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Author Topic:   evolutionary chain
Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 136 of 204 (263978)
11-28-2005 11:59 PM
Reply to: Message 112 by RAZD
11-16-2005 7:37 AM


Re: Note to Christian
Thanks RAZD, this should be helpful. It's hard to sift through all this and figure out where I left off. Interesting reading though.

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 Message 112 by RAZD, posted 11-16-2005 7:37 AM RAZD has not replied

  
Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 137 of 204 (263979)
11-29-2005 12:17 AM
Reply to: Message 115 by RAZD
11-16-2005 8:10 AM


Re: Pelycodus
The numbers down the left hand side indicate the depth (in feet) at which each group of fossils was found. As is usual in geology, the diagram gives the data for the deepest (oldest) fossils at the bottom, and the upper (youngest) fossils at the top. The diagram covers about five million years.
Are you sure the numbers down the left hand side indicate the depth at which each group of fossils were found? Because those numbers get smaller as you go down and if they indicate depth, I would think they would get larger. Am I missing something? Of course I'm not making any exciting point here, just trying to understand the chart.

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Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 138 of 204 (263980)
11-29-2005 12:25 AM
Reply to: Message 115 by RAZD
11-16-2005 8:10 AM


Re: Pelycodus
Still this seems like a transition from lemur to lemur. I would like to see pictures of these guys. Do they cross any distinctive lines?

This message is a reply to:
 Message 115 by RAZD, posted 11-16-2005 8:10 AM RAZD has replied

Replies to this message:
 Message 139 by RAZD, posted 11-29-2005 9:02 PM Christian has replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 139 of 204 (264327)
11-29-2005 9:02 PM
Reply to: Message 138 by Christian
11-29-2005 12:25 AM


Re: Pelycodus
Christian, msg 137 writes:
Are you sure the numbers down the left hand side indicate the depth ...
That is what the article says. It does look curious, but they could be referencing depth up from some datum level.
Still this seems like a transition from lemur to lemur.
From lemur-like to lemur-like. These predate lemurs, and they also diverge later into two genuses of species, so only one of them ends up possible related to lemurs:
The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus. The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.
Also this is before the time of some new finds
Page not found - Carnegie Museum of Natural History
That link monkeys and apes to these lemur-like creatures.
I would like to see pictures of these guys.
So would scientists ... after all they died out 50 million years ago.
All we could develop now would be artist renderings, which are (by nature) fanciful (colors, ornamentary features, etc).
You might want to look at mick's post on chipmunks too, for some relevance for "looks like" in this kind of thing.
Enjoy

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 138 by Christian, posted 11-29-2005 12:25 AM Christian has replied

Replies to this message:
 Message 140 by Coragyps, posted 11-29-2005 9:14 PM RAZD has replied
 Message 142 by Christian, posted 12-01-2005 5:21 PM RAZD has replied

  
Coragyps
Member (Idle past 734 days)
Posts: 5553
From: Snyder, Texas, USA
Joined: 11-12-2002


Message 140 of 204 (264331)
11-29-2005 9:14 PM
Reply to: Message 139 by RAZD
11-29-2005 9:02 PM


Re: Pelycodus
but they could be referencing depth up from some datum level.
That's standard practice, as the present-day ground surface can be pretty cut up by erosion - in Wyoming, especially. The numbers make sense when you measure from a depositional surface, though.

This message is a reply to:
 Message 139 by RAZD, posted 11-29-2005 9:02 PM RAZD has replied

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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 141 of 204 (264393)
11-30-2005 7:03 AM
Reply to: Message 140 by Coragyps
11-29-2005 9:14 PM


Re: Pelycodus
Thanks. That corresponds to the other layer listings on the side bar too.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
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Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 142 of 204 (264828)
12-01-2005 5:21 PM
Reply to: Message 139 by RAZD
11-29-2005 9:02 PM


Re: Pelycodus
From lemur-like to lemur-like. These predate lemurs, and they also diverge later into two genuses of species, so only one of them ends up possible related to lemurs:
ok so this is not what I was looking for. I would like to see something distinctive being developed. Looks like they got bigger,and then some got bigger while others got smaller. That's interesting, but not what I was looking for.
I took a look at the chipmunk thread, also interesting, but more talking about the idea that macroevolution CAN occur, by the same processes with which microevolution occurs. Still, I don't see a macroevolutionary chain.

