Triassic Nautiloid Pearl Blister

SteveM

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In a broad search for precedents to substantiate modern-day Nautilid pearls, extremely rare paleo-pathological work has been of great interest. Attached from an obscure monograph (thanks to Princeton University for an excellent scan) is a Pleuronautilus pseudoplanilateratus (Kieslinger, 1916), Middle/Late Triassic (200+MYA) from Timor, Indonesia. Alois Kieslinger was in his immediate post-doctorate career when traveling as a member of the 1916 Dutch Timor Expedition, later to become associated with research into stone monument preservation, including the Parthenon in Athens.

What is of extreme interest to me is the incredible similarity of shell morphology between the Pleuronautilus and N. Pompilius (note how Kieslinger's figure and a modern Nautilus shell section match coils perfectly, showing the body chamber location of the pearl blister). Even the most optimistic research (unpublished, P. Ward) has modern Nautilus appearing only as early as the late Mesozoic.

Kieslinger's Pleuronautilus is a dead ringer for the mysterious Allonautilus Perforatus, known only from drift shells and (along with A. Scrobiculatus) thought to be the most recent evolution of Nautilida.

Will be very interested to discover the differences between this Triassic Nautiloid and modern Nautilus shells.
 

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Architeuthoceras

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:welcome: to TONMO SteveM,

The perforate umbilicus and the more vertical and flat umbilical wall of Pleuronautilus stand out to me, the ribs a little less so.

I am leaving in the morning for ten day of field work, hopefully I can look into this a little more when I return.
 

DWhatley

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I am leaving in the morning for ten day of field work, hopefully I can look into this a little more when I return.
As in work WORK or as in fossil fun?
 

SteveM

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Architeuthoceras;178366 said:
:welcome: to TONMO SteveM,

The perforate umbilicus and the more vertical and flat umbilical wall of Pleuronautilus stand out to me, the ribs a little less so.

I am leaving in the morning for ten day of field work, hopefully I can look into this a little more when I return.
Many thanks for the welcome, and happy hunting. A good image of A. Perforatus should be posted here, I have Ward/Saunders 1997 on my office computer, which I will not be able to access until return from travel July 05.

I will also try to detail in due course Peter Ward's latest work pushing back the modern genus Nautilus to well below the KT boundary (albeit remaining 100MY distant from upper Triassic).
 

SteveM

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Architeuthoceras;178388 said:
See HERE for some Devonian cephalopod pearls
Yes, De Baets et al received a huge amount of popular press with this a few months back. Work directly related to House, and Mapes (the paper's primary reviewer). What an incredible parasite infestation was occurring in Moroccan waters at the time! But these are shell blisters, not pearl blisters, and have not given us much of a hint regarding the theoretical formation or composition of loose Nautiloidea pearls.

De Baets does offer an enticing citation from the work of Helmut Keupp. I was lucky enough to get in touch with Prof. Keupp to obtain an otherwise unavailable paper of his from 1986, and he mentioned that he is currently working on a summary paper concerning Nautiloid/Ammonite paleopathology. More to come!
 

SteveM

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Scanning my laptop in vain for the aforementioned A. Perforatus image, I did find these images to add to this discussion:

1) Side and apertural views from Kieslinger of the Timor Late Triassic Pleuronautilus with pearl blister.

2) Modern N. Pompilius shell (also from Timor!) with a similarly-located pearl blister, plus a curious reinforcement of the final septal suture that happens to correspond precisely with an exterior shell fracture. Would be curious to know of any similar experience.
 

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DWhatley

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Do pearls leave indentations in oysters (and/or clams) of modern day animals? Given Kevin's reference that they likely originated as attached parasites rather than grains of loose sand I assume not (nor have I seen internal pits but I have not found a lot of pearls in my mollask consumption.
 

SteveM

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DWhatley;178503 said:
Do pearls leave indentations in oysters (and/or clams) of modern day animals? Given Kevin's reference that they likely originated as attached parasites rather than grains of loose sand I assume not…
As I just arrived here (via pearls, via Nautilus) and cannot readily find the reference to Kevin, will just jump in although the thread goes off its tracks. CORRECT that pearls do not arise from grains of sand, a scientific impossibility as sand is anything but an irritant to a mollusk. But what a persistent myth it is.

Shell blisters arise from the mollusk reinforcing its interior shell to ward off parasitic attack. Cysts (pearl sacs if composed of mantle epithelial cells) arise from irritation by parasite or injury, resulting in loose pearls. In fact pearl sacs that abutt the shell without being expelled or attached to the shell do often result in an indentation as the shell continues to grow around the protuberance, leaving what amounts to the ultimate pearl provenance—a matching bed. This is quite the hot item among rare pearl collectors these days—a rare pearl species together with its undeniable shell of origin.
 

DWhatley

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I guess I am glad we are roughly the same age :biggrin2: younger people might have thought I was totally crazy (of course they might anyway :wink:) for the "well known" understanding of how pearls begin. Now that you have freed that piece of memory for other knowledge, how do they seed cultured pearls?

Sorry, Kevin is Architeuthoceras. I will move these three post to your original Triassic Nautloid Pearl Blister thread for continuity (Post #5). He gave me a reference to read on Nautiloid Pearls when I wondered about the possibility of ingestion rather than creation.
 

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