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Mazon Creek Shark Egg Case/Horseshoe Crab


Roby

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Just joint and wanted to get my first entry in.  This middle Pennsylvanian concretion from Mazon Creek, was discovered in 2015 in pit 2, in an area I call Ivy Ridge thanks to all the Poison Ivy in the area.  The finger near the top right should be where the shark emerged.  I did not find this shark egg case variety posted.  I hope this helps in future identification.  Eventually I will be getting the measurement blocks.

 

Shark Egg Case

Phylum: Chordata

Class: Chondrichthyes

Palaeoxyris multiplicatum

 

Horseshoe crab

Phylum: Arthopoda

Superclass:  Chelicerata

Class: Merostomata

Order: Xiphosura

Euproops danae

 

5e101a48976a2_PalaeoxyisMultiplicatumBottom.thumb.JPG.73fb2ce065689f097e9a344da709ac34.JPG

 

 

Edited by Roby
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Hello, Roby, and a very warm welcome to TFF from Morocco.

What an incredible specimen. :default_faint:

Thank you so much for sharing with us. 

Life's Good!

Tortoise Friend.

MOTM.png.61350469b02f439fd4d5d77c2c69da85.png.a47e14d65deb3f8b242019b3a81d8160-1.png.60b8b8c07f6fa194511f8b7cfb7cc190.png

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Wow! :blink:

Welcome to the Forum. :) 

    Tim    -  VETERAN SHALE SPLITTER

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7 hours ago, Roby said:

I did not find this shark egg case variety posted.

I don’t think I have seen one here before. 
 

Welcome to the forum! :) 

 

@Nimravis @RCFossils @Mark Kmiecik might be interested in seeing this. 

The good thing about science is that it's true whether or not you believe in it.  -Neil deGrasse Tyson

 

Everyone you will ever meet knows something you don't. -Bill Nye (The Science Guy)

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Super sharp detail and with two different specimens in one nodule - WOW!!!  What a spectacular find.  Any more to show us?  Welcome aboard.

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Welcome to the forum!

 

:default_faint:

 

I don't know if that find would spur me on to spend all my waking hours wading through the poison ivy to find something to top it--or if it would be a mic drop moment where I'd just declare Mazon Creek 'done'. ;)

 

Looking forward to more of your finds.

 

 

Cheers.

 

-Ken

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I agree with all of the comments of my fellow forum members above - what a great specimen - and can only add a welcome to the forum from Austin, Tx.

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This is one the best examples of Palaeoxyris multiplicatum I have seen. Unfortunately it is broken and at least two of the outer bands have cracked off from the surface. But it is still remarkably complete. Unlike other Palaezoic shark egg cases, P. multiplicatum had a rigid body which had at least 2 ridgid layers that cracked when compressed. It is my opinion that the material at the top right is unlikely to be from the shark emerging. There is only one known example of a shark clearly emerging from the egg case. It is a Bandringa rayi and the egg case is a Palaeoxyris prendelli. This is a different egg case species, but a baby or young shark has very little structure and is little more than a color differential on the rock. The anomaly near the beak is most likely a piece is of the broken egg case which is very commonly found with this species of egg case. For further information I made a website dealing with the Mazon Creek shark eggs:

http://fieldguides.fieldmuseum.org/guides/guide/978

 

Hope that helps,

Jack

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Thanks Jack.  I was told by someone with more knowledge of this being the possible exit point.  People do say things just to please.  Would it be useful for research at the Filed Museum?  Would it be OK to post the fertile fern I donated?

Edited by Roby
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Wow, what an awesome association! Welcome to the forum and thanks for sharing an incredible fossil, @Roby.

31 minutes ago, fiddlehead said:

This is one the best examples of Palaeoxyris multiplicatum I have seen. Unfortunately it is broken and at least two of the outer bands have cracked off from the surface. But it is still remarkably complete. Unlike other Palaezoic shark egg cases, P. multiplicatum had a rigid body which had at least 2 ridgid layers that cracked when compressed. It is my opinion that the material at the top right is unlikely to be from the shark emerging. There is only one known example of a shark clearly emerging from the egg case. It is a Bandringa rayi and the egg case is a Palaeoxyris prendelli. This is a different egg case species, but a baby or young shark has very little structure and is little more than a color differential on the rock. The anomaly near the beak is most likely a piece is of the broken egg case which is very commonly found with this species of egg case. For further information I made a website dealing with the Mazon Creek shark eggs:

http://fieldguides.fieldmuseum.org/guides/guide/978

 

Hope that helps,

Jack

That is great information. Do you know if the Bandringa with the egg case has been published? 

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11 minutes ago, Roby said:

Thanks Jack.  I was told by someone with more knowledge of this being the possible exit point.  People do say things just to please.  Would it be OK to post the fertile fern I donated?

It most certainly would.:popcorn:

Life's Good!

Tortoise Friend.

