From author and druid John Michael Greer's essay, "The Next Ten Billion Years"[1],

"One hundred million years from now:

The universe has a surprise in store for the corvins, though. Their first moon landing included among its goals the investigation of some odd surface features, too small to be seen clearly by Earth-based equipment. That first lander thus set down on a flat lunar plain that, a very long time ago, was called the Sea of Tranquillity, and so it was that the stunned corvin astronauts found themselves facing the unmistakable remains of a spacecraft that arrived on the moon in the unimaginably distant past.

A few equivocal traces buried in terrestrial sediments had suggested already to corvin loremasters that another intelligent species might have lived on the Earth before them, though the theory was dismissed by most as wild speculation. The scattered remnants on the Moon confirmed them, and made it hard for even the most optimistic corvins to embrace the notion that some providence guaranteed the survival of intelligent species. The curious markings on some of the remains, which some loremasters suggested might be a mode of visual communication, resisted all attempts at decipherment, and very little was ever learnt for certain about the enigmatic ancient species that left its mark on the Moon."

1. https://www.resilience.org/stories/2013-09-05/the-next-ten-b...

I can't speak to dinosaur people, but the population genetics of our own DNA reveals that there were never many humans on the planet till recently, so that rules out any very large human civilization. (Unless they genetically altered themselves to hide the evidence! Ahaaa...)

I don't think we have to go that far back. Plate tectonics, submersion and weathering does a good enough job of wiping the slate clean off the surface of the Earth, that any evidence of earlier hominids developing pre-industrial, coastal civilizations say, a million years ago, would be now under the crust. What we consider civilization is about 5000 years old, so it's not inconceivable that the cycle might have occurred multiple times during geologic time spans. Perhaps this is the first time civilization was not interrupted and made its way through to a technological civilization.

However, since we do have plenty of fossils from Silurian, it is hard to believe that none of the advanced technologies never left any hint. Any idea?

This article is a weird mash-up of an actually very interesting paper [0] with random personal slop like i've asked my rabbi, consulted my kabbalah-initiated friends and for the fun mixed it up with some fashionable ancient text (Mahabharatha)

So maybe just stick right to the paper itself and its clearly stated motivation?

> Perhaps unusually, the authors of this paper are not convinced of the correctness of their proposed hypothesis. Were it to be true it would have profound implications and not just for astrobiology. However, most readers do not need to be told that it is always a bad idea to decide on the truth or falsity of an idea based on the consequences of it being true. While we strongly doubt that any previous industrial civilization existed before our own, asking the question in a formal way that articulates explicitly what evidence for such a civilization might look like raises its own useful questions related both to astrobiology and to Anthropocene studies. Thus, we hope that this paper will serve as motivation to improve the constraints on the hypothesis so that in future we may be better placed to answer our title question.

[0]https://www.cambridge.org/core/journals/international-journa...

Isaac Asimov's Nightfall [0], but on a longer cycle?

Jokes aside, what is the evidence, beyond "Ancient mystical texts"?

[0] http://www.myths.com/pub/fiction/science-fiction/Asimov/Nigh...

> or it could’ve been the eruption of a monster volcano, the sort that presently smolders beneath the Atlantic.

I know about Yellowstone, Campi Flegrei, etc, but I haven't heard about a supervolcano below the Atlantic. What's that referring to?

Technical ceramics would have survived.

Reminds me of this comic: https://badspacecomics.com/scour-copy-copy

I think the article greatly underestimates our archaeological capabilities. We can identify five mass extinctions in the last 500 million years, so why should such a civilization simply be overlooked? Of course, we wouldn't find abandoned ruins, but the idea that an industrial civilization wouldn't leave behind any detectable artifacts is practically impossible. Perhaps there were a few primate species before that could make fire and hunt with bows and arrows, but certainly nothing industrial and hardly any extensive agricultural culture.

I have a toy hypothesis that once civilization level intelligent life emerges it never disappears barring the planet it inhabits being vaporized by some unfortunately directed GRB or some similar catastrophe.

Our knowledge is becoming holographic such that to prevent the reemergence of civilization one would have to wipe out all of us at once.

The timelines don't really add up for me.

So there could have been this hypothetical civilization 55 million years ago already. And they've only just disappeared (if they did) 10'000 or so years ago? Without a trace?

Also, no, a conspiracy cannot be the answer to a question we've not yet asked. The word has a clear meaning, it requires people to conspire to hide something from you.

if all dolphins were wiped out could we know that they were ever here from physical evidence?

