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Deltatheridium
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Deltatheridium

fossil mammal genus
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Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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History

Deltatheridium, a genus of extinct mammals found as fossils in rocks from Upper Cretaceous times (about 100–65.5 million years ago) of Asia and, questionably, North America. Deltatheridium was a small insectivorous mammal about the size of a small rat. It is now recognized to be a metatherian, a member of the group of mammals related to marsupials. Deltatheridium has figured prominently in debates about mammalian evolution because it also has some features that are similar to early placental mammals.

This article was most recently revised and updated by John P. Rafferty.