[Taxacom] Another transatlantic rafting primate named this year

John Grehan calabar.john at gmail.com
Mon Dec 21 09:01:08 CST 2020


Evangelos,

" we keep repeating for the South American tortoises of the clade
*Chelonoidis*, whose "ancestor" was probably placed in the Afrotropical."

Do you mean phyologenetically nested within an African group?

"For many years people thought that they came from North America (hence
GG Simpson named a fossil as "*Testudo*" *gringorum*), but molecular
evidence place *Chelonoidis* in a clade with an Afrotropical origin (most
probably)."

Molecular evidence can empirically denote an African relationship, but not
a biogeographic origin.

"It appears that this "raft" had room for plenty of other animals too, and
I find this idea appealing; I would love to read arguments on both
sides though."

What raft? This is pure fantasy. Like a political conspiracy theory.

" there is another possibility: a gravid female tortoise floating alone for
months, until it reaches the shores of the new continent. There is actual
evidence suggesting that tortoises can do that and survive."

Sure, one can dream up anything. A lizard might have hung onto a bird to
make it across oceans, or Noah's Ark passed by at a convenient moment.
There's a difference between an observed ecological event (such as a
floating tortoise) and the biogeographic origin of allopatry. If one has
some empirical evidence for trans-oceanic chance dispersal (keeping in mind
that time and time again this is supposed to have happened only once for
most taxa) then fine, but otherwise its kindergarten twaddle. Little better
than the adventures of adventures of snugglepot and cuddlepie. Might as
well dream up the idea that the ancestral tortoise had wings but then lost
them and we just haven't found the fossil evidence yet.

John Grehan


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