The Nastiest Feud in Science

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I listened to one paleontologist say that if the impactor caused the demise of the dinos then we would find their remains in and above the K-T boundary. That makes sense. Is that what we observe?

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@T.j_Runyon what do you think of this article?

@JoeG I suppose it depends on how quickly they died off.

Those who died immediately should be in the K-T boundary- covered by the iridium deposits. Those who died later, ie slower, should be on top of that. Right? That is what the paleontologist said anyway

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It seems to depend on how long each took to happen. If it took 300 years for the iridumnto settle and 200 for the sinks to die you’d expect on thing. If it took 1000 for them to die and 20 years for the dust to settle, I’m not sure that would even be distinguishable in the fossil record. Though I’m far outside my expertise here.

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As I understand it, the iridium deposits settled within just a few years. The iridium-enriched boundary layer is only around 1cm thick, so it would have to be a very tiny dinosaur to get caught in there!



But what we see is that virtually all creatures above a certain size in weight died off BEFORE the irridium settled.

Humans are well known to have limits for going without food and water of approx. No more than 3 days without water and no more than 10 days without food.

If a meteor impact dramatically changed the climate within weeks… and continued to do so for more than a year or two… or maybe a century?.. it would be consistent with what we find.

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The article very much sets this up as an “either or” affair. While some are no doubt deeply entrenched in one or another absolute, most of the palaeontologists I know (who aren’t specifically in this field, admittedly) are comfortable with the idea that both played a role (e.g. the volcanism teed the extinction up, and the impact drove it home), so debating “which one is true?” is meaningless. The real question is “which contributed the most?”, but of course this isn’t easy to quantify either.

As usual, the answer probably lies somewhere inbetween the 2 extremes.


That seems right. I’ve also heard some causal hypothesis like the suggestion the impact caused the increased volcanism. Once again far enough from my expertise I can’t assess.

So they died before the impact.

The iridium should settle all around the dead dinos if the impact killed them.

Not really. The iridium would cover the dinosaurs if the impact killed them.

50 shades of extinction…

Or 50 ways to leave your brother


For climate to be affected for ANY length of time… fine particulate matter has to STAY SUSPENDED in the atmosphere (in one or two fast moving layers).

Having a 3 inches of dust on the ground, though inconvenient, would not change climate.

But having the same 3 inches in a virtual “weaponized” cloud of particles that settle to the earh only through repeated rain storms… well thats going to create a problem for transmitting sunshine and allowing heat to escape the greenhouse effect.

Joe, your approach seems unusually confrontational… as though you have so little faith in natural science… you question even the most basic premises.

The dino fossils disappear… that is a fact.

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That was my instinct too.

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Are you imagining something like this?

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And? It is still going to settle all around and over everything that died because of it.

Joe, your approach seems unusually confrontational…

That is your unsupported opinion, anyway

as though you have so little faith in natural science…

False accusation de jour. How nice

you question even the most basic premises.

Like what?


SOME dinos were killed on impact. But you can’t kill 100% of the larger Dinos ON IMPACT. Not only is the earth a sphere … it is just too big.

It would take an even bigger rock to do it.

Short term changes in climate, killing even 80% of plant life, was required.

What exactly are you refuting when you say that SOME large Dinos should be above the irridium layer?

As I’ve seen he is usually confrontational but unusually unconfrontational on this thread :wink:.

No. I am imagining the magenta line running through your cigar-shaped tube, underscoring “Dinosaur fossils”. The fossils would straddle the line and rest on top of it. Fossils would go right up to, through and just above, then fade out.

What I understand is the largest fossil and closest to the boundary was 13 centimeters below the K-T boundary:

The following is from Vanderbilt:

Dinosaurs: The dinosaurs arose 225 million years ago and flourished until the end of the Cretaceous, 65 million years ago. But the dinosaurs that lived 180 MY ago were not the same species as those that died out 65 MY ago. And, whereas there were 60 species of dinosaurs on Earth 75 MY ago, only 18 of those species are found in strata from 65 MY ago. So, clearly dinosaurs were suffering, probably from some long term climatic changes. No dinosaur fossils are found above the K/T boundary; however, no dinosaur fossils are found within a meter below the K/T boundary. The last appearance of dinosaur eggshells and footprints occur 2 million years prior to the K/T boundary. Did the dinosaurs die out 100s of thousands of years before the impact? Or, are conclusions in this regard too hard to draw because there are so few large animals and even fewer fossils preserved?

@gbrooks9- I am agreeing with the paleontologist who is getting attacked- sort of how you attack me without showing an understanding of what I post. The large dinosaurs who survived the impact, if any, did not leave any traces.

@swamidass I only seem confrontational to people who can’t handle the truth but I get confrontational with people peddling nonsense and using the hand-wave as a method of argument. :wink: