It’s not likely if you assume a civilization of savanna-dwelling, tool-wielding mammals; if you consider a civilization based on a race of ocean-dwelling invertebrates, however, it is far more plausible than a technology base dependent upon fire and smelted minerals. (By “a civilization similar to ours” I’m assuming a comparable level of population, geographic distribution, cultivation, et cetera, but not necessarily identical construction materials and industrial technology.)
I’m not asserting that no traces of a past civilization from the Jurassic could possibly survive; just that it isn’t particularly likely that we would find fossil or material evidence of it. The materials we think of as being durable on anything like human timescales are not necessarily persistent on geological timescales, and statistically it isn’t especially likely we would find fossil evidence of a civilization from 145 Mya, even if they did construct objects out of rock, steel, and concrete.
well that is the crux of it, however, I am puzzled by the weird insistence on fossilization being the ONLY method by which artifacts can be preserved over millions of years. Jewelry would not need to be fossilized to be preserved. Same with gun barrels probably. They are already plenty durable. Without the necessity for fossilization the odds on their preservation goes up by orders of magnitude. I do not know if pottery shards can last for millions of years, but I don’t know why they should not be able to do so, buried underground.
So my claim is that a civilization capable of cutting hard stones like diamonds into jewelry and making steel (as opposed to rusty old iron) and maybe even just making pottery, would leave artifacts orders of magnitude more frequently than skeletons get fossilized … because some artifacts don’t HAVE to be fossilized to be preserved, and that takes the odds WAAAAY up. A jewelry box buried ANYWHERE is gonna last. A gun dumped ANYWHERE is gonna last. No fossilization needed, baby!
I’ll defer to those who understand the processes of fossilization and or properties of inorganic materials better than I, but I’m not saying that the original coins (or any other man-made object) would remain materially intact after 150 million years (although I’m confident some would, like cut-diamonds…but those may be in such minute quantity, they’d never be found). I’m saying that it would be the fossils of appropriate man-made objects that would remain after so long a period of time. If the man-made object is not in an environment conducive to fossilization, then no evidence of it will be found millions of years later, following the same rules as organic objects.
As such, I believe the primary factor affecting the likelihood of archeologists finding conclusive evidence of a technological civilization millions of years old, is how likely and by which process various inorganic materials fossilize. If some of the materials with which we make many objects are at least as likely to fossilize as the organic materials that we’ve found in fossil form, then I believe the odds favor evidentiary discovery of millions-year-old man-made objects.
Although the civilization’s layer would be razor thin archeologically speaking (hundreds of years duration), that thin layer should be rich in fossils for at least two reasons: 1) we as a species leave a great quantity of man-made objects in the ground, over large areas of Earth, in nearly all types of terrain, including environments most likely to favor fossilization, like river mouths. 2) Many of the objects that we discard would be less degradable than organic materials that fossilize, making fossilization more likely (e.g. put two objects that are able to fossilize in an environment conducive to fossilization, the object that degrades more slowly will have a better chance of becoming a fossil, simply because it’s in the right place for the longest time).
So, how likely to fossilize are the inorganic materials that we use to make things? I don’t know, but we can review the types of preservation processes (Permineralization, Casts and Molds, Replacement and Recrystalization, Compression Fossils, Biommuration), and hopefully solicit input from those who do know. It looks to me, however, that many of the materials we use may fossilize by at least one or more of the these processes.
Gun barrels are made of steel. Steel, even corrosion resistant (so-called “stainless”) steel, will corrode and eventually disintegrate. While you don’t typically see this happen on human timescales except in highly acidic or saline environments, over geologic timeframes nothing made of steel is going to remain identifiable. Under pressure and stress even hard gemstones will eventually shear and disintegrate.
One assumption several people continue to make is that “buried underground” is equivalent to being encased in some kind of impermeable protective envelope. In fact, while being under the surface of the ground protects objects from wind and rain erosion, it also subjects them to thermal and geological shearing forces, water saturation, acidity due to dissolved minerals, and (for organic materials) consumption by microorganisms. There are some very specific types of strata that will protect or at least form trace fossil shapes of embedded objects, like compacted lava ash, but for the most part being buried in the ground over geologic timescales provides no real protection. Ground moves, abrades, shears, compacts, and ultimately consumes. The soft dirt you like to run your toes through was once hard granite, ground down by eons of wear, consumed by worms, and shat out into a fine residue.
