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A few Moroccan acquisitions


Aurelius

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Just a few bits that I received yesterday, some of which may be of interest to fans of Moroccan fossils.

 

Firstly, a box full of the ubiquitous hybodontid shark fin spines (or 'spin fines', as I often call them during my less lucid moments). Common Kem Kem finds, but I do like them.

 

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The coin for scale in the middle is a shiny British fivepence, which is 18mm across, or 0.72/inch.

 

Most of them need some prep, especially this beast, which may test my prep abilities, given how encrusted it is and how delicate these are.

 

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Secondly though, are these Crinoid float bulbs. I've never knowingly seen these before. Apparently, according to dealers online, they are from the Erfoud region. I can't find a great deal of information about how they actually functioned, but I'll have a little search of the scientific literature when I get the chance. The idea seems to be that they either floated on the top of the sea, allowing the crinoid to travel great distances, or they were temporarily anchored to the sea floor. 

 

Either way, they are magnificent things.

 

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Surface texture of the above specimen.

 

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Specimen #2

 

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Specimen #3. As they are hollow, they have beautiful crystal growths on the inside, which can be seen when they break.

 

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Awesome acquisitions! I am especially fond of the Hybodus spines:).

Life started in the ocean. And so did my interest in fossils;).

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1 hour ago, ynot said:

Those are some awesome acquisitions!.

Never heard of the float balls before.

 

I know it is a hard comparison being that one is a plant and the other an animal. But maybe they worked in a similar way to the gas bulbs on kelp, to help keep the body upright in heavy currents and minimize gravitational pull.

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42 minutes ago, caldigger said:

know it is a hard comparison being that one is a plant and the other an animal. But maybe they worked in a similar way to the gas bulbs on kelp, to help keep the body upright in heavy currents and minimize gravitational pull.

I agree, and have been aware of the seaweed type.

Should have specified crinoid in My reply.

Darwin said: " Man sprang from monkeys."

Will Rogers said: " Some of them didn't spring far enough."

 

My Fossil collection - My Mineral collection

My favorite thread on TFF.

 

 

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text and figure from:

 

Lee, C.P. 2005

Discovery of plate‐type scyphocrinoid loboliths in the uppermost Pr̆ídolían–lowermost Lochkovian Upper Setul limestone of Peninsular Malaysia.

Geological Journal, 40(3):331-342

 

Hall (1879) first introduced the name Camarocrinus (i.e. chambered crinoid) for the large, bulbous, chambered structures found at several localities in Lower Devonian rocks of North America, but also known since the middle of the 19th century from the Upper Silurian of Bohemia under the vernacular French name of lobolithes (Ubaghs 1978a).  Hall also recognized their real nature as holdfasts of a crinoid determined almost certainly to belong to the camerate Scyphocrinites.  These bulbs can reach or even exceed 20 cm in diameter.  Scyphocrinoids floated upside down with the bulbous float at the surface and the crown suspended below as illustrated in Figure 4.

 

What is the advantage in expending so much energy and mineral resources to create such strongly mineralized loboliths?  I suggest that it is probably for defence against predation, as in most other animals that develop armour of some sort by secreting shells and tests to protect their vulnerable soft parts.  Although there might not have been much to protect in terms of soft tissues, yet a less palatable armoured float with attached epizoic hitch-hiking individuals for additional camouflage would still be better protected from predators than an unprotected soft-bodied float, which could not provide a suitable hard substrate for such attachments.  It would also presumably be more resistant to battering by the elements and ensure a longer survival of the float.  Haude (personal communication, 2000), however, suggested that the development of such a wall is not a question of armour, but of constructional possibilities.

 

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"These curious, bladder-like structures were definitely associated with the camerate Scyphocrinites by both Jaekel and Bather around the turn of the century when the idea of their function as buoys was first proposed.  According to Bather (1907), ‘It is . . . believed by many that this swelling was hollow and served as a float from which the crinoid hung, arms downward.  The latter hypothesis explains why it is that in various parts of the world the loboliths occur unassociated with the crowns to which they are supposed to have belonged; following death, the gradual decay of the animal would cause the crown to drop off and sink to the bottom, while the lobolith floated on.’..."

 

Hess, H. 1999

Scyphocrinitids from the Silurian-Devonian boundary of Morocco. pp.93-102

In: Hess, H., Ausich, W.I., Brett, C.E., & Simms, M.J. (eds.)

Fossil Crinoids, Cambridge University Press, 275 pp.   PDF LINK

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37 minutes ago, piranha said:

 

"These curious, bladder-like structures were definitely associated with the camerate Scyphocrinites by both Jaekel and Bather around the turn of the century when the idea of their function as buoys was first proposed.  According to Bather (1907), ‘It is . . . believed by many that this swelling was hollow and served as a float from which the crinoid hung, arms downward.  The latter hypothesis explains why it is that in various parts of the world the loboliths occur unassociated with the crowns to which they are supposed to have belonged; following death, the gradual decay of the animal would cause the crown to drop off and sink to the bottom, while the lobolith floated on.’..."

 


Thanks for that! I have to say, I find these crinoids absolutely fascinating . There's something rather wonderful about the idea of these strange, alien bulbs floating around on the surface of the ocean with these remarkable creatures hanging beneath. I've seen Scyphocrinites so often, and never realised that they lived in this manner.

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