The Avashishta bacharamensis is dated to about 72 to 66 million years ago. It is known from a single tooth from Late Cretaceous India, Avashishta may represent a late-surviving haramiyidan, a non-mammalian mammaliaform near the mammal line. Its classification is debated, so this is best marked as a tentative “possible last known” entry.

For sure, non-mammal mammaliaforms lived to about 150 million years ago. For example, the Late Jurassic docodont mammaliaform from Portugal. It had many mammal-like traits, including complex teeth and mammaliaform-style tooth replacement, but belonged to a side branch outside the living mammal line.