Ostafrikasaurus, another glorified tooth

To continue with the irritating fad of naming whole genera and species based on single vertebrae or teeth- Ostafrikasaurus is one of the latter, a tooth found in Tanzania and dating back to the late Jurassic.
Scientists say its a spinosaur; they claim that its similar to Baryonyx except that it has larger serrations indicating a less piscivorous diet. But I say, how can they be so sure it's a spinosaur? It could be any other kind of theropod, or even a croc relative. I don´t understand why they jump to conclusions like this...:(

http://theropoda.blogspot.it/2012/04/ostafrikasaurus-spinosauride-da.html

Note that some are already arguing against the spinosaur idea and calling it a ceratosaur instead.