MOTM.png.61350469b02f439fd4d5d77c2c69da85.png.a47e14d65deb3f8b242019b3a81d8160-1.png.60b8b8c07f6fa194511f8b7cfb7cc190.png

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22 hours ago, Roby said:

Just joint and wanted to get my first entry in.  This middle Pennsylvanian concretion from Mazon Creek, was discovered in 2015 in pit 2, in an area I call Ivy Ridge thanks to all the Poison Ivy in the area.  The finger near the top right should be where the shark emerged.  I did not find this shark egg case variety posted.  I hope this helps in future identification.  Eventually I will be getting the measurement blocks.

 

Shark Egg Case

Phylum: Chordata

Class: Chondrichthyes

Palaeoxyris multiplicatum

 

Horseshoe crab

Phylum: Arthopoda

Superclass:  Chelicerata

Class: Merostomata

Order: Xiphosura

Euproops danae

 

5e101a48976a2_PalaeoxyisMultiplicatumBottom.thumb.JPG.73fb2ce065689f097e9a344da709ac34.JPG

Awesome find!  Two great specimens in the same concretion!

 

Cheers,

Rich

 

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What I think can be demonstrated from observing Paleozoic shark egg cases is that egg cases of the same species come in two forms. Which I believe are produced by hatched or unhatched eggs.  Andrew is correct they hatch from the beak or tendril end, which is where your anomaly is. But what appears to happen is the baby shark pushes open the sutures at the beak causing the beak to expand.  Unhatched eggs have an unbroken straight sides from the tendril to the body. Hatched eggs have an added angle from the opened sutures and expansion of the beak. The pictures are two examples of Palaeoxyris prendelli the left is a hatched verses the unhatched at the right.

 

Keith, Of course you can post your fertile fern (Crenulopteris mazoniana) picture. In February it will be on found on page 96 as Fig. 9. Thanks for donating it.

 

Hope this clears up matters,

Jack

 

 

 PF9653.thumb.jpg.add9a53ffc932b840dda8e002bdc9de5.jpgPF9349.thumb.jpg.c4843b1283ca519cd6108822f2c8cd3d.jpg

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The Palaeoxyris prendelli I found this fall near Georgetown, IL, looked to me as nearing maturity.  The shape was too uniform to have been hatched.  Is my assumption valid?

What I got from Andrew was, it is a fertile Stellatheca ornata fern.  When you have a chance please confirm so I can post it correctly. Thanks for your input!

5e10f1072dadc_Palaeoxyrisprendelli2.thumb.JPG.acec788371e9e5a7ac964b4bfabed48f.JPG5e10f0ea5ab92_Palaeoxyrisprendelli1.thumb.JPG.dddd90b133890e80f8fc14dce4c6d15f.JPG

Edited by Roby
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I’ve got battle scars from ivy ridge!  Exquisite fossil!  Welcome aboard, finally! 

Finding my way through life; one fossil at a time.

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Welcome aboard. That is indeed a spectacular specimen. I've never seen those two species in the same concrection, let alone one that also has plant matter also. I would venture to say that this specimen is unique. I'm not convinced that the egg case is multiplicatum, though. The number of bands, their angle and width . . . . something seems off. Of course, I'm probably wrong. 

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Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

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On 1/4/2020 at 10:40 AM, fiddlehead said:

This is one the best examples of Palaeoxyris multiplicatum I have seen. Unfortunately it is broken and at least two of the outer bands have cracked off from the surface. But it is still remarkably complete. Unlike other Palaezoic shark egg cases, P. multiplicatum had a rigid body which had at least 2 ridgid layers that cracked when compressed. It is my opinion that the material at the top right is unlikely to be from the shark emerging. There is only one known example of a shark clearly emerging from the egg case. It is a Bandringa rayi and the egg case is a Palaeoxyris prendelli. This is a different egg case species, but a baby or young shark has very little structure and is little more than a color differential on the rock. The anomaly near the beak is most likely a piece is of the broken egg case which is very commonly found with this species of egg case. For further information I made a website dealing with the Mazon Creek shark eggs:

http://fieldguides.fieldmuseum.org/guides/guide/978

 

Hope that helps,

Jack

Do you have a ref for the Bandringa rayi/Palaeoxyris prendelli association?

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On 1/4/2020 at 3:16 PM, Roby said:

The Palaeoxyris prendelli I found this fall near Georgetown, IL, looked to me as nearing maturity.  The shape was too uniform to have been hatched.  Is my assumption valid?

What I got from Andrew was, it is a fertile Stellatheca ornata fern.  When you have a chance please confirm so I can post it correctly. Thanks for your input!

5e10f1072dadc_Palaeoxyrisprendelli2.thumb.JPG.acec788371e9e5a7ac964b4bfabed48f.JPG5e10f0ea5ab92_Palaeoxyrisprendelli1.thumb.JPG.dddd90b133890e80f8fc14dce4c6d15f.JPG

 

That is a nice one and big too! I also found a Palaeoxyris prendelli near Georgetown, but mine is much smaller and incomplete. 

 

20180628_074349-1.thumb.jpg.691bb449bedc17fae5c6561622990b50.jpg

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