Re: Two more gaps in the fossil record

Cliff Lundberg (cliff@noe.com)
Fri, 15 Oct 1999 10:07:46 -0700

mortongr@flash.net wrote:
>A transitional fossil of a flying dinosaur has been found. The news report
>is on the AP wire. THey call this form Archaeoraptor and it lived between
>120 and 140 myr. The fossil is reported to have traits of both dinos and
>birds, including hollow bones which is a bird trait.

How do we know it's *transitional*? If we know it's transitional, how do we
know in which *direction* the transition is occurring? Maybe all we can say
is that it's *intermediate* morphologically. If birds generally come later in
the fossil record, how do we know they didn't exist as a rare type for a long
time, prior to becoming widespread? We all know about evolution through
reduction, we know about flightless birds; why couldn't Archaeoraptor be
'on the way' toward being a solid-boned flightless creature? What about
the quite reasonable possibility that it left no descendant species at all?

I would like to make my own tiny squeak of protest against the perennial
use of terms like 'archaeo-' or 'proto-' in naming these animals. These words
are not only meaningless in terms of description, they make unjustified
implications about phylogeny and evolution.

Suppose an alien exploring the Earth in the far future found a fossilized
otter. Would he claim it was transitional between seal and badger? What
would justify his claim of the directionality of the transition? Would he be
prejudiced according to whether he himself were terrestrial or aquatic?

--
Cliff Lundberg  ~  San Francisco  ~  cliff@noe.com