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I know, I should have made the case more strongly that sometimes older scientists reject new ideas. But I did say that the cause of K-Pg extinction was well accepted before the actual crater was found. In fact that particular idea was accepted rather quickly since the evidence given for it was rather strong. A layer of enriched iridium that can be found at the same date all around the world was pretty convincing evidence.While there may be some truth in this notion, though I haven't encountered a study supporting it, it seems inapplicable in the case of the KT extinction event by asteroid impact. This was the joint effort of Luis Alvarez and his son. Luis was old enough to have played a role in the Los Alamos project, working under Oppenheimer, thirty plus years earlier.
Alvarez Theory on Dinosaur Die-Out Upheld: Experts Find Asteroid Guilty of Killing the DinosaursCitation required. Where do you get this from?
"A time when we had no fossils at all"? Are you talking about the Precambrian? We didn't have fossils because they didn't have bones or shells.Yea exactly. The fossil record has never been perfect. But time has shown us again and again that just because fossils are not present, doesn't mean that a species necessarily did not live. Such as in the case of dinosaurs. Such as in the case of every fossil we've ever found.
There used to be a time where we had no fossils at all. But this never actually meant that life didn't exist. And Darwin predicted that we would find fossils over time that demonstrate common descent. And with time, we have.
And the Permian extinction is no exception to this.
Those experts were hardly needed since it was well accepted before their proclamation. The sciences generally do not work that way. There are no high priests of science that get to decide what is accepted and what is not. By the process of peer review ideas are shown to be well evidenced or not.Alvarez Theory on Dinosaur Die-Out Upheld: Experts Find Asteroid Guilty of Killing the Dinosaurs
as well as the book I mentioned -- The Great Dinosaur Controversy
In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears for one or more periods from the fossil record, only to appear again later. Likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered.[1] The term Lazarus taxon was coined by Karl W. Flessa & David Jablonski in 1983 and was then expanded by Jablonski in 1986.[2] Wignall and Benton defined Lazarus taxon as, 'At times of biotic crisis many taxa go extinct, but others only temporarily disappeared from the fossil record, often for intervals measured in millions of years, before reappearing unchanged'.[3] Earlier work also supports the concept though without using the name Lazarus taxon, like work by Christopher R. C. Paul.[4] (From Wikipedia)And one other response. Even in today's time we have countless gaps where fossils are not found in particular strata. But it doesn't mean that life disappeared and then just magically re appeared countless times over. The more feasible explanation is that we just don't have fossils for that particular time. As has been the case with every transitional form and every fossil of every lineage that once was undiscovered but was later discovered.
my point was stated simply originally -- the old paradigm that "the present is the key to the past" led many geologists to dismiss the Alvarez hypothesis when it was first presented as being contrary to that paradigm. It was a "great debate" in the scientific community until they discovered the crater in the Yucatan, that essentially sealed the deal for most of us. That was a paradigm shift. Since then we have looked much closer at the 5 major extinction events, especially since we consider that we are now in the sixth extinction event.It's an interesting work, so I am sure re-reading it for a fourth or fifth time would still bring some new thought to the surface. Conveniently, I have a copy a couple of feet away in the philosophy section of my small library. However, I would be surprised if it persuaded me that you had a valid point. Then again, that may be because the point you are making has become increasingly obscure. Would you like to restate it succinctly so I can determine whether or not I agree with you. (And feel free to point me to specific sections of Kuhn's work you think especially relevant to your argument.)
No, he meant that there was a time when we did not even understand what fossils were so no one paid them to much attention. It was not until the 17th century that people began to realize that fossils were the remains of ancient life. During Darwin's time the fossil record was very sparse. His theory of evolution was not based upon fossils at all but he could see that fossils should support his theory. And in fact the first clear transitional fossil was discovered during his lifetime. Archaeopteryx was the first clear link between dinosaurs and birds."A time when we had no fossils at all"? Are you talking about the Precambrian? We didn't have fossils because they didn't have bones or shells.