Dr Who and the Silurians had this covered: https://tardis.fandom.com/wiki/Silurian

>The oldest place on the earth’s surface—a stretch of Israel’s Negev Desert

I do not understand this statement, I thought an area in Quebec was around 3 - 4 billion years old. I looked, seems Australia may have the oldest area:

https://www.bbc.com/travel/article/20220126-is-the-pilbara-t...

But I say the article could be true, but the only issue I have is the large dinos. I would think they could be an impediment to any organized settlements.

One other thing, didn't most of our fossil fuels come from the Carboniferous era ?

https://en.wikipedia.org/wiki/Carboniferous

So we have microbial fossils from 3.5 billion years ago, fossilised 300 million year old skin, bones from almost 200 my ago, even actually soft tissue inside a fossilised bone from 70 my ago. Ah, footprints too, the most unsubstantial matter of all: pure shape. That's in addition to all the million other fossils that are so common we hardly care: shells, small bones, etc.

And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left? Like, billions of individuals, cities, factories, metals, concrete, mines, wells, roads and bridges and tunnels, stone sculptures!, plastic, waste dumps, farms, agricultural land, billions and billions of artifacts of all materials, most of them entirely artificial. All gone because "nothing resists 400 my" and, "oh btw, check this dinosaur footprint and this fossilised piece of skin, how cool"?

To recognize the possibility, one has to grapple with incredible scale and deep time: In roughly 300 million years (1/10th of the time life has been around), the Appalachians split off from the Atlas; the Atlantic Ocean first started splitting open; uplifts underneath North America pushing the West up from the seabed and caused the rivers to carve millions of acres of sandstone landscape down, leaving towering plateaus, cliffs, and eventually river chasms. Over the 3 billion years before that, what was carried away like so much sediment? What was subsumed by subduction boundaries?

On a much more recent timescale, one of the dominant theories of the emergence of civilization places the ancestors of the Sumerians in a stupendously fertile valley at the bottom of what is now the Persian Gulf, eventually flooded during the retreat of the glacial maximum and covered in Tigris & Euphrates sediment. It could be the very origin of regional flood and primordial garden myths. But it's all buried.

This is a good thought experiment to show how time is as vast as space.

400 million years ago is as distant as the stars. The Earth was a different planet then, in a sense.

It’s also yet another Fermi paradox answer. Even if our civilization lasts for millions of years, that’s a blip. We are searching both space and time and both are incomprehensibly vast.

Time Machine movie reboot did this in opposite direction into future decently well

dude wind hundreds of thousands of years into future, sands of time, etc. modulo two warring biological descendants of humans not full diff species tho

I'm butt hurt that I'm five paragraphs in and still have no idea what the hypothesis is.

Interesting topic, but (to immediately veer off of it) I really wish he would find another word and stop misusing "conspiracy." The word has already been through hell.

The fact there is still coal(and oil) in the ground pretty much rules out any "advanced" industrialized civilization that came before us.

I also use the Carboniferous Period as a metric as to why "Advanced alien life" isn't more abundant (and I believe it should be factored into the Fermi equation)...

All those trees growing, soaking up sun, dying and just laying there to be compressed and buried without anything to decompose them, and then humans using them like solar batteries to power civilization (i.e. burning the coal), is one of those million-to-one things that enabled the human race to develop beyond basic society.

We needed all that coal and oil (and gas) based power to get to the point - industrially and technologically - where we could even build solar panels or nuclear to replace them, so its not like you could start from first principals and jump straight to modern power generation either.

The odds that the same sequence of events - fungus and bacteria not having the tools to decompose lignin (or whatever the alien equivalent is) - to happen on an extra-solar planet is ... pardon my pun ... astronomical :D

(yes, I used a dash to separate ideas in a sentence, deal with it...)

Petroleum could be the byproduct of a previous civilization.

Also, just as we "engineered" animals and plants through selective breeding, previous animals/plants could have been the results of selective breeding by a previous civilization: There'd be no way to tell just as there'd be no way to tell our "tampering" a few million years in the future.

Joe Rogan tier pseudoscience.

Silurian Hypothesis, SETI, a widely help motivation for space exploration, much of sci-fi: all posit a high-ish rate of life (or intelligent life) invention, because the alternative is terrifying. I/we need/enjoy this, but it's fiction. When humans reason about the rate, they're extremely biased by what they want to be true.