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Post by Runic on May 30, 2013 4:47:48 GMT 5
Almost impossible =/= Not impossible
Please tell me where the major difference is? Cause I don't see it. They still revolve around my main point. The chance of the 1 Livyatan we have being above average or "record" is unlikely.
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Post by Grey on May 30, 2013 4:59:02 GMT 5
That's a matter of understanding. But you were pointing the direction that it is almost impossible. Wedel says it's merely unlikely but not impossible. Here's the major difference, but whatever.
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Post by theropod on May 30, 2013 20:59:59 GMT 5
Well, anyway, everyone knows what is meant. Single specimens are most likely average-sized. The probability of being a particularly large or small specimen is lower.
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Post by Runic on May 30, 2013 21:09:31 GMT 5
Well, anyway, everyone knows what is meant. Single specimens are most likely average-sized. The probability of being a perticularly large or small specimen is not really high. That's what I tried to tell him. |
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Post by Grey on May 30, 2013 21:19:04 GMT 5
No I acknowledged this, but you were arguing it was almost impossible, whereas this is more unlikely. But that's not important.
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Post by theropod on May 30, 2013 21:28:29 GMT 5
Well, in any case most likely the Livyatan holotype is an average individual, while all the estimates people are citing for C. megalodon are at the very least for large specimens. The nursery study counted individuals above 10.5m as adults, and the vast majority of teeth I have seen is below 15cm. The Livyatan holotype is extremely unlikely to be an individual that corresponds to a 17.5m+ Megalodon, and it’s easily a match in size to pretty much everything else.
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Post by Runic on May 30, 2013 21:34:53 GMT 5
No I acknowledged this, but you were arguing it was almost impossible, whereas this is more unlikely. But that's not important. I still don't really get your point but I apologize for any confusion I might have made  |
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Post by Grey on May 30, 2013 21:40:26 GMT 5
Well, in any case most likely the Livyatan holotype is an average individual, while all the estimates for C. megalodon are at least for large specimens. If I remember correctly the nursery study counted individuals above 10m as adults, and the vast majority of teeth I have seen is below 15cm. The Livyatan holotype is probably not an individual that corresponds to an 18m+ Megalodon. Not really, most of the estimates for megalodon do not represent the maximum size (Kent 2013) but adult animals, with no indication of their exact life stage and age. Livyatan's holotype is an adult animal (Lambert pers. comm) which was somewhere between 13,5 or 17,5 m, typically listed at 15 m. The probability that slightly larger or slightly smaller adults specimens existed is obvious. The attempts to evaluate megalodon's average size are all destined to fail. We don't even know for sure what is its maximum TL (21-22 m/17-18 m ?) The indications of Pimiento et al. with the adult life stage above 10 m is misleading as adult size range in sharks can be vast within one species. The male great white sharks are mature at 3,5 m for example, whereas the largest females approach 6,5 m... And trying to etablish an average on teeth lost at different life stage, by different genders, in any region, added to the fact that we don't know really the ratio tooth/size is just a total lost cause. We do with what we have. EDIT : I've corrected my first line in bold. |
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Post by theropod on May 30, 2013 21:55:30 GMT 5
Well, what we do know is that the average would be lower than the max size, that's something to start with. just aout everything is better than taking the largest specimens in thousands of teeth and comparing them to the single specimen lf another animal as if both were maximum. Just like there are sharks or sperm whales considerably larger than average, we can assume a large livyatan would also possibly be considerably larger. We cannot give precise figures or compare them at this time, however I would be very cautious with statements about one species being bigger based on what little we have of the cetacean.
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Post by Grey on May 30, 2013 22:16:16 GMT 5
The cetacean is listed at 13,5-17,5 m, and typically 15 m. That's a huge range of plausible sizes for one adult specimen. I will not engage speculations on its maximum size without another individual. You have to understand my approach : when I compare Livyatan melvillei, I compare it with rigorous reconstructions size and/or models of megalodon. If I compare Livyatan melvillei with the 11 m specimen of the Calvert Marine Museum, typically considered as a yound adult male megalodon, the cetacean is clearly the bigger guy around.  If I compare it with the meg individual alleged to have killed the cetothere in Bakersfield, this particular shark was estimated to be a 52-footer (16 m) megalodon by Chuck Ciampaglio. I've compared then the rigorous jaws mechanical reconstruction with the predatory apparatus of Livyatan in Lima and Rotterdam, and what I see is that the shark's killing apparatus seems to just dwarf the one in the cetacean, by any mean, hinting subtle differences in their food source.  I've compared too Livyatan's skull with the jaws featured in Nat Geo Prehistoric Predators, the jaws reconstructed by the Babiarz team, from the Arizona State University. Here too, they dwarf in terms of volume the mouth of Livyatan. I talk about the dental part. I don't now what is the estimated size of the shark in this reconstruction, but following Nat Geo comments, this a 15-17 m shark.  