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Re: Digit Loss (kiwis and tyrannosaurs)



In a message dated 6/9/01 1:38:18 PM EST, dbensen@gotnet.net writes:

<< If one studies the full house of diversity of maniraptors through time, 
and not just the extremes to large size and small arms, I doubt you will see 
any trend at all. >>

The only way to find a trend in evolution is to >manufacture< it, by 
>selecting< a single lineage from the multitude of available lineages and 
rendering all its related/dependent lineages as side branches. Every lineage 
represents its own unique "trend" through time. You want a trend of forelimbs 
evolving into wings, you pick a lineage that leads to modern birds from the 
common ancestor of Archosauria. You want a trend of increasing mammalian 
brain size, you pick the lineage that begins with, say, pelycosaurs and ends 
with Homo sapiens. It's not that there are no trends, it's that there are 
incredibly many trends, going in all different directions.