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How Megalodon possibly looked like
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 (11-28-2019, 11:56 AM)edczxc Wrote: You are wrong. You have repeated the same thing in three diferent topics (all about megalodon, by the way...), whith out showing a single evidence. If you are going to say something you need to prove it. Answer these questions? 1 - Why you say that the orcas will "run" away? 2 - You say that it "is" the reality, have you actually saw that to say that is a "reality"? 3 - Show the evidence to prove that the whales in the time of Otodus megalodon were of the same size than this large shark? Don't be a "fan" boy, prove your facts, or sit down and learn. 
Credit to @evolution_soup
 *This image is copyright of its original author  *This image is copyright of its original author
Exhibited in Piitsburgh by Jurassic Quest
Credit to C Hunter Thorne  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author  *This image is copyright of its original author
Reconstructed Megalodon Jaw, the oldest Megalodon fossil is reported to be about 28 million years old, crazy how long ago they lived
Credit to @megalodoncollector  *This image is copyright of its original author
In fact, according with the new studies, this is the new representation of the Carcharocles (Otodus) megalodon:
 *This image is copyright of its original author  *This image is copyright of its original author It is a more slender form close to the sand sharks and not the copy-paste of the white shark. 
@GuateGojira
I wonder though if they got the colour right though. I would imagine megalodon was probably either a greyish or dark blue colour for camouflage. Not Sand coloured. (04-28-2020, 11:04 AM)Kingtheropod Wrote: @GuateGojira Good question, and based in the modern large predator sharks, most of them are gray or variations of gray. So probably that color in the reconstruction is incorrect. But who knows, the big bug is gone now and for good reasons! 
Interesting video! Thanks for sharing. It’s so scary to know that such a big creature used to roam around in the sea long time ago.
There are very well preserved fossils of Cretalamna, Megalodon's directly ancestral species via anagenesis. If you applied allometry to our knowledge of what Cretalamna looked like, I figure that would be a close approximation of Megalodon's real life appearance.
(01-10-2022, 12:08 PM)Ediacaran Wrote: There are very well preserved fossils of Cretalamna, Megalodon's directly ancestral species via anagenesis. If you applied allometry to our knowledge of what Cretalamna looked like, I figure that would be a close approximation of Megalodon's real life appearance. Correct, new information shows that these sharks were not close to the white shark, but much different, not only in the body itseld but also in the tail form. It is known that sharks normally do not leave fossils of the body because they do not have bones, but in some cases there are exceptional specimens that leave very good fossils. The closer known relative of the Carcharocles (Otodus) megalodon is the Cretolamna appendiculata, a relative medium sized shark and we have one of the best fossils of this species, check this:  *This image is copyright of its original author Under this image, Paleontologist know that the "megalodon" was not a fast hunter as the white shark but a slow swimer as the modern sand tiger shark or the basking shark:  *This image is copyright of its original author  *This image is copyright of its original author These sharks have heterocercal tails, which means that the uper lobule is very elongated and measn that the can make short burst of spead but not a prolonged fast travel, like the fish that have homocercal tails (lobules about the same size) characterized for fast swimers fish like sword fish or tuna. White shark and makos are closer to the homocercal than to the heterocercal, check again the tail of Cretolamna appendiculata. Newer reconstructions must and are taking this in count, check this out:  *This image is copyright of its original author Reconstruction from "Palaeos" and Paleontologist Roberto Díaz Sibaja from 2020. He scalated the animal at 18 m long. Compare it with the 6 m long female white shark.  *This image is copyright of its original author Art from Christopher Chávez, also from 2020. Good image but somewhat too pointed in the nose.  *This image is copyright of its original author And this one from Jaime Bran, again from 2020. Escalated at 15 meters long. As we can see, slowly but strongly, the idea of how the "megalodon" looked is changing and like the Spinosaurus, sooner or late the new form will be accepted. (01-21-2022, 09:15 PM)GuateGojira Wrote:(01-10-2022, 12:08 PM)Ediacaran Wrote: There are very well preserved fossils of Cretalamna, Megalodon's directly ancestral species via anagenesis. If you applied allometry to our knowledge of what Cretalamna looked like, I figure that would be a close approximation of Megalodon's real life appearance. There is no new form to be accepted, those are only paleoartists propositions based on sheer guess like many since years. The only tested and published current work about meg body plan is the research from Jack Cooper. https://www.researchgate.net/project/3D-...