The Taxonomy Thread

Hello Nikola

Please note that apes are more closely related to Old World monkeys than they are to New World monkeys. The New World monkey most closely related to apes and Old World monkeys would probably be the monkey that diverged first from the common ancestor of monkeys (and apes). http://www.bbc.co.uk/earth/story/20...t-sailed-across-the-atlantic-to-south-America suggests that this animal was Perupithecus ucayaliensis. I suspect that the living species of New World most closely related to the common ancestor would be a type of marmoset or tamarin.
 
The platyrrhines (NWMs) are monophyletic and therefore equally related to all catarrhines (apes and OWMs).
 
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Nikola Chavkosk said:
What New World monkeys would be closest relatives to Apes (or to gibbons and to orangutans)? Cebids?
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As the New World radiation is monophyletic, they are all equally related to the Old World radiation; although some forms may *resemble* the last common ancestor of the two radiations more than others, they are no closer genetically to their cousins on the Old World branch.

Interestingly, although the callitrichids look quite primitive they are probably the youngest of the New World groups, and have undergone a secondary reduction in size.
 
Dassie rat said:
BBC - Earth - The monkeys that sailed across the Atlantic to South America says Perupithecus ucayaliensis bore a striking resemblance to Talahpithecus, a monkey that lived in northern Africa in the Eocene. While a group of animals may be monophyletic, the animals that branch off first are more closely related to the common ancestor than those that branch off later.
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Sorry, but that's fundamentally incorrect. If a group is monophyletic, all extant members are equally related to the common ancestor, regardless of when they subsequently diverged. Perupithecus would be more closely related to the catarrhines than extant platyrrhines are, but only by virtue of existing in the late Eocene. Incidentally, the paper that article is based on can be found here: http://www.nature.com/nature/journal/v520/n7548/full/nature14120.html?WT.ec_id=NATURE-20150423
 
Giant Panda said:
If a group is monophyletic, all extant members are equally related to the common ancestor, regardless of when they subsequently diverged. Perupithecus would be more closely related to the catarrhines than extant platyrrhines are, but only by virtue of existing in the late Eocene.
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Nikola's original question was which New World monkey is most closely related to apes. As Giant Panda states, Perupithecus would be more closely related to catarrhines than are extant platyrrhines. This is despite the fact that Perupithecus is a platyrrhine. I accept that taxonomy is very complicated and that some scientists have placed living platyrrhines in several families, rather than the two I learned about as a child, but some genera in a monophyletic group have diverged more from the common ancestor than have some other genera.
 
Dassie rat said:
Nikola's original question was which New World monkey is most closely related to apes. As Giant Panda states, Perupithecus would be more closely related to catarrhines than are extant platyrrhines. This is despite the fact that Perupithecus is a platyrrhine. I accept that taxonomy is very complicated and that some scientists have placed living platyrrhines in several families, rather than the two I learned about as a child, but some genera in a monophyletic group have diverged more from the common ancestor than have some other genera.
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Because I can see this descending into a semantical quagmire, my attempt to clarify:

- My assumption was (and still is) that Nikola meant the most closely related extant taxon, particularly as he suggested the cebids. Your original suggestion of a callitrichid was apparently made under the same assumption.

- Even if we're including extinct taxa, the suggestion in your first post that Perupithecus was "the monkey that diverged first from the common ancestor of monkeys" is incorrect. However, it is the earliest fossil platyrrhine.

- Everyone puts platyrrhines in several families, although how many remains controversial.

- You've changed your terminology from "related" in the previous post to "diverged" in this one. Again, all extant members of a clade are equally related to their last common ancestor, so all platyrrhines are equally related to all catarrhines. You could spend all day arguing about which taxa are more or less "diverged", but it's arbitrary in my eyes. I reserve the term for describing when lineages split.
 
Giant Panda said:
Because I can see this descending into a semantical quagmire, my attempt to clarify:
- My assumption was (and still is) that Nikola meant the most closely related extant taxon, particularly as he suggested the cebids. Your original suggestion of a callitrichid was apparently made under the same assumption.
- Even if we're including extinct taxa, the suggestion in your first post that Perupithecus was "the monkey that diverged first from the common ancestor of monkeys" is incorrect. However, it is the earliest fossil platyrrhine.
- Everyone puts platyrrhines in several families, although how many remains controversial.
- You've changed your terminology from "related" in the previous post to "diverged" in this one. Again, all extant members of a clade are equally related to their last common ancestor, so all platyrrhines are equally related to all catarrhines. You could spend all day arguing about which taxa are more or less "diverged", but it's arbitrary in my eyes. I reserve the term for describing when lineages split.
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I remember my mother saying that the koala was related to wombats and that the giant panda was a type of bear, due to their appearance. At the time, the koala was placed in the Family Phalangeridae and the giant panda was placed in the family Procyonidae, but my mother was right and I was wrong. I think this conversation is really a matter of opinion and I can't prove which platyrrhine is most closely related to apes. All I can do is to use a mixture of knowledge and logic.
1. I agree with you in thinking that Nikola meant the most closely related 'extant' taxon, but this was not stated and the websites I looked at suggested that marmosets and tamarins are probably the most primitive extant platyrrhines. Several taxonomists include marmosets, tamarins, capuchins and squirrel monkeys within the Family Cebidae, but platyrrhine taxonomy is very confused.
2. I'm sorry if I've confused you. I meant that Perupithecus was the first platyrrhine monkey to diverge from the common ancestor of platyrrhines and catarrhines.
3. We're agreed on this one.
4. Please can you indicate the origin of your statement "all extant members of a clade are equally related to their last common ancestor, so all platyrrhines are equally related to all catarrhines". I suppose it may depend on which type of cladism you believe in. The clades I've seen show varying degrees of divergence from a common ancestor and strongly imply that the animals that diverge first are more closely related to the common ancestor. This seems to be one of the reasons why cladism is a useful too in taxonomy.

