Thursday, August 12, 2010

More studies - more evidence

Here is a very recently published study (Senter 2010):

"Using creation science to demonstrate evolution: application of a creationist method for visualizing gaps in the fossil record to a phylogenetic study of coelurosaurian dinosaurs"

Abstract:
http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2010.02039.x/abstract

Supporting information:
http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2010.02039.x/suppinfo

A careful read of this shows what we have seen as a definite pattern. There is great morphological evidence for a "Tyrannosaur cluster" and also for a "Bird-Like Cluster".
But no evidence that those two groups are related.

Here is the interesting way the article puts it:
"As shown here, according to one of their own statistical measures, baraminologists must consider Archaeopteryx and other basal birds – including the more typically birdlike Confuciusornis and Sapeornis– the genetic relatives of dromaeosaurids and other birdlike coelurosaurs, and possibly even compsognathid and tyrannosauroids."

It uses the word MUST in reference to the relatedness within the Bird-like cluster.
But it uses the word POSSIBLY for any relatedness between that group and compsognathid and tyrannosauroids. Which is where the actual issue is.

AND

"Tyrannosauroidea, Compsognathidae and Ornitholestes [the "Tyrannosaur cluster"] form a morphologically continuous group. Basal birds (Archaeopteryx, Confuciusornis, Sapeornis) are part of a morphologically continuous group that also includes Dromaeosauridae, Troodontidae, Epidendrosaurus + Epidexipteryx, Protarchaeopteryx + Incisivosaurus and Falcarius [the "Birdlike cluster"]. Therefore, baraminologists must consider the members of each group to be genetically related. The distance between the two groups is also small enough that within the baraminological paradigm both groups are arguably genetically related to each other."

Again the same story. There is great morphological evidence for a "Tyrannosaur cluster" and also for a "Bird-Like Cluster". But no evidence that those two groups are related.

6 comments:

  1. Does the paper not show the actual numbers then?

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  2. The abstract is available online. To see the article you need to pay.
    I understand there is no overlap in the scatterplots of the two clusters.
    But that is not surprising. When you look at the characteristics of the Tyrannosaurs and you look at the characteristics of birds they have almost nothing in common.

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  3. If there are graphs then is it not possible to work out the numerical distance between the two groups at their closest point?

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  4. Anonymous said...
    "If there are graphs then is it not possible to work out the numerical distance between the two groups at their closest point?"

    That seems like a great question. I am looking into it. (I just wish I had more time. There are so many interesting things to research.)
    Here is a quote from the article that:
    "It is noteworthy that bifurcating trajectories are visible in the 2009 scatter plot in a number of places (Fig. 2). Within Dromaeosauridae, the sequence Velociraptor→Deinonychus and the sequence Sinornithosaurus→Microraptor extend in different directions from Bambiraptor, which is at the apex of the 'V'. Another bifurcation is present within the Tyrannosaur Cluster, with Guanlong + Ornitholestes at its apex and with Gorgosaurus→Tyrannosaurus leading in one direction and Huaxiagnathus→ (Sinosauropteryx + Compsognathus) leading in another direction. Baraminologists recognize that a trajectory of dots within a CMDS or ANOPA scatter plot represents morphological evolution within a lineage (Wood & Cavanaugh, 2003; Wood, 2005a,b), in which case bifurcating trajectories must represent speciation. It is also noteworthy that these bifurcating patterns correspond reasonably well to the bifurcations on the cladogram in Fig. 1, with the more basal members of each group closer to the origin of each scatter plot bifurcation."

    So it would seem that the lack of a "trajectory of dots" between the two clusters indicates that they are not related. They do not "represent speciation" between the two clusters.

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  5. So you can't actually see on the graphs what numbers the dots correspond to and work out distances? They don't sound like very good graph's then. Doesn't the author even state what the numerical distances are?

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  6. The "Supporting Information" page (http://bit.ly/8XvxMt) has a link to a file "JEB_2039_sm_AppS1-S4-TabS1-S10-FigS1-S2.doc" (http://bit.ly/9Cib2R) which includes the Phylogenetic Data Matrix, as well as "Three-dimensional coordinates of the CMDS visualization for [YEAR] matrix" and "Morphological distances between taxa as found by CMDS analysis of the [YEAR] matrix" for matrices from five years.

    Here's a (poorly formatted) copy-paste. Is this what you're looking for?

    Table S1 Morphological distances between taxa as found by CMDS analysis of the 1920 matrix.

    Allo.s Arch. Comp. Gorg. Orn’l. Str.
    Allosaurus 0.000
    Archaeopteryx 0.440 0.000
    Compsognathus 0.270 0.284 0.000
    Gorgosaurus 0.184 0.454 0.326 0.000
    Ornitholestes 0.270 0.255 0.121 0.284 0.000
    Struthiomimus 0.376 0.390 0.262 0.376 0.255 0.000

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