Cambrian Explosion

[Mallon]

Yes, so this relates to what I said in what way?

Mammals were the impetus for the massive radiation of grasses starting in the Miocene.

 

[Oncedeceived]

Mammals were the impetus for the massive radiation of grasses starting in the Miocene.

So what was the impetus for the radiation of grasses during the early creteaous?

 

[Mallon]

So what was the impetus for the radiation of grasses during the early creteaous?

There was no adaptive radiation of grass in the Early Cretaceous, such as that seen in the Miocene. Grass was present, yes, but in very short order.

 

[Oncedeceived]

There was no adaptive radiation of grass in the Early Cretaceous, such as that seen in the Miocene. Grass was present, yes, but in very short order.

In very short order? What do you mean by that?

 

[Nooj]

I think Mallon means grass was not very common or diverse.

 

[Mallon]

I think Mallon means grass was not very common or diverse.

Exactly. Grass didn't have a foothold in the Cretaceous. It was new. It was sparse. It was dominated by ferns and the like.

 

[caravelair]

Ever hear of convergent evolution?

yes, and it doesn't work quite like that.

Anyway, it doesn't matter. Grasses and trees could have been very different and still be grasses and trees.

no, if they were different, they would be something else.

 

[Oncedeceived]

Exactly. Grass didn't have a foothold in the Cretaceous. It was new. It was sparse. It was dominated by ferns and the like.

It was diverse enough that at least five types were present. This means that it was diverse and not as sparse as you seem to think.

 

[Oncedeceived]

yes, and it doesn't work quite like that.

Quite like what exactly?

no, if they were different, they would be something else.

You can't know that.

 

[caravelair]

Quite like what exactly?

convergent evolution is like bats wings and birds wings. they evolved independantly, and so there are clear structural differences. a bat is not a bird just because it evolved wings, and it would not be correct to call it that. and if we have 2 completely different evolutionary trees, then we would expect the differences to be even greater and more fundamental, even if there is some convergence present. things are classified by their place in the evolutionary hierarchy.

You can't know that.

sure i can, because that's how it works.

 

[Tacticus]

It was diverse enough that at least five types were present. This means that it was diverse and not as sparse as you seem to think.

Oh wow, a whole five types? Considering there are 20,000 types of fern now and many evolved in the Cretaceous it really makes the five types insignificant.

Besides which, if you look at the size of the surface area they could cover, and the different types of climate, then the existance of only five types supports the premiss that grass was sparse.

 

[Jet Black]

I think that we were discussing the coevolution between grazers and grasses. Considering your viewpoint I doubt that you believe that there were many of these during the triassic.

therapsids were the dominant animals during the permian and much of the triassic, and many of them were herbiverous. One of the big things about the therapsids was the development of the jaw (and ear) from the reptillian form to the mammalian form. The main improvement in the movement of the jaw joint was that which allowed much more efficient chewing action, far better than reptiles which swallow things more or less whole, and the dinosaurs which did the same. The herbiverous dinosaurs had to use stones to grind up their food, whereas the therapsids used their teeth. There were plenty herbiverous therapsids.

I think you understand my point. IF bees could be present for twice as long as originally thought, with the theories of co-evolution being questioned it is not a stretch to see that other theories may be proven questionable as well.

I see. I think the reason I didn't get your point there was because the two are rather unrelated. On one hand there is some quesion as to whether two groups coevolved or not, and on the other hand there is the question of whether one of those two groups was around for some half a billion or so years longer than we think that even it's ancestors have been around for. Bees, perhaps suprisingly, survive mostly on pollen (the nectar is critical as well of course, but that is mostly an energy source) So I don't see where any potential problem would arise with bees evolving long before plants, since bees are paraphyletic within the Spheciform wasps anyway.

I still don't see this as a problem for my premise of the possibility of precambrian plant life. IF it were all destroyed and re-evolved it would be just as we see it. The genetic and morphological simularity present. In fact, we would probably see genetic and morphological simularity in the plant life that was destroyed earlier too if that is what happened.

not really. While it might be possible to have morphological similarity between two groups which did not derive the same kinds of phenotypical traits directly from their ancestors (gosh that was horrible, I mean something like the shapes of say, dolphins and sharks, which are quite similar, but have evolved separately) That does not mean they are both in the same group, or that there would be much genetic similarity. Take for example the Itjaritjari, the marsupial mole. It shares alot of features with the placental mole, but genetically they are very different indeed. you couldn't really lump them together in the group "moles" with any real scientific meaning.

