Rex/Dux?

This link has been posted here before but it was many months ago and you probably would not find it without trawling through the old message boards for hours.

Alternatively, you could use the Message Board search feature (upper right corner) and try the word "fossil" and come up with it in a few minutes... :wink:

TONMO Cephalopod Community
 
tomossan said:
i woudl think the meso's size and strength would be a necessity rather than an exception, if you see where oim coming from; once a creature became over a certain size, (perhaps 2 meters (?) ) they would become such a potential prey source that a larger size would be required in order to defend;

Maybe, but a lot of deep sea creatures seem to be slow moving and small. And I don't think it is known how deep Mesonychoteuthis lives. Also speed and camoflage are good alternatives to size increase as a means of defence, not to mention mimicry of something bigger and scarier. As to whales finding a good meal quicker, well the ocean is a big place and the larger you are, the fewer of you I guess there will be, so if you become a dedicated hunter of large squid then you need to be good at finding them (Dr O for example!!)

However, I am not an expert either and I really have no idea about the dymnamics of ocean ecology which govern animal size. So maybe we need to lie in wait here until one of the vastly knowledgable experts known to frequent these waters swims by and then grapple them (with swivelling hooks perhaps?) Lets leave them some bait, aah-haargh! :wine:
 
ubiquity said:
any info on relations between prehistoric cephs and prehistoric whales?

Hmm.......having a tenous crack at this one....

Well certainly the late Eocene toothed whale Basilosaurus has been found with squid stomach contents, though it has also been found with the remnants of shark, perhaps demonstrating that it had a somewhat non-exclusive and opportunistic diet. Basilosaurus was an extremely long and serpentine creature stretching almost 40 meters from head to tail. It lived roughly 40-38 million years ago and fossils are known from Egypt, very close to the Valley of the Kings near Cairo, of all places!

It is generally thought, I think, that the mystecetes (baleen) whales radiated from the basilosaurids early in the subsequent Oligocene period (35-23 mya), leaving the basilosaurids to evolve into the odontocetes or toothed whales we know today. Precisely how closely related the modern three species of Sperm Whale are to Basilosaurus would be interesting to find out.

The point is, it seems to me that giant squids were prey to large carnivores right up until the end of the Cretaceous when the large marine reptiles died out in the along with the dinosaurs and many other forms of marine life (65mya). There was then a huge gap of 25 million years when gigantic forms of cephalopods, if they existed, would have been relatively free of predatory attack. In the adult stages creatures such as Tusoteuthis or Architeuthis would have been fairly safe as there do not appear to be any large marine predator that would have been capable of taking them on, except possibly sharks.

I am speculating here but I doubt if Tusoteuthis is the direct ancestor of Architeuthis simply due to the paucity of evidence of large fossil squid in the intervening 80 million years. It seems likely that large squid pens from the intervening period would have been found by now. Admittedly the fossils may be out there and we simply have not discovered them yet, but their absence could demonstrate that they were not present and that large squid evolved at least twice in unconnected families, one in the late Cretaceous and one fairly recently. Could it be that Cretaceous extinction event wiped out the prehistoric giant squid leaving the cephalopods to exploit this niche at a later time?

Perhaps one could surmise that to attain a large size through rapid growth rate would be a useful evolutionary end during this hiatus of large marine predation. Smaller squid sizes are vunerable to be eaten, perhaps the growth of Architeuthis' and Mesonychoteuthis' ancestors to an extreme size was a direct result of being able to exploit this safer ecological niche.

Again, if anyone knows of any large fossil squid in any fossil deposit, I'd love to hear about it.

This is purely my own speculation, so please feel free to shoot it down!
 
Hi Phil,

Thats all very interesting. I can't remember the reference but BBC Wildlife magazine had an article reporting a study which linked Sperm Whale evolution to the baleen whales rather than the other toothed species. (This study was probably published in the scientific press eg Nature, Science etc so you could find it there - theres an excellent search engine on the Nature website)

I guess sharks would make a very good top predator in the absence of any marine reptiles and before the evolution of large toothed whales. Though the only fossil I know of which I guess is quite well known is the Carcharodon megalodon (up to about 40ft long Great White relative) but that is, I think, quite recent (past 2 million years or so). There were large bony fish too, one of which was from the Cretaceous and was about 12 ft long, but whose name I forget - watch this space and I'll add it later -> [Xiphactinus molossus or the Bulldog fish - up to 16 ft long] .

This is a good link http://www.flmnh.ufl.edu/fish/Sharks/InNews/megatoothshark.htm

later dudes
 
Yo, thanks for that Geoff. That's a great link to Megalodon. It's amazing to think that this creature is known from the teeth alone. What an amazing animal.

I'd love to read that BBC Wildlife magazine article. I really should buy it more often - it's a very good magazine.

Anyway, as to the origin of the sperm whale I am aware there has been some debate about this. Apparently a recent theory put forward by Milinkovitch (1995) has suggested upon molecular studies that the sperm whale diverged from the mysticetes about 25 mya during the late Oligocene. Yet prior to this publication it was assumed, on morphology alone, that it was classified as an odontocete.

I can give you the reference of the article if you like. I have not read it, and I'm sure I would not understand most of it if I did, but I'm sure you could find a copy in the Carnagie!
 
You're welcome Ubiquity,

Thanks Phil, I think the report I half remembered was based on that article. That was the gist of the theory that got reported anyway.

It's actually quite interesting to consider what was going on in the period between the late Cretaceous and the appearance of whales. I guess there must be at least 15 million years there between the extiction of sea reptiles and the earliest whales...

Cheers, Geoff (soon not to be in Pittsburgh PA... :frown: )
 
Speaking of fossil whales, this just in:

700,000 year old Humpback Whale discovery:

Whale fossil

Nice, though it might take up a bit too much room in the lounge!
 

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