gastropods Maclurites Le Sueur, 1818 and Maclurina Ulrich and Scofield, 1897 lived more like suspension-feeding oysters than typical algivorous snails. Geometric and eigenshape morphometrics demonstrate the plausibility of this lifestyle, but with a twist. The apertures of these gastropods were small ellipsoids when young, transitioning rapidly to polygonal morphologies at maturity, with angulations (sinuses) occurring in regions associated with development of mature ctenidia (gills) and enhanced stability on the seafloor. Combined with knowledge of extant suspension-feeding gastropods and functional and phylogenetic analysis of the anatomy of other fossil relatives, this ontogenetic pattern suggests these snails began life as typical mobile algae-grazers, but switched to sedentary suspension-feeders as they aged.

Entire PDF here and available for free download:

http://www.bluffcountryfossils.net/blog/maclurites-as-suspension-feeders-pdf/

So, as they got older they stuck themselves to the rock and used little feeler-like thingys and mucus to feed in a fixed area...

[Bev]

And here is a pic of one Mac on top of another, rather like those current snails you mentioned do!

Learn something new all the time!

THANK YOU GUYS!!!

[Auspex]

Fascinating stuff; good topic!

[fossilized6s]

Interesting.

I wonder if any of the body portion would be exposed while attached, other then the head/feelers?

Bev, this is getting trickier and trickier! Hahaha

[Bev]

https://www.flickr.com/photos/31856336@N03/11442780273/in/photostream/

So, I've been looking for models all over and I found this one, link above. Lower right hand corner there is what appears to be a snail but the artist almost represents it as a natiloid..

Snails have eyes, probably antennae, .it would be anchored, and the gills would have tiny feelers covered in mucus that would allow it to suspension feed. Gills on the sides or top of the fleshy body?

And I'm thinking it is the females that do this as fertilization would have to happen somehow, or not... Given that currently male snails crawl on top of female snails that are suspension feeding and tethered. And my rock seems to indicate the same in the Ordovician...

Hmmm, so how DID the corals, etc. that were suspension feeders reproduce?

Apparently, no one has ever attempted to draw a model of a living Maclurites or at least it is not on the Web that I can find... :-( I have a 5" Maclurites which is large for Minnesota. I think the largest was 25" across in Canada where everything gets bigger it seems - in the Ordo. They are an Ordovician only snail - there's a word for that but it eludes me right now. I believe, bigger than any snails currently living on Earth.

A 2' across snail would have to have a lot of critter in there and potential to be exposed, I would think...

[Bev]

So, digging around into gender, I came up with this:

"Even if the groups of prosobranch gastropods are placed to form independent separate groups, most of them have in common to have separate sexes, which means there are males and females with different sexual organs: The snail's gonad either produces egg cells or sperm cells.

In contrary to this there are, for example, the terrestrial pulmonate snails (Stylommatophora), the gastropod group richest in species, have in common to be hermaphrodites, which have one common apparatus with male, female and hermaphroditic organs. Terrestrial pulmonate snails have a hermaphroditic gonad producing egg cells as well as sperm cells. In a Roman snail's hermaphroditic gland, however, this happens at different times, so there can be no self-fertilization. On the other hand this exactly is what may happen in other snail groups (see below).

This is the place to explicitly use the term "terrestrial pulmonate snails", as there are other terrestrial snail species that are counted systematically among a group of prosobranchs, and which, in contrary to terrestrial pulmonate snails possess a shell lid (operculum) and separate sexes. Among those are the terrestrial operculate snails (Pomatiasidae).

Change of gender

Slipper limpets (Crepidula fornicata) mating.
Picture: Keith Hiscock, Marine Life Network.

While most snails have definite separate sexes, or in case of the terrestrial pulmonates, generally are hermaphrodites, it may also happen in some species that the gender changes during the lifetime. So slipper limpets (Crepidula fornicata) are mobile males in the beginning of their life and change into sessile females at a later time. That is how the spectacular mating "ladders" of slipper limpets come into existence, when younger males sit on older females to mate with them, with even younger males mating with them later, when they are females. A similar development takes place among violet snails (Janthinidae), which are males first and females later, though there is no sessile phase in their life."

