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Author | Topic: evolutionary chain | |||||||||||||||||||||||
RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
and concluded that it is most likely not what I am looking for. What if we start with any type of animal with a distinguishing characteristic, and then move backward to show what their ancestor without that characteristic could've been? Try this one Christian: Therapsid fossils - reptile to mammal jaw transitions (click) - complete with an intermediate stage where the critter had two jaw joints:
Probainognathus possessed characteristics of both reptile and mammal, and this transitional aspect was shown most clearly by the fact that it had TWO jaw joints--one reptilian, one mammalian And then the development of the mammal ear bones from the previous reptile jaw bones. Enjoy. by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
could these animals actually have evolved from each other? Do you mean one individual directly from another individual? Highly unlikely event, and not necessary. Each generation descends from the previous one, and each individual is a representative of its generation. We can compare human skeletons over the last 4,000 years and note changes over that time (due to diet, climate, changing racial characteristics, etc), but we do not need them to be directly related to do so. If you mean did one species evolve from another then the answer is yes, but not unequivocally, and again not necessarily directly. It is possible for a species in the group to be a cousin species to the actual line of descent, (the way Neanderthals are cousin species to Homo sapiens). This would only be determined by uncovering more specimens until we determined (as occurred with Neanderthals) that one of the originals is on a branch from the main line instead of on it. There could also easily be an intermediate specimen or more between any two fossils that have been found, just as there are intermediates between you and your great-great-great-great grandparents, but you don't need to know that level to know that your generation descended from theirs. Does this invalidate the picture of gradual transition from point {A} to point {B} that we see based on the current knowledge?
If so, could you give me the chain of actual animals that could've evolved from each other Again, if you want an individual {A} begat individual {B} begat individual {C} in the fossil record then the answer is no. We would also never know if we did uncover two specimens how closely they were related even if found together unless it were extraordinary circumstances. If you want a species {A} begat species {B} begat species {C}, then the answer is that we have such a list -- although I don't have such a specific species by species list -- based on the fossil evidence that is available. This might make an interesting topic to research for someone interested in the actual sequences. But, there certainly are ones listed in the article that one can place in a rough chronology from the context. How this "link by link chain" would actually help you is another question. We have a gradual transition of specific features over a given time period going from point {A} to point {B} - but how those fossils are divided into "species" is rather arbitrary and based on human interpretation of accumulated differences. There is even the arbitrary dividing line between "reptile" side of the transition (Therapsid) and "mammal" side of the divide (Morganucodonts), where the ones each side of the "dividing line" have the same level of change as between them and the next species away from the dividing line, both of the "borderline" species having a double jointed jaw. We make the distinctions of species to aid in our description of what is happening. Nature has no need to do so -- all that is needed is breeding, change in population characteristics over time, and natural selection of {survival\reproduction} enhancing features. If you could take a snapshot of each ancestor of any human individual back 70 million years and play them like a time-lapse 'movie' you would see a gradual transition, a morphing of characteristics, back to the point where the final ancestor in the series would look something like a small four-legged mammal with a longish snout and a tail. Where does one species end and the other begin? How goes the {age dating correlations} study? by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Presumably this is from the randman files ...
It would be interesting to me to see some kind of representation of the fossil record to go with the graphic and show some drift from one to another in the process. Not sure how you could tie it together coherently though. You can get an idea of what I mean fromhttp://www.mnh.si.edu/anthro/humanorigins/ha/a_tree.html Although the linked information is not related strictly to the fossil record density. by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
here is another example of what I mean
A Smooth Fossil Transition: Pelycodus You get a feeling for the number of fossils within the tree structure and the diversity at each level before and after the split. This one strikes me as a general trend to larger and larger size for the main population from P. ralstoni through P. jarrovii and on to N. venticolus with a branching speciation event at P. jarrovii to N. nunienus that reverts rapidly in size to the P. ralstoni range.
When two similar species compete, it is not uncommon that one fairly quickly becomes different - in this case, smaller. This presumably reduces the competition between the species. This would also indicate to me that the original habitat was gradually abandoned by the larger and larger versions in favor of other {food\niche\behavior} - perhaps more time on the ground and less in the upper branches - until there was sufficient opportunity for a smaller version to take advantage of the old one with pre-adapted abilities. by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
I think it is better than thinking of images in chains and branches because it reflects the actual information better while still showing the overall trends
and the divergences are more easiliy seen as a parting of the ways of individuals rather than one individual type becoming two types - a herd of animals divided in a stampede through time into separate paths by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
There is no new information between your last post and this one, so you don't have to worry about reading through the whole post to get to the points. For reference it was
EvC Forum: evolutionary chain I for one am sorry to see this happen on this thread, as it was going in a good direction before. I hope that can be recaptured. Regards. by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Christian,
There is no new information between your last post and this one, so you don't have to worry about reading through the whole post to get to the points. For reference it was http://EvC Forum: evolutionary chain I for one am sorry to see this happen on this thread, as it was going in a good direction before. I hope that can be recaptured. Others: Please provide information on {chains\trees\webs} of evolution and stop this distractionary tactic by randman. Regards. This message has been edited by RAZD, 11*16*2005 07:53 AM by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
FROM: A Smooth Fossil Transition: Pelycodus, a primate (click)
(image copied to satellite site for access concerns) Pelycodus was a tree-dwelling primate that looked much like a modern lemur. The skull shown is probably 7.5 centimeters long. 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. 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. Pelycodus is from a group of creatures which collectively are thought to be the ancestors of modern monkeys and apes. The diagram represents the whole of the early Eocene, spanning very approximately 55 million years ago to 50 million years ago. The fossils are from sediment in the Bighorn Basin of Wyoming. Note that the distinction that began as a speciation event here documented has in later development become two different genus classifications. This is one level above speciation. http://www.msu.edu/%7Enixonjos/armadillo/taxonomy.html That's a pretty solid branch in the tree of evolution. Enjoy. This message has been edited by RAZD, 11*16*2005 08:11 AM by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Can we return this to Christians topic and not let randman hijack it?
thanks
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Can you please take this to another thread so that the topic that Christian started can be dealt with specifically?
Now that you are an admin I expect you to be much more careful on this issue. Enjoy. by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
ANd I hope the others follow such good intentions. Thanks.
by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
see
http://EvC Forum: evolutionary chain -->EvC Forum: evolutionary chainhttp://EvC Forum: evolutionary chain -->EvC Forum: evolutionary chain
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
see
http://EvC Forum: evolutionary chain -->EvC Forum: evolutionary chainhttp://EvC Forum: evolutionary chain -->EvC Forum: evolutionary chain
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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 findsPage 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 by our ability to understand RebelAAmerican.Zen[Deist
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RAZD Member (Idle past 1435 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Thanks. That corresponds to the other layer listings on the side bar too.
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