Egg Case Or Not Egg Case: That's The Question

[Nandomas]

Hello everyone, in the Entries - November 2010 Finds Of The Month there was an interesting discussion about the Paleozoic Sharks Egg Case: http://www.thefossilforum.com/index.php/topic/16609-entries-november-2010-finds-of-the-month/

Last year, at Macomb Fossil show, I bought a Mazon Creek nodule and I was asking to myself if the fossil into the nodule was really a shark egg case or some other fossil, so I was very happy to see the Terry Dactyl (very nice) find

Steve was so kind to send me the publication about shark egg case, so now I am sure I have an egg case from paleozoic shark :D

But the debate is still open....

Please throw here your idea(s)

Nando

jpc wrote (11 November 2010 - 05:08 AM):

That is way cool, but...

I must be a skeptic... so how does that get to be an egg case? I have seen many skate egg cases on the beaches in Massachusetts as a wee lad, and they look nothing like that. OK, I realize that there are many different sizes and shapes of shark/ray egg cases, but how do you identify one as a fossil? I'm not asking to be a wiseguy critic, but rather to get me some edumacation.

Coco wrote (11 November 2010 - 10:25 AM):

I think like JPC. How do you recognize a shark or a skate egg case in this stone ? Eggs of current selachians is a subject which I know well. I have approximately one thousand current eggs at home, and this rock shows nothing resembling with that I know. Nevertheless, it is not the first time I see on the web this kind of article, and every time I ask me this question...

Eggs of selachians are made with a rotproof material, and my opinion is that one eggs fossil of selachian should more look like current eggs of selachians.

Terry, may we have a a close-up on one of the faces of your stone to see better the fossil?

MichiganTim wrote (11 November 2010 - 12:39 PM):

In "The Richardson's Guide to The Fossil Fauna of Mazon Creek," Palaeoxyris is listed in the Problematica chapter and has been assigned to both plants and animals. "The current opinion is that they are ancient chondrichthyan egg cases."

Looks like a Palaeoxyris to me. Nice find.

Terry Dactyl wrote 12 November 2010 - 12:17 PM.... rather than me try and go into specifics in a field I know very little about there was a scientific paper written to explain the early miss-identifications of the carboniferous shark eggcases outlining the species that have been found with supporting references to previous research papers carried out in this area... I'll be glad to forward you a copy of the paper when I can get to my own pc so you can have a read yourselves... maybe in the mean time you could pm me an email address for me to send it to you in PDF format...

Just an observation from just a 'fossil finders' perspective as I'm no expert in this field... there is no plant material whatsoever in the layer that these eggcases are found in with only the very scarce poorly preserved Cyclus... and an accompanying stone band of ripple beds .. This tells me that rather than a forested area where you would find plant remains, this was possibly a river channel or levee that was part of the vast river delta that covered our area during the upper carboniferous period...

I'll do a couple of closeup photos at the same time to show you the defining details/patternation on the fossil so you will be able to ID it yourself as a Palaeoxyris shark eggcase...

Edited December 2, 2010 by Nandomas

[Nandomas]

Terry Dactyl Shark Egg case and my mazon creek nodule

[Bill]

Well I agree, they're shark eggcases. The nodules have, in these cases, split through them. See here for others and a more complete one, (2nd from bottom on the left).

[Terry Dactyll]

''Please throw here your idea(s)

Nando''

Nice Shark eggcase... I'm glad it turned out you bought what you thought you bought without knowing if it was what you bought...

I would imagine 2 sharks fossils in one rock are pretty rare... meet the ' Fossil Baby Shark Twins '...

and the very rare Vetacapsula eggcase...

[oilshale]

I am not sure if you have seen these sites about egg capsules from living sharks, skates and chimaeras

http://home.planet.nl/~bor00213/

and about fossil egg capsules:

http://home.planet.n...213/fossil.html

This is a shark egg capsule (Palaeoxyris muensteri ) from the Lower Jurassic of Unternschreez in Bayreuth, Germany (Length: 20cm ).

Thomas

[Terry Dactyll]

Thomas.... Very nice preservation on your eggcase... and thanks for the links....

[Coco]

Hi,

Goode idea, Nando, to open this post ! I am writting a post on recent selachian eggcases wich could be useful, but I have to add 2 species and do pics before sending it.

I know the website you indicate oilshale. For me, it is the best one on recent selachian sharks. I can see he added more fossil eggs.

Coco

[Nandomas]

Coco, I :D just saw your beautiful post on modern eggcase!!! Thanks to post it

I Found these photos I did at Munich Fossil show:

a tithonian shark eggcase (the shape is conventional, very similiar to the modern shark eggcase) on Solnhofen limestone. The vendor was very kind, but asked for 3.500 euros

... not for my pockets

Edited November 18, 2010 by Nandomas

[Bill]

Hi Nando,

Here's a Cretaceous, Lower Weald Clay specimen. The nearest described specimen to this is Palaeoxyris versabundus. Probably from either Lissodus or Lonchidion sp. - but who can tell for certain. det. David Ward.

Total length, including pedicle is 58mm. There is part of a second pedicle on the left side. The second egg disintegrated on exposure, and fell on, around, and in-between, lots of already split rock and was not retrievable.

Edited November 18, 2010 by Bill

[florida_fossils]

To beat or not to beat, that is the question.