Hence, I compare Livyatan with a published specimen, the largest found in the nursery in 2010, at 16,8 m. This adult was thus probably larger than the one reconstructed that killed the whale in Bakersfield, which itself demonstrates a larger predatory apparatus than Livyatan. At the end, I have no problem to use 18 m life sized reconstruction structure by the FMNH, supervised by Bob Purdy, Dana Ehret and Cliff Jeremiah, which here again show an opening mouth with a volume potency far to be approached by Livyatan. I have no problem because : - 18 m is a large size for megalodon, but not the maximum suggested by paleontologists (21 m). - Livyatan's holotye is certainly not the maximum sized individual in this species, but could be anything, we only have this one, it could be also a large representative in the same manner a 17-18 m meg could be depending the viewpoint. There's no reason to segregate a 18 m meg here. At the end, I keep in mind the words and suggestions by Mike Siversson that stem-physeteroids do not seem to have successfully replaced the megatoothed sharks, and the other suggestion that megalodon could have had the upper fin against Livyatan because of its superior ability to hunt and attack at night (reminiscent of lamniforms sharks over dophins in modern days). Now, there's no certainty in paleontology, but mainly, here, I rely on common sense, looking at the reconstructions which in no case show maximum-sized animals ( Livyatan or megalodon). |
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Post by Life on May 30, 2013 22:29:15 GMT 5
I edited my reply before you quoted Grey. God I can't get this quoting right -_- Quote system working fine as per my testing. If you are confused about it, feel free to ask for assistance. --- As far as this contest is concerned, much about both of these gigantic animals is shrouded in mystery. C. megalodon needed to be an extremely formidable macropredator for its lifestyle and habitat; cooperative hunting is not common occurrence in some species. It makes sense for C. megalodon to occupy the top position in the food chain with extremely formidable characteristics because it had to maintain advantage one way or other over all other animals in the marine environment. Alternative would be large raptorial pack predators such as O. Orca. L. melvillei appears to be an experimental weapon from the "competitor camp" unleashed to challenge the reign of gigantic megatoothed sharks. Though we can be mistaken about this since we have no concrete evidence of prey preferences of L. melvillei yet; most likely the experts are correct in their assumption but still the importance of actual evidence does not diminishes. We might get some answers in the future about this. Peru is a paleontological treasure-trove for sure. I hope that more and more scientists carry out expeditions in this country for the greater benefit of advancing existing knowledge about many prehistoric animals. |
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Post by Grey on May 30, 2013 22:40:44 GMT 5
I would quote in that way Mike Siversson.
In any case we donÂ’t have any data to suggest that the rise and fall of various physeteroids had any impact on the megalodon population. By the time megalodon went extinct the once mighty physeteroids were scooping up slimy squid on the ocean floor.
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Post by theropod on May 30, 2013 22:53:02 GMT 5
I do not suggest starting to speculate about the maximum size of Livyatan, I however suggest not to use sizes close to or within the range of maximum sizes given for C. megalodon and comparing that to a conservative approach to the size of Livyatan melvillei.
And as already explained, comparing jaw volume among an elasmobranch and a cetacean is not conclusive. In fact, its hardly better than using jaw lenght. Both are different in their (functional) morphology, maybe even most notably in their jaws. Therefore I would not consider the comparison of jaw volumes relevant for size and potency of the killing apparatus. That is about like comparing the gapes of T. rex and G. carolinii and inferring G. carolinii to be in a completely different league based on that.
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Post by Grey on May 30, 2013 22:59:43 GMT 5
I do not suggest starting to speculate about the maximum size of Livyatan, I however suggest not to use sizes close to or within the range of maximum sizes given for C. megalodon and comparing that to a conservative approach to the size of Livyatan melvillei.. I don't compare the maximum sizes (18 m+) proposed for megalodon with the most conservative sizes in Livyatan (13,5 m), I compare the skull and jaws of Livyatan with rigorous jaws reconstruction of not maximum-sized megalodon. And as already explained, comparing jaw volume among an elasmobranch and a cetacean is not conclusive. In fact, its hardly better than using jaw lenght. Both are different in their (functional) morphology, maybe even most notably in their jaws. Therefore I would not consider the comparison of jaw volumes relevant for size and potency of the killing apparatus. That is about like comparing the gapes of T. rex and G. carolinii and inferring G. carolinii to be in a completely different league based on that Following your thought then, comparing the jaws of a gharial with the jaws of a bull shark would be then irrevelant for size and potency of the killing apparatus ? Follow your logic, just look at the photos. You can easily walk into the mouth of a megalodon, even two persons could. You cannot do this in Livyatan's mouth. |
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Post by Life on May 30, 2013 23:07:17 GMT 5
Physical characteristics and lifestyle complement each other! No? If L. melvillei was a (predominantly) solitary macropredator then it makes sense for it to attain extreme sizes like C. megalodon. However, if L. melvillei subsisted (predominately) through cooperative hunting then extreme sizes were not necessary for it to attain. A pack of 12 - 14 m long L. melvillei (weighing 20 - 30 tons each) would be a force to be reckoned with even for the largest C. megalodon individuals in history. I do assume that L. melvillei would be social to certain degree if not on the level of delphinids; pack wise, I doubt that it would have formed very big ones like O. orca occasionally do because such packs might be unsustainable. I think that JFC got the "Deep Sea Killers" episode partially right.  --- As far as skull morphologies are concerned: extreme size coupled with extreme killing apparatus of C. megalodon suggests that this animal was a big-game hunter in absolute sense. Almost any kind of whale or another giant animal would be potential prey for C. megalodon. In contrast, L. melvillei could be more specialized. |
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