Dinosaur Extinction and Evolution...?

If it was a giant meteor, comet or some other ELE, that killed off the dinosaurs, here is a question I have.
Why didn't the original dinosaurs come back through evolution again? Why a different set of mammals?
It was the same Earth the Dinosaurs evolved from in the first place so why the difference?

Probably a good explanation for this, but I'll ask anyway.

Originally posted by earth2
If it was a giant meteor, comet or some other ELE, that killed off the dinosaurs, here is a question I have.
Why didn't the original dinosaurs come back through evolution again? Why a different set of mammals?
It was the same Earth the Dinosaurs evolved from in the first place so why the difference?

Probably a good explanation for this, but I'll ask anyway.

Thanks for the topic. I am curious as well. That is a very good question.
S/F

Originally posted by earth2
If it was a giant meteor, comet or some other ELE, that killed off the dinosaurs, here is a question I have.
Why didn't the original dinosaurs come back through evolution again? Why a different set of mammals?
It was the same Earth the Dinosaurs evolved from in the first place so why the difference?
Probably a good explanation for this, but I'll ask anyway.

For one thing, dinosaurs never went extinct. Apparently, really, yeah. See Are Dinosaurs Really Birds? and The Dinosauria. So while some species of dinosaurs went extinct, others did not. Their descendants today are called birds.

reply to post by earth2


Because that's not how evolution works. It doesn't work towards specific life forms, it just works with what works. Whatever survives passes on its genetic information. The (larger) dinosaurs didn't survive, those that did changed.

it would seem whatever conditions caused them to grow big and flourish, had changed.

whatever caused that it seemed warm blooded animals managed to survive it better.
as has been pointed out, they are not extinct. even you carry some reptilian legacy in your brain.

medulla ablongata.

when the majority of dinosaurs were wiped out, it created a niche in the ecosystem which was begging to be filled. it just so happened that the mammals who were around at the time were more capable of fulfilling that role compared to the few lizards that remained.

Early mammals

reply to post by toreishi


Aye. That is a simple explanation and it makes a lot of sense.

I think what the OP is trying to ask is why dinosaurs didn't live long enough to adapt or evolve to the change and reclaim their position as the apex organisms.

I'm not an expert, but the way i see this extinction is as a huge bottleneck effect that occurred as a result of a meteor/comet etc. This made conditions to extreme for dinosaurs and allowed mammals to overtake them. For example, and to be more specific, I have read and seen several shows that describe early mammals as small burrowers who were easy meals for dinosaurs. When the asteroid hit, the gases, fumes, dust and especially heat that resulted killed off many dinosaur predators, too many in fact that they could not recover. While this was happening, mammals were just relaxing in their holes and when they were able to multiply without so much predation, they boomed. The smaller reptiles who survived many believe evolved into modern birds (this may have been occurring before the event), while others became prey for mammals.

Larger dinosaurs also took a hit when most of the vegetation was destroyed, leaving nothing to eat and then nothing to prey on.

"Mammals, in contrast, could eat insects and aquatic plants, which were relatively abundant after the meteor strike. As the remaining dinosaurs died off, mammals began to flourish. Although representatives from other classes of animals also survived the K/T extinction -- crocodiles, for instance, had the saving ability to take to water -- mammals were clearly the main beneficiaries and they have since spread to nearly every corner of the planet.

In short, classic dinosaurs weren't genetically equipped to fight the changes at hand. Many dinosaurs though are survived through birds and modern reptiles and crocodilians.

www.sciencedaily.com...

reply to post by earth2


well you have to understand that dinosaurs are cold blooded meaning they relied on their surrounding to regulate their body temp.

mammals on the other hand, can maintain their temp much much better on their own.

after the comet, there would of been a "nuclear" winter, and that is the last climate for cold blooded land dwellers.

the dinosaurs were extremely large compared to the mammals(think rats) and were much more susceptible to the changing climate.

after the ELE, mammals were able to eat more (dead/dying) dinosaurs than there were dinosaurs who could've eaten them. the abundance of food meant that mammals and their young didn't go hungry thus resulting in a population boom, and without dinosaurs to keep their numbers down, the mammals exploded all over the landscape.

(mammals ate dinosaur eggs too.)

reply to post by earth2


I don't really prescribe to Darwin's theory of evolution.

