If an Asteroid struck the Earth today?

[theropod]

Fish and amphibians are obsolete, loosely defined, common-language terms that I try to avoid using. Of course the evolutionary pathways would not be the same, but gross morphology and nich-partitioning is always similar in similar ecosystems. It's the details that make the difference.

[Deleted]

Jul 26, 2013 11:49:05 GMT 5 LeopJag said:

Jul 23, 2013 13:46:36 GMT 5 @brolyeuphyfusion said:

Homo sapiens dies out along with the other ~70-75% of animal life.

I think that dinosaurs(birds are dinosaurs, deal with it), small mammals, non-amniote tetrapods, and lizards would make it through. This would probably be the end of the "Age of Mammals", and the "Second Age of Dinosaurs" begins(but this time they're all feathered).

What makes you think that very small and highly adaptable mammals such as rats and mice, wouldn't pull through?

You did not read my post carefully. I included small mammals in the examples of survivors I listed.

[Life]

Here is decent read: users.tpg.com.au/users/tps-seti/climate.htm

Humans are most likely to end up extinct from such an event. Initial devastation aside, the environmental and climatic conditions will remain unfavorable for a very long time in the aftermath.

Do not get fooled by reports of some species surviving KT extinction event; mostly "very small" life-forms survived but their populace thinned out for a long time (such life-forms do not have demanding metabolic requirements). Large complex life-forms are most vulnerable during apocalyptic events due to their demanding metabolic requirements and high degree of sensitivity to environmental conditions.

Unlike dinosaurs, we lack in tolerance capacity.

[theropod]

50% of genera and 80% of families survived the C/P event (Archibald & Fastkovsky, 2004), and as I explained earlier the meteorite is only one factor in the whole extinction event, and no consensus has been reached on its importance, but most researchers seem to agree it is not as big as often portrayed.

Volcanism, climate change and marine regression probably overally played a much greater role, the meteorite impact would have merely tipped the scales and caused final extinction to the already greatly decreased biodiversity.

I wonder if anyone here has read the literature on the terminal-cretaceous extinction:

Chapter 30 in THE DINOSAURIA notes acid rain, sudden and extreme temparature drops and global wildfires to be incompatible with the fossil record and not based on unequivocal evidence, and most hypotheses concerning the impact are not testable. Therefore, it is concluded as likely the extinction was the result of multiple causes.

"Literally, almost everything that could go wrong did so surrounding the K/T boundary."

EXTINCTION explains very elaborately how pretty much all mass extinctions seem to have been caused by more or less gradual climate and flora change, and that the K/P extinction pattern was consistent with global cooling.

In fact it appears many of the supposed consequences of the meteorite impact can be explained much better as results of terrestrial catastrophes.

The real importance and danger of meteorite impacts regarding their potential to cause extinction events is too debated to say anything specific, but the general opinion among scientists seems to be that an asteroid alone cannot be the cause of an extinction like the C/P event.

[stomatopod]

^ You forgot 100% of Kingdoms survived xD

Given that after the impact the goverments of most countries would run rampant, I think 99.99% of humanity would die.
Better have some kinf of fallout shelter...

[theropod]

That's possible. But there are more than 7 billion people on this planet, so even if 99,99% die there may still be enough to start anew.

And that's assuming there is not some kind of "emergency plan" to organise what happens after the catastrophe.

[creature386]

I believe some humans living in the wild (somewhere in Africa maybe) could be adaptable enough to survive. The civilization however will likely die.

By the way, does the asteroid come unsuspected or do astronomers already spot it years before the impact?

[theropod]

I'd also envision that to make considerable differences. If the human community is prepared, there will be some kind of emergency measures taken that will at least reduce the chaos and resulting human deaths.

Because honestly, I don't see the immediate geological and climatological consequences of the impact itself being the greatest problem.

[Life]

How will "supposed" survivors cope with "extremely unfavorable climatic conditions" which will last a long time after a big asteroid hit? Humans cannot just magically make it through in caves and bunkers for lengthy durations.

theropod

Dinosaurs have survived several mass extinction events. Fact remains that asteroid impact sealed their fate.

[theropod]

The asteroid is merely a single factor, along with extreme vulkanism, tektonic activity, climate change and resculpturing of the earths surface, and all the major overhauls this caused to the ecosystems, when they were likely already on the demise. And their most successful group survived and still flourishes. The food chains during this time were vulnerable (gigantic herbivores and carnivores with tremendous nutritional requirements, vast shallow oceans) and already wounded by these other factors. An event doesn't necessarily have to be sufficient to whipe out a tremendously successful and adaptable species in order to make this ecosystem collapse.

The problem with the whole impact hypothesis is that it is a hypothesis. Little or none of its consequences (including the extremely unfavourable conditions in the aftermath, that, if they occurred, I can imagine a remaining population to survive by teamwork and using remaining shelter and supplies) are actually confirmed.