[Coco]

It is surprising to see that the majority of these eggs seem fossilized "on the side" (or while they are very narrow), except yours Nando, because if I saw well your photos, you surrounded in red the shape of the egg which would be fossilized in flat (of face).

Here is the link of my file on recent selachian eggcases :

http://www.thefossilforum.com/index.php/topic/16894-recent-selachian-eggcases-mermaid-purses/page__gopid__186798

Coco

[Terry Dactyll]

Coco.... I think these eggs were rounded in cross section rather than rectangular in shape so regardless of how they fell into the sediments they would appear the same width as the ones photographed above....

Heres one 'unopened' ...

[Terry Dactyll]

Heres another rare find found at the weekend off a completely different coalseam and is the first to come from that level a hundred metres or so higher than the others which represents quite a substantial amount of geological time I would imagine.... there probably wont be a 2nd as its a very small exposure....

Palaeoxyris Shark Eggcase...

Edited November 23, 2010 by Terry Dactyll

[pleecan]

I finally found my Mazon Creek shark egg case (purchased) for comparison.....

Edited December 1, 2010 by pleecan

[PaleoPastels]

Huh, very interesting! I didnt know there were fossil egg cases found at Mazon Creek. I bet those are very rare to find. Who ever owns it, take very good care of it!

[RCFossils]

Palaeoxyris (shark egg cases) are fairly common in the Braidwood portion of Mazon Creek. There are at least a half a dozen described types although my guess is that several are synonomous. There are a few rarer types such as Fayolia and Vetacapsula. Most are believed to come from Hybodont sharks which is interesting because Hybodont material other then egg cases is very rare. Fayolia is believed to be an egg case from a Xenacanth shark

I am attaching a few pictures of the more common type. The first is the most abundant Palaeoxyris prendeli.

[RCFossils]

Palaeoxyris appendiculata is also rather abundant and can be highly variable. This is a nice large example with two cases preserved. I am also attaching a picture of a second rarer variation.

[RCFossils]

This is another unusual example whuich does not conform to any of the described types. It is more robust and I have only seen this variation from some of the older sites.

[RCFossils]

This is one of the rarest egg capsules Fayolia sp. I believe this is the largest egg capsule that has been found to date. It is thought to be from a xenacanth shark. It is much larger then Palaeoxyris.

[Coco]

Hi,

RC, your fossil eggcases are marvelous. Their forms are unusual, and I had never seen it fellow men before.

Coco

[Terry Dactyll]

RCFossils..... Great examples.....The Vetacapsula is the rare one from our neck of the woods although I was fortunate enough to find one and we are still looking for a Fayolia.... There was a hint of one from Yorkshire recently but its looking doubtful it is one for sure....

Peter.... Very nice example....Thanks for sharing it....

Edited December 1, 2010 by Terry Dactyll

[siteseer]

Nando,

I have thought about this too. Yesterday, I asked Dr. John Hedley (Natural Canvas) about the latest information on Palaeoxyris (he knows a lot about soft-bodied fossils). He said there is a German article on it, adding that it has yet to be confirmed that it is a shark egg case as no one has ever found an embryo inside one. He left open the possibility that it could be a fruiting body of a plant. He mentioned the find from the Early Cretaceous of England - interesting because it would seem more likely to be a shark egg case than the same kind of plant from the Carboniferous (but not impossible).

It would be great if it is a shark egg case because I have one from a Mazon Creek site.

As you said, the debate is still open.

Last year, at Macomb Fossil show, I bought a Mazon Creek nodule and I was asking to myself if the fossil into the nodule was really an shark egg case or some other fossil, so I was very happy to see the Terry Dactyl (very nice) find

Steve was so kind to send me the publication about shark egg case, so now I am sure I have an egg case from paleozoic shark :D

But the debate is still open....

Please throw here your idea(s)

Nando

[Nandomas]

Thanks for your info, sitseer, looking forward to read the german article... actually to try to read :wacko:

[Terry Dactyll]

Siteseer....

''He said there is a German article on it, adding that it has yet to be confirmed that it is a shark egg case as no one has ever found an embryo inside one.''

I dont think there are many collectors who find a shark eggcase that would consider destroying the fossil to see whats inside it....although very often there are some lumps and bumps....and realistically speaking, Megalodon's (the biggest shark that ever lived)only remains from just a few million years are teeth and the odd vert with sharks skeleton being cartiladge... so what are the chances of unformed embryo shark teeth and verts surviving 300 million years.....was this guy serious?

Edited December 3, 2010 by Terry Dactyll

[siteseer]

Perhaps a CT scan would reveal something imperceptible to the naked eye or microscope.

I'd have to ask him about that but if a shark egg case could survive in some way perhaps at least the teeth of an embryo would be preserved especially if the egg was about to hatch when it was buried. Also, if something as soft-bodied as a worm could be preserved, why not a shark embryo? Complete sharks are known from Mazon Creek and a few appear to be at least young as juveniles.

Siteseer....

I dont think there are many collectors who find a shark eggcase that would consider destroying the fossil to see whats inside it....although very often there are some lumps and bumps....and realistically speaking, Megalodon's (the biggest shark that ever lived)only remains from just a few million years are teeth and the odd vert with sharks skeleton being cartiladge... so what are the chances of unformed embryo shark teeth and verts surviving 300 million years.....was this guy serious?