-Megalodon Kent in Renz (2002) and in his 2018 chapter has already more or less debunked the bottom feeder sandtiger-like body plan, those fins cannot operate at meg scale. (06-18-2022, 10:46 PM)Semyon Wrote: There is no new form to be accepted, those are only paleoartists proposions based on sheer guess like many since years. The only tested current work about meg body plan is the research from Jack Cooper. Poor study, check this: "This model will be created in Blender using a combination of CT scans of an exceptional vertebral column fossil (~150 vertebrae), a skull of a great white shark (Megalodon's most commonly used ecological analogue) & a full body scan of the great white shark." They still use the white shark as surrogate, so they are running in circles again. By the way, some of those paleoartists were mentored by real paleontologists, so they have their value and at least they're not copying and pasting the same great white shark over and over again. The sand tiger body plan has not been debunked at all, and why those fins can't operate at meg scale? Specially when we don't know the meg scale! At this moment, estimations run from 10 to 20 meters, very problematic if you ask. That is the problem with this particular animal and that is why I am bored about it, one month one person publish something and the next month other person debunk it, apparently, and propose other hypotesis and they continue and continue and continue with the same thing. I am not interested in this animal at all. (06-20-2022, 09:08 PM)GuateGojira Wrote:(06-18-2022, 10:46 PM)Semyon Wrote: There is no new form to be accepted, those are only paleoartists proposions based on sheer guess like many since years. The only tested current work about meg body plan is the research from Jack Cooper. If you are not interested in this animal at all, don't reply and don't post erroneous claims. And no, there is no "one month, next month", the research is steady but there is a growing consensus anyway. You just don't know much about Otodus phylogeny, this is all recent : https://www.researchgate.net/publication...todontidae Lamnids are the closest living relatives to otodontids and together may form a superfamilly the "lamnoidae". Even Kent (2018) acknowledges that the closest taxa comparable in the vertebral count and structure are C. carcharias and I. oxyrinchus. Sorry but you have absolutely no autority to judge the quality of an article not yet published, especially since using Carcharodon carcharias as a closest analogue has been used by all the modern otodontids researchers in two decades, especially in the morphology of the backbone, lamnids centra are definitely the closest to megatooth centra. Exactly my point, there is no living marine taxa in the 10-20 m range that has the locomotion apparatus of a bottom feeding sandtiger, because this caudal and those fins can't operate properly at such a scale, read below. Yes the sandtiger body plan is not supported anywhere in the peer reviewed literature, the best two alternatives given the shape of the centra are the fusiform plan and the carangiform plan (Kent 2018). Kent in Renz (2002) : Bretton W. Kent, author of "Fossil Sharks of the Chesapeake Bay Region" believes that if Meg is more closely related to sand tiger sharks, the relationship is largely irrelevant for determining body shape. "I'm a functional morphologist by training and argue that the constraints on shape are so severe for an axial swimmer (i.e., that flexes the body to provide propulsion) of this size that a sand tiger style of body is physically impossible," says Kent. "Sand tigers have an acceleration body form and use drag to displace water when swimming. Displacement swimmers need to move a water mass equivalent to 3-4 times their body mass with each stroke of the tail to swim by this mechanism." Kent says that the problem arises at really big sizes like that of Meg. "This problem is based on classic biological scaling," he says. For objects of similar shape, doubling the length causes surface area (e.g., fins) to increase four times and volume (i.e., mass) to increase eight times. Consequently, a really large sand tiger would need enormous fins to offset the tremendous increase in mass. Unfortunately, these fins would also generate an enormous amount of nonproductive drag that would impede swimming.
"The only way large axial swimmers have evolved is to switch over to a cruising body form that generates propulsion by lift rather than drag," says Kent. "Cruising fish need only displace a fraction of their body weight when swimming, relying instead on increasing the speed, rather than the mass, of the water over the tail. All of the large marine, axial swimmers (tunas, porpoises, whales, great white, mako, basking and whale sharks) use a cruising body form. As far as we know, no really large marine animal with an acceleration body shape has ever evolved. They all appear to be cruisers."
@GuateGojira
I may add that indeed you're not interested in this animal because you did not even notice the obviously all new data in this research : the backbone from Belgium was actually measured at 11.1 m on its own, while Gottfried 1996 equation based on great white centra diameter only got a TL estimate of 9.2 m. Which means that the column itself is almost 2 m longer than the estimate for the whole shark by Gottfried, who's estimates for maximum TL in the species were close to those of Shimada's. Add the tail and skull, I may say even whatever their actual shape, you automatically get a TL close to 15-16 m. This suggests that upper estimates limited to 15 m (Shimada 2019) are near impossible, unless the highly improbable case where otodontids would have disproportionately wide jaws/head/body. Check rather this talk https://youtu.be/X4FA45QwlIA Contrary to what you argue, the giant Miocene fossil shark research is well going and extremely interesting, you just rely too much on offline discussions from people not necessarily well informed. I know all the paleoartists behind the sandtiger like shape, they are not based on anything published. The Cretalamna specimen absolutely does not discount Cooper et al. suggestions, this shark has a clear cruisiform body. (06-22-2022, 01:10 AM)Semyon Wrote: If you are not interested in this animal at all, don't reply and don't post erroneous claims. Erroneous claims? Yeah right, I have talked with people that actually investigated this animal and they shared they opinions with me, that is why all the information that I shared is correct and had an backup. BUT, like I say before, this animal is not important for me, so good luck, I will not waist time in an animal which not even the experts had a consensus on its size/weight (based only in teeth and vertebraes and a lot of assumption), I am not interested at all. Bye. |
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