Of course impact-theorists like to make it look like this, but all of this is far from being as certain as claimed in some places. The metoerite impact is what the general public wants to see (hyped), they don't want slow demise through background extinction in a slowly changing environment with some unusual event sealing their fate. They want a big bank, an impact with immediate fatal consequences to even a flourishing fauna.

I don't doubt this event would still be a great catastrophy. But it isn't the apocalypse.

[Life]

Aug 5, 2013 16:26:24 GMT 5 theropod said:

The asteroid is merely a single factor, along with extreme vulkanism, tektonic activity, climate change and resculpturing of the earths surface, and all the major overhauls this caused to the ecosystems, when they were likely already on the demise. And their most successful group survived and still flourishes. The food chains during this time were vulnerable (gigantic herbivores and carnivores with tremendous nutritional requirements, vast shallow oceans) and already wounded by these other factors. An event doesn't necessarily have to be sufficient to whipe out a tremendously successful and adaptable species in order to make this ecosystem collapse.

The problem with the whole impact hypothesis is that it is a hypothesis. Little or none of its consequences (including the extremely unfavourable conditions in the aftermath, that, if they occurred, I can imagine a remaining population to survive by teamwork and using remaining shelter and supplies) are actually confirmed.

Of course impact-theorists like to make it look like this, but all of this is far from being as certain as claimed in some places. The metoerite impact is what the general public wants to see (hyped), they don't want slow demise through background extinction in a slowly changing environment with some unusual event sealing their fate. They want a big bank, an impact with immediate fatal consequences to even a flourishing fauna.

I don't doubt this event would still be a great catastrophy. But it isn't the apocalypse.

This mystery can be easily resolved with common sense:-

I am not disputing the possibility of dinosaurs being thinned out or vulnerable due to the combination of climatic and geographic shifts with passage of time (the environment of Earth is not static in nature) but dinosaurs have bounced back from such shifts or crises periods prior to K/T extinction event (several times in history to be precise). It is not necessary for every species of dinosaur to survive a "mass extinction" event; even if some species would make through, this would have been sufficient for future evolution of the dinosaurs in new ages. However, K/T extinction event is unique in the sense that it involves "cosmic or extraterrestrial interference" which eliminated all of the possibilities for dinosaurs to make it through the K/T mass extinction related developments/pressures.

Fair enough?

[theropod]

Yes, this is another influence that came to play here (but maybe we should not be so focused on dinosaurs, especially since they did not go extinct and various previous mass extinctions were overall more devastating). But it was only in part responsible for what happened.

[Deleted]

Aug 5, 2013 16:43:08 GMT 5 Life said:

eliminated all of the possibilities for dinosaurs to make it through the K/T mass extinction related developments/pressures.

Sorry, but that's wrong. There are currently more species of extant dinosaurs than there are extant mammals. Also they have spread to occupy land, sea, and air.

Birds may not be usually associated by the masses with dinosaurs, but the fact is that birds are dinosaurs and they are very successful and diverse.

Dinosaurs survived the KT extinction event.

[theropod]

^And for those that did not there are reasons I already elaborated, along with size, nutritional requirements (which applies to mosasaurs and plesiosaurs as well, which should be the prime example of what went extinct during the C/P event, since dinosaurs actually continued to roam the earth) and the according lack of adaptability.

Who knows whether more dinosaurs had survives without the impact, probably, but these animals were already highly vulnerable and prone to extiction with ANY event causing instability of their ecosystems.
The same can probably be said for plesiosaurs and mosasaurs, oceanic food chains and especially large marine fauna simply tend to be affected strongly by events, that's why they demised durng an era of climate change and oceanic regression and perhaps were ultimately whiped out completely when an asteroid hit the earth.
And Pterosaurs, well, they were already being repressed by birds anyway. These are the prominent examples, but we can see marked regression in the numbers and biodiversity of most major groups prior to the impact.

So their extinction should not be equated with ours, since considering how we are doing at the moment we are more likely among the 50% of genera that would survive.

[Life]

I don't think that Mosasaurs and plesiosaurs lacked in adaptability aspect. The environment of the world was significantly damaged by the asteroid strike which led to extinction of lot of life-forms worldwide. It is hard to determine what life-forms had been through during those times.

Issue of humans is that (regardless of size), have high metabolic requirements. In addition, humans are also prone to conflicts when shit hits the fan. Furthermore, humans have realistic limits about what they can handle at environmental level. Yes, humans have survived Ice Ages but KT event sets the bar too high, IMO.

Of-course, human survival period may vary depending upon the size of the asteroid that hypothetically strikes the Earth. The one which struck 65 million years ago may not wipe whole humanity on the spot but packs sufficient punch to immensely reduce the possibility of human survival in the long run. Humans may die out maybe in a span of decades or a century; reason is that environmental conditions would be unfavorable for a long time in the aftermath of a big asteroid strike.