Evolution is based on the idea that a mutation in DNA improves a creature's ability to survive, so it is more likely to reproduce (natural selection). That is evolution's only tool for making new creatures. It might even work if it took just one gene to make and control one part. But parts of living creatures are constructed of intricate components with connections that all need to be in place for the thing to work, controlled by many genes that have to act in the proper sequence. Natural selection would not choose parts that did not have all their components existing, in place, connected, and regulated because the parts would not work. Thus all the right mutations (and none of the destructive ones) must happen at the same time by pure chance. That is physically impossible.

Debunking Evolution

Great question!

This question leads to some rather large implications either way.

Go with me on this:

Let's start by looking at our place in the Universe. Our science is quite feeble, at this point in time, on a universal scale in terms of some fairly basic questions. For example, how many galaxies are in the Universe? How old is the Universe? How many solar systems are in our own Milky Way? It is quite obvious that any answer given by science is an educated guess...at best.

But let's look at the educated guesses to some of these questions. A German supercomputer recently came up with 500 Billion galaxies in the Universe. Scientists are dating the Universe to roughly 13.7 Billion years old. More recently, the announcement came that the Milky Way has at LEAST 50 Billion planets in it, of which 500 Million are in the right place to support life.

Let's play with these guestimates a little further. If each of the 500 Billion other galaxies, averaged out, contain the same amount of planets the Milky Way contains, then we could have 2.5e+22 planets in the Universe. Of those, 2.5e+20 could be "Goldilocks." 2.5 Sextrillion planets in the Universe capable of sustaining the evolution of intelligent life.

So here we (Earth) sit. Are we the only planet with advanced life? Are we the most advanced life in the Universe? Are we #1 out of 2.5 Sextrillion?

Let's look at Earth's path of evolution now.
en.wikipedia.org...
(I dont like using wiki but for this demonstration it should be fine)

Earth has had several interuptions in it's evolutionary development. If comets and asteroids have come and reset our evolutionary clock several times, how are we the only one to evolve in the Universe? Perhaps the answer is not that the comets/astroids did destruction but that they brought evolution. I'm not saying that lifeforms/DNA was brought by comets. I'm saying that perhaps the comets were responcible for elevating the oxygen levels. However, this raises a little problem. Planets get hit by comets all the time. We got to witness this event in our lifetime, remember Jupiter? So what would make the comet/astroid that hit Earth so special? So special that we are the most advanced lifeform in the entire Universe? Allow me to wield Occam's Razor of Simplicity here, which is simply that we are not the most advanced lifeform and that there is nothing special about any of the asteroid/comets that hit the Earth.

I am of the opinion that the majority of dinosaurs became extinct from a comet strike some 65 million years ago. The rest of the dinosaurs that survived slowly died off due to the changes brought by the collision. Only the strongest of the strong managed to survive for any significant amount of time. More importantly, it put us (humans) far behind on the evolutionary scale. I imagine there are lifeforms in our Universe many times more advanced than we are.

reply to post by WeRpeons


Behe's theory of irreducible complexity actually doesn't disprove evolution. Here is TalkOrigin's explanation for why it does not disprove evolution.

Irreducible Complexity Demystified

reply to post by WeRpeons
Out of the virtually infinite ways genes can convene and particulate to make a working body, the ones that spread are the ones that most contribute to an organisms reproductive fitness. If there was only one way for a genome to function than there would be no reason to think anything more "complex" than a DNA plasmid or even something simpler than that would have existed. Organisms are how they are because that's the genetic stable strategy, and that's why there are over 5 million species and counting. And of course organisms change because tiny mutations or the cumulative products of genetic recombination can over time result in drastic changes.

The genotype is a chaotic system, one error in translation and a new amino acid creates a domino effect. New protein, activated at different times, expressed in different parts of the body, etc...

To give you an idea about how canalized and robust the genome is, take a functioning "eyeless" gene from a fruit fly (the gene that leads to a mutated eye if altered in the wrong way), graft it onto a human embryo devoid of normal "eyeless" gene, and you get a normal human eye.

Originally posted by WeRpeons
reply to post by earth2

 

I don't really prescribe to Darwin's theory of evolution.

Evolution is based on the idea that a mutation in DNA improves a creature's ability to survive, so it is more likely to reproduce (natural selection). That is evolution's only tool for making new creatures. It might even work if it took just one gene to make and control one part. But parts of living creatures are constructed of intricate components with connections that all need to be in place for the thing to work, controlled by many genes that have to act in the proper sequence. Natural selection would not choose parts that did not have all their components existing, in place, connected, and regulated because the parts would not work. Thus all the right mutations (and none of the destructive ones) must happen at the same time by pure chance. That is physically impossible.

