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Re: THERIZINOSAURS AND LOGIC



        A few addenda:
        1) Jerry D. Harris has pointed out that the correct term for
"four-toedness" is tetradactyly, not "quadrudactyly". Apologies to all for
the confusion.
        2) Mary Kirkaldy very helpfully produced excerpts from the Nature
paper on the new therizinosaur from China. The new specimen is indeed from
the Early Jurassic, although how early it is is still questionable. the
authors do not suggest that this implies a Triassic radiation of
Maniraptorformes. Indeed, they suggest that this implies that the "major
clades" of non-avian coelurosaurs must have diverged by the Late Jurassic.
        However, applying what I know of the analysis of the termporal
ranges of taxa, this would mean  that Therizinosaurs and their sister clade
(possibly Maniraptora, possibly Paraves?) had diverged at latest in the
Early Jurassic. Certainly there ais no requirement of pre-Jurassic
divergence, unless one is willing to say that there is a set minimum amount
of time in which certain evolutionary changes can take place. I'm not
willing to go that far.
        Thanks to the above named individuals.
        Wagner
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    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
                    "...To fight legends." - Kosh Naranek