No K-T extinction event: No Dinosaur Killer WI

http://en.wikipedia.org/wiki/Cretaceous-Tertiary_extinction_event

Assuming that the hypothesis that a 10-kilometer diameter asteroid, with the force of 100 trillion tons of TNT caused this extinction event, what would happen if said asteroid does not collide with Earth?

Pretty big deal here. End of the dinosaurs, end of sessile marine animals... so, predict what the world might be like 65 million years after.

The dinosaurs would have evolved away, they had already spawned birds and the Antarcitc/Australian Allosaurus had feathers at the time of the strike.

The atmosphere was getting thinner anyway. So the days of the massive thunder-lizards were numbered in any case.

True. Most would develop into full birds within a couple million years, and the rest would become smaller and smaller increasingly. Mammals would eventually overtake reptiles as the more dominant ground-dwelling herbivores and carnivores. The changing climate would make that definite.
Perhaps most interesting, we may had seen a totally different sapient organism form from. The evolution of the Troodon and similar animals, like Compsognathus, would eventually yield a sentient, sapient, probably semi-erect reptilian organism capable of using tools and eventually developing weapons, agriculture, written communication, and settlements: the foundations of civilization. Over a very long period of time, of course.

You want to have a look at the Speculative Dinosaur Project...

I've heard it suggested that had the dinosaurs not died out, they would have evolved into something fairly human looking. And I don't think its much a stretch, personally. After all, many species of dinosaurs were bipedal and some such as velocoraptors were very intelligenet, at least as smart as a human child. Its not inconcievable that with sufficient time, they could learn how to use and make tools.

Tony Jones said:

You want to have a look at the Speculative Dinosaur Project...

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Yes, this is the most thorough and believable discussion there is. It deals to some degree or another with a wide variety of flora and fauna, not just dinosaurs. What I particularly like (and consider very believeable) is the fact that the traditional ways we have/had of classifying fauna collapse when we are no longer trying to do this on the basis of the spotty fossil record.

One area into which the Spec group do not go is sapience. Their alternate world (at least that which appears on the web site) is completely devoid of "intelligent" beings. This seems to be a conscious decision by the site managers. As an anthropologist, I find this somewhat disappointing, but in all other respects there is a lot of fascinating speculation, well-written text, and beautiuful illustrations.

Hapsburg said:

True. Most would develop into full birds within a couple million years, and the rest would become smaller and smaller increasingly. Mammals would eventually overtake reptiles as the more dominant ground-dwelling herbivores and carnivores. The changing climate would make that definite.
Perhaps most interesting, we may had seen a totally different sapient organism form from. The evolution of the Troodon and similar animals, like Compsognathus, would eventually yield a sentient, sapient, probably semi-erect reptilian organism capable of using tools and eventually developing weapons, agriculture, written communication, and settlements: the foundations of civilization. Over a very long period of time, of course.

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I disagree in regards to mammals. In OTL they only got their chance after the huge extinction event killed off 90~% of the reptiles. If the change in climate was much more gradual reptiles would have more time to adapt and mammals would never get that golden oppurtunity.

Mammals are smarter than reptiles, and if gradual climate change equalises the size differences between the two the smarter mammals with get the edge.

Riain said:

Mammals are smarter than reptiles, and if gradual climate change equalises the size differences between the two the smarter mammals with get the edge.

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Dinosaurs weren't dumb lizards, either. There is a reason because despite mammaliforms were the top vertebrates 250 million years ago, they failed then and remained tiny insect-eating rats for the next 190 million years. And that reason was the dinosaurs.

Mammals have IIRC better eyes and ears than reptiles. If this isn't an evolutionary advantage, I don't know what is. And it would help developing their brains either.

wasn't there a Voyager episode about dinosaurs evolving like this?

Tocomocho said:

Dinosaurs weren't dumb lizards, either. There is a reason because despite mammaliforms were the top vertebrates 250 million years ago, they failed then and remained tiny insect-eating rats for the next 190 million years. And that reason was the dinosaurs.

