ancient hairy tick found in New Jersey
barry_roth at YAHOO.COM
Tue Apr 10 15:34:57 CDT 2001
Equally important in those tabulations, although likewise often ignored, is the age of the sister-group of the taxon in question, which may have older fossils. Since sister-groups are of identical age, the oldest fossils of the sister-group set a minimum age for the taxon of interest.
This line of thinking, of course, assumes that the characters by which we recognize the clade in its fossil state date from the origin of the two sister-taxa. But then, that's the standard caveat in any kind of fossil-assisted phylogenetic reconstruction.
"John R. Grehan" <jrg13 at PSU.EDU> wrote:
This is a nice example of fossils representing the minimal age of fossilization
rather than the absolute phylogenetic age of a lineage. Although 'everyone'
this distinction is often ignored, particularly in biogeography and with
clocks (although sometimes with propaganda to convince the reader that
the fossil record in question is accurate, reliable, precise, well known etc.).
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