I’m not sure how many other ways to say this, but fossils don’t just form out of any old material. Permineralization, which is what most people mean by fossils, occurs when organic material–typically osseous tissue (bone, teeth), or more rarely, dessicated soft tissue–is slowly replaced by minerals that precipitate as the original substrate dissolves away. This requires a material that is slightly porous. Metals and other typical artificially produced materials will not permineralize. There are so-called trace fossils–impressions that form and harden, such as footprints in compacted ash–but these are extremely rare as the particular conditions that result in them only occur under special circumstances.
There are species of macrofauna from the Jurassic and Cretaceous periods that existed for millions of years and (based upon reasonable assumptions about breeding rates and distribution) must have numbered in the billions over the span of existence that we know only from a handful of fragmentary fossils. As I indicated previously, the Tyrannosaurids are one of the most complete families of megafauna genera from the Cretaceous period, likely comprised somewhere on the order of 100 billion individuals, and the fossil record is less than two hundred identifiable “complete” fossils across this family, which is, again, one of the most complete on record. If a species existed in quantity for, say, 100,000 years, it is statistically likely that there would not be even one identifiable fossil. And over such timespans, even the most durable artificial materials will corrode, abrade, dissolve, or otherwise be reduced to rubble. It is entirely possible that an industrial civilization from the Jurassic era, even one using hard tools and materials, could completely disappear, leaving no readily identifiable traces in the geologic record.
What you are missing is that it is a crap-shoot; under some conditions, yes, even things as inherently tough as porcelin will be crushed, ground up, eroded into sand. But take a few trillion porcelin plates, electrical insulators, glass bottles - and scatter and bury them all over the globe. What are the chances that some significant and discoverable number of them will survive?
We don’t actually have the data - yet - and so this is all speculative - but I find it hard to believe that all potential locations are gonna experience the same levels of destructive stress. Some places, as we know, experience very little - by pure random chance. Porcelin insulators, glass bottles, carved stones etc. will survive in those places just as nicely as sedimentary rock.
While the chances of any single bottle, pot sherd, stone carving, granite kitchen countertop or tile, road cutting, mine scar, or other durable remnant surving may be small - there are billions upon billions of such chances, in pretty well every courner of the globe. T. Rex did not routinely shit out glass bottles by the thousands, or chew through solid rock - we do. Find just one remnant and your case for civilization becomes strong.
I’m still not buying it. Limestone, the most common source of fossils, is formed from the shells of sea creatures like clams and snails and brachiopods and corals and crinoids that build shells from calcium carbonate. The Calcium carbonate is not REPLACED in any sense in limestone, it’s all mixed together in a jumble … essentially, the calcium carbonate fossils ARE the limestone. And they last for hundreds of millions of years (yes, some limestone is recrystallized into marble in the mountain building process, but plenty of limestone is NOT recystallized).
But diamonds which are MUCH harder than limestone, are more likely to degrade? How does that work, exactly? I dont KNOW about the degredation rate of stainless steel, but … I bet a fair amount of it could easily wind up in strata that are favorable to its preservation, and it wouldnt have to be totally anaerobic fine layers of volcanic ash to get that accomplished.
I guess the point I’ve been trying to make is that even if nothing survives that is recognizable as a fossil or an artifact, humans (and presumably comparable Jurrasic dino-people) are having an effect on the world. Even after things break down over time, there’s still going to be anomalous concentrations of certain materials and possibly anomalous sedimentary structures.
Now, I think some of you are conflating the incompleteness of the fossil record with the incompleteness of the stratigraphic record. The fact of the matter is that since at least the late precambrian we have almost a complete record of time in the rocks. There are some global unconformities, but it’s controversial whether these necessarilly represent the same time period world wide. And at any rate, they’re relatively rare and represent relatively brief periods of time. The chances of a civilization happening to form during one of them are not that good (unless it turns out there’s something about those climatic conditions that are particularly amenable to civilizations, but let’s ignore that).
