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Re: Platypuses may be older than we think...
You don't think so? What if Rowe &c are correct? As it says in the SVP
abstract, which you kindly posted
"New evidence from high-resolution X-ray computed tomography indicates
that *Teinolophos*, an Early Cretaceous fossil from Australia's Flat Rocks
locality (121-112.5 Ma), lies within the crown clade Monotremata, as a
basal platypus. Divergence of the two monotreme clades therefore had
occurred in or before the Early Cretaceous."
I interpret this to mean that the tomography shows the presence of a nerve
that ended in a bill with electrosensory organs. If this nerve is
secondarily reduced in the echidnas (which have a bill and an apparently
reduced electro-sense), we can't tell where on the monotreme tree
I know this contradicts Bininda-Emonds et al. (2007; Nature 446: 507-512),
who provide a molecular-clock-based divergence at around the end-K
extinction for the echidna and platypus lineages.
Worse. They used the latest possible date of this divergence to _calibrate_
Still worse: they got that minimal age by means of assuming that the
Palaeocene *Monotrematum* was a platypodan. Problem is, *M.* is only known
from two teeth, and not a single tachyglossan tooth is known, so we can say
absolutely nothing about its phylogenetic position with respect to
Thus, if Bininda-Emonds &c are correct on the divergence times of the
major placental groups
There are several more mistakes in their calibration points; several times
they used the appearance of total groups as the appearance of crown-groups.
Advice to peer-reviewers: Read the whole supplementary information, tables