Dinosaurs are mentioned in the Quran. But you should note that the word 'dinosaurs' is a modern word that refers to the gigantic animals that existed millions of years ago, The word dinosaur appeared around 1841 AD. Allah in the Quan says he created 'beasts' as 'dabbah'. A 'dabbah' in the Quran consists of all animals, including the dinosaurs and these are mentioned to have existed before Humans
Here are some of the verses mentioning Dinosaurs in the Quran
Quran, 2:164 'Behold! in the creation of the heavens and the earth; in the alternation of the night and the day; in the sailing of the ships through the ocean for the profit of mankind; in the rain which God Sends down from the skies, and the life which He gives therewith to an earth that is dead; in the beasts of all kinds that He scatters through the earth; in the change of the winds, and the clouds which they Trail like their slaves between the sky and the earth;- (Here) indeed are Signs for a people that are wise'
Quran, 31:10 'He created the heavens without any pillars that ye can see; He set on the earth mountains standing firm, lest it should shake with you; and He scattered through it beasts of all kinds. We send down rain from the sky, and produce on the earth every kind of noble creature, in pairs'
These beasts that were created before mankind are what we call today 'dinosaurs' Another interesting Ayah in the Quran says 29:28 And Lot! (Remember) when he said unto his folk: Lo! ye commit lewdness such as no creature did before you. So clearly there were creatures roaming the Earth before Humans, And The True God Allah tells us about this
Quran 16:8 "He has created horses and mules for you to ride and show; and He has created other (creatures) that you don’t know."
Note: The bible says the earth is only 6000 years old, this is obviously wrong, But The Quran gives no such age for the Earth as you read above, Allah created creatures before Humans, thus indicating That Human beings lived before human beings.