This message is a reply to:
 Message 139 by RAZD, posted 11-29-2005 9:02 PM RAZD has replied

Replies to this message:
 Message 143 by RAZD, posted 12-03-2005 10:11 PM Christian has replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 143 of 204 (265350)
12-03-2005 10:11 PM
Reply to: Message 142 by Christian
12-01-2005 5:21 PM


Re: Pelycodus
I've taken a while to respond thinking of the ramifications and implications of expectations here.
Still, I don't see a macroevolutionary chain.
What you need to understand is that you will never see a massive change in a short time, that all change is of the normal microevolutionary level -- here we have a speciation event, marked as the two sizes seperate into two distinct groups.
Looks like they got bigger,and then some got bigger while others got smaller.
There is a "rule" that given the opportunity all species will tend to increase in size. It is a general rule rather than a hard and fast one, but it often pans out in practice. We see this happening here, up until the point of dividing, and beyond -- the larger species continues the same size trend line.
What I find intersting is that the size increase likely means that at some point the behavior of the species has to change (especially for an arboreal creature) as it is no longer able to take advantage of the original habitat of the smaller original species, and thus it is likely leaving a void for a smaller animal to take advantage of. The rapid (relatively speaking) reduction in size of the second species down to the original species size does two things then: it takes advantage of the void left by the increase in size and it differentiates the niche of the smaller one from the bigger one so that they are not in such direct competition as would otherwise be the case.
But that is my speculation on what happened.
That's interesting, but not what I was looking for.
The problem here is to more fully define what exactly it is you are looking for.
This is the point at which these two species split, the moment of division between their lines, but it is also the point at which two genuses split: One goes on to become the genus Smilodectes and the other goes on to become the genus Notharctus. This is a division above the species level, as each genus includes several species that are more closely related to each other than they are to the other genus species:
The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus. The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.
I took a look at the chipmunk thread, also interesting, but more talking about the idea that macroevolution CAN occur, by the same processes with which microevolution occurs.
That is what happens. The original event is a microevolutionary speciation. After that has happened the species diverge further, and more microevolutionary events happen, and the subsequent species diverge further, and this keeps happening until you get such differences that you have significant changes in size, behavior, features and other characteristics that even genus level taxonomy does not do them justice. The significance of the event is not evident at the time, but only after many other microevolutionary events have layered on top of it do we see that {{here}} is when the divide began.
I guess I have to ask what you think macroevolution is and how it occurs?
I would like to see something distinctive being developed.
Perhaps this is the crux of the problem. We can talk about horses and the development of the modern horse and hoof from the splayed toed dog sized "eohippus" (or more properly Hyracotherium.
http://www.flmnh.ufl.edu/natsci/vertpaleo/fhc/Stratmap1.htm
The hoof take several intermediate stages to develop from the four toes of eohippus to the one toe of the modern horse. There were several other changes too, increase in size, change in teeth, etc.
It's your call. Define what you want to see a little more, and we'll see where we can go from there.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 142 by Christian, posted 12-01-2005 5:21 PM Christian has replied

Replies to this message:
 Message 144 by Christian, posted 12-05-2005 5:12 PM RAZD has replied

  
Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 144 of 204 (265825)
12-05-2005 5:12 PM
Reply to: Message 143 by RAZD
12-03-2005 10:11 PM


