all ears?

Linnaeus

The adorable little creature called Oligokyphus was an advanced cynodont which lived in the late Triassic-early Jurassic periods. He was literally as cute as a pup: only 20 inches long, covered with soft fur; perky whiskers, apparently, grew on his very puppyish face. Oligokyphus was formerly thought to be a true early mammal; but he is now known to be a Mammaliamorph, due to his lack of certain essential mammalian anatomical traits.

Oligokyphus, this furry, weasel-like creature, in spite of the fact that he is today classified as a cynodont reptile, was indeed a transitional, borderline species, closer in most ways to the mammals than to the reptilian stock from which he sprung and to which, technically, he still belonged. Looking at a live Oligokyphus, anyone but a non-specialist would swear that they were beholding a genuine mammal. Many modern illustrations of Oligokyphus represent this appealing tiny creature with pointed, fox-like external ears. We must ask ourselves: did the last of the therapsid reptiles really possess external ears, such as had never previously been seen on any living creature?

We cannot be certain that Oligokyphus or similar borderline cynodonts did, indeed, have external ears. Their fossils reveal no such impressions. Yet it is difficult for soft parts such as ears to be fossilized or to show up as impressions. So the debate goes on: did at least some of the most derived cynodonts have external ears, or did these appear only with true mammals?

Please, Adam and other members, let me have your opinions. The whole matter intrigues me.

Adam Khor

This is a good question, I'd love to know the answer as well but from what I've read thus far, nobody really knows.

The most primitive mammals today are the monotremes, but they don´t help the matter much; echidnas do have (very small and almost unnoticeable) ears, whereas the platypus does not (but platypodes are aquatic and probably lost theirs secondarily).

I think one way to know for sure would be to study the lower jaw bones of the cynodonts. There are bones that are part of the ear in modern mammals due to their being no longer needed in the jaw; they are what give us mammals better hearing than reptiles, and our external ears evolved in order to help increase it even further. So if your cynodont has those particular bones in its lower jaw, it probably didn´t have external ears; if the bones are already part of the ear, then chances are high it did.

Probably very discrete ones, tho, nothing like what we see today...

Linnaeus

Thanks for your response. I'm going to read up on Oligokyphus' jaw anatomy.

What is that lovely, huge-eared mammal in the photo? As you surely know by now, I have a weakness for cute little creatures! Sure would like to cuddle this sweet one!

Adam Khor

It's a fennec fox (smallest living fox and canid)

Linnaeus

Can this darling, furry sweetie-pie be domesticated? Where do these beautiful animals live?

Adam Khor

They come from the Sahara desert (hence the large ears, which act as radiators to get rid of excess body heat).

They're playful even as adults and don´t smell as bad as other foxes, so they've become fairly popular as exotic pets but they are not domesticated; they can´t be housbroken, will laugh at any commands you try to give them (not literally, of course) and will happily run away if not motivated enough to stay. As cute as they may look they're most definitely wild animals.

Rubecula

One minor point, how do we know it was covered in soft fur?

Adam Khor

Rubecula wrote: »

One minor point, how do we know it was covered in soft fur?

We don't. Cynodonts appear to have had whiskers and whiskers are supossed to be specialized hair, so the asumption is they had hair elsewhere. BUT, Cretaceous land crocodiles such as Baurusuchus do show posible signs of having had whiskers as well and nobody thinks they were hairy, so there's that...

Linnaeus

I've read that some of the Oligokyphus fossils display faint impressions of fur on the tail and elsewhere on the body. The muzzle of this animal definitely bore those small notches which are associated with mammalian whiskers. I have not seen the fossils, however, and would not like to accept as absolute truth everything I read in Internet. But, considering that Oligokyphus was only a hair's breadth away from being a mammal, it does seem very likely that he was furry.