I don't think we're going to agree on this one. I was trying to help Nikola without going out on a complete tangent. In 1920, François de Loys claimed that a large South American primate was a kind of ape, but the photo is so obviously a spider monkey, it is difficult to understand how many people were misled.
 
Dassie rat said:
I remember my mother saying that the koala was related to wombats and that the giant panda was a type of bear, due to their appearance. At the time, the koala was placed in the Family Phalangeridae and the giant panda was placed in the family Procyonidae, but my mother was right and I was wrong. I think this conversation is really a matter of opinion and I can't prove which platyrrhine is most closely related to apes. All I can do is to use a mixture of knowledge and logic.
1. I agree with you in thinking that Nikola meant the most closely related 'extant' taxon, but this was not stated and the websites I looked at suggested that marmosets and tamarins are probably the most primitive extant platyrrhines. Several taxonomists include marmosets, tamarins, capuchins and squirrel monkeys within the Family Cebidae, but platyrrhine taxonomy is very confused.
2. I'm sorry if I've confused you. I meant that Perupithecus was the first platyrrhine monkey to diverge from the common ancestor of platyrrhines and catarrhines.
3. We're agreed on this one.
4. Please can you indicate the origin of your statement "all extant members of a clade are equally related to their last common ancestor, so all platyrrhines are equally related to all catarrhines". I suppose it may depend on which type of cladism you believe in. The clades I've seen show varying degrees of divergence from a common ancestor and strongly imply that the animals that diverge first are more closely related to the common ancestor. This seems to be one of the reasons why cladism is a useful too in taxonomy.

I don't think we're going to agree on this one. I was trying to help Nikola without going out on a complete tangent. In 1920, François de Loys claimed that a large South American primate was a kind of ape, but the photo is so obviously a spider monkey, it is difficult to understand how many people were misled.
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Without meaning to sound bullish, this is a question of fact rather than a difference of opinion. What I'm saying is counterintuitive, and you're far from the first to make the mistake, but it's basic phylogenetic taxonomy that "all extant members of a clade are equally related to their last common ancestor, so all platyrrhines are equally related to all catarrhines". There are exceptions to this rule, but they're not relevant to this discussion.

This article saves me time and provides a simple example: Phylogenetic Trees and Monophyletic Groups | Learn Science at Scitable. Skip to the section "How to Read an Evolutionary Tree" and, for present purposes, imagine A represents the catarrhines and B, C, and D are your pick of platyrrhines (depending on what evolutionary relationship you choose). The second paragraph basically says this, but to reiterate: A can branch all it likes, but everything that branched off A will still be equally closely related to everything in the BCD clade, provided we only look at extant species. Likewise, however early B diverged, it will still be equally closely related to A as C and D are, even though C and D are more closely related to each other than they are to B. So whilst B may be more basal and C and D may be more derived, that's irrelevant in the context of their relationship to A.

Moving onto the callitrichids, as TLD says, they arguably belong to the most recent family. And, although significant controversy surrounds platyrrhine relationships (reviewed by Perez & Rosenberger 2014*), it's rare to see them at the base. However, it doesn't matter whether they were the first or last to diverge, because they would still be equally related to the catarrhines.

As for Perupithecus, your meaning didn't confuse me, but your interpretation is wrong. Aside from the fact that there never was a monkey common ancestor (at least, not one that excluded apes), Perupithecus wasn't a platyrrhine common ancestor. It represents the earliest fossil platyrrhine, but the fossil record is incomplete. To put that another way, the platyrrhine founder is unlikely to have lived in Peru!


*Perez, S. I., & Rosenberger, A. L. (2014). The status of platyrrhine phylogeny: A meta-analysis and quantitative appraisal of topological hypotheses. Journal of human evolution, 76, 177-187. [https://www.researchgate.net/profil...ypotheses/links/553593750cf20ea35f10daeb.pdf]
 
Thank you all for abundant description, DR, GP, TLD.

Yes I meant on closest extant NWM taxon to the apes, or first maybe to the old world monkeys.

Capuchins would be the most intelligent of all NWMs, and maybe more intelligent that any Old World monkey?
 
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