I don't think any of that was conveyed by the phrase "Dinosaurs weren't a species" :)

I guess I do have a tendency to not specify everything but to just leave some things as implied, that said I think the amount of dinosaur species vs. the amount of shark species is strongly implied when saying dinosaurs is not a species in context.

The land thing was not as strongly implied but again one might consider it when thinking yeah dinosaurs aren't a species, neither are sharks but the numbers don't align...hmm,hmm oh yeah and also the dinosaur species covered many more possible environments.

Haha I do that too sometimes. But for perspective, it's quite a leap for me (and it seems most others reading this too), and not at all "strongly implied" by your statement, even in context. I'm sure that chain of inference might be natural and automatic with your style of thinking, but my mind naturally goes down a completely different path when confronted with your initial statement, so it's probably best to elaborate what you're actually implying to avoid miscommunication :)