[Taxacom] Poor crawling chordates

[John Grehan]

Taxa - clades - whatever term is preferred.

In reference to the expression of support coming from New Zealand, this
region provides excellent evidence, and with extensive documentation, of
Mesozoic tectonic correlations with the living distributions of
differentiated entities. These correlations were apparently dismissed
out of hand by proponents of a post-Mesozoic origin for the extant New
Zealand biota based on theory that at one time all NZ topography was
submarine and so all extant taxa had to originate after that time (a
good example of one theory built up on the backs of another - and one
that was not biogeographic in origin). 

Recently Climo and Mahfeld (2011) showed that the land snail genus
Kokopapa include species that are transcurrently displaced along the
Alpine Fault (geologically predicted to have its inception about 23 Ma)
while other species are associated with faults inherited from Late
Cretaceous-Paleocene and Eocene extensional tectonics. Ironically,
although various dispersal theorists invoked geology to argue for
complete submersion, Climo and Mahfeld point out that detailed
geological mapping does indeed provide evidence for persistent
terrestrial conditions through the Cenozoic and that small refugia
throughout this time supported ancestral land snail populations (and
obviously other terrestrial biota).

John Grehan 

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Rob Smissen
Sent: Wednesday, October 12, 2011 5:55 AM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Poor crawling chordates

Hi y'all

John correctly writes

"As for surviving the Cretaceous extinction, 'specialized' or not, the
spatial correlation of distributions and tectonics does indeed suggest
that many taxa survived the end of the Cretaceous and leave their
biogeographic mark in the present."

I would like to endorse the idea that most of the biota extant today
probably had ancestors predating the end of the Cretaceous. I presume
they were clades - so what in this context are taxa?

cheers
Rob



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