Not if it were destroyed and began again.

but then it would be totally different. There might be phylogenetic similarities, but it wouldn't be the same thing any more than the placental and marsupial moles are the same thing. lets say there was something in the precambrian that looked a bit like grass. If you called both grass, it would only have the most basic morphological meaning. There would be no cladistic relationship between the two, and no scientists would give them both the same name.

 

[Oncedeceived]

Jet, I am sorry. This new time change is just not working with me. (daylight savings time). I am up but I need to shower before work and so I'll not have time again to respond to your post. I really hate this time change.

 

[Jet Black]

I'll make arrangements with the government to stop them from interfering with our conversation Don't worry! enjoy your shower and breakfast, and hear from you soon.

 

[caravelair]

I really hate this time change.

but this is the best time change! sure, you lose an hour one day, but then every day after that for the next 6 months, the sun is up a whole hour later! personally, the other time change is the one i hate.

 

[food4thought]

sorry...

 

[Oncedeceived]

Oh wow, a whole five types? Considering there are 20,000 types of fern now and many evolved in the Cretaceous it really makes the five types insignificant.

They found five types in the Dino, it is hard to say just how many were present of course. The scientists felt it was very significant. So much so that they feel it may change the whole outlook on how grasses evolved.

Besides which, if you look at the size of the surface area they could cover, and the different types of climate, then the existance of only five types supports the premiss that grass was sparse.

The scientists were amazed at the diversity and didn't feel at all that it was sparse but in fact very abundant.

 

[Oncedeceived]

therapsids were the dominant animals during the permian and much of the triassic, and many of them were herbiverous. One of the big things about the therapsids was the development of the jaw (and ear) from the reptillian form to the mammalian form. The main improvement in the movement of the jaw joint was that which allowed much more efficient chewing action, far better than reptiles which swallow things more or less whole, and the dinosaurs which did the same. The herbiverous dinosaurs had to use stones to grind up their food, whereas the therapsids used their teeth. There were plenty herbiverous therapsids.

Very true, but the therapsids developed this movement in the jaw after the dino extinction...correct? So it is not relative to my point.

I see. I think the reason I didn't get your point there was because the two are rather unrelated. On one hand there is some quesion as to whether two groups coevolved or not, and on the other hand there is the question of whether one of those two groups was around for some half a billion or so years longer than we think that even it's ancestors have been around for. Bees, perhaps suprisingly, survive mostly on pollen (the nectar is critical as well of course, but that is mostly an energy source) So I don't see where any potential problem would arise with bees evolving long before plants, since bees are paraphyletic within the Spheciform wasps anyway.

I was making two separate points but I feel both are relative to the discussion.

not really. While it might be possible to have morphological similarity between two groups which did not derive the same kinds of phenotypical traits directly from their ancestors (gosh that was horrible, I mean something like the shapes of say, dolphins and sharks, which are quite similar, but have evolved separately) That does not mean they are both in the same group, or that there would be much genetic similarity. Take for example the Itjaritjari, the marsupial mole. It shares alot of features with the placental mole, but genetically they are very different indeed. you couldn't really lump them together in the group "moles" with any real scientific meaning.

Perhaps not scientifically, but if they were grass in form if not in genetic similarity, it would still be "grass". Remember I am not claiming that the Bible is a scientific journal, but only that it should not really conflict with known Scientific data. So it could remain grass...or grass like in our understanding but not be scientifically genetically linked to grass today. There are many forms that are extinct that have no known genetic links to organisms today.

but then it would be totally different. There might be phylogenetic similarities, but it wouldn't be the same thing any more than the placental and marsupial moles are the same thing. lets say there was something in the precambrian that looked a bit like grass. If you called both grass, it would only have the most basic morphological meaning. There would be no cladistic relationship between the two, and no scientists would give them both the same name.

But grass is grass according to form if nothing else. It would not be necessary for it to be scientifically named by cladistic relationship to be "grass" in form only.

 

[Oncedeceived]

I'll make arrangements with the government to stop them from interfering with our conversation

What a great guy!! I really appreciate it.

Don't worry! enjoy your shower and breakfast, and hear from you soon.

 

[Oncedeceived]

but this is the best time change! sure, you lose an hour one day, but then every day after that for the next 6 months, the sun is up a whole hour later! personally, the other time change is the one i hate.

I agree with that point, I love the longer daylight hours, but I have a great difficulty getting my butt out of bed.

I was late again this morning. I think that I would be one of those organisms that went extinct due to lack of adaptability in times past.