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Post by Grey on Nov 12, 2019 22:07:56 GMT 5
That is not only my opinion, the guy is no authority and is not well respected by paleontologists or paleo-nerds.
Megalodon has not been downsized as there is more research, more qualitative, about it that is done as of now. Dude, you're new on this forum, be sure there are many experienced people here far more knowledgeable than David Spletzer (aka Hawthorne).
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denis
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Post by denis on Nov 12, 2019 22:08:22 GMT 5
That is not only my opinion, the guy is no authority and is not well respected by paleontologists or paleo-nerds. Megalodon has not been downsized as there is more research, more qualitative, about it that is done as of now. Dude, you're new on this forum, be sure there are many experienced people here far more knowledgeable than David Spletzer (aka Hawthorne). Source? |
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Post by Grey on Nov 12, 2019 22:09:41 GMT 5
Don't spam, write actual posts. Source for what ? Given your name and how you formulate your sentences, I guess you're a French enthusiast.
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Post by Life on Nov 16, 2019 22:16:36 GMT 5
Max Hawthorne is overenthusiastic about pliosaurs and probably 90 % of what he writes about them or fossil marine life is suspicious if not utterly wrong. We have discussed pliosaur size A LOT on this board : there is no direct material indicating a 15 m pliosaur. The largest material we have suggests animals that ranged in the 10-20 tonnes. And it is way possible the Kronosaurus/Sachicasaurus genus grew larger (at least in skull size) than Pliosaurus. Don't trust Max Hawthorne and his falacious calculations and "research", he is a novelist fan of pliosaurs for some reasons, not an actual scientific authority in this particular field and he was ridiculed a number of times on FB by actual paleontologists... Livyatan is definitely far larger than any pliosaur from any genus known so far, by a long shot. I doubt that, don’t think he’s a Pliosaur fanboy. He had done several things on like how the largest Megalodon was likely very slow for it’s size. Pliosaurs are very rare in remains. It’s very unlikely Livyatan weighed like 50 tons. I mean Megalodon has been downsized, I can see that happening to Livyatan. If so then it’s likely Livyatan was likely around 13 meters long and weigh 30 tons. Max Hawthorne is not a scientist/marine biologist (not a mark against him but he does have a problematic mindset to put it mildly). Do not even bother to consult him about sharks; his articles about megatoothed sharks are mostly nonsense. I attempted to debunk one of his writings but he refused to publish my response in his blog - talk about being insecure. When I have time, I will debunk his articles in this forum one-by-one. You may consult theropod about any prehistoric animal. He is an emerging paleontologist and very well learned. Megalodon is not downsized (15 - 16m TL range is widely considered), rather Kensu Shimada is sticking to estimating the size of Megalodon on the basis of size of its Anterior teeth. He overlook other aspects of shark dentition in his methods which is ill-advised. Megalodon have thick teeth (symmetry) and wider curvature than a great white shark of similar size (A3 not mesial)*, and an upcoming study will highlight this fact to advance a new method to estimate the size of Megalodon accordingly - this would be the finest study of its kind yet ( Grey is one of the authors) - so you are dealing with very well learned people here. *I pointed this out years ago in another forum and I am glad that Grey noticed. This matter will be scientifically established soon. Livyatan is huge actually, in the 17 - 18m territory. Its teeth are unusually large for killer whale forms, and also for sperm whales. |
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denis
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Post by denis on Nov 17, 2019 10:27:05 GMT 5
I doubt that, don’t think he’s a Pliosaur fanboy. He had done several things on like how the largest Megalodon was likely very slow for it’s size. Pliosaurs are very rare in remains. It’s very unlikely Livyatan weighed like 50 tons. I mean Megalodon has been downsized, I can see that happening to Livyatan. If so then it’s likely Livyatan was likely around 13 meters long and weigh 30 tons. Max Hawthorne is not a scientist/marine biologist (not a mark against him but he does have a problematic mindset to put it mildly or lacking in intellectual capacity). Do not even bother to consult him about sharks; his articles about megatoothed sharks are mostly nonsense. I attempted to debunk one of his writings but he refused to publish my response in his blog - talk about being insecure. When I have time, I will debunk his articles in this forum one-by-one. You may consult theropod about any prehistoric animal. He is an emerging paleontologist and very well learned. Megalodon is not downsized (15 - 16m TL range is widely considered), rather Kensu Shimada is sticking to estimating the size of Megalodon on the basis of size of its Anterior teeth. He overlook other aspects of shark dentition in his methods which is ill-advised. Megalodon have thick teeth (symmetry) and wider curvature than a great white