question on evolution

I do believe in evolution, but I have a question, mainly for my own curiosity.

There are two evolutionary items that happened of which I can't get around my head. Any explanation would be great:


1). Most, if not all birds before the K-T extinction event had teeth. Strong teeth! But afterwards, globally, strong teeth disappeared from the species and all birds could no longer produce the proper calcium for it. Why is it that this was a global evolutionary event, and not selective in one species of birds? Sure, ducks and the like still have remnants of it, but they're crap teeth, and it still doesn't explain why EVERY species of bird evolved this way, globally. It wasn't limited to one specific region or area of change, globally they lost teeth.

And no, it wasn't because of the K-T event, because there are records of most birds still having teeth shortly after, in the mammalian era. But by the time more complex mammals came about, teeth were gone.

2) Why did flowers evolve 'en mass in the Cretaceous. It wasn't limited to one species of plant. A Member of virtually every plant species suddenly evolved flowers: bushes, shrubs, trees, grasses, weeds, and small flowers themselves. It seems odd how ever species of plant had a member of it suddenly evolve flowers.




The reason I ask is simply that it's odd. Usually evolution is within one species, with one common ancestor. But for the above, it happened in multiple common ancestors. And strangest of all, all at the same time (as opposed to the mutation showing up a few times once in awhile until it was viable ie: the flying Triassic feathered lizard with the later-evolved feathered gliding sauropod dinosaurs.)





Please no arguing here, it's a simple question to both sides. I consider my self an evolutionist, so don't call me otherwise.


[edit on 17-6-2008 by Gorman91]

Originally posted by Gorman91
1). Most, if not all birds before the K-T extinction event had teeth. Strong teeth! But afterwards, globally, strong teeth disappeared from the species and all birds could no longer produce the proper calcium for it. Why is it that this was a global evolutionary event, and not selective in one species of birds? Sure, ducks and the like still have remnants of it, but they're crap teeth, and it still doesn't explain why EVERY species of bird evolved this way, globally. It wasn't limited to one specific region or area of change, globally they lost teeth.

I have to run and do something else, but I'll give a quick response...

Why do you think that this happened to all species globally? Why not one or a few more species who eventually diverged to what we see today?

So, we have numerous species of birds with teeth, most die out, one or more lose teeth and diverge (appears to be a developmental change, as the gene can be 'turned' back on). Or various scenarios like this: 100 with teeth, 1 diverges and evolves no teeth (100 teeth, one none), the none toothed species diverges into 20 (100 teeth, 20 none), then all toothed become extinct (20 none), beakies become sole avians (lots).

2) Why did flowers evolve 'en mass in the Cretaceous. It wasn't limited to one species of plant. A Member of virtually every plant species suddenly evolved flowers: bushes, shrubs, trees, grasses, weeds, and small flowers themselves. It seems odd how ever species of plant had a member of it suddenly evolve flowers.

Same here. Why do you think there had to be evolution in every species of plant, rather than a couple of novel early angiosperms (these are the flowering plants)? A new species evolves, is very successful, diverges quickly into new environments.

For example, from studying human fossils we see that at times there was more than one early homo around, but now there is one. Perhaps in 5 million years we'll have 20 (I doubt it, but you hopefully get the gist).

And I don't want to argue. Just wondering why you think that was the case.

[edit on 17-6-2008 by melatonin]

reply to post by melatonin


Thanks, but there's a few issues.

Evolutionary scientists say most birds of today are related to dinosaur-era birds who all split off eons ago. There were owls, ducks, cranes, songbirds, etc in the dinosaur era. All of which survived and specifically diversified into their modern parts. All of which lost teeth, no matter where in the globe they were.


and I don't feel your plants explanation is good enough. If we see anything, plant evolution is extremely slow. ( for example, the Brits just had a documentary where they said the success of apatasaurus and the likes led to forests being crushed, but it took another 100 million years or so until the Cretaceous, when they finally shifted to bug-relationships the spread seeds further, away from herds.) It still seems odd that multiple species with separate conditions and living methods would all evolve similar object, at the same time.

And it was from multiple species, because today anything from small weeds to tall barked trees grow flowers. The likes of which would have taken longer to evolve from each other based on current knowledge.

as to humans, that's because we were a young species with many break off groups. Most of those groups came together and merged into the human species (some of which mated with apes, eww)


and the arguing part was with regards of these topics usually going off course in creationists vs evolutionist arguing.

[edit on 17-6-2008 by Gorman91]

[edit on 17-6-2008 by Gorman91]

Originally posted by Gorman91
and I don't feel your plants explanation is good enough. If we see anything, plant evolution is extremely slow. ( for example, the Brits just had a documentary where they said the success of apatasaurus and the likes led to forests being crushed, but it took another 100 million years or so until the Cretaceous, when they finally shifted to bug-relationships the spread seeds further, away from herds.) It still seems odd that multiple species with separate conditions and living methods would all evolve similar object, at the same time.

And it was from multiple species, because today anything from small weeds to tall barked trees grow flowers. The likes of which would have taken longer to evolve from each other based on current knowledge.

Okie doke. I'll focus on the angiosperms.

