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Re: Digit Loss (kiwis and tyrannosaurs)



> <Not that I'm trying to get the last word or anything, but it
> seems that our argument is getting bogged down by particulars,
> so we should probably end this thread.>
>
>   The point of evolutionary theory is particulars. There are no
> generalities :)

Well said!!!

> <There is no trend towards larger size in horses, but since
> horses began near the minimum horse [=perissodactyl, as
> *Hyracotherium* is very similar to the form of the common
> ancestor of horses, tapirs, and rhinos, and has even been
> suggested as _it_] size, a randomly diverse speciation of these
> animals produced animals larger than the precursers.>
>
>   If one takes the basal horse lineage, and goes from the Eocene
> up to the Holocene, one sees that later lineages are bigger than
> their predescesors. This is what is called a "trend."

If one goes from the Eocene to the Pliocene, one sees LOTS of DIVERSE
lineages, with size varying almost like hair color. *Hyracotherium* (BTW, an
SVP meeting abstract has totally split this apparent waste basket and
resurrected *Eohippus*) underwent a size _decrease_ at first, and its size
was repeatedly reached by later lineages (*Nannippus*...). If one goes from
the Pliocene to the Holocene, they all die out except *Equus*, so we're
constructing all those trends a posteriori. Main ref: Stephen J. Gould: Full
House.