Lappets | The Octopus News Magazine Online
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Lappets

Architeuthoceras

Architeuthis
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#2
Great specimen Hajar! Many other mature modifications to the shell shown, such as the expansion of the body chamber, the reduction of the ribs, and the dorsal extension onto the older part of the shell. Thanks for posting this pic. :heee:
 

Hajar

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#8
I love those intellectual French.

Here's a very bizarre Oecoptychius from the French Middle Jurassic. The macroconch to go with it is Phlycticeras.
 

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DWhatley

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#10
It was fun to attempt to translate using my college second language. I was rather surprised that I could mostly get the gist of what was being said but the subtlties were completely lost.
 

Architeuthoceras

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#11
Hajar;140680 said:
I love those intellectual French.

Here's a very bizarre Oecoptychius from the French Middle Jurassic. The macroconch to go with it is Phlycticeras.
That is a very bizarre ammonite! And thanks for posting that article, very informative even though I have to google translate all the text a little at a time. :notworth:
 

Neale Monks

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#12
I can't speak for regular ammonites, but at least some heteromorph ammonites show distinct apertural modifications depending on their gender. Among Lechites for example (if I remember correctly) the macroconchs have a curved aperture, so that the end effectively curls over by almost 90 degrees; by contrast the microconchs this is not the case, but the aperture is fluted, a bit like a complex spout. I think Sciponoceras shows a similar thing.

Cheers, Neale

Architeuthoceras;140551 said:
If I'm not mistaking, these are all micro-conchs, do you have any macro-conchs that show any kind of mature modification to the shell, or maybe just a mature macro-conch that we can compare with these?
 

Architeuthoceras

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#13
Now that you mention it, most Scaphites have different modifications on the adult body chamber. The Macro-conchs are generally inflated, possibly to serve as an egg chamber (dont remember where I read that). When I get home I will look thru the collection and see if I can get some pics. :smile:
 

Architeuthoceras

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#14
Scaphites whitfieldi from the Late Turonian part of the Mancos Shale in East Central Utah, macroconch on the left, Microconch on the right. Though they dont show lappets, the hook itself is a mature modification. The shell coils normally planispiral until the animal reaches sexual maturity, then the shell forms a straight shaft and finally a hook on the end, bent back towards the phragmocone. There is a constriction on both forms at the peristome. The hook on the macroconch expands quickly at the start of the straight part, the hook on the microconch seems to expand regularly over its entire length.
 

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DWhatley

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#15
You can tell I am just a sightseer on this thread, I was expecting lap pets when I clicked.:oops::grin:
 

Hajar

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#18
Here's a dimorphic pair - Phlycticeras and Oecoptychius, both 15 mm and preserved in pyrite. They are from the Callovian (Middle Jurassic) of Gruibingen, Germany. This Oecoptychius hasn't retained its lappets unfortunately (but what they look like can be seen in the French example posted earlier).
 

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