Re: Pelycodus
What you need to understand is that you will never see a massive change in a short time
I'm not looking for change in a short time. I don't care how long the chain is, I only want to see that one could've evolved from the previous up until we have something distinctively different. It doesn't even have to be from the fossil record. If evolution were correct, I would think there would be countless possible chains like this, living and fossilized. The big horse with one toe and the little horse with three toes are both horses. There are many different kinds of dogs and many different kinds of cats. I think it is possible that all cats evolved from a common cat ancestor. What I would like to know is what did the first cats evolve from that were not cats and how did the transition likely take place?
There is a "rule" that given the opportunity all species will tend to increase in size. It is a general rule rather than a hard and fast one, but it often pans out in practice.
Are we on a "downward trend" then? Because it is my understanding that there used to be giant dragonflies and beetles and lizzards, larger than any we know of today. This may be off topic though.
What I find intersting is that the size increase likely means that at some point the behavior of the species has to change (especially for an arboreal creature) as it is no longer able to take advantage of the original habitat of the smaller original species, and thus it is likely leaving a void for a smaller animal to take advantage of. The rapid (relatively speaking) reduction in size of the second species down to the original species size does two things then: it takes advantage of the void left by the increase in size and it differentiates the niche of the smaller one from the bigger one so that they are not in such direct competition as would otherwise be the case.
Same question as above, then. Why are there not larger creatures than what once existed, long ago?
This is the point at which these two species split, the moment of division between their lines, but it is also the point at which two genuses split: One goes on to become the genus Smilodectes and the other goes on to become the genus Notharctus. This is a division above the species level, as each genus includes several species that are more closely related to each other than they are to the other genus species:
They may be classified as different genuses, but what is so different about them? All I could tell from the chart is that they changed in size.
The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.
Then maybe you can show me the chain of them becoming more distinct?
I guess I have to ask what you think macroevolution is and how it occurs?
I think macroevolution is where there is a change from one "kind" of animal to another. I don't know, though, how to define "kind" except that it includes animals which are distinct meaning they do not interbreed, or have some feature which is distinct from other animals. I do not think it occurs. The man-made classifications don't seem adequate for drawing lines, but wherever there is something distinct, it is unknown what the most recent ancestors were, as far as I can tell. I realize there are animals which do not interbreed, but likely have common ancestry. All I'm saying is that it is obvious to me that aminals which DO interbreed are an exception.
Some examples of what I would like to see the chain of development for: The amniotic egg of reptiles, the jumping aparatus of the click beetle, the pentadactyl limb of tetrapods, the spinneret and male copulating organ of spiders, the wing of a bat the water vascular and ambulacaral systems of echinoderms, the neck of the giraffe, the male reproductive organs of the dragonfly. Those examples were taken from Michael Denton's book "Evolution: a Theory in Crisis" But I could add the metamorphis of the butterfly or the shell of a turtle. Any of those would be very interesting to me.
Hope that's helpful. Actually, to be honest, I hope I've stumped you, since I don't want evolution to be true.

This message is a reply to:
 Message 143 by RAZD, posted 12-03-2005 10:11 PM RAZD has replied

Replies to this message:
 Message 145 by RAZD, posted 12-05-2005 8:39 PM Christian has replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 145 of 204 (265871)
12-05-2005 8:39 PM
Reply to: Message 144 by Christian
12-05-2005 5:12 PM


