are dinosaurs extinct because they didnt get vaccinated

Don’t start this again :/ 

They aren't extinct.
They left for another planet, when their astronomers saw the coming comet.
That's why we find so few remains ... those are the few who chose not to leave.  Like Harry Truman when Mt St Helens blew.

They don't exist because they got vaccinated.  

They just morphed into something horrid and really  scary.

Hard to vaccinate for a huge meteor strike I think......:( 

No, they farted too much and caused global warming. 

There were frogs on the Earth same time as dinosaurs. So you have to explain what killed the dinosaurs without killing the frogs.

My theory is gravity increased so anything taller than a modern giraffe could no longer pump blood to its head.

Maybe we should call our clones "Giraffic Park".

Another actual scientific observation is that in the days of dinosaurs, plants were mostly gymnosperms, meaning evergreens and ferns. After the mammals took over, plants were mostly angiosperms, meaning flowering annuals. I'm not qualified to analyze reasons for the difference, but I know that's a biggie.

No.  They were just at the right place at the wrong time.

Serious answer now. In his book The Dinosaur Heresies, paleontologist Robert Bakker concluded that viruses actually did kill them off as the continents shifted around, allowing foreign viruses to come in contact with different groups. The same thing happened when Europeans first explored the southern islands and Central and south America. Tribes of the natives were wiped out by foreign diseases.