The foramen ovale is not equivalent to the foramen of Panizza. The foramen of Panizza is located OUTSIDE of the actual heart. It occurs between the two aortae. The foramen ovale in humans, occurs INSIDE the heart, between the two atria.
Oops, true.
As for the Bennet-Stamper et al article, all I really gathered from it was this basic argument:
.) Early crocodylomorphs were more active than extant crocodylomorphs
.) Activity requires endothermy.
.) Therefore early crocodylomorphs were likely to be endothermic.
As the second assumption has never been experimentally born out (with plenty extant examples to the contrary), I don't really buy it.
Plus I felt they just glossed over the heart morphology of pythons and varanids in an attempt to explain why crocodylians have 4 chambered hearts (both varanid & python hearts [possibly more species as well] are functionally 4-chambered, and capable of pressure separations equivalent to those seen in mammals & birds).
How does that work?
Yes, but that's not gigantothermy. Those tunas (not all) and sharks do have increased metabolic rates.
No they don't.
Really?
They use the same counter-current heat exchange system that _D.coriacea_ uses.
Besides that, there is at least one study out there (that isn't Paladino et al's infamous one), which shows that the metabolism of _D.coriacea_ does increase when in colder waters.