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Post by Grey on Jun 22, 2013 19:22:47 GMT 5
True, only at the end, I constat that the winner is often the most robust, or at least evolves even more robust than its predecessor. In any case, pliosaurs as apex predators evolved more spectacular and longer than macropredatory ichthyosaurs, although I agree that the data is lacking regarding the laters. How long giant macrophagous ichthyosaurs existed is not known to date. Which is actually more formidable has to be determined on the basis of anatomy, not evolutionary history. Evolutionnary is related to the power. Weak predators do not reign as supreme. But I agree that these ichthyosaurs are interesting. Only, beware of any overenthusiasm at this point. In any case, I don't see them at now matching pliosaurs predatory apparatus. |
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Post by coherentsheaf on Jun 22, 2013 19:25:11 GMT 5
How long giant macrophagous ichthyosaurs existed is not known to date. Which is actually more formidable has to be determined on the basis of anatomy, not evolutionary history. Evolutionnary is related to the power. Weak predators do not reign as supreme. But I agree that these ichthyosaurs are interesting. Only, beware of any overenthusiasm at this point. In any case, I don't see them at now matching pliosaurs predatory apparatus. Evolutionary success and and "power" are probably not that well correlated. Other stuff such as top speed, an efficient sensory aparatus and behavioral flexibility are probably more indicative. |
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Post by creature386 on Jun 22, 2013 19:25:56 GMT 5
But to date we have not a single pliosaur that was larger than these ichthyosaurs. Maybe not larger than the earliest ones, but the later ones were smaller. The unnamed Ichtyosaur which lived 170-175 m long was only 6 m long. That's also probably closer to the time when the competition started. |
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Post by Grey on Jun 22, 2013 19:28:43 GMT 5
Evolutionnary is related to the power. Weak predators do not reign as supreme. But I agree that these ichthyosaurs are interesting. Only, beware of any overenthusiasm at this point. In any case, I don't see them at now matching pliosaurs predatory apparatus. Evolutionary success and and "power" are probably not that well correlated. Other stuff such as top speed, an efficient sensory aparatus and behavioral flexibility are probably more indicative. The speed, the sensory ability and even at some extend the behavorial adaptability are factors in interspecific conflict. That's why I meant firstly. |
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Post by theropod on Jun 22, 2013 19:32:00 GMT 5
And, which one would you favour in a fight, Galeocerdo cuvier or Carcharodon carcharias?
From what you expressed on CF, you clearly consider Carcharodon the more formidable creature. And you are probably right, since it clearly appears to be bigger on average, despite occasional similar maximum sizes.
Yet it can be outcompeted and/or replaced by other creatures that are somewhat less formidable in direct conflict.
Their predatory apparata have yet to be compared, you are only imagining it that way in the absence of hard data.
Nice we can both accept obvious facts, just in which regard is this relevant here?
Yes, that's the point. that Pliosaurs apparently outcompeted giant raptorial ichthyosaurs doesn't mean the latter were inferior in a direct physical contest regarding their killing apparatus or other capabilities.
Aaaand?
Maybe pod hunting could play a role here, since it makes them highly adaptable?
So are you.
At least not supported by good fossils, but we simply see no clear line to which somehow all marine apex predators save for ones from one specific time were limited. We still have a large number of huge whales today (or would at least if there were no humans hunting them into extinction), so if predator size is related to prey size in that manner, how come today is one of the few periods since the triassic with raptorial predators actually topping out at less than 10t in weight?
Fossil record indicates predators above 20t are rare and fragmentary in nature, this is logical and as could be expected. Fossil record doesn't proove their absense, we just haven't got precise evidence at now.
Some ecosystems are richer than others, likely related to the climate, geography and disturbances. But not ONE reigns over all the others in terms of diversity, radiations and abundance of prey. Very diverse ecosystems that are rich in prey occurred for several times, and in fact they are common. That doesn’t mean predators from all these ecosystems were all the same size, in holocene seas for example there used to be a tremendous abundance of huge prey, among the largest ever to exist, nevertheless the largest apex predator is the orca that maxes out below 10t.
"Just another" Which would already be enough to invalidate a rule like "no apex predator except for ones in the Miocene/Pliocene ever exceeded 20t".
You are right, I will think what I want, not what you want, and not stop thinking just because to you this seems to be an affront.
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Post by coherentsheaf on Jun 22, 2013 19:40:45 GMT 5
Evolutionary success and and "power" are probably not that well correlated. Other stuff such as top speed, an efficient sensory aparatus and behavioral flexibility are probably more indicative. The speed, the sensory ability and even at some extend the behavorial adaptability are factors in interspecific conflict. That's why I meant firstly. Yes top speed is often a tradeoff for flexibility, the latter being probably far more important for fighting- so increasing your speed often decreases your ability to fight: An example would be cats- modern panthera is far more cursorial than creatures such as Smilodon, the latter being an incredibly robust and presumably "powerful" creature.. The other characteristis are probably small factors in fights. |
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Post by Grey on Jun 22, 2013 19:41:41 GMT 5
Theropod once again I'm tired to discuss and repeat all the time the same things. I'm maybe wrong on some points but my main argumentation still stands by McHenry points :
- oceanic predators during history were in the 20 tons range.
