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Research Article

Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology

  • Jens L. Franzen,

    Affiliations: Forschungsinstitut Senckenberg, Frankfurt, Germany, Naturhistorisches Museum Basel, Basel, Switzerland

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  • Philip D. Gingerich,

    Affiliation: Museum of Paleontology and Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan, United States of America

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  • Jörg Habersetzer,

    Affiliation: Forschungsinstitut Senckenberg, Frankfurt, Germany

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  • Jørn H. Hurum mail,

    j.h.hurum@nhm.uio.no

    Affiliation: Natural History Museum, University of Oslo, Oslo, Norway

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  • Wighart von Koenigswald,

    Affiliation: Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Bonn, Germany

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  • B. Holly Smith

    Affiliation: Museum of Anthropology, University of Michigan, Ann Arbor, Michigan, United States of America

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  • Published: May 19, 2009
  • DOI: 10.1371/journal.pone.0005723
  • Published in PLOS ONE

Reader Comments (13)

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Determination of Polarity

Posted by keesey on 20 May 2009 at 22:00 GMT

The final column at the right in Table 3 shows which character states can reasonably be considered synapomorphies of Darwinius and either Strepsirrhini or Haplorhini (requiring that states be both derived and present).
http://plosone.org/article/info:doi/10.1371/journal.pone.0005723#article1.body1.sec4.sec2.p4

How was character polarity determined? Shouldn't a stem-primate outgroup have been included, or was this implicit?

No competing interests declared.

RE: Determination of Polarity

Quietman replied to keesey on 24 May 2009 at 08:24 GMT

The sentence after the one marked as #1 in "Discussion":
"Some characters may be noted as indeterminate for Darwinius because of evidence of convergence, for example, presence of tritubercular molars in extant and early Eocene representatives of Tarsioidea means quadrate molars evolved independently and convergently in Strepsirrhini and most later Haplorhini."
I would think that assigning it to subordor Euprimates it would make Haplorhini implicit (IMO).

No competing interests declared.

RE: Determination of Polarity

Quietman replied to keesey on 24 May 2009 at 08:40 GMT

ps
"Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification." is explicit IMO.

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RE: Determination of Polarity

keesey replied to Quietman on 27 May 2009 at 19:05 GMT

Perhaps I wasn't clear. You can't tell which characters are plesiomorphies or apomorphies for crown-group primates without looking at stem-group primates. E.g., if crown-strepsirrhines have trait X and crown-haplorhines don't, that tells us nothing about X's polarity with regard to the primate crown group. We have to look at stem-primates -- if they have X, then it's (probably) a plesiomorphy and the loss of X is an apomorphy of crown-haplorhines. If they don't, then the lack of X is (probably) the plesiomorphy and its presence is derived in crown-strepsirrhines.

They mark "tooth comb of lower incisors-canines" and "loss of grooming all claws" as derived in Table 3. Presumably, then, there are stem-primates with grooming claws but not tooth combs, but I don't see where this is made explicit. Same question goes for all the other traits. Is the polarity just common knowledge for people who study non-simian primates, or am I missing something?

Also, that statement seems to me to contain an unwarranted assumption. If the tooth comb is a synapomorphy of crown-strepsirrhines, then that doesn't mean that tooth combs were present in all stem-strepsirrhines. That is, when the strepsirrhine and haplorhine lineages diverged, the first members of the strepsirrhine total group almost certainly didn't instantaneously develop tooth combs. So, that trait would just as easily agree with a stem-strepsirrhine position as a stem-haplorhine position. (The grooming claw, though, if it is a plesiomorphy for crown-group primates, would indeed agree better with a stem-haplorhine position.)

No competing interests declared.

RE: RE: Determination of Polarity

Quietman replied to keesey on 29 May 2009 at 05:20 GMT

I think that is the bush they are beating around. This hints that it is close to the ghost lineage that Beard's talks about in his book "Hunt for the Dawn Monkey" and that a rewrite of the taxonomy for Euprimates is needed. Considering how long the Lemur lineage has been isolated from the rest of the primate lineage they may have to do a rethink of just how far this split occurred and what is the actual stem lineage. Beard disagrees that it even close to the Tarsier lineage and presents a credible argument for it in his book. To me this fossil lends credence to his argument.

No competing interests declared.