We know fur had evolved in the Permian, but we don't know the specifics yet. Gorgonopsids like Lycaenops didn't show signs of having evolved whiskers yet, but that doesn't necessarily mean they weren't hairy. If whiskers evolved from specialized hair (rather than hair evolving from generalized whiskers, I guess) they may have appeared only in those therapsids that had the most use for them, the nocturnal and crepuscular small predators and insectivores hunting close to the ground or in close spaces. Some modern mammal groups like monotremes and xenarthrans don't seem to have them at all, and in fact have fairly hariless snouts. Perhaps that was a common thing in early therapsids as well? Hopefully we will know one day.
Now this I love!
We don’t know how hairy they were, we don’t know when pinnae evolved (do we? I’m out of the loop), but it makes NO sense to have such a thick, extended lower jaw, for those saber teeth to be out in the open. Neatly tucked into the lower lip, this looks like a real animal.Completely unlike that Primeval Gorgonops... *shivers*
Shared to my blog, paleo-mammalia.tumblr.com. ^_^
I think the main challenge with the reconstruction of basal mammals is that there's nothing like them now. We have only scaly sauropsids and highly-derived mammalian synapsids to compare them to.
Most reconstructions look like skinned mammals. The most baffling thing is how many artists treat the temporal fenestra as if it were a simple hole or depression in the skull. It's so weird to see the animals with holes where thick and hard muscle should be attached.
I wonder when it did evolve. There's a recent study on the evolution of nasal anatomy across synapsids (non-therian mammals included), yet nothing relating specifically to the rhinarium.