Re: Pelycodus
Are we on a "downward trend" then? Because it is my understanding that there used to be giant dragonflies and beetles and lizzards, larger than any we know of today. This may be off topic though.
Same question as above, then. Why are there not larger creatures than what once existed, long ago?
I said a general rule not a mandatory one. It has to do with fitness and survival and mating opportunities that tend to favor small increases in size over time. This doesn't mean that it always happens.
The other thing we see is resetting of the sizes in mass extinction events and where the larger versions become extinct for other reasons (giant sloths were killed off by early man in america), while smaller species still survive.
Remember that one branch of Pelycodus became much smaller than the other which continued the size trend, but once it bottomed out it likely started back getting bigger again, but now would be under selection pressure from the cousins to keep them small.
I'm not looking for change in a short time. I don't care how long the chain is, I only want to see that one could've evolved from the previous up until we have something distinctively different.
Then maybe you can show me the chain of them becoming more distinct?
That would be the next step. I would need some help with the actual links, though, and that is why I suggested looking at the horses.
I only want to see that one could've evolved from the previous up until we have something distinctively different.
The big horse with one toe and the little horse with three toes are both horses.
Do you agree that one toe is distinctivly different from three toes? Or are we redefining what "distinctively" means? As I said we may need some further definition of the positions.
distinctively
adv : in an identifiably distinctive manner; "the distinctively conservative district of the county"
distinctly
adv 1: clear to the mind; with distinct mental discernment; "it's distinctly possible"; "I could clearly see myself in his situation" [syn: clearly] 2: in a distinct and distinguishable manner; "the subtleties of this distinctly British occasion" 3: to a distinct degree; "urbanization in Spain is distinctly correlated with a fall in reproductive rate"
dis·tinc·tive
adj.
1. Serving to identify; distinguishing: distinctive tribal tattoos. See Usage Note at distinct.
2. Characteristic or typical: “Jerusalem has a distinctive Middle East flavor” (Curtis Wilkie).
3. Linguistics. Phonemically relevant and capable of conveying a difference in meaning, as nasalization in the initial sound of mat versus bat.
To me the difference between the horses is very distinctive, based not just on one having three (back) and four (front) toes and the other only one on each foot, but in the relative sizes, the changes in the teeth, the changes in the jaw, the changes in the legs, the changes in the torso, the changes in the tail ....
from: Eohippus
Eohippus was a descendent of the Condylarth, a dog-sized, five-toed creature that lived about 75 million years ago. It lived during the early Eocene period, which took place 50 to 60 million years ago. Eohippus, which means "dawn horse," stood about twelve to fourteen inches at the shoulder and weighed about twelve pounds. It looked nothing like a horse. It had an arched back, short neck, short snout, short legs, and a long tail. Its color probably most resembled that of a deer, a darker background with lighter spots.
The legs of Eohippus were flexible and rotating with all major bones present and unfused. It had a choppy, up-down gait and was not very fast. There were four toes on each front foot and three toes on the hind. The vestigial toes - two on the front feet and one on the hind - were still present.
It had a small brain and low-crowned teeth with three incisors, one canine, four distinct premolars, and three "grinding" molars in each side of each jaw. Browsing on fruit and fairly soft foliage, Eohippus probably lived in an environment with soft soil, the kind found on jungle floors and around the edges of pools. Since Eohippus walked on the pads of its feet, it was able to cross wet, marshy ground without much difficulty.
The coloration of course, is pure speculation.
But that also makes for different diet and environment.
(This last description kind of brings to mind the sitatunga, talked about (briefly) at the {Pakicetus being presented with webbed feet} thread -- is it possible eohippus had webbed feet? LOL)
There are many different kinds of dogs and many different kinds of cats.
Any with different numbers of {claws\toes}? With different kinds of teeth?
I guess the question is - how much change is enough?

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 144 by Christian, posted 12-05-2005 5:12 PM Christian has replied

Replies to this message:
 Message 146 by Christian, posted 12-08-2005 4:46 PM RAZD has replied
 Message 148 by Christian, posted 12-08-2005 6:08 PM RAZD has replied

  
Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 146 of 204 (266916)
12-08-2005 4:46 PM
Reply to: Message 145 by RAZD
12-05-2005 8:39 PM


horse evolution
this is from the link you gave me about horse evolution:
Professor Marsh (who also named eohippus and Pliohippus) was not trying to confuse us when he named Miohippus in 1974. At the time, he believed that these fossils came from Miocene rocks. More recent work indicates that nearly all species of Miohippus, in fact, lived in the Oligocene. Though the name is somewhat misleading, we are stuck with it.
Why is it that he thought they were found in the Miocene rocks? Didn't the people who found the fossils tell him which layer of rocks they were found in? I suspect that this isn't as clear cut as it seems. That dating layers isn't as easy as you guys make it seem.

This message is a reply to:
 Message 145 by RAZD, posted 12-05-2005 8:39 PM RAZD has replied

Replies to this message:
 Message 147 by NosyNed, posted 12-08-2005 4:53 PM Christian has replied
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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 147 of 204 (266917)
12-08-2005 4:53 PM
Reply to: Message 146 by Christian
12-08-2005 4:46 PM


Maintaining focus
That dating layers isn't as easy as you guys make it seem.
It isn't easy; care is needed if you want as precise a date as possible. You do realize that Marsh was active over a century ago?
However, that is all beside the point. We are not discussing details of dating in this thread. If you don't want to get into a complete jumble I suggest you try to stick to one thing at a time.
Of course, everything is related to everything else but if you follow every single interesting point that comes up you will make zero progress on all of them.
For now, work with relative dates (which is all Marsh had). You are looking for a "chain" -- how much time that represents can, perhaps, be left to one side for now. Do you think?
If you really want to dig into dating there is a lot of material in the dateing forum. (However, I haven't found a date for Saturday night there )

This message is a reply to:
 Message 146 by Christian, posted 12-08-2005 4:46 PM Christian has replied

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Christian
Member (Idle past 6255 days)
Posts: 157
Joined: 10-16-2005


