No, it is not. A dinosaur is an extinct reptile, a noun, and is a noun adjunct when used with other nouns as in dinosaur bones or dinosaur droppings (coprolites).
colossal fossil
The prepositional phrase is "about dinosaur extinction" and the object is "extinction." The word "dinosaur" is called a "noun adjunct" rather than an adjective.
Dinosaur cat dinosaur dinosaur dinosaur mat.
dinosaur dinosaur dinosaur
Dinosaur fish dinosaur dinosaur.
Dinosaur 35 is arrhinosaurus.
under the dinosaur
My favourite dinosaur is the triceratops.I had a dinosaur lunch box as a kid.We will take her to the dinosaur museum this weekend.
Barney is a dinosaur from our imagination...
The word dinosaur's means "terrible lizard".
as loud as a dinosaur
A cranky dinosaur is a dinosaur nobody wants to mess with! lol :)