Couldn't find anything on Macs specifically. But changing gender is currently an options, soooo...

And then I ran across this wonderful little poem that I thought I would share as it gave me a smile. :=D

THE FOSSILS

At midnight in the museum hail

The fossils gathered for a ball.

There were no drums or saxophones

But just the clatter of their bones,

A rolling, rattling, carefree circus

Of mammoth polkas and mazurkas.

Pterodactyls and brontosauruses

Sang ghostly prehistoric choruses.

Amid the mastodonic wassail

I caught the eye of one small fossil.

Cheerup, sad world, he said, and winked-

It's kind of fun to be extinct.

Copyright 1953 ()gdeii Nrih

[fossilized6s]

Wow Bev, you're really doing your homework on this one. Reading all of this has inspired a few ideas.

[Al Dente]

Slipper limpets (Crepidula fornicata) mating.

Picture: Keith Hiscock, Marine Life Network.

While most snails have definite separate sexes, or in case of the terrestrial pulmonates, generally are hermaphrodites, it may also happen in some species that the gender changes during the lifetime. So slipper limpets (Crepidula fornicata) are mobile males in the beginning of their life and change into sessile females at a later time. That is how the spectacular mating "ladders" of slipper limpets come into existence, when younger males sit on older females to mate with them, with even younger males mating with them later, when they are females.

I just wanted to post this picture to show that these Crepidula mating ladders can be found in the fossil record. Usually these will fall apart when I clean them but I used some diluted glue to treat these before I cleaned them. These are from the Pleistocene Waccamaw Formation in NC.

[Bev]

I just wanted to post this picture to show that these Crepidula mating ladders can be found in the fossil record. Usually these will fall apart when I clean them but I used some diluted glue to treat these before I cleaned them. These are from the Pleistocene Waccamaw Formation in NC.

crepidula.jpg

Fascinating! "Mating Ladders" LOL Never even considered that... in gastropods... :-D

[Tethys]

This is all fascinating Bev. The paper makes a good case for an attached, filter feeding mode for those species. I do have a few questions that it doesn't address, maybe someone here knows the answers.? I wonder how they attached? It is clear that the slipper shells just cement themselves to the substrate, but maclurites aperture isn't on the bottom, and being a gastropod they don't have a byssus. The operculum is mentioned briefly as a possibility, but I can't picture how that would work. My other thought is that here in MN, we have a "snail rock" layer that is pretty much all maclurites IIRC. It is reconstructed as a hyper-saline environment, which would have allowed them to get very large without affecting their mobility.

[izak_]

Ok, Bev. You clearly do like these animals >.<! In the good way ._.

You are teaching me, and probably tons of over people, a lot about this stuff! Thanks for sharing your knowledge!

Edited February 25, 2015 by izak_

[Bev]

Ok, Bev. You clearly do like these animals >.<! In the good way ._.

You are teaching me, and probably tons of over people, a lot about this stuff! Thanks for sharing your knowledge!

What knowledge?

I'm doing the homework and learning as I'm going at the direction of much more knowledgeable members!

Do love those Macs though! My heart beats just a bit faster every time I find one!

And Tethy's brought up some excellent questions!

I had no idea that Minnesota had a "snail layer" in our rocks!

[Wrangellian]

Double mac.jpg

And here is a pic of one Mac on top of another, rather like those current snails you mentioned do!

Learn something new all the time!

THANK YOU GUYS!!!

This pic doesn't enlarge for me, just a thumbnail,

and the diorama in your post #16, is that not supposed to be some sort of nautiloid rather than a Maclurites?

[Bev]

On the diorama, I don't think it is a Maclurites representation, but it could be a Mac crassus given the coil. I have found NO Maclurites drawings envisioning how the creature would have looked in life.

Yes, that is a thumbnail I just picked up from another photo. I have that rock inside by my ponds, so I will take a proper picture and put it up shortly.