That’s just crazy talk, right? Geoscientist Dirk Schulze-Makuch, author of The Cosmic Zoo (2017), asks us to think again before dismissing it:

Let’s imagine for a moment that some civilization went extinct millions of years before hominids even appeared. Although there isn’t a precise definition of “civilization,” we usually associate it with a species capable of altering its physical environment on a regional or even planetary scale. How would we know, millions of years later, that they had been here?

All evidence of their technological achievements is almost certain to have disappeared long ago, as persuasively shown by Alan Weisman in his 2007 book, The World Without Us. Cities and large constructions like dams would quickly crumble and return to rubble. Farms and parks would become forest or jungle. And if this pre-human civilization had technology similar to ours, most of it would simply vanish — even plastic trash eventually decays due to UV radiation and bacteria. Large structures fare no better. In a few million years, Mount Rushmore will look just like any other mountain.

Very little remains from the Neanderthals, who lived just a few tens of thousands of years ago. Even very recent, very advanced human civilizations, like those of pre-Columbian America, made most of their constructions from organic materials like wood, so that evidence is hard to come by after only a few hundred years.

Dirk Schulze-Makuch, “Was there an intelligent civilization before humans existed?” at Big Think (May 13, 2022)

As he notes, Star Trek played with this idea in “Distant Origin” (1998):

Of course, an asteroid hit, roiling the planet’s atmosphere for thousands of years, put an end to anything the dinosaurs were doing so we’ll never know.

Cambridge palaeobiologist Simon Conway Morris, doesn’t subscribe to the idea that dinosaurs had a civilization so much as that, had they continued, they eventually would have developed one — one a lot like ours. He explains his view to the BBC here:

Conway Morris is a prominent proponent of convergent evolution — from very different starting points, life navigates to similar solutions. There asre only so many solutions to basic survival problems that actually work, which is why very different life forms converge on the same ones.

Following this line of thought, we might anticipate that, if we find life forms on planets that have many features like Earth, those life forms will show many similar features to Earth’s abundance. We shall see.

You may also wish to read: Neuralink cofounder: We can bring “exotic” dinosaurs to life now Whether Max Hodak can do that or not, many scientists ponder, when SHOULD we try to bring back extinct species? If extinct species like the mammoth were brought back by genetic engineering, they would be mostly elephant and only a bit mammoth.