>Another conclusion I would like to make is that an animal's gape has
nothing to do with its ability to gnaw into a hard-shelled egg. But I
can't. I don't know how the armadillo get into the egg.
In the past, when feeding some Varanid lizards, I have had to use a variety of egg sizes (ranging from small to extra jumbo) because of their inabilty to crack the shell of the eggs that were too large for the animals gape (which is considerable). However, I will admit that armadillos are likely probably more "inventive" (relatively greater capacity for insight learning) than varanids.
Also, and I raised this point before in an old stealthy oviphagus thread, there is (was at that time at least), no evidence in the fossil record of eutherian mammals having preyed on dinosaur eggs. My guess is that if mammals were preying upon dinosaur eggs in the fashion that was ascribed to the hairy armadillo, that the same event/process that led to the fossilization of a dino-nesting site, would similarily preserve some evidence of this form of predation in/and the network of underground tunnels.