Here's a great clip explaining the thinking behind the consolidation of three dinosaur species into one. UCMP Curator Mark Goodwin and Museum of the Rockies Curator Jack Horner argue that there were fewer dinosaur species than previously thought.
I know I'm making you sit through science class here (and on a Saturday morning no less...) but this is cutting edge stuff, a real re-thinking about how paleontologists will look at fossils from now on. This isn't settled science yet, but I suspect that this perspective is out there to stay.
If you'd rather read than watch, the same material is covered in a Science Daily article here: New Analyses Of Dinosaur Growth May Wipe Out One-third Of Species.