Eocene Cuttles

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and there's a good discussion of the history of the expanding Earth idea here. ".. since the recognition of plate tectonics in the 1970s, the scientific consensus has rejected any expansion of the Earth. Measurements suggest that, on very long timescales, the Earth is slowly shrinking, due to thermal contraction."
 

Architeuthoceras

Architeuthis
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Hajar;167874 said:
So a sketched outline might be something like the following?: Late Eocene extinction of Belosaepia and Anomalosaepia in American seas; appearance of Sepia in the seas of Bohemian Europe via Hungarosepia and the opening North Atlantic proving an obstacle to migration of Sepia westwards.

This may explain the Eastern side of NA, but why haven't they crossed the Pacific?
 
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Well, even in its present reduced state (see plate tectonic reconstructions here) that's a much larger ocean than the Atlantic.

So, what are the controls on cuttlefish distribution in the present? e.g. is there a lower bound of water temperature beneath which they don't thrive? Are they restricted to a certain band of water depths? Do they live in the open ocean or only in a belt around coastal waters (i.e. continental shelves)? Experts on modern cuttlefish please help!

This states that "Cuttlefish inhabit shallow tropical or temperate coastal waters, usually migrating to deeper water in winter. They are not usually found below 500m (1,640 ft)." If they are creatures of coastal waters and continental shelves and not open ocean animals then they would have a migration path along the Aleutians to take to reach the Americas and those are very cold waters.

I found this on a pygmy cuttlefish in Russian Pacific waters. "The Russian Maritime Province is by all means the northernmost outskirt of the species geographical range". The sea gets very cold north of here, and the Sea of Okhotsk freezes over in winter. If you look at the map of sea surface temperature shown here you can see that the 10-12 degree C band passes through the Sea of Japan; now look at the North Atlantic, that band of temperatures occurs much further north there, extending as far as Scotland (Sepia oficinalis territory), but not as far as Iceland.
 

Architeuthoceras

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According to THIS MAP, there is a current running east from the Philippines to central america. They must lay benthic eggs and not float on currents, or they would have road them across. Are there many cephalopods that are found on both sides of the Pacific and/or Atlantic?
 

DWhatley

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It seems odd to me that we have both squid and octopuses but no cuttlefish or nautilus. I don't know much about squid but I am learning about octopuses. We have octopus species that drift in the plankton for a month or so (so these you would expect a wide range) as well as the species that are benthic from birth (would not roam far from home or be expected to traverse large bodies of water). If I understood right, there is evidence that they lived in this hemosphere at one time but became extinct but not so of the squid and octopuses (or possibly the squid and octopuses repopulated). Puzzling.

I was never taught the expanding earth theory (which seems a bit odd since my only exposure would have been in the 60's) so when I rabbit trailed you link I did not know if this was something new. I had recently read about the sea floor being far newer than we thought and that an exchange of mass was shown along the rifts. The only part that is different from what I remember being taught :old: is that scientists feel they have discovered where it goes and where it comes from which had been missing evidence.
 

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