Message 148 of 204 (266947)
12-08-2005 6:08 PM
Reply to: Message 145 by RAZD
12-05-2005 8:39 PM


Re: Pelycodus
Do you agree that one toe is distinctivly different from three toes? Or are we redefining what "distinctively" means? As I said we may need some further definition of the positions.
Actually, I think that #1 under distictive is a pretty good definition: 1. Serving to identify; distinguishing: distinctive tribal tattoos. See Usage Note at distinct. What I mean is a defining characteristic. Something like the trunk of the elephant, or the quills on a porcupine.
To me the difference between the horses is very distinctive, based not just on one having three (back) and four (front) toes and the other only one on each foot, but in the relative sizes, the changes in the teeth, the changes in the jaw, the changes in the legs, the changes in the torso, the changes in the tail ....
Perhaps, but I would think you could find something better. I gave you lots of possible options, can you not find chains for any of those?

This message is a reply to:
 Message 145 by RAZD, posted 12-05-2005 8:39 PM RAZD has replied

Replies to this message:
 Message 149 by RAZD, posted 12-08-2005 11:25 PM Christian has replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 149 of 204 (267041)
12-08-2005 11:25 PM
Reply to: Message 148 by Christian
12-08-2005 6:08 PM


Re: Pelycodus ...Horse ...Elephant?
Actually, I think that #1 under distictive is a pretty good definition: 1. Serving to identify; distinguishing: distinctive tribal tattoos. See Usage Note at distinct. What I mean is a defining characteristic. Something like the trunk of the elephant, or the quills on a porcupine.
But the elephant nose is still just a nose and the porcupine quills are still just fur...
Trunks, being soft tissue, are poorly represented in fossils ... usually all there is consists of a big hole in the center of the skull (and possibly the origin of the cyclops myth btw, as mammoth skulls were common in ancient greece).
The change from five toes to one toe is much more dramatic than a nose that just gets longer. Look at the tapir and you can see that this is the same feature "prehensile nose" ... just not as long as an elephants.
In fact we can go back further in the history of the horse, before eohippus to the Condylarths mentioned previously, which is actually a very large classification grouping of many species over a large area and time-frame. From Condylarths: Archaic hoofed mammals(click):
Back in the northern hemisphere, another family of condylarths, the Phenacodontidae, may include the ancestors of a more familiar ungulate order: The odd-toed ungulates or Perissodactyla, represented by horses, rhinos and tapirs in the recent fauna. Historically, phenacodontids form the core of the Condylarthra. Well-preserved skeletons are known for the type genus Phenacodus, which is a good model of an ancestral ungulate with beginning adaptations for running. Unlike arctocyonids, periptychids or mioclaenids, the phenacodontids are not part of the first wave of condylarths that populated North America. They first appear with the fox-sized Tetraclaenodon in the middle Paleocene of that continent. The appearance of the more advanced phenacodontids Phenacodus and Ectocion marks the beginning of late Paleocene time in North America. The type genus Phenacodus covers the large size range of phenacodontids and includes roughly sheep-sized animals. Members of the genus Ectocion were usually smaller, with a body mass of only 3 kg in the smallest species, but there is some overlap in size between the two genera. Phenacodontids were the dominant mammals in the latest Paleocene of North America and account for up to 50% of all mammal specimens in faunas of that age.
You can see the similarity of the condylarth meniscotherium here to eohippus shown before eh? Do you still think this is indistinct from a horse? This is the most horse like artistic rendering I saw of what it might have looked like:
The fact is that the horse fossils do have very distinct differences -- distinct differences is what each species definition is really based on, and the horse chart is talking about genuses (groups of species ... remember that level of division that the Pelycodus ends up at?) to get from eohippus to modern horse you have to go through at least 8 distinct genus level changes to get to modern equus (which includes horse, zebra and donkey\ass, each distinctly different).
Now let's look at that horse hoof a little closer, from Functional Anatomy of the Horse Foot (click):
A horse's hoof is composed of the wall, sole and frog. The wall is simply that part of the hoof that is visible when the horse is standing. It covers the front and sides of the third phalanx, or coffin bone. The wall is made up of the toe (front), quarters (sides) and heel.
The wall of the hoof is composed of a horny material that is produced continuously and must be worn off or trimmed off. The hoof wall does not contain blood vessels or nerves. In the front feet, the wall is thickest at the toe; in the hind feet the hoof wall is of a more uniform thickness. The wall, bars and frog are the weight-bearing structures of the foot. Normally the sole does not contact the ground.
As weight is placed on the hoof, pressure is transmitted through the phalanges to the wall and onto the digital cushion and frog. The frog, a highly elastic wedge-shaped mass, normally makes contact with the ground first. The frog presses up on the digital cushion, which flattens and is forced outward against the lateral cartilages. The frog also is flattened and tends to push the bars of the wall apart (Figure 3). When the foot is lifted, the frog and other flexible structures of the foot return to their original position.
When the foot is placed on the ground, blood is forced from the foot to the leg by the increase in pressure and by the change in shape of the digital cushion and the frog. The pressure and the change in shape compress the veins in the foot. When the foot is lifted, the compression is relieved and blood flows into the veins again. In this way, the movement of these structures in the hoof acts as a pump.
This is much more difference in a feature than "just an increase in length" (as in an elephants trunk), it is a totally different structure to stand on (eohippus stood on his toes pads, equus stands on a hoof which not only is not a toe pad, but a feature that wasn't present in the eohippus) and it incorporates a new {added\changed} structure to increase blood flow by acting as a secondary pump.
Not only that the effect of changing the foot structure from a flat footed splayed toed eohippus to the single toed equus also involves standing the foot up on the tip of the toe and using each of the bones between the tip and the heel to effectively make the leg longer for faster running while also making it more flexible than just adding length to the bones of the leg. Probably useful for getting through tight spots and to keep from tripping ... it certainly helps horses jumping in shows from hitting that top bar.
Totally different foot structure, coupled with totally different leg structure (with some ex toe bones now effectively used as leg bones).
The question again is how much change is enough? Try walking around the house on the tip of one toe, then compare your foot to that of eohippus.
I gave you lots of possible options, can you not find chains for any of those?
When you keep denying that the chains are "good enough" then I have trouble with the moving goal post syndrome. As I said you need to make a definition ... and then you need to stand by it.
K?
btw, if you are interested in elephant trunks you can google on "earliest elephant" (with the quotes) and you should find sufficient information. One source I found with a quick summary of the highlights is Elephant Evolution (click):
Moeritherium, pronounced mee-ri-THEER-ee-um, is the earliest known member of the order Proboscidea. The first fossils were discovered in 1904 at El Faiyum oasis in Egypt. This oasis was known as Lake Moeris in ancient Egypt Moeritherium fossils showed the beginnings of enlarged incisors (tusks) but there is no evidence of a trunk. They lived about 50 million years ago with a hippo-like lifestyle. In fact, they have been described as pygmy hippopotami. They were about the size of a pig standing 70cm at the shoulders with stout elephantine legs and a long body.
That's about the same time frame for the evolution of the horse from eohippus btw.
Enjoy.
This message has been edited by RAZD, 12*08*2005 11:25 PM
This message has been edited by RAZD, 12*08*2005 11:26 PM