shark of similar size (A3 not mesial)*, and an upcoming study will highlight this fact to advance a new method to estimate the size of Megalodon accordingly - this would be the finest study of its kind yet ( Grey is one of the authors) - so you are dealing with very well learned people here. *I pointed this out years ago in another forum and I am glad that Grey noticed. This matter will be scientifically established soon. Livyatan is huge actually, in the 17 - 18m territory. Its teeth are unusually large for killer whale forms, and also for sperm whales. He has major points that are true. There’s a reason why larger Great White Sharks are not as fast as the juvenile. Because of their skeleton, since it was similar to rubber, it has a limit. If the rubber reaches that limit, it would collapse under it’s weight. |
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Post by Life on Nov 17, 2019 23:20:09 GMT 5
Max Hawthorne is not a scientist/marine biologist (not a mark against him but he does have a problematic mindset to put it mildly or lacking in intellectual capacity). Do not even bother to consult him about sharks; his articles about megatoothed sharks are mostly nonsense. I attempted to debunk one of his writings but he refused to publish my response in his blog - talk about being insecure. When I have time, I will debunk his articles in this forum one-by-one. You may consult theropod about any prehistoric animal. He is an emerging paleontologist and very well learned. Megalodon is not downsized (15 - 16m TL range is widely considered), rather Kensu Shimada is sticking to estimating the size of Megalodon on the basis of size of its Anterior teeth. He overlook other aspects of shark dentition in his methods which is ill-advised. Megalodon have thick teeth (symmetry) and wider curvature than a great white shark of similar size (A3 not mesial)*, and an upcoming study will highlight this fact to advance a new method to estimate the size of Megalodon accordingly - this would be the finest study of its kind yet ( Grey is one of the authors) - so you are dealing with very well learned people here. *I pointed this out years ago in another forum and I am glad that Grey noticed. This matter will be scientifically established soon. Livyatan is huge actually, in the 17 - 18m territory. Its teeth are unusually large for killer whale forms, and also for sperm whales. He has major points that are true. There’s a reason why larger Great White Sharks are not as fast as the juvenile. Because of their skeleton, since it was similar to rubber, it has a limit. If the rubber reaches that limit, it would collapse under it’s weight. He have good writing and photography skills but he tend to jump to premature conclusions - intentionally, in the case of sharks to say the least. A very large Megalodon does not need to be as fast as a juvenile to be able to acquire prey. Nevertheless, numerous factors influence speed of sharks including regional endothermy, structure of fins, and properties of skin. Mako sharks are very fast swimmers due to properties of their skin. However, gigantism is a double-edge sword; it really helps in being a macropredator in numerous environments but it does not help in "constrained conditions." Sharks first acquired 'regional endothermy' during Cretaceous in order to compete with, and prey upon highly capable animals such as mosasaurs, pliosaurs, flying reptiles and more. Excellent read: journals.plos.org/plosone/article?id=10.1371/journal.pone.0185185WE cannot tell much about structure of fins and properties of skin of Megalodon due to lack of preservation of soft tissue but it safe to assume that this shark was a very advanced form, and fossil records do suggest that it was far more capable macropredator than modern great white sharks even as a juvenile. In fact, recent research indicate that Megalodon was improving during the course of Miocene: phys.org/news/2019-03-megalodon-teeth-evolved-ultimate-tools.htmlTeeth with cusplets = early Megalodon (Carcharocles chubutensis) Teeth without cusplets = Late Megalodon (pushing boundaries in size and hunting prowess) The aforementioned evolutionary pattern coincide with whales becoming larger on average as well as emergence of Livyatan-types in the Southern hemisphere during the course of Miocene. Great white shark is continuation of small-toothed lineage and very advanced form in its own right - not to belittle this beautiful creature. |
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Post by Grey on Nov 18, 2019 19:22:42 GMT 5
Very large white sharks are only observed in calm situations but given their metabolism and stomach contents we know they can be fast enough to capture fast-swimming, warm-blooded preys such as dolphins.
We know that basking sharks, usually in the 1-5 tonnes range, potentially up to 20 tonnes, can breach energetically out of the water. Despite being "cold-blooded" and a filter-feeder of cold waters.
Megalodon very rare centra alone strongly suggest 15 m was not an unusual size for the species and a recent abstract and on-going study indicates megalodon body temperature was 10-15 degrees hotter than in the contemporary white sharks and makos, as hot as large modern whales.
Max Hawthorne is dead wrong, the most advanced research suggests meg was a >15 m active macropredatory animal, probably with unique anatomical adaptations given its unique occurence in history.
