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Author Topic:   Definition of Species
Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 151 of 450 (572274)
08-05-2010 6:10 AM
Reply to: Message 147 by Blue Jay
08-04-2010 11:24 AM


Re: Species Definition
Bluejay writes:

I argue that the only reason to use the methodology you espouse is because it satisfyingly parcels things into convenient packages of information that sound nice to you. But, it isn’t any more accurate or correct than any other proposed methodology, and it severely restricts the number of people who can do it.

I am not the one advocating the newer definitions of species. Scientists working in the field are actively doing this as it gives significant advantages. And yes I do like convenient parcels and packages. Why not.

As regards the expensive equipment and the restrictions on people, I am happy for them to continue to use the older or existing definitions of species. For the vast majority of people these older models work perfectly adequately.


This message is a reply to:
 Message 147 by Blue Jay, posted 08-04-2010 11:24 AM Blue Jay has responded

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Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 152 of 450 (572275)
08-05-2010 6:27 AM
Reply to: Message 150 by Dr Jack
08-05-2010 6:02 AM


Re: Species Definition
Mr Jack writes:

"Fish" is not a species. "Fish" is not even a genus, a family, an order, a class or a phylum. (And "Fish" is certainly not a clade!)

If you reject the word fish, I am guessing you will reject the word shark (also not a species). Here is a link showing that we cannot establish the species of shark in the fossil records in most cases due to lack of information ->http://www.elasmo-research.org/education/evolution/earliest.htm

If I can't use the word fish...and I can't use the word shark...there are no other words to use as we don't have enough data. These creatures date back 400 million years. I think it's safe to assume that the modern sharks came from these ancient sharks.


This message is a reply to:
 Message 150 by Dr Jack, posted 08-05-2010 6:02 AM Dr Jack has responded

Replies to this message:
 Message 153 by Dr Jack, posted 08-05-2010 6:34 AM Big_Al35 has responded

    
Dr Jack
Member (Idle past 365 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 153 of 450 (572277)
08-05-2010 6:34 AM
Reply to: Message 152 by Big_Al35
08-05-2010 6:27 AM


Re: Species Definition
I don't reject the word "fish", I pointed out it isn't a species! It's also not terribly biologically useful because it's paraphyletic.

Shark is better (if you're willing to include the rays as well) because the Elasmobranch group appears to be a monophyletic clade.

It's still not a species though so, again, I find myself wondering what it's relevance to our current discussion is?

These creatures date back 400 million years. I think it's safe to assume that the modern sharks came from these ancient sharks.

No, it isn't. It's safe to assume that modern sharks descended from them or similar creatures living at the same time but it is not safe to assume that those ancient sharks in particular were ancestral. Any more than it's safe to assume an arbitrarily picked Englishman from the 16th century is my ancestor.


This message is a reply to:
 Message 152 by Big_Al35, posted 08-05-2010 6:27 AM Big_Al35 has responded

Replies to this message:
 Message 154 by Big_Al35, posted 08-05-2010 6:51 AM Dr Jack has responded

  
Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 154 of 450 (572279)
08-05-2010 6:51 AM
Reply to: Message 153 by Dr Jack
08-05-2010 6:34 AM


Re: Species Definition
I don't reject the word "fish", I pointed out it isn't a species! It's also not terribly biologically useful because it's paraphyletic.
Shark is better (if you're willing to include the rays as well) because the Elasmobranch group appears to be a monophyletic clade.

It's still not a species though so, again, I find myself wondering what it's relevance to our current discussion is?

The point I am making is that any definition of species must be based on a snapshot in time and that snapshot in time must be now. We don't have enough data for any other period of time. We then have no choice but to apply today's snapshot in time to the ancient fossil records. We must classify the ancient species against known species of today. Anything else does not make sense.

eg..if we found a fossil and then declared it a missing link between the bears and cats...and then further established it as a new species this would be absurd. We simply don't have enough data.


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Huntard
Member (Idle past 555 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 155 of 450 (572281)
08-05-2010 7:04 AM
Reply to: Message 154 by Big_Al35
08-05-2010 6:51 AM


Re: Species Definition
Big_Al35 writes:

eg..if we found a fossil and then declared it a missing link between the bears and cats


There is no missing link between bears and cats. They share a common ancestor though.

and then further established it as a new species this would be absurd.

