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RE: attack on dinosaur--horrific video
John Bois wrote:
> Placentals enjoy a great diversity of
> morphologies--probably a greater diversity than is available to, for
> example, marsupials. .... Point
> is, ontogenic imperatives are a limit on morhological diversity in
> marsupials. This is not going to go away for them.
In brief... I don't know how one would go about quantifying "morphological
diversity", but by whatever yardstick you might use, marsupial diversity is
pretty darn impressive. With the exception of volant (bats) and fully
aquatic/marine (cetaceans, pinnipeds, sirenians), almost every niche occupied
by a placental has at least an approximate equivalent among the marsupials.
There's a vast array of marsupial carnivores (thylacoleonids, dasyuroids,
didelphids, borhyaenoids, etc); marsupial moles (notoryctids); marsupial
gliders (various phalangeroid taxa); big herbivores (diprotodontids,
zygomaturids, tapir-like palorchestids, etc); small hopping herbivores (many
macropods, argyrolagids); small insectivores/omnivores (myrmecobiids,
microbiotheriids, perameloids, etc); nectar-feeders (tarsipedids); and so on.
True, marsupials seem to have been shouldered aside by the placentals in every
continent except Australia (where the opposite may be true, based on the
'condylarth' _Tingamarra_). But this speaks to the relative success of the two
clades, and doesn't take anything away from the high level of morphological
diversity represented by the Marsupialia.
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