The Silurian Hypothesis

[Barrister]

Also the earth is 4.5 billion years old. I know the proposal is for a more recent period, but what if there was an ancient civilization 2.5 billion years ago? That makes the challenge doubly difficult: 1) so much more time has past, and 2) the earth's environment was likely different enough to lead to an ancient civilization quite different from our own (and hence we may be oblivious to some signs).

Problem is 2.5 billion years ago there wasn't even any multi-cellular life on earth, and I'm not even sure there was much atmospheric oxygen.  Any civilization that long ago would have had to come from somewhere else.

You and Malthus are both completely missing the point....How can we be sure there wasn't multicellular life on earth 2.5 billion years ago?

I didn't pick that date at random. That is the date that atmospheric oxygen basically exploded.

Well for starters I was wrong - there was multicellular life at 2.5 billion years ago, but it was multicellular cyanobacteria.  There was no even remotely complex multicellular life.

When you're going that far back there are never any guarantees, but we can say there is no evidence in the fossil record of any form of complex life in the precambrian era.

[Malthus]

Also the earth is 4.5 billion years old. I know the proposal is for a more recent period, but what if there was an ancient civilization 2.5 billion years ago? That makes the challenge doubly difficult: 1) so much more time has past, and 2) the earth's environment was likely different enough to lead to an ancient civilization quite different from our own (and hence we may be oblivious to some signs).

Problem is 2.5 billion years ago there wasn't even any multi-cellular life on earth, and I'm not even sure there was much atmospheric oxygen.  Any civilization that long ago would have had to come from somewhere else.

You and Malthus are both completely missing the point....How can we be sure there wasn't multicellular life on earth 2.5 billion years ago?

I didn't pick that date at random. That is the date that atmospheric oxygen basically exploded.

Because there is no evidence for anything very complex back then, and lots of evidence for a slow evolution towards greater complexity since then? Oxygen exploded it is true, but there was nothing, as far as we know, more complicated than bacteria 2.5 BYA. Things as complex as a worm only developed much later. Nearly two billion years later.

https://www.newscientist.com/article/2146935-tiny-worm-burrows-may-reveal-when-first-complex-animals-evolved/

Unless we are missing a whole evolutionary history in the fossil record, which seems very unlikely.

[frunk]

About the only point in favor of this hypothesis is the Great Unconformity, where rocks for a big chunk of time are just gone.  The problem is that there isn't any obvious discontinuity in the progression of life before or after this missing data, so we are back to some lifeforms that not only left no presence themselves but also left no mark on anything that came after.

[alfred russel]

Well for starters I was wrong - there was multicellular life at 2.5 billion years ago, but it was multicellular cyanobacteria.  There was no even remotely complex multicellular life.

When you're going that far back there are never any guarantees, but we can say there is no evidence in the fossil record of any form of complex life in the precambrian era.

BB--both you and Malthus are missing the point...this thread is dedicated to the idea we may be missing a major civilization 400m years ago. If that is possible, then why wouldn't we be missing something 2.5 billion years ago? At least Malthus is consistent in saying "no" to both theories.

The fossil record in that era is not especially complete, especially considering that there is no guarantee that they would easily be preserved (such as bones). 100 million years is a very long time in evolutionary history, and the environment radically changed in the period, which could explain a truly mass extinction leaving few traces.

I'm not saying this happened, just trying to expand the scope of what we could be wrong about.

[grumbler]

Also the earth is 4.5 billion years old. I know the proposal is for a more recent period, but what if there was an ancient civilization 2.5 billion years ago? That makes the challenge doubly difficult: 1) so much more time has past, and 2) the earth's environment was likely different enough to lead to an ancient civilization quite different from our own (and hence we may be oblivious to some signs).

Problem is 2.5 billion years ago there wasn't even any multi-cellular life on earth, and I'm not even sure there was much atmospheric oxygen.  Any civilization that long ago would have had to come from somewhere else.

Aliens! 

[Grey Fox]

Also the earth is 4.5 billion years old. I know the proposal is for a more recent period, but what if there was an ancient civilization 2.5 billion years ago? That makes the challenge doubly difficult: 1) so much more time has past, and 2) the earth's environment was likely different enough to lead to an ancient civilization quite different from our own (and hence we may be oblivious to some signs).

Problem is 2.5 billion years ago there wasn't even any multi-cellular life on earth, and I'm not even sure there was much atmospheric oxygen.  Any civilization that long ago would have had to come from somewhere else.

You and Malthus are both completely missing the point....How can we be sure there wasn't multicellular life on earth 2.5 billion years ago?

I didn't pick that date at random. That is the date that atmospheric oxygen basically exploded.

Well for starters I was wrong - there was multicellular life at 2.5 billion years ago, but it was multicellular cyanobacteria.  There was no even remotely complex multicellular life.

When you're going that far back there are never any guarantees, but we can say there is no evidence in the fossil record of any form of complex life in the precambrian era.

Carbon based multicellular life.