Fossilization is a very rare event. Most land species do not leave any fossil evidence at all. For example man's very recent evolution is much clearer than the recent evolution of our closest relatives, the chimpanzee and the bonobos. The reason for that is clear. Our ancestors left the tropical rain forests. Bones do not tend to get preserved in tropical rain forests They are far more likely to decay before they can be preserved. Our ancestors left the forests and inhabited the open plains where the conditions for preservation are more favorable.In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears for one or more periods from the fossil record, only to appear again later. Likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered.[1] The term Lazarus taxon was coined by Karl W. Flessa & David Jablonski in 1983 and was then expanded by Jablonski in 1986.[2] Wignall and Benton defined Lazarus taxon as, 'At times of biotic crisis many taxa go extinct, but others only temporarily disappeared from the fossil record, often for intervals measured in millions of years, before reappearing unchanged'.[3] Earlier work also supports the concept though without using the name Lazarus taxon, like work by Christopher R. C. Paul.[4] (From Wikipedia)
Great, you have solved the mystery, they didn't go extinct, just went into witness protection program.
That does not make any sense at all. I was talking about Lazarus taxa, this is something that we discovered now that the fossil record is very accurate with geologists all over the world collecting fossils. Why would your explanation refer to a time when the fossil record was not studied?No, he meant that there was a time when we did not even understand what fossils were so no one paid them to much attention. It was not until the 17th century that people began to realize that fossils were the remains of ancient life. During Darwin's time the fossil record was very sparse. His theory of evolution was not based upon fossils at all but he could see that fossils should support his theory. And in fact the first clear transitional fossil was discovered during his lifetime. Archaeopteryx was the first clear link between dinosaurs and birds.
OKaaaay....Which explains why the most complete collection of fossils are marine creatures, especially foraminifera which float throughout the ocean and when they die the sink below the benthic zone where we get lots of fossils. In this zone you often have a continuous settling of fine sediment and shells and sea creatures with little or no decay.Fossilization is a very rare event. Most land species do not leave any fossil evidence at all. For example man's very recent evolution is much clearer than the recent evolution of our closest relatives, the chimpanzee and the bonobos. The reason for that is clear. Our ancestors left the tropical rain forests. Bones do not tend to get preserved in tropical rain forests They are far more likely to decay before they can be preserved. Our ancestors left the forests and inhabited the open plains where the conditions for preservation are more favorable.
There is nothing all that surprising about Lazurus species. The Coelacanth is an entire family of such. They used to live in shallow inland seas. The ones that live in the deep oceans of course do not leave a fossil record. So until we found living ones we did not know that they never went extinct.
In paleontology, a Lazarus taxon (plural taxa) is a taxon that disappears for one or more periods from the fossil record, only to appear again later. Likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered.[1] The term Lazarus taxon was coined by Karl W. Flessa & David Jablonski in 1983 and was then expanded by Jablonski in 1986.[2] Wignall and Benton defined Lazarus taxon as, 'At times of biotic crisis many taxa go extinct, but others only temporarily disappeared from the fossil record, often for intervals measured in millions of years, before reappearing unchanged'.[3] Earlier work also supports the concept though without using the name Lazarus taxon, like work by Christopher R. C. Paul.[4] (From Wikipedia)
Great, you have solved the mystery, they didn't go extinct, just went into witness protection program.
"A time when we had no fossils at all"? Are you talking about the Precambrian? We didn't have fossils because they didn't have bones or shells.
Then we have partial, but not total agreement. Some derivative points:my point was stated simply originally -- the old paradigm that "the present is the key to the past" led many geologists to dismiss the Alvarez hypothesis when it was first presented as being contrary to that paradigm. It was a "great debate" in the scientific community until they discovered the crater in the Yucatan, that essentially sealed the deal for most of us. That was a paradigm shift. Since then we have looked much closer at the 5 major extinction events, especially since we consider that we are now in the sixth extinction event.
I don't have an explanation, however, I feel it might be tied to the DNA that we have since discovered lurks in our genome that has been turned off, just like converting a chicken into what appears to be a dinosaur. My point in raising this is that there is a whole lot to evolution that we don't know and if you are pushing the theory you should be interested in figuring it out.We all know the definition. Do you have a technical response beyond talking about witness programs?
