Have I missed something ? There are really evidences of 20 m pliosaurs ?

[Newt]

I'm sure Dr. Admin will have more insight, but my immediate reaction is "what about allometry"? Different parts of an animal do not grow at the same rate. A baby is not proportioned like an adult, and any attempt to just scale up from a juvenile specimen is pretty shaky.

Of course, it is not clear which direction allometry runs in, without measurements from more specimens. The 20m figure could be an over- or an under-estimate.

Also, who says these isolated teeth come from the same species? They could come from a species with proportionately larger (or smaller) teeth.

None of this means there's anything wrong with Hawthorne's attempts to calculate size of animals known only from teeth.The trouble is that he does not make it clear that his reasoning is replete with uncertainty and should be taken as only a vague indication of possible size, not any sort of reliable evidence. This is the same sort of reasoning used to determine the size of things like Amphicoelias fragillimus and should be taken with a whole handful of salt.

[Sim]

I agree with Newt.  Also, I thought it had been established skulls from Liopleurodon (and Kronosaurus) are about one-fifth of their body length?  The Liopleurodon Wikipedia page mentions this has been deduced from, among other things, a complete Liopleurodon ferox skeleton.  It's under the "Size" section, with references.  It's interesting he says, "Slowly but surely, proof is coming to light that shows these scaly macropredators were both the most massive and the deadliest marine predators of all time.", since the only plesiosaur skin known shows the skin was smooth, without apparent scales but with small wrinkles.

[Komodo]

I agree with Newt.  Also, I thought it had been established skulls from Liopleurodon (and Kronosaurus) are about one-fifth of their body length?  The Liopleurodon Wikipedia page mentions this has been deduced from, among other things, a complete Liopleurodon ferox skeleton.  It's under the "Size" section, with references.  It's interesting he says, "Slowly but surely, proof is coming to light that shows these scaly macropredators were both the most massive and the deadliest marine predators of all time.", since the only plesiosaur skin known shows the skin was smooth, without apparent scales but with small wrinkles.

Well I really believe this guy (Hawthorne) is only a fanboy with little biological understanding and no clues about what he's talking about.

There are as much evidences for 80 feet pliosaurs than there are evidences for real life Godzilla (and I think he has a tendency to mistake marine reptiles with kaijus).

Another point to raise : why would pliosaurs need to evolve 20m or more since a 10-12m pliosaur was already plenty big compared to all its potential prey items ?

[Komodo]

Thanks for the links.

One point about the Monster of Aramberri being a juvenile. Paedomorphism is common in plesiosaurs, that is, retention of juvenile characteristics in sexually mature adults. This is a possible explanation for the apparent immaturity of the Monster of Aramberri.

By the way, I need to update my blog article (http://plesiosauria.com/news/index.php/mines-bigger-than-yours-the-monster-of-aramberri-predator-x-and-other-monster-pliosaurs-in-the-media/) with the new information from the Dinos of Mexico book...

Apparently they base their observation of immaturity on the unfused cervical vertebra.
Are there pliosaurs specimens known with totally fused vertebra ?

This is a question I'm currently exploring. If you (or anyone) is aware of any thalassophonean cervical vertebrae where the neurocentral sutures are completely fused, please let me know!

Apparently the new small-sized Russian pliosaur has fused neural centra.