[KRonn]

[ur] https://www.ancient-origins.net/news-history-archaeology/ancient-underwater-ruins-atlantis-0011008 [/url]

The Latest Discovery of the Legendary City of Atlantis
Scientists at Merlin Burrows are celebrating having discovered the most important archaeological finding of all time, exactly where Plato said it was, "in front of "the pillars of Heracles." According to a report in The Daily Mail , Atlantis, is located "north of the city of Cadiz, Andalucía, centered around the Doñana National Park," which the Merlin Burrows historians "believe was once a vast inland sea."

Even though a Live Science feature in February applied clear scientific logic to establish that "Plato's lost city of Atlantis was never lost; it is where it always was: in Plato's books," using satellite investigation techniques, aerial photography and ground observations, the Merlin Burrows experts believe they have "found all the features of Atlantis Plato described" and that "that south and north of the park there is further evidence of the ancient civilization, with 15 other settlements dotted along the coastline." What is more, they have found evidence that the city was destroyed by a tsunami, again, just like Plato said happened to Atlantis.

Showing utter defiance in the face of what will amount to a towering wall of rock hard skepticism, Maritime historian Tim Akers, head of research at Merlin Burrows, went so far as to tell reporters that his team "have collected samples which have been scientifically tested in a lab in Modena, Italy, which is used to test ancient Roman finds. The results of the tests prove the age of the finds are older than Roman or Greek, and that they were more advanced."

Plato wrote that the harbor wall was "50 stadia" (five-and-a-half miles) in length and the satellite images show what Merlin Burrows claim is "evidence still visible today of sand dunes where this massive wall was destroyed by a huge influx of water" measuring an incredible 75 meters (245 ft) thick. The team also claim, "Laboratory analysis' of material recovered from Spain showed evidence of a type of cement not seen before, as well as ancient advanced metallurgy." "A greenish blue patina has been found covering some of the ruins which tests have shown is an ancient combination of metals. Plato describes in detail a patina on the buildings and structures of the cities and temples making up this complex," Akers added.

More supposed discovery of Plato's Atlantis, an advanced civ thousands of years old. As usual though, much skepticism ensues.

[Valmy]

How old are we talking about here? Like Egypt Old Kingdom old? Neolithic old?

[KRonn]

The Ancient Origins site says scientists claim about 10,000 years old. Here's another part of the story. This is the first time I've seen this website. A while ago I had read about findings of pillars and structures found underwater which baffled scientists, so I searched on those words and found this site.

The coast of southern Spain is an archaeological wonderland with thousands of ruins from ancient Roman and Greek cultures, but hidden among these crumbling stones, scientists from a private satellite imaging firm claim to have found evidence of "a lost city with huge harbour walls", which they believe was built by the legendary "Atlanteans," over 10,000 years ago – the legendary city of Atlantis.
In 400 BC Greek philosopher Plato wrote not the history of, but the ' story' of Atlantis in his dialogues, the Timaeus and the Critias, written about 330 BC. Describing the catastrophic collapse of an island dwelling maritime civilization that had used high technology 9,000 years before Plato's own lifetime, the capital city of Atlantis was described as having "huge entrance pillars, a temple to the god Poseidon, massive circular pieces of habitable land, and all this protected by 'enormous harbour walls'.

Despite any proven truth to the story, countless Atlantis "experts" have all successfully located the famous lost continent in places such as: the Atlantic Ocean, Antarctica, Bolivia, Turkey, Germany, Malta and the Caribbean. Only two months ago The Express published a similar article claiming a researcher had "finally discovered Atlantis" in the Sahara. Plato, however, was crystal clear about where Atlantis was located: "in front of the mouth which you Greeks call, as you say, 'the pillars of Heracles,' i.e. "The pillars of Hercules" or the Straits of Gibraltar, at the mouth of the Mediterranean.

[grumbler]

Santorini (ancient Thera) is almost certainly what Plato's sources were describing, from everything I have seen.  Destroyed in a volcanic explosion roughly 1500 BCE (the exact date is debatable).

There are numerous "pillars of Hercules" in the ancient Mediterranean.

[Eddie Teach]

How did you escape that volcano?

[Syt]

Santorini (ancient Thera) is almost certainly what Plato's sources were describing, from everything I have seen.  Destroyed in a volcanic explosion roughly 1500 BCE (the exact date is debatable).

Agreed, and there seems to be some consensus that it inspired Plato's dialogues. What I never understood is why people presume it was a real place as described in the Kritias/Timaios (IIRC). It seems a bit as if people were looking for the island of Utopia.

[The Brain]

I guess isotope changes caused by nuclear technology could be detected long (billions of years) after the civilization was gone.

[Maladict]

Santorini (ancient Thera) is almost certainly what Plato's sources were describing, from everything I have seen.  Destroyed in a volcanic explosion roughly 1500 BCE (the exact date is debatable).

There are numerous "pillars of Hercules" in the ancient Mediterranean.

Yeah, most likely that or the Black Sea deluge theory.

[jimmy olsen]

It took billions of years to build up the massive amounts of coal and oil we have found. Removing it from the Earth is not a pretty process. Mountains are ripped apart and giant sinkholes formed. If a civilization reached the stage of 20th century global exploitation of fossil fuels we would know. So any Saurian civilization must have been simpler than that.