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WHERE ICHTHYOSAURS GO
After days and days of hard slog the final proofs for the Pal. Ass. Isle
of Wight book are finally done... watch this space for further info.
> Ichthyosaurs are like turtles, they jump around the reptilian
> tree too much, even outside it.
To the best of my knowledge this isn't true - of the relatively few
studies that have included ichthyopterygians (Ichthyosauria +
Hupehsuchia) in an analysis together with other reptiles, ichthyosaurs
are diapsids, usually neodiapsids, and either lepidosauromorphs or
archosauromorphs (John Merck has published abstracts on the latter
position and I hope he's working on the paper that will present the
data). Huene, Maisch, Osborn and others have famously argued that
ichthyosaurs are not diapsids, or even not reptiles, but these
conclusions are not based on parsimony analyses, rather on
consideration of a few aberrant features that are probably
ichthyosaurian autapomorphies (e.g. robust suspensorium, infolded
Likewise Nichols et al's suggestion that ichthyosaurs might be closest
to younginiforms was based on simple comparison with the character
lists given in Mike Benton's papers on diapsid phylogeny.
There is a nice quotation that sums up this sort of controversy in
Farlow et al's recent _American Zoologist_ theropod locomotion
paper. It is....
'Is it reasonable to let a phylogeny based on a large number of
characters [to] be 'trumped' by one or a few characters seemingly at
variance with it?' (p. 643).
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