Actually the tear duct is on the inner part of the orbit (where the orbit bone slopes towards the eye). It's difficult to see on a two-dimensional image, but I've enhanced the image below.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6FwTNEcLvLFAwHaEGSrw10auiX9hBlXYeNFwmVn_NdP70G1N9Fi97yklbUHSftOU9EBlSoD9Sd5H-_-Do_d0vd5sawjX9YwNIS-3TZgrmi_pM_OAU38vr7Q3hmk-aUE3e5bQ0hnP7gBnX/s400/Anteaterskulls4.jpeg)
In each image, the tear duct is actually the smaller hole (ringed in the lower image) - the larger hole is a nerve opening. In each instance, the duct is positioned just slightly on the inner side of the orbit. The limit of the orbit is indicated with a dotted line in the lower image.
In the image linked to appears to be a cast, and, as such, only shows the larger nerve opening and not the tear duct. Small openings are often missing from casts.
More on monotreme-marsupial-placental evolution soon.
Thank you for the explaination. I don't know that much about skulls but found it interesting when I stumbled across you blog.
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