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Big aquatic vertebrates (WAS: Re: Pterosaur size)

On 12/13/06, David Marjanovic <david.marjanovic@gmx.at> wrote:

As clear as for terrestrial vertebrates, I'd say. You might like the fact that 
the biggest ichthyosaur (and probably the biggest marine vertebrate before 
*Basilosaurus*) was Triassic, though -- but then it is far from the ancestry of 
the later ichthyosaurs.

This reminds me of something I've long found a bit odd - since the Triassic or so, most of the really big aquatic vertebrates, both predators and plankton-feeders, have been tetrapods. The whales win in both categories (sperm whales and blue whales respectively), but even discounting them the biggest non-tetrapods are beaten by various marine reptiles, far as I know. (Leedsichthys and whale sharks are smaller than that mega-ichthyosaur, and the biggest pliosaurs appears to have out-sized Carcharodon megalodon, the biggest predatory fish I know of.)

Land might seem an odd route to maritime gigantism, but it's
apparently the best one. The only explanation I've seen suggested is
that air-breathing is more effective than gill-breathing, even tho the
gill-breathers can breathe continuously.

Andreas Johansson

Why can't you be a non-conformist just like everybody else?