How do Certain Animals Survive Extinction Events while other Do not?

The Cretaceous extinction event of 65 million years ago wiped out the The non avian Dinosaurs. But other species not really related were wiped out too , marine reptiles and ammonites. The Ammonites were shelled mollusks related to both squid and octopuses died out as well and yet their closest relative The Nautilus which was very similar , somehow survived.

The climate after the initial disaster cooled down due ti the debris blocking the sunlight . This killed the plants and plant eating Dinos and the meat eating dinos followed suit. . But how is it that animals like frogs and toads , alligators, , snakes and turtles ect .... which were more primitive and had a lower body temperature then Dinos managed to survive this?

This is an excellent question. As humans, I think we tend to be very egotistical about our place on Earth. But there are many animals more hardy than we are.

I've been wondering about tardigrades ever since I saw them on Cosmos. Apparantly they have survived with little change through 5 extinction events. They are extremophiles, able to survive heat, cold, and even the radiation of space.

So why haven't we all evolved like this?

They hadn't evolved and were in the water...

anno said:

They hadn't evolved and were in the water...

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But they were more primitive then the Dinos that didn't survive.

Amphibians evolved from fish and into modern day reptiles,Dinosaurs weren't like our modern day reptiles in a number of ways,but the timeline shows evolutionary progression - and it wasn't overnight.
Primitive is relative and a very human centric concept Baylor,also aliens had bagged stuff up and hid them behind Alder Baren 2...

As we don't know the exact particulars of the previous major extinction events we can't be 100% sure why some things survived and others didn't. It would not surprise me if sometimes surviving just meant that they were in the right place, at the right time and avoided whatever it was that caused the mass extinction.

Ergo I would say one of hte first ways to survive is to be within a niche that is unaffected, or which at the very least remains viable, before, during and after the extinction event. Thus if the habitat niche remains mostly in-tact then those species that rely upon it can thus survive and repopulate.

Then there is survivability in itself, which would counter my last claim. See a niche means that whilst you can carve out a very exact and specialist corner, it also means that if anything happens to that corner chances are you're in trouble. Thus generalists will have the option to thrive and survive because in a changing system they are most capable of adapting (we can see this fantastically in todays world - those niche animals are wiped out as their ecosystems are destroyed - whilst the generalists shift around and adapt to the changing times).


Humanity is an oddball; however we have one trump card which is technology (and only time will tell if it also plays a part in any downfall we might experience); even if we can't support high populations its likely that we can survive more extreme variations in habitat than many other species; even if at a biological level we are actually rather limited.

The best way to survive climate upheaval is to be small, non-specialized, and not picky about what you eat. Or be nowhere near where things are tanking.

Animals that become highly specialized are enormously successful in their niche, as long as their niche persists. But when things start to change, it's the generalists that survive. And small animals can burrow, hide under rocks, in hollow trees, or for that matter in the dead bodies of the large animals. In the latter case they'll be okay as long as they don't eat themselves out of house and home.

Sorry, I couldn't help myself.

kythe said:

This is an excellent question. As humans, I think we tend to be very egotistical about our place on Earth. But there are many animals more hardy than we are.

I've been wondering about tardigrades ever since I saw them on Cosmos. Apparantly they have survived with little change through 5 extinction events. They are extremophiles, able to survive heat, cold, and even the radiation of space.

So why haven't we all evolved like this?

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That's one way of surviving. They are tough little buggers and a very successful adaptation to the Universe. As @Bizmuth says being small and (I assume) extremely numerous means they can quickly find all the 'correct' environmental niches that will support them. We are big animals that can't ride out big extinction events that easily. The number of human 'reservoirs' is limited compared to those of the water bears.

However in our defence, I would argue that we have excelled at adapting ourselves to whatever conditions we find ourselves in, using our intelligence to compensate for our slow evolving bodies and to alter the environment. Also we are...

....non-specialized, and not picky about what you eat. Or (try to) be nowhere near where things are tanking.