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True. However, by this time, the climate was changing drastically and in a totally natural manner, even before the K-T asteroid impact. If the impact doesn't occur, it's logical to assume that the change would continue. The dinosaurs would reduce in size, all of them becoming birds gradually, because of the thinning oxygen in the atmosphere. The lowered oxygen levels would not and could not support large reptiles like the sauropods or the tyrannosaurs much longer. The ground-dwelling herbivorous dinosaurs would most likely evolve to being the size of a hippo, and not much bigger.

There is no necessary reason why mammals must be smarter than reptiles. That, or any other advantage, could easily be usurped by the dinosaurids.

ninebucks said:

I disagree in regards to mammals. In OTL they only got their chance after the huge extinction event killed off 90~% of the reptiles. If the change in climate was much more gradual reptiles would have more time to adapt and mammals would never get that golden oppurtunity.

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I do not quite agree - for instance, climate-wise, the Cretaceous was an unchanging tropical paradise compared to the Cenozoic, which was rife with climate changes that are extreme compared to anything seen in the Cretaceous. And believe me, the climate changes I'm talking about here, were by no means gradual.

Furthermore, the radical climate changes that marked the transition of the Eocene to the Oligocene resulted in a whole new mass-exctinction, and because most of the tropical rainforests of the Eocene were gone after these climate changes (the Oligocene was much dryer than the Eocene), most dinosaurs, who simply couldn't live without the lush tropical rainforests etc., would still have a hard time surviving this transition, and most of them would simply die out, just like many OTL Eocene mammals.

And like I said, there were more climate changes like this in the Cenozoic, and dinosaurs just never had to adapt to such radical climate changes throughout the Cretaceous and, in this case, also the Paleocene and Eocene.

The mammals on the other hand, were far less specialized, and the fossil record shows that they dealed much better with the climate changes and the mass-exctinctions because of this, so they would clearly have an edge over the dinosaurs in the Cenozoic.

I'm still pretty sure that a significant number of dinosaurs would survive the transition from the Eocene to the Oligocene, but they would evolve into species of more modest sizes, propably with the smaller raptors and Ornithischia being the most successful dinosaurs.

They would only live in a world in which mammals and birds have a far stronger presence,
and they would therefore face much more competition from these groups.

Max Sinister said:

Mammals have IIRC better eyes and ears than reptiles. If this isn't an evolutionary advantage, I don't know what is. And it would help developing their brains either.

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But Dinosaurs are not reptiles. You meantion eyes and ears, but not the fact of war blooded animals vs cold blooded?

The sentient survivng Dinosaur doesnt have to turn into a human like figure. Here is an example of such an idea: http://www.nemoramjet.com/dinowhat.htmlhttp://www.nemoramjet.com/dinowhat.html

and an article debunking the Dinosauroid

Well, there are some concept errors here.

First of all, the dinosaurs weren't evolving into birds. There were birds before the K/T. Better said, there is a group of dinosaurs who "learned" to fly at the end of the Jurassic, survived the K/T extinction event and we called "birds" today. But a Triceratops becoming a bird then was as unlikely as a water buffalo becoming a bat today. Evolution isn't lineal. There isn't a way of perfection to follow or something like that. You can evolve in any way unless you are too advanced in other different way to come back and change. And if you cannot change a bit, you are extinct. End of story.

Second, don't compare dinosaurs with current reptiles. The most "advanced" crocodyle has a metabolism more "primitive" than the earliest dinosaur. The dinosaurs walked with their legs behind the body, had a four camera heart and therefore where warm blooded. There are even clues that the kind of respiratory system which birds have today (which is more efficient and advanced than the one of any other animal, including mammals) was actually a development "made" by the dinosaurs in the Triassic. If you want to compare dinosaurs with present-day animals, the most close thing is a bird. An impossible bird with four functional legs and a long tail, actually.
So I can agree that the ear of a dinosaur was probably worse than the ear of a mammal, as they had not our 3 ear bones, but I wouldn't be so sure in the case of the eyes. In the case of the brain, well, today the brain full of circunvolutions of a mammal seems to be superior and more able to develop inteligence than the smooth brain of a bird (or a dinosaur, or a crocodyle), but where was the mammal brain 65 million years ago? I don't know if there is any mold of a mammal brain in the fossil record from that age. It can be a more recent adaptation... an adaptation that an alternate lineage of post K/T dinosaurs could develop as well. And even if it was an ancient adaptation, does it really matter? 60% of present day mammals, if not more, are rodents as dumb as the mammals who lived with the dinosaurs. Is the equation mammal brain = more inteligence = superiority really correct? Probably not.

