The big paleontological news of last week was the announcement that fossil footprints have been discovered that predate - by about 20 million years - the previous contender for the earliest fossil evidence of tetrapods. Naturally, this announcement led almost immediately to a new round of "learning anything new about evolution means that Darwinism is totally wrong" claims from the Creationists.
Their complaints don't impress me much. There's very little difference between the Discovery Institute's "if there were tetrapod footprints 20 million years before Tiktaalik, how can something Tiktaalik-like have been an ancestor to tetrapods" line and the far older "if we descended from apes, why are their still apes" canard. If you're interested in another explanation of why you shouldn't be bothered by having ancestors and descendants alive at the same time, PZ's written a good one. I'm going to look at a different question.
It seems like someone finds some new fossil form somewhere every couple of years that changes our understanding of the evolution of some major group of plants or animals. Paleontology has been a serious scientific pursuit for the better part of the last two centuries. How is it that we continue to make so many spectacular new discoveries? Shouldn't we be at the point where we're just filling in the little gaps in the fossil record?
How thoroughly have we actually examined the fossil record? How much rock have we actually looked through in our quest to understand the evolution of the major branches of life?
Paleontology is time and labor intensive. When it comes to detecting fossils in rock, there is still no substitute for the Mark 1, Mod 0 eyeball. Finding fossils is a slow process. Removing fossils from rock is a slow process. Identifying and describing fossils is a slow process. It takes a lot of time to thoroughly examine a little bit of rock.
Still, there's been a lot of time and a lot of people working. So let's make some back-of-the-envelope calculations. I'm going to be very generous in my basic assumption.
Let's presume that one paleontologist can thoroughly examine 2 cubic meters of rock per day.
If that's the case, then 10,000 paleontologists, working continuously (365.25 days/year) for 150 years will have thoroughly examined 1,095,750,000 cubic meters of rock. That sounds like a lot, until you remember just how big the planet is. So let's put that figure in perspective.
According to the US Geological Survey, the explosive 18 May 1980 Mt. St. Helens eruption removed 0.67 cubic miles of the mountain. That converts, according to Google, to 2,792,681,820 cubic meters - that's more than twice the amount of rock that our hypothetical ten thousand paleontologists spent 150 years combing through.
Still surprised that we keep finding new tetrapod remains?
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There is also the problem that although smaller animals make up the greater numbers and biomass in it is larger animals that are much more likely to become fossilized. For instance if you tried to draw a picture of European fauna from fifty thousand years ago you would get mostly mammoth and giant deer and almost zero rodents.
And it takes money that almost nobody provides!
"Money is not everything!
But without money everything is nothing!"
â On the wall in Scrooge McDuck's office in his money bin.
May i turn one of the creats questions back at them?
If we're all descended from god why is there still a god?
If we all came from dust, why is there still dust?
Another indicator that we haven't seen a decent fraction of extinct organisms is the way pre-historic times are portrayed in SciFi. In order to get a believable amount of diversity, they usually throw together animals that lived in widely different times and places. That's not just because the writers don't know any better (although that may also be true) but because there must have been a lot of organisms that didn't fossilize well in any environment, not to mention whole environments for which we don't have fossils.
Creationist nitpicking about the evolution of horses is partly due to the fact that Quaternary terrestrial fossils are hard to come by; the record is not as good as we would like. The living coelacanth surprised people largely because there are not many deep water fossils for the last 65 million years. East African fossil apes from the potentially very exciting time period of 6-7 million years ago are hard to come by because remains don't stick around much in tropical jungles. So another major factor is that many environments have a very poor fossil record.
Q: If we're descended from apes, why are there still apes?
A: There very nearly aren't, give it another century.
And, of course, of the vast number of creatures that have ever lived, an enormous number of them were eaten and digested, and didn't conveniently leave their structural arrangements lying around for fossilisation and later discovery.
(I actually had someone once tell me that, obviously, palaeontologists weren't excavating fossils, but sculpting them from the rock; otherwise, since there've been so many animals since the Dawn of Time, there should be humongous vertebrate fossils everywhere you dig, especially if you hold to the ridiculous notion that the Earth is as old as geologists insist. Therefore, "proof" that there's no evidence for evolution, and "proof" of the Young Earth theory, all in one neat, delusional package!)
In the vast majority of cases, it absolutely is because the writers don't know any better. A lot more fossil vertebrates are known than most laypeople even imagine. Quick, list all borhyaenids, all champsosaurs, and all embolomeres... and then all fossil hamsters... <crickets chirping>
Consider the minuscule probability that a particular animal will be fossilized, times the minuscule probability that the fossil will not be eroded away or buried so deep it will never be found, times the minuscule probability that the particular fossil will be found and dug up, times the small possibility that someone knowledgeable will actually examine it and publish on it. That we know of any fossils at all is a fine demonstration of improbable things happening.
Just what I needed to fill another gap in my knowledge! Thanks. This was useful.
Obviously I overstated my case in #5 above, as David Marjanovic points out. But I think the point that some environments are under-represented, and that we don't know about all of the organisms even in well-studied fossil communities is still valid.
I can answer your question. TOO thoroughly.
I found a spoon in my back yard. I willing to bet you would tell me it was "millions of years" old. Better yet, it might turn out to be global warming's (or whining)fault. Either way, I'll bet it has nothing to do with a child playing in the dirt with mommy's spoon.
The earth is less than 10,000 years old. The dinos that survived the flood(on the ark) were hunted to extinction over the next few centuries, and no Noah's ark had no CO2 emissions standards (men were free back then) but I'll bet the earth's climate changed after the flood. The whole earth encountered an ice age as a result of this global flood. Now, even Al Gore should be jealous of Noah for warning about climate change killing people.