Max Hawthorne is a biased fanboy who follows an agenda. I'd like his fantasies of blue whale-sized pliosaurs to be true but actually a blue whale-sized Livyatan or meg is more plausible than this for the very reason these two Neogene (not a coincidence) superpredators are clearly more massive than any previous macropredator.
And I know that his biased mind will make him choose Livyatan because he is unable to grasp that the relationship between meg and Livyatan was certainly much different than between Briggs orcas and white sharks.
But this is not the thread.
Anyway, Pliosaurus macromerus was most likely in the 10-15 tonnes rather than the 30-40 tonnes range that has never been actually really indicated by any material.
There are big pliosaurs specimens described every couple of years, we know more and more of them and they all show animals that seem to be really large once they reach 10 meters.
In short, the biggest known pliosaurs are cow sperm whale-sized, while Livyatan and megalodon were at the very least humpback-sized, potentially fin whale-sized looking at some megalodon fossil teeth and considerations.
Pliosaurs are badass enough, a 12 m one would have a peak bite force that would rival that of a 15 m megalodon. But they were not the kaijus Hawthorne describes.
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denis
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Post by denis on Nov 18, 2019 21:28:40 GMT 5
Very large white sharks are only observed in calm situations but given their metabolism and stomach contents we know they can be fast enough to capture fast-swimming, warm-blooded preys such as dolphins. We know that basking sharks, usually in the 1-5 tonnes range, potentially up to 20 tonnes, can breach energetically out of the water. Despite being "cold-blooded" and a filter-feeder of cold waters. Megalodon very rare centra alone strongly suggest 15 m was not an unusual size for the species and a recent abstract and on-going study indicates megalodon body temperature was 10-15 degrees hotter than in the contemporary white sharks and makos, as hot as large modern whales. Max Hawthorne is dead wrong, the most advanced research suggests meg was a >15 m active macropredatory animal, probably with unique anatomical adaptations given its unique occurence in history. Max Hawthorne is a biased fanboy who follows an agenda. I'd like his fantasies of blue whale-sized pliosaurs to be true but actually a blue whale-sized Livyatan or meg is more plausible than this for the very reason these two Neogene (not a coincidence) superpredators are clearly more massive than any previous macropredator. And I know that his biased mind will make him choose Livyatan because he is unable to grasp that the relationship between meg and Livyatan was certainly much different than between Briggs orcas and white sharks. But this is not the thread. Anyway, Pliosaurus macromerus was most likely in the 10-15 tonnes rather than the 30-40 tonnes range that has never been actually really indicated by any material. There are big pliosaurs specimens described every couple of years, we know more and more of them and they all show animals that seem to be really large once they reach 10 meters. In short, the biggest known pliosaurs are cow sperm whale-sized, while Livyatan and megalodon were at the very least humpback-sized, potentially fin whale-sized looking at some megalodon fossil teeth and considerations. Pliosaurs are badass enough, a 12 m one would have a peak bite force that would rival that of a 15 m megalodon. But they were not the kaijus Hawthorne describes. Basking Sharks are warm blooded. Megalodon was NO where near as big as the Fin Whale. The largest was the size of a Humpback Whale, could’ve been ever smaller thanks to a new study putting it’s estimates at 15.3 meters. Also 10-15 tons is likely too light. 20 tons seems more accurate, possibly more. But remember, unlike Mosasaurs, Pliosaurs head were 17% of their body length. Mosasaurs body length were mostly the tail, which explains why they were light compared to predators their size. A Blue Whale sized Megalodon is very unlikely. A shark that big would starve to death. More massive than another previous macro predators. Yeah doubt that. Their less fossils yeah but that doesn’t mean anything until you find a complete skeleton. Heck, even the largest Ichthyosaur was larger than a Megalodon. Only baleen whales were larger, but that could change thanks to the recent discovery of Lilstock Monster and Aust Colossus. |
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Post by Grey on Nov 18, 2019 22:06:51 GMT 5
Okay, can someone explain him please ? It is now 3 times I fail to explain him. Basking sharks are ectotherms... The recent Shimada estimate is near certainly totally wrong and I've already explained you why; there are also two posters available of this on researchgate. No, meg max size is not 15 m, you should read the responses more carefully because we are talking about data that will be published in a few months, so you should read this more carefully and understand you're surrounded by VERY knowledgeable people about these matters here. The 17 % ratio is only one of those proposed since years and certainly not the most recent or accurate. I did not say there was a blue whale-sized meg, I said a blue whale-sized is more likely in absolute because megalodon was much larger than the pliosaurs (sorry Max Hawthorne). The Aust and Lilstock animals could be in the 25-30 m but as shastasaurids, they would be 50-100 tonnes, not more. And what is the purpose of this comparison anyway ? These were toothless squid-eaters, not true macropredators. This discussion needs some update, we're going in circles. Instead of arguing without sources other than Hawthorne's fantasy, try this author, a bit more scientific : www.deviantart.com/randomdinos/art/Toothy-Toothy-Whales-Mk-III-630335385 |
