What animal is this fossil of?

[amargasaurus cazaui]

Thank you very much yet again, but sorry about this, what do you think of this one?

http://www.ebay.co.uk/itm/201321942694?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I think the terrible spelling should be a tip off. As always, a professional will present themselves well.

One big flag, to me, is that they don't say what the bone is supposed to be (as in, what body part?). And in some of those pictures, it barely looks, to my eye, like actual bone.

The texture you can see looks alot like highly agatized dinosaur bone, but sort of odd the hollowing or worn areas. I would say it is likely fossil bone of some type, but determining precisely what type, and even moreso, what bone is problematic . Generally bone has an outer skin, that keeps you from viewing the texture that well...its almost like something ground or wore the outside away to make it more clear. I am with Sbell that it looks.......questionable at best.

[Wellnhoferia]

Does anybody know of any reputable fossil selling websites apart from the ones previously stated?

[Wellnhoferia]

 Would you say that this is a genuine or fake fossil?

http://www.ebay.co.uk/itm/351383857762?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[DinoLord]

Would you say that this is a genuine or fake fossil?

http://www.ebay.co.uk/itm/351383857762?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Definitely a fake; no animal has a jaw that looks anything like that. Even the bases of the teeth look suspect. I recommend you familiarize yourself with some examples of real fossils and prehistoric animal anatomy so you'll have an idea of what to look for. Unfortunately real mosasaur jaws without any compositing/significant restoration are rare. I would look for the teeth to be rooted in sockets and for the matrix to be consistent.

I highly recommend checking out The Fossil Forum; there are a lot of knowledgeable fossil hunters and collectors on there.

[amargasaurus cazaui]

When buying an expensive fossil, if you have to ask is it real or fake...you perhaps have no business considering purchasing it, because you can get taken advantage of quite easily. The higher the cost of a fossil the more the possibility it has been heavily restored, is fake or has some other issues. You should acquire specimens from dealers that give no nonsense refund policies, and have a stellar reputation . And finally as dinolord is suggesting, take the time to learn and educate yourself about the items you want to obtain ...the more you can learn, the less easy it will be take you for a ride.

[Wellnhoferia]

Thanks very much for your help guys, much appreciated!