I’ve had months to think about this and it has occurred to me that Oda chooses obscure dinosaurs that fit with the characters personalities rather than the popular choice. Here’s my list for the flying six:
Sasaki : Brutish,overweight and appears to be a fish man, also seems driven and strong, looking at him you would think ok Triceratops, but I think that is too mainstream for Oda. I think we are gonna get a herbivorous ancient Zoan Stegosaurus. Still pretty mainstream but I think it is a bit more out there in terms of his character.
Who’s Who seems to be extremely prideful and is not afraid of his superiors and with the cat theme of his crew I think he is going to have a cat like devil fruit. Now we would all go ok he’s a saver tooth cat but I think that is too mainstream again, we are going to get something obscure like he has a Neko Neko no Mi: Cave Lion.
Black Maria being a too put it kindly a courtesan is flamboyant and she is gigantic in size so I would have thought she would be something like an Agentosaurus or a Brachiosaurus but I think that is too obvious, I think she could be the obvious answer I think she is going to be a velociraptor something whilst small certainly made up for it by its ferocity kind of highlighting her actual size and the larger than life character of the velociraptor.
However if I could choose the devil fruits
Page One - Spinosaurus (Awesome the way it is)
Ulti - Ankylosaurus
Black Maria - Argentosaurus
Sasaki - Wooly Rhino
Who’s Who - T. rex