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Armadillos at the K/T?
"The xenarthran radiation, which corresponds to the emergence of
armadillos, is estimated here to have occurred close to the K/T boundary
(59-76 Myr) and the separation between anteaters and sloths during the
Palaeocene era (51-65 Myr)." So says Delsuc et al. 2001. The evol. of
armadillos, anteaters and sloths depicted by nuclear and mitochondrial
phylogenies: implications for the status of the enigmatic fossil
_Eurtamandua_. Proceedings: Biological Sciences (The Royal
Society) Vol. 1267. Number 1476. Pp. 1605-1615.
Also notes that fossoriality and carapace is the primitive condition.
Sometime ago, I said that small hairy armadillos which take a penalty-free
heavy toll on rhea eggs, were a good model for potential predation on
dinosaur eggs at or around the K/T boundary. HP Kenneth Carpenter
responded that specific adaptations possessed by these creatures
(particularly digging muscles) ruled them out as models. I argued that
the loose matrix of dinosaur nests made this adaptation unnecessary, that
the relevant point was the ability of small mammals to get into eggs
without crushing them with their jaws (e.g., by knocking them
together). And that's where
it stopped. I wonder 1) if this new finding, especially were it to have
fossil support (eventually), would strengthen the notion of large scale
depredations of non-concealed nests; 2) what are the biogeographical
possibilities of a K/T armadillo--wouldn't this animal have the potential
for a semi-global distribution--North and South America--Asia, at
least; and 3) if such depredations occurred, would one expect to find
evidence for it at affected nests?