Of course most of our oil reserves come from the Mesozoic age (66-252 million years ago) so either the Silurians quickly transitioned away from fossil fuels, or blew themselves up and went extinct before they could extract all of it.
One example of those - Intact fossils are very rare, and life has been ever present on the surface of the planet a billion+ years, near as we can tell.
That said, unless they weren’t around for long or didn’t have much success/impact, some difficult to dismiss evidence would likely to be present somewhere we ran across already - like fossils. Even if 99.99999% of all our evidence gets subducted, anyone doing as much digging 50 million years from now as we’ve done recently would have a hard time missing all of traces we’ve left.
A really weird set of isotopes and geological features (like in Oklo, but not explainable naturally) from something like the National Test Site, or a layer of something like lead or mercury or radioisotopes in the sediment record not explainable by other means (like we’ve left), or a landfill full of plastic+stainless steel+carbon since metamorphized, or weird geological features like road fragments with no plausible natural explanation.
So unlikely, but not impossible. We are talking lengths of time 1000x (approx.) the furthest back of our own artifacts we’ve found.
- evolutionary evidence pointing at the possibility of species with large enough brains to build industrial civilizations
- sedimentary proof of artificial pollution and CO2 levels
- fossils
Any hypothesis has to be proven to be true, proofing it to be wrong is impossible and not things work. What the cambrisge paper did, was pointing towards wayw to proof the existence of an ibdustrial civilization millions of years ago. Now the work is on the people believing that theory to proof it.
Speculating without considering the basic principles behind said claim, concluding it is impossible to proof that theory wrong and finishing all that off with a the claim that such a civilization most definetly did or could have existed is just stupid. It worries me so, that this kind of shit shows up on HN more and more often.
That's pretty much entirely how science works ever since Karl Popper: You find an observation that the hypothesis cannot predict or predicts wrong. Bam, hypothesis falsified and rejected, no matter how much positive proof was uncovered until that point.
Or, if you like, find and show proof making the existence of such a civilaztion likely. And no, the burden of proof is not on the side diaputing the claim of such an civilization, as only the existence of something can be proven, not the absence. Hence the very exact formulation of any null-hypothesis.
Coming back to some pre-dinosaur industrial civilization (why stop at industrial so, why not an instellar one?): there is a ton of data and samples from that time periods (litterally reaching back hundreda of million of years), so everyone trying to find evidence for such a very bald claim has a lot of data to work with. Just putting out the claim and saying it must be true brcause nody can proof it wrong is not how things work, in reality that is, on the internet everything goes apparantly.