Then we have partial, but not total agreement. Some derivative points:
1. I would call the "The Present is the Key to the Past" an aphorism rather than a paradigm.
2. Describing it as "the old paradigm" suggests it past its Sell-by-Date. That is certainly not the case. We have simply recognised that The Present encompasses a broader range of events than we had hitherto considered. Or, put another way, The Present extends beyond the immediate present. It's the contrast between weather and climate.
3. While many geologists rightly questioned the Alvarez hypothesis - that's what scientists do - only a few dismissed it outright.
4. The main bone of contention - which I am surprised you seem not mention - was not that there had been a bolide strike, but that the main cause of K-Pg extinction was Deccan vulcanicity.
5. Your recollection of timing seems flawed. The reality of the strike and its relation (if only partial) to the extinction was broadly accepted before the crater was identified.
6. Again, you speak as if the Alvarez hypothesis is now accepted as the primary cause of the extinction. This is certainly not my reading of the literature. Since you like paradigm shifts the one that has occurred over the last couple of decades is recognition that such events are complex. The consensus now appears to be that the combination of impact and volcanism was responsible. Debate is now focused on deciding the relative importance of each.
I lean to impact being the nail in the coffin of an already damaged global ecosystem, but I would not be surprised to have to change my mind on that as new evidence and perspectives emerge. (/Since I'm not a practising geologist, being old doesn't prevent me from changing my mind./sarcasm)
That does not make any sense at all. I was talking about Lazarus taxa, this is something that we discovered now that the fossil record is very accurate with geologists all over the world collecting fossils. Why would your explanation refer to a time when the fossil record was not studied?
You continually demonstrate a quite strong ignorance of geology. The marine fossils that we have are all actually all continental fossils from when the continents were lower and the sea were higher (the icecaps are geologically recent). Deep sea life does not leave a fossil record. You should be able to figure out why.OKaaaay....Which explains why the most complete collection of fossils are marine creatures, especially foraminifera which float throughout the ocean and when they die the sink below the benthic zone where we get lots of fossils. In this zone you often have a continuous settling of fine sediment and shells and sea creatures with little or no decay.
1. I agree, however it had become a paradigm to those that didn't want to accept extinction due to meteorite because of it.
2. "Old paradigm" refers to the way some were using the concept. New paradigm refers to our realization of the impact these major extinction events have played.
3. I have no issue with debating an issue, my main bone of contention was what I perceived to be an arrogant attitude that scientists never dismiss evidence and always use objective analysis of evidence. Even the absurd thought that scientists don't lie. A study was done that showed the majority of scientific studies are not replicable. This doesn't mean the scientist fabricated their results, what is more likely is that corporations paid to have 20 studies done, and only published the 1 that appeared to show that their product was beneficial while hiding the results of the other 19.
4. This thread is not about the Dinosaur extinction, I felt this topic was tangential.
5. I read a book that was quite entertaining and presented this differently, though perhaps to make their point concerning paradigm shifts.
6. Alvarez hypothesized that there was a meteorite, that has been proven. How all the different factors played into the extinction is still up for debate. They have modeled the impact of that meteorite on climate and it would certainly be a huge stressor.
Wow, I need to talk to my professors in graduate school, they had me study books with the 4,000 species we have identified which have lived over the last 540 million years. You do realize that we can study rock formations from the deep sea either from well cores, or as a result of uplift. I guess what threw me off is your signature with a reference to plate tectonics, figured you would know that.You continually demonstrate a quite strong ignorance of geology. The marine fossils that we have are all actually all continental fossils from when the continents were lower and the sea were higher (the icecaps are geologically recent). Deep sea life does not leave a fossil record. You should be able to figure out why.
Wow, I need to talk to my professors in graduate school, they had me study books with the 4,000 species we have identified which have lived over the last 540 million years. You do realize that we can study rock formations from the deep sea either from well cores, or as a result of uplift. I guess what threw me off is your signature with a reference to plate tectonics, figured you would know that.
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