Debunking Evolution

Based on your description, you don't get evolution.

I was pondering on the KT Boundary and extinctions the other day and got to wondering if the scientific community has been interpreting this incorrectly. As someone once pointed out to me, only a small percentage of dinosaurs ever got fossilized. The conditions necessary for fossilization are not common.

So my question is, was there an event at KT that prevented the conditions for fossilization from occurring? And was that change in conditions around long enough for a subset of Dinosaurs and Pterosaurs to evolve into something else? Scientists have already reclassified birds as reptiles. I wonder if this was the triggering event?

I think I can answer this. I've been working in a museum lab for about 5 years, preparing dinosaur bones and I hang out with Real Paleontologists. I've learned a LOT in that time, and I've learned how much I don't know.

Originally posted by earth2
If it was a giant meteor, comet or some other ELE, that killed off the dinosaurs, here is a question I have.
Why didn't the original dinosaurs come back through evolution again?

A couple of reasons -- one being that it took over 300 million years for dinosaurs to evolve (from Precambrian times to the earliest dinosaurs in Jurassic times. Dinosaurs started out as very simple beasts and evolved over a period of about 180 million years. The last ones were very different from the original stock. One of the adaptations (feathers) enabled some of them to survive the changes associated with the impact event.

Why a different set of mammals?

Dinos didn't evolve into mammals. They were in decline before the meteor hit and went into a rapid decline (100,000 years or so) after the impact event. There's sort of a perception that the impact happened and all dinosaurs dropped dead in their tracks, leaving mammals dancing happily on the carcasses. That didn't happen.

It was the same Earth the Dinosaurs evolved from in the first place so why the difference?

Actually, it wasn't and that was part of the problem.

They initially arise after the great Permian Extinction, when the Earth was a single continent (Pangaea) en.wikipedia.org... and replace the earlier pelycosaurs and therapsids (very gradually... 100 million years or so). During this time, Pangaea splits and becomes Laurentia and Gondwannaland and plants continue to evolve. The two smaller continents drift from their original place, climates change, and vegetation and other life forms change. About the time of the end of the dinosaurs, the ancestor of bamboo and rice appears and weather patterns change as well. The earth starts cooling down, and there's a slight change in the amount of oxygen and carbon dioxide.

So the Earth wasn't the same. Mammals (particularly ones with short lives) started to evolve quickly and take over niches formerly taken by the dinosaurs. Smaller feathered insect-eating dinosaurs also found a happy niche and continued to evolve and thrive.

Originally posted by rogerstigers
So my question is, was there an event at KT that prevented the conditions for fossilization from occurring?

No. Not that's recorded in the rocks.

And was that change in conditions around long enough for a subset of Dinosaurs and Pterosaurs to evolve into something else? Scientists have already reclassified birds as reptiles. I wonder if this was the triggering event?

No.. .and btw, Pterosaurs aren't dinosaurs. That line died while the dinosaurs went on to become birds.

Originally posted by Byrd

Originally posted by rogerstigers
So my question is, was there an event at KT that prevented the conditions for fossilization from occurring?

No. Not that's recorded in the rocks.

And was that change in conditions around long enough for a subset of Dinosaurs and Pterosaurs to evolve into something else? Scientists have already reclassified birds as reptiles. I wonder if this was the triggering event?

No.. .and btw, Pterosaurs aren't dinosaurs. That line died while the dinosaurs went on to become birds.

Hmm.. I knew the two types were differant, which is why I mentioned them seperately.. I was under the impression, though, that current thinking is that some pterosaurs may have survived and evolved... course I can see that it may have just been the raptors who evolved (assuming that defines the branch of reptiles that feathered out)

Originally posted by rogerstigers
I was under the impression, though, that current thinking is that some pterosaurs may have survived and evolved... course I can see that it may have just been the raptors who evolved (assuming that defines the branch of reptiles that feathered out)

The Wikipedia article has a somewhat confusing but reasonable outline of them: en.wikipedia.org...

In any case, they're thought to have all died out following the KT extinction event and left no descendants (or none that are not extinct today (talk about convoluted sentences!!)) I know that to many, the bones look pretty similar to birds but they really aren't as similar as the bones of the feathered raptors.

Another group related to the birds are the huge titanosaurs (like "brontosaurus".) You wouldn't think it to look at them -- huge four-legged things -- but their bones are more similar to birds and t rexes than to other dinosaurs and pterosaurs.