A corollary of our reasonably complete picture of the rock record is that we have a fairly complete picture of processes at work on the earth throughout that time. Essentially everything we see in sedimentary rocks, from their composition and textures and the structures we see in them (those ripple marks, for example) is explainable by modern natural processes or are fairly easy to explain given what we know about the ancient earth. If all of a sudden there’s a world-wide layer where you have anomalous concentrations of iron-oxide (as our things rust away) or things like the remnants of carbonate-based cements in otherwise non-carbonate containing rock units, you’re going to know something strange was going on. And I would claim that there is no natural explaination for something like that which would be less preposterous than ancient beings altering their environment.
It’d be pretty subtle, and indeed the purely stratigraphic evidence might be less than compelling to most, but I definitely think it would definitely be detectable. And then if someone then does finally one day dig a Coke bottle out of the global wierdness horizon, we’ll have our proof.
That’s a good point. Plus cement is chemically not that different than limestone and like you point out limestone doesn’t have any problem surviving more or less unaltered. Not that concrete structures would survive, but you’d still have great big piles of calcium carbonate laying around where they don’t belong that can’t just disappear and won’t just magically travel back to the environment where they “belong” naturally.
I’m simply suggesting that the total output of fossils generated by a species, of which we have limited, but multiple examples, over a long time-span is somewhat on par with the total potential fossil output of humans, over a much shorter time-span. Let’s stay with the Tyrannosaurids as the example. You list their total population being in the order of 100-billion (I assume this is over their entire duration on Earth). How many potential fossils may each individual leave? Figuring bones, teeth, coprolites, foot prints and eggs, this should pan out to a few hundred each—let’s say 300. Therefore, the total potential output of Tyrannosaurid fossils is ~30 trillion. Out of a potential pool of 30-trillion, we’ve found “less than two hundred identifiable ‘complete’ fossils across this family”. Surely many more Tyrannosaurid fossils lay yet undiscovered, but, still, it’s a paltry few—testament no doubt to the rarity of fossilization.
There are currently ~6.8-billion humans on Earth. What is the total human population since we’ve started leaving significant numbers of man-made objects? Perhaps 10-billion? Figure that each individual human has about the same potential fossil output on the organic side as Tyrannosaurids (i.e.~300), this translates to ~3-trillion, or about one-tenth the potential fossil output of Tyrannosaurids. Indeed, using this guideline, we’d be lucky to find fossil evidence for even one or two humans.
But, we output more than just our organic material as potential fossils. We leave behind significant quantities of man-made objects. I do understand that “fossils don’t just form out of any old material” and I accept your suggestion that most of the materials in these man-made objects cannot fossilize via permineralization (I agree this should be the benchmark process), since they are not porous enough. However, man-made objects made of porous materials do exist. Wood certainly qualifies, surely there are more. So, how many objects does the average human discard over a lifetime that have the potential to fossilize via permineralization? I think 100 would be a conservative estimate. This ups the total potential fossil output of humans to ~300-trillion, or, ten times that of the Tyrannosaurids. Using this criterion, archeologists 150-million years in the future should find ~2-thousand human fossils. We just need a few to demonstrate evidence of a technological civilization.
Alright, I’m being somewhat facetious and my estimates are probably way off, but I do think there is a point to made in favor of increased odds in favor of human fossil discovery in the distant future.
Sure, steel will. But will a porcelin electrical insulator? Your more general point - that, for example, “Under pressure and stress even hard gemstones will eventually shear and disintegrate” and that “… over such timespans, even the most durable artificial materials will corrode, abrade, dissolve, or otherwise be reduced to rubble”, seems to be that most every human artifact would disappear under geological time-frames.
Mine is that while most every object can, under the right conditions, corrode, dissolve, or otherwise dissappear - under the right conditions many would (almost certainly) survive a hundred million years intact; and given the **sheer number ** of such objects - of various materials ranging from impermiable ceramics, glass, carved hard stone, etc., scattered across almost every possible type of land- and sea-scape, the chances of a noticible number surviving appears quite high.
Hell, old “tels” in the middle east are mostly made out of pot sherds, each sherd a visible proof of civilization (a large bit of sherd cannot possibly be mistaken for ‘natural’) and we produce an exponential level of durable garbage more than them …
Og, you guys lose the forest for the trees sometimes. The vast majority of every object or substance discussed stems from the result of our culture as driven by our biology. We need shelter, clothing, containers and the like. We invented harder and more durable substances to fuel these needs; many of which wouldn’t have arisen at all if not for our agriculture.
