Planet Earth has been a series of experiments to see what would survive and be of benefit to the development of spiritual life on Earth and what would not help.
So, whether you believe it or not, once planet Earth had been properly created, the first lifeforms introduced were these stone giants. Then, jellyfish sort of water creatures, then, eventually lizard type creatures (dinosaurs), then mammals and, finally, man.
I may have got the order a bit wrong and I may have missed a few experiments.
The archangels tried to use the natural elements found on earth: stone, water air and so on.

Obviously, some elements were unsuitable for transforming into ‘life’ forms so, over vast periods of time, different types of life forms were introduced and, if they didn’t work, allowed to die out.
In the case of lizards, they evolved for a long time until, I believe, there was an Extinction Level Event (ELE) and the oxygen supply lessened and so smaller mammals were introduced and the lizards allowed to die out.

So, the answer to the question is, yes dinosaurs did exist in a variety of shapes and types for a very long time.
As planet Earth evolved and changed, they were no longer suitable, so they were allowed, as a distinct species, to die out.
Some forms and descendants still exist; birds, lizards etc.

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