- the fact that these ichthyosaurs may have equalled or exceeded pliosaurs in size does not change that pattern.
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Post by Grey on Jun 22, 2013 19:44:20 GMT 5
The speed, the sensory ability and even at some extend the behavorial adaptability are factors in interspecific conflict. That's why I meant firstly. Yes top speed is often a tradeoff for flexibility, the latter being probably far more important for fighting- so increasing your speed often decreases your ability to fight: An example would be cats- modern panthera is far more cursorial than creatures such as Smilodon, the latter being an incredibly robust and presumably "powerful" creature.. The other characteristis are probably small factors in fights. Fair enough, I recognise that I may have exagerrated the importance of physical superiority here. However, I stil see that the predator outcompeting the other often evolve to superior sizes. Would you disregard McHenry's points regarding trophics systems evolution though or be agreed with my very last post ? |
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Post by coherentsheaf on Jun 22, 2013 19:47:34 GMT 5
Yes top speed is often a tradeoff for flexibility, the latter being probably far more important for fighting- so increasing your speed often decreases your ability to fight: An example would be cats- modern panthera is far more cursorial than creatures such as Smilodon, the latter being an incredibly robust and presumably "powerful" creature.. The other characteristis are probably small factors in fights. Fair enough, I recognise that I may have exagerrated the importance of physical superiority here. However, I stil see that the predator outcompeting the other often evolve to superior sizes. Would you disregard McHenry's points regarding trophics systems evolution though or be agreed with my very last post ? I think that McHenry is correct that predators in excess of 10 tonnes have been rare. How rare they were still needs to be determined. |
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Post by Grey on Jun 22, 2013 19:54:04 GMT 5
Fair enough, I recognise that I may have exagerrated the importance of physical superiority here. However, I stil see that the predator outcompeting the other often evolve to superior sizes. Would you disregard McHenry's points regarding trophics systems evolution though or be agreed with my very last post ? I think that McHenry is correct that predators in excess of 10 tonnes have been rare. How rare they were still needs to be determined. That's why I argue that these probably very large predatory ichthyosaurs does not change that rule Actually this is not even surprising since all the others were below the 10 tons range. I'm however skeptical in that they reached the sizes of megatooth and leviathan which evolved certainly in excess of the 30 tons range for very specific reasons to their epoch. These ichthyosaurs are still analogous to the largest pliosaurs, even if they've indeed exceeded these in body mass, which remains to be determined. |
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Post by theropod on Jun 22, 2013 20:11:23 GMT 5
If there are exceptions, it is not an obligate rule any more. We simply cannot be sure of it by any means. That such large predators are rare in most ecosystems is out of the question, but that doesn't mean they don't exist. Tigers or lions at 250-300kg are very rare. If one had found just fossils and would have to make a similar rule, one would conclude that no mammalian hypercarnivore exceeds 200kg. Grizzlys are seemingly below 300kg in the majority of cases, yet some grow much larger. There are always exceptions in nature, and solely on the basis of something not being well supported by fossils you cannot exclude it, just say it is relatively rare. You know this I presume. Truly large individuals of most animals are rare, that doesn't mean they don't exist. The vast majority which you will find in most giant marine predators will be below a certain size, I presume somewhere between 20 and 40t depending on the animal, but that doesn't mean there were no larger specimens, nor that this is a rule that necessarily applies to all ecosystems. |
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Post by Grey on Jun 22, 2013 20:14:39 GMT 5
If there are exceptions, it is not an obligate rule any more. We simply cannot be sure of it by any means. That such large predators are rare in most ecosystems is out of the question, but that doesn't mean they don't exist. Tigers or lions at 250-300kg are very rare. If one had found just fossils and would have to make a similar rule, one would conclude that no mammalian hypercarnivore exceeds 200kg. Grizzlys are seemingly below 300kg in the majority of cases, yet some grow much larger. There are always exceptions in nature, and solely on the basis of something not being well supported by fossils you cannot exclude it, just say it is relatively rare. The rule is that these exceptions are rare. And the situation for the size in these ichthyosaurs is uncertain for now. |
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Post by theropod on Jun 22, 2013 20:17:59 GMT 5
^I didn't even mention the ichthyosaurs in that post!
That these exceptions are rare is not the question here, the point is that animals always average at one size and max out at another, and that tough infrequent, there will always be exceptions (if you want to call those "exceptions", a wording I'd prefer would be "occasional exceeders").
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Post by Grey on Jun 22, 2013 20:21:52 GMT 5
^I didn't even mention the ichthyosaurs in that post! That these exceptions are rare is not the question here, the point is that animals always average at one size and max out at another, and that tough infrequent, there will always be exceptions. We talk about natural trends, not abnormal exceptions. The fact that only the Cumnor P. macromerus did reach the 20 tons mark as a predator does not mean that only that specimen within the species did it. That shows the potential size of these predators. The point we are talking is about predators greatly exceeding that 20 tons mark. |
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Post by theropod on Jun 22, 2013 20:23:45 GMT 5
I did not refer to "abnormal exceptions"
I meant completely normal differences between average, large and very large specimens. I brought the example of komodo dragons up elsewhere. how large do you think they are on average, and how large are large specimens?
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