There has been an edit war about when T. rex appears in the fossil record. One side says it appears 75 mya, the68-67 mya. I see four major problems wiht the former.
2)Ttrannosaur teeth, the "evidence" for T. rex being around 75 mya, are non-diaognostic, and you can't determin anything beyond that they're of a tyrannsaurid, genera and species are undeterminable,
.3)Even if these teeth exist, no other tyrannosaurus fossils are know before 67-68 mya, despite there being many known fossils.
4)NO north american dinosaur genus, nevermind species, is known to have lasted from the early-mid campanian, to the end of the maastrichtian, wy would T.rex be different. No speices even comes close to this.
Post opinions or arguments for either side below.