A civilization does not require cars, glass, coins, metal jewelry etc. It only needs
It is quite possible to have large cities without using long lasting synthetic materials or even needing to use cut and dressed stone. The time span between the jurassic and us is absolutely staggering. A people that had different biological needs, might well have never developed many of the things we associate with human cities.
Well see this is where I think you are making a mistake. Permineralization is a rare process. A very, very, very rare process. If we have artifacts that do not require permineralization to survive for millions of years, we have the potential for MANY orders of magnitude more evidence in the geologic record than the dinosaurs left. Pottery sherds, gun barrels, jewels … there are a LOT of very durable artifacts we keep. Hell, I got a stainless steel fork here on my desk and many more stainless steel artifacts in my kitchen.
Nope, not buying it. A human civilization like ours is gonna leave evidence, lots of it, in the geological record. Not subtle stuff either. :::Jabs naysayers with a fork to make his point.:::
Not really. The Mongolians ruled a huge amount of asia and europe. They had a complex culture, trade system, armies, politics, art, music, and everything else. Yet they didn’t build huge stone cities or need to create concrete. They ARE us. The question as posed in the OP either makes no sense, or needs to be narrowed down. If the question is: Supposing a human civilization similar to our current one existed in the Jurassic would we find anything? then it makes sense to theorize about such things. The problem is the OP didn’t specify, and I see no reason to assume that a civilization composed of beings with a completely different set of biological demands would solve their technological problems in the manner we have done.
We certainly have not always utilized the best solutions either. For modern culture, technology has become deeply entwined with both money and politics. That has driven the innovations more than logic or scientific principle that have become our current solutions.
I suppose if you want to argue about scaly romans carving marble and driving about in steel and petrochemical vehicles, then go ahead, but it makes no sense.
Huh, buy “ours” I took the OP to mean ‘the one we are in now’ - which is narrowed down. That’s the natural meaning of “ours”. We are not Medieval Mongolians or Romans.
BTW, you are quite wrong about Medieval Mongolians not building “huge stone” cities.
“It’s not likely if you assume a civilization of savanna-dwelling, tool-wielding mammals; if you consider a civilization based on a race of ocean-dwelling invertebrates, however, it is far more plausible than a technology base dependent upon fire and smelted minerals.”
Im just not seeing it. No direct manipulation of DNA, no ability to separate chemicals unless you create glass vessels or the like, no ability to create said glass vessels or the like underwater, writing would be a major problem, etc. The roadblocks would be enormous. Breeding I could see, but that can only go so far in meaningful timeframes.
This simply isn’t true. Organic soft tissues can and do fossilize under the right conditions. Yes, this is a rarer occurrence than skeletal/shell fossilization, but not *so *rare - there are hundreds of sites and more occurrences being found by revisiting older finds. Sometimes this is as compressed carbon films or replacement aluminosilicates and pyrites, under anoxic conditions, like in the Burgess Shale and other Konservat-Lagerstätten, but other times iron-mediated polymerization can occur.
Isn’t it probable that permineralization is the most common process for creating the fossils we’re familiar with, simply because it is the best process for fossilizing organic material? We don’t see as many fossils created by the other methods (casts/molds, compression, bioimmuration), perhaps, because the materials (particularly in concentrated, organized form) favored by those methods simply didn’t exist our distant past.
Isn’t it reasonable to assume that at least one major factor for their being so few finds of cast/mold type fossils may be due to the relatively rapid decomposition of organic material compared to many inorganic materials that are so commonly used today? Even bone, under normal conditions, will decompose in only hundreds of years. If bone lasted tens of thousands of years before decomposing, maybe that would tip the scale in favor of casts/mold type fossils being more common than permineralization.
It’s remarkable to me that we have any examples of soft tissue impression fossils, like those of ferns—they begin to decompose immediately. Of course conditions for their fossilizing need to be extremely exact and complicated (and therefore exceedingly rare), there’s a miniscule envelope of time within which fossilization may occur. If some of our most durable building materials last, say, 100-thousand years before decomposing, doesn’t this factor alone change the playing field, perhaps making the less common fossilization methods more common?
and my estimates are probably way off, but I do think there is a point to made in favor of increased odds in favor of human fossil discovery in the distant future.