Well, if it isn't around today, it sure as hell is a different species, wouldn't you say?

We simply don't have enough data.

If it's not around today, it's a different species. What more data do you need?

Edited by Huntard, : typos


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Dr Jack
Member (Idle past 365 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 156 of 450 (572282)
08-05-2010 7:05 AM
Reply to: Message 154 by Big_Al35
08-05-2010 6:51 AM


Re: Species Definition
So, according to you, we should shoe-horn any, and all, extinct animal into a currently extant species? Really?

Where would you put this fella? Or any of these cute little tykes?

The fossil record drips with organisms which are clearly, and indisputably, not a member of any current species. To talk about them as if they are is to hugely distort reality.

The classification of extinct organisms is always going to be more tentative than living organisms, since we have much less data to go on but to suggest we should simply abandon the effort makes no sense to me. How would you suggest paleontologists discuss extinct organisms?


This message is a reply to:
 Message 154 by Big_Al35, posted 08-05-2010 6:51 AM Big_Al35 has responded

Replies to this message:
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Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 157 of 450 (572300)
08-05-2010 8:34 AM
Reply to: Message 156 by Dr Jack
08-05-2010 7:05 AM


Re: Species Definition
So, according to you, we should shoe-horn any, and all, extinct animal into a currently extant species? Really?

No...your putting words into my mouth. I never said this. The best we can do is to identify living species and the known extinct species (like the dodo). Fossils that don't fall into the known categories/species would need another system. I don't know what this system would be...I am not a paleontologist or biologist.

But we can't just make up ad hoc species and lump these fossils under that category. It couldn't be defined as a species under any of our definitions anyway. We don't have access to the DNA, we don't know their behaviour and we can never know if they could interbreed. It has become an exercise in futility.

Paleontologists must discuss extinct organisms using some new criterion but they should never evangelise this new methodology to the proletariat as their new system has no basis in fact.


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Replies to this message:
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Huntard
Member (Idle past 555 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 158 of 450 (572302)
08-05-2010 8:48 AM
Reply to: Message 157 by Big_Al35
08-05-2010 8:34 AM


Re: Species Definition
Big_Al35 writes:

The best we can do is to identify living species and the known extinct species (like the dodo).


The "known extinct species" include every fossil ever found.

Fossils that don't fall into the known categories/species would need another system.

Well, so far, there aren't any. And why would they require a new system anyway? Why not use the current one we used for all the "extinct species"?

But we can't just make up ad hoc species and lump these fossils under that category.

Why not?

We don't have access to the DNA, we don't know their behaviour and we can never know if they could interbreed. It has become an exercise in futility.

That's the problem with life. Everything is related to everything else. "Species" serve merely as an easy box to put everything in for us humans.

Paleontologists must discuss extinct organisms using some new criterion but they should never evangelise this new methodology to the proletariat as their new system has no basis in fact.

But why? What is wrong with the current system, that you advocate using on "all known extinct species", which include all fosills?

This message is a reply to:
 Message 157 by Big_Al35, posted 08-05-2010 8:34 AM Big_Al35 has responded

Replies to this message:
 Message 160 by Big_Al35, posted 08-05-2010 9:12 AM Huntard has responded

    
Dr Jack
Member (Idle past 365 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 159 of 450 (572309)
08-05-2010 9:10 AM
Reply to: Message 157 by Big_Al35
08-05-2010 8:34 AM


Re: Species Definition
No...your putting words into my mouth. I never said this. The best we can do is to identify living species and the known extinct species (like the dodo). Fossils that don't fall into the known categories/species would need another system. I don't know what this system would be...I am not a paleontologist or biologist.

Ah, okay. I understand now

I don't see why you think our existing methods of assigning fossils to species is so flawed? After all the majority of living organisms that would leave fossils could be correctly assigned to a species by their fossils.


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Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 160 of 450 (572312)
08-05-2010 9:12 AM
Reply to: Message 158 by Huntard
08-05-2010 8:48 AM


Re: Species Definition
Huntard writes:

The "known extinct species" include every fossil ever found.

I see a huge difference between the dodo and the TRex in terms of our knowledge of the creatures. The dodo was known to man. TRex never was. I think we even have stuffed dodos in museums. Also the behaviour of dodos has been documented extensively. We can safely say that that was a species.