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denis
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Post by denis on Nov 19, 2019 0:35:34 GMT 5
Okay, can someone explain him please ? It is now 3 times I fail to explain him. Basking sharks are ectotherms... The recent Shimada estimate is near certainly totally wrong and I've already explained you why; there are also two posters available of this on researchgate. No, meg max size is not 15 m, you should read the responses more carefully because we are talking about data that will be published in a few months, so you should read this more carefully and understand you're surrounded by VERY knowledgeable people about these matters here. The 17 % ratio is only one of those proposed since years and certainly not the most recent or accurate. I did not say there was a blue whale-sized meg, I said a blue whale-sized is more likely in absolute because megalodon was much larger than the pliosaurs (sorry Max Hawthorne). The Aust and Lilstock animals could be in the 25-30 m but as shastasaurids, they would be 50-100 tonnes, not more. And what is the purpose of this comparison anyway ? These were toothless squid-eaters, not true macropredators. This discussion needs some update, we're going in circles. Instead of arguing without sources other than Hawthorne's fantasy, try this author, a bit more scientific : www.deviantart.com/randomdinos/art/Toothy-Toothy-Whales-Mk-III-630335385I doubt everything you said bro. I suggest checking out The Vividen’s video about it. Also since Pliosaurus Macromerus was likely 17% thanks to more complete skeletons from Kronosaurus, the estimate of the animal was likely 17-18 meters. |
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Post by spartan on Nov 19, 2019 0:56:49 GMT 5
Everyone here is aware of these skull-body ratios, it has been discussed to death. It's far more complex than simply 1:6 across the board.
I suggest you read the relevant threads on here or the actual papers/discussions among paleontologists instead of referring to some youtube videos or paleo-fiction authors.
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Post by sam1 on Nov 19, 2019 3:12:13 GMT 5
To me, there's a kind of an irony building up in this thread.
Denis seems to be pliosaur fan, and he argues for p.macromerus being much bigger than what the recent downsizes suggest.
While I don't think Denis is right, what I find ironic is that Grey, a megalodon fan, basically is of the opinion that meg reached up to 20+m despite of the most recent study putting it at 12-13m on average.
Now, I'm not saying the two examples are completely in the same category, but they're similar enough for this discussion to come across as a little ironic.
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Post by theropod on Nov 19, 2019 3:25:37 GMT 5
While it’s true Pimiento & Balk’s data rather imply (both using their original method and adapting their dataset of total length using overall dentition width of actual megalodon dentitions as a proxy for body size) averages below 14 m, or at best shy of 15 m using the most optimistic estimates, which tends to get soundly ignored by people who prefer to only look at the more sensational maximum size, that doesn’t mean the largest individuals couldn’t be 20 m or more based on that same methodology. Depending on the method (bite circumference, jaw perimeter or summed crown width), anywhere from 18 to 21 m might be realistic.
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denis
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Post by denis on Nov 19, 2019 7:58:56 GMT 5
While it’s true Pimiento & Balk’s data rather imply (both using their original method and adapting their dataset of total length using overall dentition width of actual megalodon dentitions as a proxy for body size) averages below 14 m, or at best shy of 15 m using the most optimistic estimates, which tends to get soundly ignored by people who prefer to only look at the more sensational maximum size, that doesn’t mean the largest individuals couldn’t be 20 m or more based on that same methodology. Depending on the method (bite circumference, jaw perimeter or summed crown width), anywhere from 18 to 21 m might be realistic. The Pliosaurus Macromerus jaw was incomplete from what I heard. If anyone wants to know where I got most of this from check out Dino Bios from Blogspot. I can’t put links so don’t tell me to send links. Also I think Megalodon was likely around 16-17 meters max. 18 meters may seem possible, but I don’t know. |
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denis
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Post by denis on Nov 19, 2019 7:59:35 GMT 5
To me, there's a kind of an irony building up in this thread. Denis seems to be pliosaur fan, and he argues for p.macromerus being much bigger than what the recent downsizes suggest. While I don't think Denis is right, what I find ironic is that Grey, a megalodon fan, basically is of the opinion that meg reached up to 20+m despite of the most recent study putting it at 12-13m on average. Now, I'm not saying the two examples are completely in the same category, but they're similar enough for this discussion to come across as a little ironic. I can get the downsized source for Pliosaurus Macromerus? |
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