What if, 66 million years ago, that asteroid did not wipe out the dinosaurs?

[Itoero]

What if, 66 million years ago, that asteroid did not wipe out the dinosaurs?

Would mammals still have displaced the dinosaurs?

Could dinosaurs develop childcare, complex societies, and adaptive intelligence?Those are properties we subscribe to mammals...

[Delta1212]

Nobody knows what would have happened. An intelligent civilization might have evolved from some other line of animal or it might not have arisen at all. Mammals as we currently know them almost certainly wouldn't exist, though.

[pavelcherepan]

The asteroid did make an impact and made things quicker, but the extinction event had started before the Chixhulub event. There was severe volcanism on Indian plate similar to Siberian sills that were involved in the previous extinction event, divergent boundaries at many other plate boundaries. Whole ecosystems were getting destroyed and climate was changing rapidly.

 

Cenozoic also had recurring ice ages throughout, not the conditions where large cold blooded animals could proliferate and be successful.

 

Hence there is a good chance that dinosaurs would've died off regardless, asteroid impact just made it all end faster.

 

So mammals woulve probably still had taken all the land based ecosystems and we'd come to about the same result we see now.

[Delta1212]

The asteroid did make an impact and made things quicker, but the extinction event had started before the Chixhulub event. There was severe volcanism on Indian plate similar to Siberian sills that were involved in the previous extinction event, divergent boundaries at many other plate boundaries. Whole ecosystems were getting destroyed and climate was changing rapidly.

 

Cenozoic also had recurring ice ages throughout, not the conditions where large cold blooded animals could proliferate and be successful.

 

Hence there is a good chance that dinosaurs would've died off regardless, asteroid impact just made it all end faster.

 

So mammals woulve probably still had taken all the land based ecosystems and we'd come to about the same result we see now.

 

 

That presumes that a change in timing and circumstance wouldn't have altered what creature or creatures expanded into the niches left vacant by the extinction. The space rock may very well have killed off a variety of different forms of life that would have taken the place of mammals as the new group of dominant megafauna. some breeds of dinosaur survived to become modern birds as it is. It's possible more would have done so, or that some other tangent that life moved down that was clipped off by having a rock dropped on its head would have flourished during a more gradual decline in dinosaurian dominance.

 

It's really too big of an event to predict what would have happened because by its very nature it erased a lot of "what ifs" that we simply have no way of knowing about. An eventual decline in dinosaurs as we know them either way doesn't mean what comes next is also inevitable, or even likely.

[Ophiolite]

Cenozoic also had recurring ice ages throughout, not the conditions where large cold blooded animals could proliferate and be successful.

 

Hence there is a good chance that dinosaurs would've died off regardless, asteroid impact just made it all end faster.

 

So mammals woulve probably still had taken all the land based ecosystems and we'd come to about the same result we see now.

Most dinosaurs were small, or medium sized. Many were warm blooded. Only the larger "models" would have been disadvantaged. And dinosaurs did survive the impact. I can see several flying outside my window at the moment.

[J.C.MacSwell]

[pavelcherepan]

 

 

Most dinosaurs were small, or medium sized. Many were warm blooded. Only the larger "models" would have been disadvantaged. And dinosaurs did survive the impact. I can see several flying outside my window at the moment.

 

I wanted to edit that part, but them sort of forgot about it.

 

Love the picture J.C.

[J.C.MacSwell]

 

I wanted to edit that part, but them sort of forgot about it.

 

Love the picture J.C.

Thanks. Just realized it might not be clear it was a Far Side. Always loved Gary Larson.

[Moontanman]

What if, 66 million years ago, that asteroid did not wipe out the dinosaurs?

Would mammals still have displaced the dinosaurs?

Could dinosaurs develop childcare, complex societies, and adaptive intelligence?Those are properties we subscribe to mammals...

 

It is important to note that brain size between dinosaurs and mammals might not be a very good way of measuring the ability of each against each other... Birds such a crows have small brains compared to mammals but are capable of far more intelligence than similar brain sized mammals. I see no reason to assume that dinosaurs were not capable of everything mammals have accomplished given time.

 

The asteroid did make an impact and made things quicker, but the extinction event had started before the Chixhulub event. There was severe volcanism on Indian plate similar to Siberian sills that were involved in the previous extinction event, divergent boundaries at many other plate boundaries. Whole ecosystems were getting destroyed and climate was changing rapidly.

 

Cenozoic also had recurring ice ages throughout, not the conditions where large cold blooded animals could proliferate and be successful.

 

Hence there is a good chance that dinosaurs would've died off regardless, asteroid impact just made it all end faster.

 

So mammals woulve probably still had taken all the land based ecosystems and we'd come to about the same result we see now.

 

I am not really sure i understand your reasoning on this, while some research has indicated that large dinosaurs might have been in decline dinosaurs had been in decline before and managed to come out the other side. It is important to point out that not all and maybe no significant numbers of dinosaur species were ectotherms, much like mammals most were endotherms.

