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Who linked Roger Rabbit?

Last updated on 22 Jun 2018

Movie_poster_who_framed_roger_rabbit.jpg I’ve been rather busy of late, including being in a movie review club for a beautiful little French film The Hedgehog, based on a book The Elegance of the Hedgehog, which is a much better title. I recommend it.

Anyway, lots of biological linkery to cover. To start with, Henry Gee, the master of Cromer’s pier, is on a roll with another excellent piece, this time on why sauropods got so big. Also, Stop Following Me! We are not the end of the evolutionary line. On a related note, Ryan Gregory at Genomicron, discusses the notion of “primitive“, something I have discussed myself before.

I don’t know what I think about this claim that marsupials evolved in South America, based on jumping gene genealogies. We knew already that South America shared marsupials when Gondwana was united, but how one might tell that the LCA of all marsupials was South American is beyond me.

Mike Keesey has been trying to visualise primate fossils based on their age and distribution. Here’s one version, and here’s another. I prefer the latter, myself.

The New York Times had a nice piece about the Ediacaran fossils, with cute pix.

Here is a review of Carol Kaesuk Yoon’s recent book on classification Naming Nature. However, it indicates the book is anti-cladistics and is a continuation of Mayrian subjectivism.

Now it’s Nature Network’s turn to upset science bloggers.

Now for some philosophy:

Quinn O’Neill at 3quarksdaily gives the knockdown argument about why gay marriage is okay. I made a similar argument myself a while back.

Does science save theology? I can’t tell as I no longer have access to PNAS. But Philosophical Disquisitions continues the series on Gwiazda’s takedown of Swinburne’s proof of God’s existence.

u n d e r v e r s e discusses Coyne on free will.

The Unpublishable Philosopher detects an inconsistency in Owen Flanagan’s promotion of Buddhism as rational and Catholicism as not.


    • John S. Wilkins John S. Wilkins

      I mean that this is a classic case of “centres of origin”. There are several ways that this data might have evolved, and one of them is that the basal taxa went extinct in Australia but that the LCA lived there. Another is that the LCA was distributed across both regions. None of this would show up in the molecular data.

  1. Allen Hazen Allen Hazen

    Thanks for the reference to the Marsupial article! I’ll look at it at PLoS and get back to you if I have anything intelligent to say. … I assume the argument for a South American Center (as we Americans spell it) of Origin is of the same general form as the argument that “Mitochondrial Eve” lived in Africa: it is certainly consistent with the evidence to say she lived in Macedonia and that various of her descendants with mDNA sequences that have died out in Eurasia immigrated to Africa, but more parsimonious to say she probably lived on the continent which still shows the widest range of mDNA types.

    South American C. of O. for living Marsupials is the majority bet, I think, among paleontologists. Marsupials (and Deltatheridians: D is believed to be a sister-taxon of Marsupialia) are known from Asia and North America from the Cretaceous and early Cenozoic, but later died out in the North. (Extant North American Opossum is a comparatively recent re-immigrant from South America.) So it is widely believed that they had C. of O. there, and got to Australia by way of South America and Antarctica (early Cenozoic Marsupial fossils are known from Antarctic islands). Some travel in the opposite direction (Australia–>Antarctica–>South America) is possible, but to get an Australian C. of O. you have to assume that several basal lineages, after separating from the ancestors of ‘Roos and Possums, all went back to South America and died out in Oz.

    • John S. Wilkins John S. Wilkins

      Is it parsimony or Bayesian priors? All parsimony does is give you the least complex distribution; to make out that the CoO was South America, you need also to make assumptions about how taxa are distributed, and it doesn’t seem to me we have sufficient information to be sure that the basal taxa weren’t once distributed in Australia, Antarctica or all three. A lack of evidence is not evidence, especially in paleontology, and we do not know as much about ecology and evolution as we think we might. We multiply hypothesis upon hypothesis, and so I think that the inferences are not well founded.

  2. Allen Hazen Allen Hazen

    John– Still haven’t read the article: will get back to you when.

    I was using “parsimony” in a pretty vague manner. I guess I COULD claim literal parsimony: assuming the center of origin is where the basal branches are involves postulating only one migration event (ancestor of Australian marsupials goes south and west before turning north) and a “pseudo-extinction”: its derived descendants are still with us, but no surviving lineage in Australia preserves the plesiomorphic state of the ancestor. In contrast, assuming the c. of a. was in Australia involves postulating at least three migration events (ancestor of common ancestor goes from South America to Australia– since paleontology and geography suggests Metatherians (=Marsupials and extinct forms closer to Didelphis than to Mus) came to Australia by that route, migration of at least two, maybe three, basal marsupial branches from Oz to S.A., plus extinction of those basal branches in Oz.

    Of course, using that sort of parsimony as a basis for inference requires a “prior” to the effect that migration and extinction events aren’t too likely. (Which is, of course, a license to convert absence of evidence into evidence of absence!)

    But I wasn’t really being very rigorous. I’ll write if, after reading the article, I have any intelligent thoughts.

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