No it's not unlikely and stupid. And T. Rex isn't a mammal.

You have given no good reason why.

And I know, I was using that to disprove your "idea". Non-avain dinosaurs where more like mammals the others, non-archosaurian, sauropsids. The average time span of a late cretaceous large dinosaur is even less.

No. Many late Cretaceous animals have huge time ranges, such as Pteranodon.

Pteranodon lived for 4 my, and that's only if we include Geosternbergia as pteranodon. And I said Late Cretaceous large DINOSAUR. Pteranodon is a pterosaur.

I know, but because pteranodon had several species, it lived for 60m years.

Pteranodon had one species, P. longiceps.  If Geosternbergia sternbergi was just a species of Pteranodon, then we have two.  P. longiceps' temporal range was 86 to 84.5 mya.  Geosternbergia sternbergi had a temporal range of roughly 86 to 83 mya.  Together, that's a temporal range of about 3 million years, not 60 million years.

I think you may have been confused with species and synonyms.

There are TWO accepted species of Pteranodon nowadays, P. sternbergi, and P. longiceps. Recently, P. sternbergi has been given it's own genus, Geosternbergia, but this has been debated. Then, a second species of species of Geosternbergia was named G. maysei. If these where within pternodon, this increases the time range to 8 my, no 4 my bad. Then there is the also recent Genus Dawndraco, which even if a synonym of Pteranodon would not increase the time range. Even the potential second species currnetly though to be part of P. longiceps wouldn't help. So between the 1-5 species you never each more then 4-8 my.

How bout Pteranodon ingens?

No longer valid.

Colector1, your opinion?