If dinosaurs existed at the end of the Copper Age, that means at the same as Abraham and Buddha and the start of written, carved or drawn record and yet there is basically none at all.
The Copper Age was about 2500 years ago. This is the time when the "wisdom" of humans took a great leap forward on a global level. Many philosophers all over the world erupted with sparks of wisdom at the same time.
I do not know the exact dates (does anyone really?), but in general around this time, in Ancient Greece there were the ancestors or philosophy such as Telis, Heraclitus and Democritus (who I think had something to do with the Theory of the Atoms), as well as obvious wise ones such as Socrates, Plato and Aristotle. In China there were the philosophers on human and the universe by Lao Zi, Zhuang Zi, as well as those philosophers on principle and morals of human and social inter-relations such as Confucious and Meng Zi, plus other shools of thought by Sun Zi, Mo Zi, Hang Fei Zi.
I am sure there are others in other parts of the world, but at least in Greece and China for starters these were quite well developed civilisations. And some of these teachings still exist today. One could also say about Hinduism, Jainism, Yoga, Buddhism, etc.
Now, dinosaurs have seemingly seem to have roamed all over the planet, so surely such philosophers who were writers would have noted the very existence of living dinosaurs and made sense of them, even if religious folks may have thought of them as demons and mythological creatures.
I hope PBKs can ask Baba for a more comprehensive answer on the topic of dinosaurs.
However, I like to point out a statement a Buddhist friend told me on one of their Universal Truths : "Any beliefs that we accept as true without
personal verification is called "superstition". Only when we hold supposed truth to the light of
personal verification, can we achieve proper beliefs. In essence, you can believe whatever you want as long as you have
personally verified, it actually does not matter who said it or not."
So maybe we'll never know if dinosaurs actually existed or not, or otherwise simply accept what is said by someone else.