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What the tardigrades have done through millions of years blind evolution we are quickly catching up with - using our brains to build machines and environments to survive these extremes. And who is to say with the continuing advances in genetics, biochemistry and all the other sciences we could be altering our flesh to remove the need for these devices (way off in the future, of course...if we get there without wiping out civilisation )

We will have to see, if we are around, what we do at the next extinction level event. Still, you'd put your money on the water bears 'out-surviving' us right now...

Venusian Broon said:

However in our defence, I would argue that we have excelled at adapting ourselves to whatever conditions we find ourselves in, using our intelligence to compensate for our slow evolving bodies and to alter the environment. Also we are...

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The way I look at it is that all the other living things have their adaptability in hardware. Humans have developed generalized hardware and put their adaptability in software. Far easier to do updates.

In the case of Ammonites, how is it that they died off, but their closest relative the Nautilus which ,is very similar and likely occupied the same niche, survived the extinction event.

If you can tell the difference between ammonites and nautili (?) then they are different. They might inhabit different environmental ranges, eat different food, have different predators, different life cycles, whatever. I think it's fair to say that any of the great extinction events were Hard Times for everyone. The difference between squeaking through and dying off can be razor-thin. In fact, it could be that the ammonites dying off first tipped the scales for the nautili, allowing them to take advantage of the sudden lack of competition.

Bizmuth said:

If you can tell the difference between ammonites and nautili (?) then they are different. They might inhabit different environmental ranges, eat different food, have different predators, different life cycles, whatever. I think it's fair to say that any of the great extinction events were Hard Times for everyone. The difference between squeaking through and dying off can be razor-thin. In fact, it could be that the ammonites dying off first tipped the scales for the nautili, allowing them to take advantage of the sudden lack of competition.

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Unfortunately, What we do know about them is based on fossil evidence and reconstruction . As to life cycles, we can extrapolate those from from Nautilus, Squids and Octopuses of which they were related, but even then we don't know for sure how similar. Or if they were similar at all . They had some kind of a vulnerability that the Nautilus didn't have.

Imo, the best reply to the question is: Richard Fortey, Survivors, and Michael Benton, When Life Nearly Died.

BAYLOR said:

Unfortunately, What we do know about them is based on fossil evidence and reconstruction . As to life cycles, we can extrapolate those from from Nautilus, Squids and Octopuses of which they were related, but even then we don't know for sure how similar. Or if they were similar at all . They had some kind of a vulnerability that the Nautilus didn't have.

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Yes, and thus the difference between "we don't know" and "there's no explanation." Sometimes, we just don't have enough information. That doesn't mean it's automatically space aliens from another dimension.

That's not a dig at you, I just get tired of true believers who insist that if you don't have an explanation handy, it JUST HAS TO BE aliens or god or a miracle or the guvmint...

Bizmuth said:

Yes, and thus the difference between "we don't know" and "there's no explanation." Sometimes, we just don't have enough information. That doesn't mean it's automatically space aliens from another dimension.

That's not a dig at you, I just get tired of true believers who insist that if you don't have an explanation handy, it JUST HAS TO BE aliens or god or a miracle or the guvmint...

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No worries on that score Bizmuth

Space aliens? hm , Ammonites do bear an uncanny resemblance to Cthulu. They both have that same distinctive profile.

Stephen Palmer said:

Imo, the best reply to the question is: Richard Fortey, Survivors, and Michael Benton, When Life Nearly Died.

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That book is on my to read list.

kythe said:

This is an excellent question. As humans, I think we tend to be very egotistical about our place on Earth. But there are many animals more hardy than we are.

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We live in the Age of Bacteria. And it has always been the Age of Bacteria.

To the "tbr" list I must now add the outstanding: Life On A Young Planet by Andrew Knoll.

Horseshoe Crabs , exited before the Dinosaurs and are are still alive , They are virtually unchanged.

BAYLOR said:

Horseshoe Crabs , exited before the Dinosaurs and are are still alive , They are virtually unchanged.

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as filmed by Richard Fortey for his tv series Survivors.