Max Sinister said:

Mammals have IIRC better eyes and ears than reptiles. If this isn't an evolutionary advantage, I don't know what is. And it would help developing their brains either.

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Though mammals have better eyes than the modern-day reptiles, many dinosaurs may have had much more developed eyes that were a lot like those of birds, so mammals would not have that much of an evolutionairy advantage on this one.

However, when it comes to the ears, mammals have a great evolutionairy advantage over both reptiles and birds, because mammals have three auditory ossicles in each ear, while reptiles, dinosaurs and birds only have one auditory ossicle in each ear.

This makes the mammalian ear more adaptable and flexible, and therefore more efficient, which definitely gives mammals an edge over reptiles, dinosaurs and birds. And it is also the reason why some groups of mammals have evolved and perfected echolocation, while only a handful of species of birds has evolved what can only be described a crude prototype of echolocation, compared to what bats have.

ninebucks said:

There is no necessary reason why mammals must be smarter than reptiles. That, or any other advantage, could easily be usurped by the dinosaurids.

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I disagree. There is just no way that the dinosaurs could ever have developed a sense of hearing that is as acute and adaptable as that of mammals, but I have already explained why that is.

And another noteworthy detail: ever taken a good look at mammalian brains?

You see, if you compare the brains of placental mammals to those of birds, reptiles, or even non-placental mammals, you'll immediately see an obvious difference: the brains of placental mammals have this typical 'wrinkly' structure, which is unique to placental mammals (even though it is less developed in some species [rabbits, for example] than it is in others [felines, primates, cetaceans, etc.]).

Now then, the function of these 'wrinkles' is that they increase the surface of the cerebral cortex, and thus its capacity. This gives placental mammals an edge over non-mammals and non-placental mammals, although other types of brains can be very efficient as well, such as the brains of octopi, crows and parrots.

Having said that, most dinosaurs just didn't have the kind of brains that were as flexible and adaptable as those of the placental mammals that were around at the end of the Cretaceous.

Tocomocho said:

Well, there are some concept errors here.

First of all, the dinosaurs weren't evolving into birds. There were birds before the K/T. Better said, there is a group of dinosaurs who "learned" to fly at the end of the Jurassic, survived the K/T extinction event and we called "birds" today. But a Triceratops becoming a bird then was as unlikely as a water buffalo becoming a bat today. Evolution isn't lineal. There isn't a way of perfection to follow or something like that. You can evolve in any way unless you are too advanced in other different way to come back and change. And if you cannot change a bit, you are extinct. End of story.

Second, don't compare dinosaurs with current reptiles. The most "advanced" crocodyle has a metabolism more "primitive" than the earliest dinosaur. The dinosaurs walked with their legs behind the body, had a four camera heart and therefore where warm blooded. There are even clues that the kind of respiratory system which birds have today (which is more efficient and advanced than the one of any other animal, including mammals) was actually a development "made" by the dinosaurs in the Triassic. If you want to compare dinosaurs with present-day animals, the most close thing is a bird. An impossible bird with four functional legs and a long tail, actually.
So I can agree that the ear of a dinosaur was probably worse than the ear of a mammal, as they had not our 3 ear bones, but I wouldn't be so sure in the case of the eyes. In the case of the brain, well, today the brain full of circunvolutions of a mammal seems to be superior and more able to develop inteligence than the smooth brain of a bird (or a dinosaur, or a crocodyle), but where was the mammal brain 65 million years ago? I don't know if there is any mold of a mammal brain in the fossil record from that age. It can be a more recent adaptation... an adaptation that an alternate lineage of post K/T dinosaurs could develop as well. And even if it was an ancient adaptation, does it really matter? 60% of present day mammals, if not more, are rodents as dumb as the mammals who lived with the dinosaurs. Is the equation mammal brain = more inteligence = superiority really correct? Probably not.

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I agree with you here. Birds were a distinct lineage by 65mya, they were distinct from probably the mid jurassic, hell some theories even propose that the earliest bird like creatures evolved way back in the late triassic, and the coelosaurs, maniraptors and later tyrannosaurs are descended from that branch.