TRex is a mystery. All we have are movie images and directors imaginations to go on. If you found two TRex half skeletons I think you would be hard pushed to even show that it was the same animal. You would have no idea if they could interbreed and their behaviour is unknown.


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 Message 158 by Huntard, posted 08-05-2010 8:48 AM Huntard has responded

Replies to this message:
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Huntard
Member (Idle past 555 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 161 of 450 (572316)
08-05-2010 9:16 AM
Reply to: Message 160 by Big_Al35
08-05-2010 9:12 AM


Re: Species Definition
Big_Al35 writes:

I see a huge difference between the dodo and the TRex in terms of our knowledge of the creatures. The dodo was known to man. TRex never was. I think we even have stuffed dodos in museums. Also the behaviour of dodos has been documented extensively. We can safely say that that was a species.


We can also safely say that T. Rex was a species.

TRex is a mystery. All we have are movie images and directors imaginations to go on. If you found two TRex half skeletons I think you would be hard pushed to even show that it was the same animal.

I would be, the experts, not really, no. With half a skeleton I predict a 100% sure identification.

You would have no idea if they could interbreed and their behaviour is unknown.

So? Also, there is quite a lot known about the behaviour of T. Rex.

Edited by Huntard, : added a bit


This message is a reply to:
 Message 160 by Big_Al35, posted 08-05-2010 9:12 AM Big_Al35 has responded

Replies to this message:
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Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 162 of 450 (572321)
08-05-2010 9:32 AM
Reply to: Message 161 by Huntard
08-05-2010 9:16 AM


Re: Species Definition
Huntard writes:

I would be, the experts, not really, no. With half a skeleton I predict a 100% sure identification.

Again I must refer you to a link that I already supplied in another debate about the differences between lions and tigers.

Ok here is one link from potentially many that supports my claim that the differences are hard to distinguish.

I think you will agree that lions and tigers are different species, yet they have almost identical skeletons.


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Huntard
Member (Idle past 555 days)
Posts: 2870
From: Limburg, The Netherlands
Joined: 09-02-2008


Message 163 of 450 (572322)
08-05-2010 9:37 AM
Reply to: Message 162 by Big_Al35
08-05-2010 9:32 AM


Re: Species Definition
Big_Al35 writes:

Again I must refer you to a link that I already supplied in another debate about the differences between lions and tigers.


Why? We're not talking about lions and tigers.

Ok here is one link from potentially many that supports my claim that the differences are hard to distinguish.

That says nothing about T. Rexes, and Wounded King supplied two (if I recall correctly, but at least one) link that showed that there are several very different things about lions and tigers.

I think you will agree that lions and tigers are different species, yet they have almost identical skeletons.

Yes, almost identical, but enough to distinguish the two. What this has to do with T. Rex identification however, is beyond me.

This message is a reply to:
 Message 162 by Big_Al35, posted 08-05-2010 9:32 AM Big_Al35 has not yet responded

    
Big_Al35
Member (Idle past 31 days)
Posts: 384
Joined: 06-02-2010


Message 164 of 450 (572328)
08-05-2010 9:43 AM
Reply to: Message 161 by Huntard
08-05-2010 9:16 AM


Re: Species Definition
Huntard writes:

So? Also, there is quite a lot known about the behaviour of T. Rex.

We don't even know if TRex was a top predator or just a scavenger.


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caffeine
Member
Posts: 1699
From: Prague, Czech Republic
Joined: 10-22-2008
Member Rating: 2.8


Message 165 of 450 (572332)
08-05-2010 9:48 AM
Reply to: Message 164 by Big_Al35
08-05-2010 9:43 AM


Re: Species Definition
quote:
We don't even know if TRex was a top predator or just a scavenger.

We can be fairly confident about it. We know that T Rex was not 'just' a scavenger, because fossils of prey animals have been found with wounds inflicted by Tyrannousarus teeth, which have since partially healed, suggesting an unsuccessful hunt.

I read an interesting article about this recently, which I've since lost. Get back to you when I find it.

ABE: Here we go - it was on Dave Hone's blog. Clear evidence has been found of both predation and scavenging in tyrannosaurs.

Edited by caffeine, : No reason given.


This message is a reply to:
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