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 148 by Christian, posted 12-08-2005 6:08 PM Christian has replied

Replies to this message:
 Message 152 by Christian, posted 12-12-2005 6:45 PM RAZD has replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 150 of 204 (267287)
12-09-2005 5:52 PM
Reply to: Message 146 by Christian
12-08-2005 4:46 PM


Re: horse evolution
as noted by Ned, Marsh was one of the early pioneers of paleontology, working before radiometric dating was developed, so all they had was stratiography and relations to other fossils to go from in developing relative dating relationships.
In a paper published in 1874 in American Naturalist, Marsh describes some of the horse fossils he found on an expedition in Wyoming and Utah. One of these skeletons, he named Eohippus, or "the dawn horse." However, instead of using Eohippus in this paper, he used Orohippus, as the former hadn't yet been described. The different skeletons had different numbers of toes and different degrees of variation, which would eventually be Marsh's main proof of development. He believed that the correct line of descent was Orohippus, Miohippus and Anchitherium, Anchippus, Hipparion, Protohippus and Pliohippus, and Equus, the most recent. The way Marsh determined the line of descent was mostly by examining the metacarpal bones of the different horses.
Looks like there's a typo on the Miohippus page.

This message is a reply to:
 Message 146 by Christian, posted 12-08-2005 4:46 PM Christian has not replied

  
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