What you would see is the extinction of some of the larger herbiverious species, such as the last remaining sauropods, cerotopsians and some ankylosaurs. I'd expect the hadrosaurs to do okay, divirsifying and becoming the ungandulates of this world. Theropods would likely thrive, especially smaller species such as the maniraptors. As for mammals I would see mammals being the most common large animal in the northern regions, elsewhere filling the niche of small scavengers, predators and aboreal dwelling animals.

Tocomocho said:

So I can agree that the ear of a dinosaur was probably worse than the ear of a mammal, as they had not our 3 ear bones, but I wouldn't be so sure in the case of the eyes. In the case of the brain, well, today the brain full of circunvolutions of a mammal seems to be superior and more able to develop inteligence than the smooth brain of a bird (or a dinosaur, or a crocodyle), but where was the mammal brain 65 million years ago? I don't know if there is any mold of a mammal brain in the fossil record from that age. It can be a more recent adaptation... an adaptation that an alternate lineage of post K/T dinosaurs could develop as well.

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Nonsense, the basic design of the placental mammals and the typical brain of the placental mammals was already around in the mid-, perhaps even the early Cretaceous, and the lineages of placental mammals were already growing apart long before the K-T mass extinction,
(relatively recent genetic research and recent fossil findings strongly suggest that the lineages of the marsupials and the placental mammals split about 175 million years ago, and the same genetic research suggests that the four major lineages (the four cohorts that were proposed on the basis of genetic analysis) of placental mammals grew apart IIRC at least 100 million years ago), and because all the mammals from these lineages (i.e. all the known placental mammals) clearly share this same brain type, the simplest and most propable explanation for that is that this basic brain type was present in their common ancestor.

And the advanced brain of the placental mammals did not just come out of the blue. Basically, after the dinosaurs began to dominate in the Triassic, all the ancestors of the mammals did was evolve to become more efficient and make up for no longer being the biggest and strongest beast around, and evolving more efficient brains was part of that whole evolution.

And then about the propability of a branch of dinosaurs developing such a complex brain: assuming for a while that there is 75 million years between the (proto-)placental mammals separating from the marsupials, and the point that the common ancestor of all modern mammals lived, then the whole process of developing the typical mammalian brain took *at most* 75 million years, and propably somewhere around 50 or 60 million years (but that's a guesstimate), so it's not exactly something the dino's would 'just do' in a few million years...

Tocomocho said:

And even if it was an ancient adaptation, does it really matter? 60% of present day mammals, if not more, are rodents as dumb as the mammals who lived with the dinosaurs. Is the equation mammal brain = more inteligence = superiority really correct? Probably not.

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Actually, about 50% of the present day mammalian species are rodents, then about 25% are bats and all the other mammals make up the remaining 25% of the mammalian species.

And many rodents aren't exactly dumb (just look at rats), and I'm pretty certain that today's rodents are on average a lot smarter than most of the mammals that scurried around during the Mesozoic, although most mammals that lived during this age (even the Cretaceous) were not placental mammals...

However, to come to your point: the advantage of a greater intelligence is that an animal with a greater intelligence can learn a few tricks and thus be better and more efficient at a certain thing as a similar animal that is less intelligent. It's not a guarantee, but statistically, it will give a clear advantage, and that is also one of the main reasons why small dinosaurs never outcompeted the mammals.

And another reason is that more adaptable types of brains evolve far more easily into larger, more efficient brains. In other words: there's more than just the intelligence of the average mammal that we're talking about here, it's also the efficiency of the basic design of the mammalian brain, so it's also an evolutionairy advantage we're talking about.

..
Nonetheless, I agree that the (relatively) big brains of the placental mammals didn't do much againest the larger dinosaurs except that they may have frustrated their dinosaur predators a little more than the average frog or lizard would have, and that it wasn't intelligence alone that made the mammals dominate the Earth after the dinosaurs went extinct.

But nonetheless, their intelligence was one of the evolutionairy advantages (along with being warm-blooded, evolving at a very fast rate, efficient hearing, etc.) that allows mammals to bounce back from a disaster like a climate change or mass-extinction far more quickly than any 'rival' animal group, giving mammals an advantage in changing environments.