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RE: CNN:Mammal groups showed up before dinos died out
If you're already subscribed to VRTPaleo you can delete this now. If
not: it's one of the messages that was sent in response to a message
Betty Cunningham sent both here and there. Henry tried to respond to
both lists, but he's not subscribed to this one so listproc kicked it
to me. If you have any comments on the content below and wish said
comments to be seen by the writer of the words below, please make sure
you send a copy to:
Mickey Rowe (firstname.lastname@example.org)
P.S. Betty actually kicked off a big discussion on VRTPaleo. Consider
subscribing and checking the archives if you'd like to see it.
Date: Fri, 1 May 1998 10:06:00 +0100
From: "Gee, Henry" <H.Gee@nature.com>
To: ",email@example.com " <firstname.lastname@example.org>, ",email@example.com "@usc.edu
Subject: RE: CNN:Mammal groups showed up before dinos died out
I can attribute most reactions to the CNN post below to one of two
things -- the journalist who wrote it either didn't understand the
paper or didn't bother to read it in the first place.
Here is what the Nature press release (which I wrote) actually
"EVOLUTION: CHANGING TIMES (pp917-920)
Evolutionary biologists need a timescale against which rates of
morphological and molecular change can be calibrated.
these times are obtained from the fossil record, where the earliest
representatives of two lineages provide a minimum divergence time.
clock-like accumulation of differences in genes provides an
alternative method, but this clock may be wayward - which is why
Sudhir Kumar and S. Blair Hedges of Pennsylvania State University,
University Park, Pennsylvania examined no fewer than 658 nuclear
to establish an evolutionary time scale (see their report on p917).
Most of the divergence times estimated from molecules agree with
fossil record - but there are interesting exceptions. In
the results suggest that a least five lineages of placental mammal
arose more than 100 million years ago, and most modern mammalian
orders appear to have diversified well before the
boundary 65 million years ago. A picture of mammalian
immediately after the dinosaurs died out no longer seems tenable. "
Clocks may be wayward, but a clock based on 658 genes must be less
wayward than a clock based on one or two or twenty. And
paleontologists will get a nice fuzzy glow to know that the results
agree with divergence times of lineages as estimated from the
record -- which is why the disagreements between molecules and
for certain eutherian lineages stand out so starkly.
Perhaps people would do themselves, the authors and one another the
honor of reading the paper before taking a CNN posting at its word,
and flying off the handle.
Dr Henry Gee
______________________________ Reply Separator
Subject: CNN:Mammal groups showed up before dinos died out
Author: ,Betty Cunningham [SMTP:firstname.lastname@example.org] at Nature-UK
Date: 30/04/98 18:49
CNN article appears at:
Major mammal groups appeared before dinosaurs died out, study says
April 29, 1998
The work suggests at least five major lineages, which today include
such creatures as rodents, elephants and armadillos, might have
appeared more than 100 million years ago.
The results, based on analysis of genes, are presented in Thursday's
issue of the journal Nature by S. Blair Hedges and a colleague at
Pennsylvania State University. Hedges and co-authors published a
similar study in 1996, but their new study includes many more genes.