 

It should also be noted that mammals and dinosaurs evolved at about the same time, it may be argued mammals evolved a bit sooner, but dinosaurs were superior to mammals in many if not most ways and this allowed them to limit the evolution of mammals to speciality niches.

 

The double hammer blow of asteroid and the lava flood in India was probably the reason that dinosaurs of larger size didn't make it.

 

It should also be noted that like most extinctions serendipity played a part as did the survival strategies of the survivors. Endotherms and ectotherms survived the event but animals that hibernated (which some birds do) like crocodilians, mammals, and amphibians or were able to live in microhabitats and eat carrion appeared to be more likely to survive.

 

It should also be remembered that ocean dwelling organisms took a hit as well.

 

 

 

That presumes that a change in timing and circumstance wouldn't have altered what creature or creatures expanded into the niches left vacant by the extinction. The space rock may very well have killed off a variety of different forms of life that would have taken the place of mammals as the new group of dominant megafauna. some breeds of dinosaur survived to become modern birds as it is. It's possible more would have done so, or that some other tangent that life moved down that was clipped off by having a rock dropped on its head would have flourished during a more gradual decline in dinosaurian dominance.

 

It's really too big of an event to predict what would have happened because by its very nature it erased a lot of "what ifs" that we simply have no way of knowing about. An eventual decline in dinosaurs as we know them either way doesn't mean what comes next is also inevitable, or even likely.

 

 

I think it is a bit misleading to say that some dinosaurs survived and became birds, birds had already evolved and been around for many tens of millions of years. In fact it's safe to say that birds went through the eye of the extinction barely. The abundance of birds was greatly diminished with only one of the many "types" of birds surviving.

Edited October 3, 2016 by Moontanman

[pavelcherepan]

 

 

I am not really sure i understand your reasoning on this, while some research has indicated that large dinosaurs might have been in decline dinosaurs had been in decline before and managed to come out the other side. It is important to point out that not all and maybe no significant numbers of dinosaur species were ectotherms, much like mammals most were endotherms.

 

I have already agreed in post #7 that I've failed to address this point in my original post, but I accept that it was my bad and what you and Ophiolite said is correct.

 

 

 

It should also be noted that mammals and dinosaurs evolved at about the same time, it may be argued mammals evolved a bit sooner, but dinosaurs were superior to mammals in many if not most ways and this allowed them to limit the evolution of mammals to speciality niches.

 

That's not exactly true. During Permian age synapsids were the largest terrestrial vertebrates, while diapsids were smaller and less numerous. But then a wild Great Dying appeared. It used Extinction and it was super-effective!

 

And as always during extinction events largest animals are the first to suffer and that resulted in a great reduction of number of synapsid species and those that did survive had to adapt to new conditions. When dust settled (both figuratively and literally) the newly formed ecosystems have been taken over by diapsids, which during Triassic evolved into dinosaurs as we know them today.

 

Hence, the fact that mostly during Jurassic and Cretaceous dinosaurs were dominant land-based animals was not specifically a result of them being "better" than ancestors of mammals, but was a matter of luck (in the form of great dying) and favourable climate that provided plenty of food among other factors. One useful characteristic that allowed them to become successful was of course skull structure, since compared to synapsids, diapsids can grow to a larger size slightly more easily simply because the skull is lighter. But this characteristic would not have made much difference if the other two conditions I've listed above didn't get fulfilled.

[MigL]

As others have already pointed out, and I'm repeating ( just to be annoying ).

A sudden cataclysmic event can become an extinction event, but a gradual, drawn-out event is simply an evolutionary forcing.

 

I remember reading a science fiction story about intelligent, evolved dinosaurs, but for the life of me, can't recall title or author.

( damned old age ! )

[pavelcherepan]

MigL I think you're referring to Harry Harrison's West of Eden series. Loved those books!

Edited October 4, 2016 by pavelcherepan

[Itoero]

Titanosaurus and Tyrannosaurus lived until the asteroid made his move.

Titanosaurs were probably the biggest creatures ever to have walked the earth.

So they were doing pretty good.

 

Could big dinosaurs adapt to a cooling climate?

[Sensei]

Titanosaurs were probably the biggest creatures ever to have walked the earth.

According to wikipedia

https://en.wikipedia.org/wiki/Titanosaurus

Titanosaurus had 9-12 meters and 13t weight.

 

While f.e. Brachiosaurs

https://en.wikipedia.org/wiki/Brachiosaurus

had 26-27 meters and 35 t weight.

 

https://en.wikipedia.org/wiki/Diplodocus

Diplodocus had 28-32 meters.

 

Could big dinosaurs adapt to a cooling climate?

Perhaps. If change is slow, the next generations thanks to mutations have time to adopt.

 

But you also have to take into account that such large animals need plentiful of food.

In cold climate plants have problem with growing. Summer season is short.

