More news on pre-Chicxulub mammalia. Cell has the full report: Neil Brocklehurst, Elsa Panciroli, Gemma Louise Benevento, and Roger B.J. Benson "Mammaliaform extinctions as a driver of the morphological radiation of Cenozoic mammals".
Two issues are at play here: the "therian" mammals up to Cretaceous aren't very big, and they aren't very diverse. Therians are us placentals and marsupials; monotremes are out. So're multituberculates and that psychedelic monster they found in Malagasy.
They figure that although the dinosaurs kept us short (and out of the air I guess), they wouldn't have kept us monotonous. Below dino height is also below man height. Scurrying arould our forests are a wide range of badger, lemur, mouse, shrew, and all manner of other little woodland critters. At least, so it is today, under far more dangerous conditions than held under less-intelligent dinos. Where they all at in 70 Mya? This blog has documented some diversification but, we're being told, it's still not enough.
Brocklehurst's crew figures that our ancestors must have been competing with lingering nontherians. Maybe egg-laying Tasmanian Devils.
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