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06-18-2022, 10:46 PM( This post was last modified: 06-23-2022, 06:19 PM by Semyon )
(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.
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 Cretolamnaappendiculata, 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 Cretolamnaappendiculata. 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.
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.
