For a civilisation roughly comparable to ours, there should be several things remaining. Mines and holes in the ground in general would fill up with sediment, and even if they collapse, many of the details would remain in situ. A few artifacts would be preserved, too; articles made of gold, maybe coins (assuming they were stupid enough to use money) and some electronics would be preserved as deposits rich in rare elements. I’d look in estuarine sediments, which contain innumerable articles from our own civilisation which have been dropped in the water, washed into drains, dumped as garbage or sunk. Some river deposits survive from the Permian and earlier.
I don’t accept the general thesis that all signs of civilisation would vanish- we have changed the world too much for that. At least some of the long-distance rail and road tunnels would survive, and maybe some metro systems too.
Opening a fish tank and crawling out does not seem to me to be intelligent.
Although crawling out, realizing he can’t breathe and crawling back in is intelligent. Perhaps they do it often, and we don’t know about it.
Actually scientist estimate we are probably up to about 29%. So again, this greatly diminishes the odds of an intelligent dinosaur and its predecessors all failing to show up by this time.
If a Hyper intelligent theropod did exist that reached even Roman level civilization, they would have been pretty populous in numbers I would think and we probably would have unearthed one by now.
Want to keep this alive? Lets speculate that one civilization arose and it was on what is now Antarctica. Our fossil record of Antarctica is the most sparce.
Look on Youtube, they have filmed Octopods getting out of their tanks and opening another and enjoying the buffet and apparently even returning to their tanks. They are very intelligent animals.
It is not impossible somewhere in the past a much more intelligent octopod species existed.
I stand corrected.
I’m imagining a cephalopod civilisation farming electric eels for their generating purposes. Without metal conductors, though, their technology would be restricted.
Perhaps the cephalopods, or archosaurs, could create a civilisation entirely made up of cultural elements, with no physical artefacts at all. They could tell each other stories, sing songs, and debate philosophy. This sort of civilisation would leave no trace; maybe most of the civilisations in our galaxy are like this, with no tools or constructions - which may explain why they haven’t contacted us yet.
Maybe the songs of whales and dolphins constitute such a civilisation on our world - one we haven’t recognised yet. This would leave no trace.
I tend to think that some Cetaceans might qualify. Orcas in particular have very complex social interactions, idea exchanges and teaching. But hard to equate such to human civilization.
That’s my feeling as well. A world-wide civilization with intensive agricultural and mineral production would leave traces in the geologic record, even if the sapients themselves never fossilized. The questions would be 1) is our geology complete enough to have found those traces, and 2) have we actually looked for these traces? I’m sure we could detect a micro-layer of nano-plastics in sedimentary deposits, but has anyone looked to confirm they’re not there?
This is a key point. We have BURROWS from animals of all ages and sizes preserved in the fossil record; surely a mine would leave an imprint too.
Definitely. But it’s like measuring the mass of neutrinos. Our data gives us an upper bound, which we’re improving, but we haven’t measured a zero mass.
Given what we know of human evolution (that is, the time and area needed), we have a rough estimate for how complete in time and location the fossil record needs to be to give us high confidence there couldn’t have been a sapient dinosaur species.
I would think we could compare the idea of that against our own fossil record. For example, early human civilizations left trash middens that hold a treasure trove of evidence for how they lived, and the middens themselves are evidence of civilization. I would think a civilized dino trash midden could provide clues about tool use, animal husbandry, and possibly art, communication and organization. So far, all dino fossils appear to just be random deaths by nature, with no evidence of organization, tools or created materials.
If we found something that looked like a dino burial or a pile of fossil dino bones with saw marks on them, then we’d be on to something new.
Even if most plastic breaks down in say 450 years into microplastic and a few hundred years later into nanoplastics that are undetectable unless we know to look for them - most dead animals break down in a few years to a few decades, but some small handful become fossilized. The same would apply to plastic items. Some handful would be preserved, just like some biological remnants are preserved, and we could find those.
This is kind of getting into the definition of a civilization. I’ve been thinking in terms of intensive resource exploitation, which is probably showing my human bias. But besides the obvious disruptions to the terrain, it’s also possible that it would lead to disruptions in the phylogenic record. There’s the intercontinental dispersals mentioned earlier, and also the impact on domesticated and other co-adapting species. This is likely more subtle.
Maybe someone can find the original article. But I recently read a story of an aquarium that kept losing fish and couldn’t figure out how. Finally, the set up an infra camera overnight. What it showed was that an octopus had opened its tank by undoing a catch, gone over to a fish tank and eaten a fish, then gotten back into its tank and refastened the catch. That last suggests–to me at least–that it has a theory of mind, especially that of the aquarium keeper’s. At any rate it goes well beyond opening a tank and crawling out.
Good point. I think the lack of these is stronger evidence than lack of specimens. Individuals only die once, but they each leave a lifetime of trash. And trash probably fossilizes better than individual corpses.
Well, we pretty much have to assume that such a civilization would have gone through a stone age, and flint relics would still be around. We’d find dino skeletons with flint spear or arrowheads in them, and certainly signs of dino bones when the prey was killed and butchered.
Right.
Right. Even tool using. But no fire.
Phosphorous?
When modern-day scientists investigate a site they don’t look for dinosaur bones and throw the rest in a heap. Every dig is looked at by a team of scientists with a bunch of different specialties. They work from the mega-scales of bones down to the micro-scales of pollens. They don’t just look for indivdual fossils but at the environment as a whole, to see how life was being lived at that moment by the entire ecosystem. That’s how we have so much information on dinosaur herds, feeding, predation, nesting, migration, and all the other elements from birth to death.
So the OP’s question comes down to whether in this sweeping x-ray of the past, something could have been there without leaving any even microscopic evidence or patterns of absence or disappearance while at the very same time leaving evidence of the animals and their daily lives.
The answer to that has to be no. It doesn’t matter if materials would break down over time, because the industries needed to collect and process the materials would themselves leave traces behind and so would the patterns and tracks of the civilization created. If the dinosaurs built towns of any sort in which to provide shelter for egg-laying, to give one example, the existence of a town and the materials and the differences between it and the surrounding unbuilt territory would be obvious in multiple ways, from the different percentages of organic and inorganic materials to the track marks that the building and occupation would have left. It can’t be argued that all of these could have vanished utterly while leaving all the evidence of the eggs and nests behind. Nor can it be seriously argued that all traces of every dinosaur which built a civilization vanished along with the civilization but non-civilization building dinosaurs are found everywhere at every time during the eras.
I believe that the question comes from the lack of understanding of the scope and depth of modern paleontology, a multidisciplinary set of sciences that has vastly advanced in the last few decades. If all you have to go by is the bones in a museum, then you might be able to wonder what else we know. The answer is that scientists know amazing amounts in amazing depth, so conclusively ruling out any past vanished civilizations that literally all of science today would have to wrong in everything it does to make one viable.
To be fair, that used to happen in the early days of dino hunters. And some modern day private dino hunters, who dig for the money, still do that.