The very earliest potential angiosperm fossil we have was archeofructus from 130ish million years ago, and we see pollen for some time before that. These angiosperms have pretty basic 'flowers'.

What you appear to be talking about is the expansive divergence of angiosperms during the mid cretaceous (a few dozen of million years later). They were probably around well before that, possibly as far back as 200+ million.

A good article, freely available, that discusses the various evolutionary relationships is here.

Abstract

The angiosperms, one of five groups of extant seed plants, are the largest group of land plants. Despite their relatively recent origin, this clade is extremely diverse morphologically and ecologically. However, angiosperms are clearly united by several synapomorphies. During the past 10 years, higher-level relationships of the angiosperms have been resolved. For example, most analyses are consistent in identifying Amborella, Nymphaeaceae, and Austrobaileyales as the basal most branches of the angiosperm tree. Other basal lineages include Chloranthaceae, magnoliids, and monocots. Approximately three quarters of all angiosperm species belong to the eudicot clade, which is strongly supported by molecular data but united morphologically by a single synapomorphy—triaperturate pollen. Major clades of eudicots include Ranunculales, which are sister to all other eudicots, and a clade of core eudicots, the largest members of which are Saxifragales, Caryophyllales, rosids, and asterids. Despite rapid progress in resolving angiosperm relationships, several significant problems remain: (1) relationships among the monocots, Chloranthaceae, magnoliids, and eudicots, (2) branching order among basal eudicots, (3) relationships among the major clades of core eudicots, (4) relationships within rosids, (5) relationships of the many lineages of parasitic plants, and (6) integration of fossils with extant taxa into a comprehensive tree of angiosperm phylogeny.

Although still unclear in places, there are phylogenetic relationships in the angiosperms. So, we have some oldest ancestal angiosperm, this produced Amborellaceae (shrubbish), then followed by Nymphaeaceae (water lilies), then Austrobaileyales (woody plants). After that come the remainder (monocots etc; much more opaque). And the proposal is that the earliest angiosperms evolved from some form of gymnosperm.

Up to you whether you accept it, I don't mind - the suggestion is not that all angiosperm species evolved independently in some form of mass convergence, but diverged from ancestral angiosperms.

as to humans, that's because we were a young species with many break off groups.

And 140+ million years ago or so, the same would most likely have applied to those very first angiosperms.

[edit on 17-6-2008 by melatonin]

reply to post by melatonin


thank you, very informative.

I still don't completely get it, but it makes it much clearer.

I mean, I don't exactly see small weeds becoming massive treed in such small time when other barked trees took the entire time period from trilobite to mamal-like reptiles to develop bark. And It still doesn't make clear flowering weed-flowering tree relationship lineage, but it goes pretty well.


Got any good explanation on birds?

I mainly interested for my own interests, but I want to also create a 3d spin off of something like natural geographic's extraterrestrial. Might as well learn all I can on life's change.

[edit on 17-6-2008 by Gorman91]

Originally posted by Gorman91
I mean, I don't exactly see small weeds becoming massive treed in such small time when other barked trees took the entire time period from trilobite to mamal-like reptiles to develop bark. And It still doesn't make clear flowering weed-flowering tree relationship lineage, but it goes pretty well.

Not so much a short time though. We are talking on scales of millions of years. It is hard for our puny human minds to comprehend such timescales though.

Got any good explanation on birds?

I mainly interested for my own interests, but I want to also create a 3d spin off of something like natural geographic's extraterrestrial. Might as well learn all I can on life's change.

That's the way to be. You look around consume some information, make some inferences, and test them out. Curiosity is a great thing, not so much for cats though apparently.

If I get some time later, I'll do a little bit of research for you. I really have some things I must do most of today. So later possibly.

melatonin wrote:

1). Most, if not all birds before the K-T extinction event had teeth. Strong teeth! But afterwards, globally, strong teeth disappeared from the species and all birds could no longer produce the proper calcium for it. Why is it that this was a global evolutionary event, and not selective in one species of birds? Sure, ducks and the like still have remnants of it, but they're crap teeth, and it still doesn't explain why EVERY species of bird evolved this way, globally. It wasn't limited to one specific region or area of change, globally they lost teeth.

And no, it wasn't because of the K-T event, because there are records of most birds still having teeth shortly after, in the mammalian era. But by the time more complex mammals came about, teeth were gone.

I would guess that it was no longer an advantage for birds to have teeth, anywhere in the world. So birds with teeth had the same chance of producing offspring as birds without teeth, and the birds without teeth "won".

melatonin wrote:

2) Why did flowers evolve 'en mass in the Cretaceous. It wasn't limited to one species of plant. A Member of virtually every plant species suddenly evolved flowers: bushes, shrubs, trees, grasses, weeds, and small flowers themselves. It seems odd how ever species of plant had a member of it suddenly evolve flowers.

Because dinosaurs -- planteating dinosaurs specifically -- began to eat plants that grew close to the ground. The would-be flowers could grow faster (and therefore become out of reach) than the other plants, and they could also reproduce faster because of their new flower-reproduction system. Basically, it was become a flower or get eaten before you reproduce, and the goal of the plants was to reproduce. You can't reproduce if you get eaten, and you can reproduce really fast if you're a flower.

[edit on 25-6-2008 by nathan_p]