Mammals to survive in cold climate, hibernate, or are making food stores (f.e. squirrels)

Edited October 4, 2016 by Sensei

[Itoero]

According to wikipedia

https://en.wikipedia.org/wiki/Titanosaurus

Titanosaurus had 9-12 meters and 13t weight.

Titanosaurs were a diverse group of sauropods.

Titanosaurus was a Titanosaur.

Argentinosaurus was also a Titanosaur and was estimated at 30 m.

https://en.wikipedia.org/wiki/Titanosaur

[Ophiolite]

 

I think it is a bit misleading to say that some dinosaurs survived and became birds, birds had already evolved and been around for many tens of millions of years. In fact it's safe to say that birds went through the eye of the extinction barely. The abundance of birds was greatly diminished with only one of the many "types" of birds surviving.

However, that is not what I said. I said that some dinosaurs survived, not that some dinosaurs survived and became birds. Birds are dinosaurs.

[Sriman Dutta]

Dinosaurs existed in the Mesozoic Era. In the Cretaceous Period, they were wiped out due to massive meteor showers. But, if time were given, they could have become civilized and would have developed their own language. Really, it's interesting - it's like a science fiction.

Thumbs up .... I like this thread.

[CharonY]

While mainstream topics are being discussed in this thread, the whole premise is, by definition, speculative. So I have moved it here for the time being.

[Itoero]

Would humans still have evolved?

[Ophiolite]

Would humans still have evolved?

Absolutely not. Too many variables responsible for humans would have been different. This is not to say that evolution would not have produced a bipedal mammal with high intelligence, binocular vision, opposable thumbs and a predilection for reality TV shows.

[DrmDoc]

Would humans still have evolved?

 

I agree with Ophiolite in that humanity could not have evolved without extinction of the dinosaurs. The animals ancestral to humans were likely prey and their smaller size was a survival advantage that probably would have persisted if the dinosaurs had survived as they were. Also, I think the environment that would have favored dinosaur survival would also have likely favored survival conditions that didn't require ancestral animals to be any bigger or smarter than they were. Dinosaurs thrived for hundreds of millions of years without needing or evolving technology suggesting the measure of sophistication humanity has gained in just a couple of hundred thousand years. For humans to have evolved on a dinosaur dominated planet, it would have required a lack of predation on human ancestry to achieve a larger size and a competitive environment where survival demands compel mental adaptions and development.

Edited October 6, 2016 by DrmDoc

[Itoero]

Also, I think the environment that would have favored dinosaur survival would also have likely favored survival conditions that didn't require ancestral animals to be any bigger or smarter than they were.

But in the Cenozoic the environment changed. About 49 million years ago a long term cooling started which was favorable for mammals.

I think the bigger dinosaurs would go extinct or would reduce in size.

https://en.wikipedia.org/wiki/Cenozoic#Climate

[DrmDoc]

But in the Cenozoic the environment changed. About 49 million years ago a long term cooling started which was favorable for mammals.

I think the bigger dinosaurs would go extinct or would reduce in size.

https://en.wikipedia.org/wiki/Cenozoic#Climate

 

Regarding human evolution in the shadow of dinosaurs, my opinion is based on conditions favoring dinosaurs that remaining stable and unchanged. I agree that environmental changes that decrease predation and promoted new survival skills would likely have favored the further evolution of animals ancestral to humans.

[Moontanman]

But in the Cenozoic the environment changed. About 49 million years ago a long term cooling started which was favorable for mammals.

I think the bigger dinosaurs would go extinct or would reduce in size.

https://en.wikipedia.org/wiki/Cenozoic#Climate

 

 

Not sure why you would think this, there were dinosaurs in the polar regions..

[Delta1212]

 

Regarding human evolution in the shadow of dinosaurs, my opinion is based on conditions favoring dinosaurs that remaining stable and unchanged. I agree that environmental changes that decrease predation and promoted new survival skills would likely have favored the further evolution of animals ancestral to humans.

But probably not actually into humans. At most maybe something vaguely human-like, but even that may not be the case. Humanity as it exists seems more like a semi-random fluke than a niche that needed filling. If it were, you'd expect that something like us in behavior if not exactly in form would have cropped up at some point outside of our own immediate and quite recent line, but there's no evidence of it.

 

It's entirely possible that we're the happy accident of just the right selection pressures combined with some very lucky mutations in a genome that had the capacity for them, and that anything else in the same environment wouldn't have gone the same way we did.

 

There's no simple set selection pressures for which advanced intelligence is a trivial solution, the way that certain features of aquatic animals converge towards similar streamlined shapes or the way body coverings like für and feathers or extended skinflaps like big thin ears are responses to thermoregulagion.

 

Because our sample size is effectively one, we don't really have a good handle on how likely or unlikely human-like intelligence really is to evolve, but the fact that the world seemingly went for billions of years without advanced tool users evolving on the scale of humanity makes me think that if the Earth had gone down a slightly different path, tha the chances of it evolving in a similar way at approximately the same time that it did in this "timeline" are pretty slim.