Creationists/fossil disputers - what do you say fossils are?

[johnhanks]

I think fossils support the ideology that most major animal phyla appeared rapidly during the Cambrian explosion...

Depends on your definition of "rapidly". The Cambrian "explosion" took place over tens of millions of years - a very small fraction of total geological time, but in absolute terms a long period. And bear in mind a sudden appearance in the fossil record may reflect one specific event in a long and otherwise unrecorded development - in this case the evolution of shells and other hard body parts.

... and also think fossils support punctuated equilibrium over gradualism.

Parts of the fossil record support either or both; depends where you look. Few biologists claim evolution can work only one way or the other.

 

[idea]

Depends on your definition of "rapidly". The Cambrian "explosion" took place over tens of millions of years - a very small fraction of total geological time, but in absolute terms a long period. And bear in mind a sudden appearance in the fossil record may reflect one specific event in a long and otherwise unrecorded development - in this case the evolution of shells and other hard body parts.
Parts of the fossil record support either or both; depends where you look. Few biologists claim evolution can work only one way or the other.

I think panspermia explains the CE better than anything else does...
[youtube]5-XWAXe4xJg[/youtube]
Origin of Life - Panspermia (2 of 3) - YouTube

I think new species are created when new info is added via HGT:
Horizontal gene transfer - Wikipedia, the free encyclopedia

 

[tumbleweed41]

Panspermia is a viable explanation of how life came to Earth, but still leaves open the question of the origins of life.

And neither one really has anything to do with the process of biological evolution after life came to be on Earth.

 

[Krok]

I think fossils support the ideology that most major animal phyla appeared rapidly during the Cambrian explosion...

No ideology involved in this. We've got the fossils.

The Cambrian Explosion lasted tens of millions of years.

Of 30 or so phyla, 5-9 phyla existed before the Cambrian Explosion. At least 8 phyla only appear after the explosion.

After the end of the Cambrian Explosion, we still had almost nothing remotely resembling anything you find in your local zoo today: No mammals, no reptiles, no amphibians, no jawed fish, no birds, no insects, no land life, no primates.

....and also think fossils support punctuated equilibrium over gradualism.

In some areas it does. In other areas it does not. In other areas it supports both. Evolution occurrs and occurred in very diverse circumstances.

In some areas the environment changes slowly or stays the same, therefore evolution will occur gradually (as in for example the deep sea), in other areas the environment changes quickly (for example an asteroid hitting earth, where some organisms die out and others adapt relatively rapidly to the new environment).

 

[idea]

In some areas the environment changes slowly or stays the same, therefore evolution will occur gradually (as in for example the deep sea), in other areas the environment changes quickly (for example an asteroid hitting earth, where some organisms die out and others adapt relatively rapidly to the new environment).

I think it is driven by more than just environmental factors - sure, those play a part, but animals have the ability to migrate or to choose their own environment... we choose where to live, we choose who to mate with, we choose what types of food to eat - there is intelligence involved in the process, not just environment. We have the ability to act - not just react. I think some discount our ability to act.

 

[outhouse]

Panspermia is a viable explanation of how life came to Earth, but still leaves open the question of the origins of life.

And neither one really has anything to do with the process of biological evolution after life came to be on Earth.

A point I love is, life rapidly evolved in many different directions as if the chemistry originated here.


panspermia is possible, but im finding it unlikely.

life arose when our enviroment became stable enough.


now pro-panspermia, might suggest that we are always bombarded with life bearing material from outerspace and during this early period, it finally took.


But, what are the odds that this life would survive in our oceans chemistry and not only survive but rapidly evolve ???


im also looking at how the universe was formed, and is expanding. The odd's of having compatible life form stuck to a rock or ice will not be able to travel billions of light years and make it across the galaxy let alone the universe. Time is not on panspermia's side.

In other words, we would have to look at time and figure out how many millions or billions of light years away could material actually come from. today, i dont think the work has been done yet.

At some point there will be a limit as to how far material could have come from. And then one might ask is it only limited to this galaxy? what effect does gravity have on this time?

 

[Krok]

I think it is driven by more than just environmental factors - sure, those play a part, but animals have the ability to migrate or to choose their own environment... we choose where to live, we choose who to mate with, we choose what types of food to eat - there is intelligence involved in the process, not just environment. We have the ability to act - not just react. I think some discount our ability to act.

Of course there's lots of different factors. For example, birds had the ability to fly somewhere else to get food after that asteroid strike, while non-avian dinosaurs disn't have that ability and went extinct. Another example; some organisms live on islands. When the environment changes quickly, those organisms don't have too much of a "choice in choosing to migrate".

However, the fact remains, sometimes the fossils favour punctuated equilibrium, other times they favour gradualism, other times they indicate both.

 

[painted wolf]

I think a lot of people don't understand what exactly phyla means. When they hear that our phyla was present during the Cambiran I doubt they realize the implications.

This is our phyla.

And this is what the members of our phyla looked like during the Cambrian.

You still will have to grant that humans evolved from something not much different than a worm.

wa:do

 

[Krok]

I think.. different than a worm.

wa:do

Thanks painted wolf. That fossil is beautiful.

Can I ask you a few questions (please describe these in the terms a lay person would understand). You've seen that apparantly I am as clever as a carrot When I read your expertise, I do feel like one!

What is a nanochord?
What is a proto-nanochord?
Do we have fossils showing these?

I know jerry Coyne explained something about it, but I didn't get much of the details.

 

[painted wolf]

Thanks painted wolf. That fossil is beautiful.

Can I ask you a few questions (please describe these in the terms a lay person would understand). You've seen that apparantly I am as clever as a carrot When I read your expertise, I do feel like one!

What is a nanochord?

A notochord is a stiff but flexible "rod" of tissue that provides muscle attachment in chordates. Most of us vertebrates only have a full notochord as embryos, it provides a scaffold for our developing back bone and remains as part of it, but some keep it.

What is a proto-nanochord?

Proto-notochord is something I'm less familiar with. But there are questions about if the notochord of Pikaia is structurally the same as other chordates. If it extends through enough of the body (it doesn't appear to reach all the way to the head like with us) and if it is associated with the nerve chord in the same way.

Do we have fossils showing these?

Indeed we do. Pikaia shows a likely proto-notochord.
Plus, there are now several basal chordates from various times in the Cambrian. Not just Pikaia but also Cathaymyrus, Haikouichthys, Metaspriggina, Myllokunmingia, and Zhongxiniscus.
All of which are wormish to almost fish in form.

I know jerry Coyne explained something about it, but I didn't get much of the details.

I'll have to look for that! I really enjoy listening and reading Coyne's work.

This is the most basal living chordates today the Lancelets and they looks quite similar to the first chordates.

wa:do

 

[Krok]

Thanks painted wolf. You explain things very clearly.

Considering going into a teaching one day?