Sometimes when it looks like a cat and acts like a cat it’s not; it’s a nimravid! Nimravids are a rather problematic group in the order Carnivora of uncertain descent. Entering the fossil record in the late Eocene (36 million years ago), their exact relationship to other carnivore families is unresolved, but they paralleled cats to an amazing degree. With short faces and fully hooded, retractile claws, they came in body shapes and sizes that covered all of the diversity that true cats would later manifest. Some were as small as house cats, while others were the ecological and functional equivalents of lynx, cheetah and leopard. And all except one lone genus were saber-toothed.

Before we go on, let’s get these curved teeth straight. Saber-teeth evolved from normal, conical canine teeth into two forms. Dirk teeth were the long, curved, finely serrated blades that we normally think of when we think saber-toothed. The famous Smilodon - the saber-toothed “tiger” of LaBrea Tar Pits fame - was a dirk-toothed true felid. There were also scimitar-toothed animals with shorter, more coarsely serrated blades that usually evolved in conjunction with longer-legged cursorial body types. Most of the dirk-toothed animals were compact, robust stalkers.

For a closer look at Barbourofelis fricki click here

Barbourofelis fricki was the last of the nimravids, dirk-toothed and huge. Its name, “Barbour’s Cat“, shows just how close and how confusing convergent similarities can be. This was a massive creature, the size of a modern lion, but more heavily built. At rest or when walking, it stood and moved in a plantigrade fashion, rather like a bear. One look at the business end of the animal however, lets you know that Barbourofelis wasn’t looking for berries. It possessed some of the largest saber-teeth of all time, and the body to back them up. Behind the catlike face, the head had a flat profile caused by the expanded occipital region at the back of the skull. This allowed for the attachment of powerful neck and shoulder musculature, the driving force behind the sabers. This was a stalker and killer of large game.

Nimravids have an interesting history in North America. Throughout the Oligocene, they assumed all the predatory roles later taken by true cats. But by the beginning of the Miocene, 23 million years ago, they had all disappeared. For whatever reason, perhaps because there was an abundance of arctoid (doglike) carnivores of all descriptions present here at the time, there were no nimravids in North America for the next few million years. Felids also were missing and made their North American debut in the form of a small conical-toothed animal, Pseudailurus, about 17 million years ago. (Showing up to really confuse things a few million years later was a scimitar-toothed true cat named Nimravides! Got that? “Barbour’s Cat” is a nimravid, and Nimravides is a real cat! Aurgh!!!)

Finally, after a 10 million year absence, nimravids returned, most likely from Asia, in the form of Barbourofelis. They show up as moderate-sized creatures with moderate-sized dirk teeth.

For a closer look at Hipparion’s very bad day click here

This is an early barbourofelid species based on California material attacking the three-toed horse Hipparion. It is also one of my very first digital paintings. It was done a few years ago for an article by Joe Eaton in the September, 2001 issue of Bay Nature, a Northern California publication dedicated to all aspects of San Francisco Bay Area natural history. Getting this image ready for Olduvai - and I did work on it - I was amazed at how much I’ve improved with this computerized medium. The drawing is fine, except that I gave Barbourofelis a tail that was too long (digitally fixed now), but the color rendering was primitive. My thanks to the editor, David Loeb, for letting me experiment on his dime.

One of the problems with having killing teeth like this was eating the meat once it was secured. Barbourofelis solved the problem by having robust incisors and shearing carnassial teeth to strip and slice meat from bone. Utilizing the carnassials must have been problematic, because the animal had to move its cheek out of the way behind and outside the sabers. You don’t have a 5 million year history without solving those gnawing problems. (I’m SO sorry! I couldn’t stop myself.)

The trouble with a post like this is that it’s a book in the making. There is so much to draw and write about, and so many questions yet to be answered, that I really don’t know what to leave out and what tidbit people might find most interesting. For instance, looking at the paintings the one thing you can’t help but notice is the dependent flange on the mandible of the animals. These protected the sabers when the mouth was closed and there was little room to spare between the saber and the bone of the lower jaw. Maybe I’ve missed it, but I can’t recall having seen anybody paint this as the gum-lined half sheath I’ve portrayed here. There certainly wasn’t enough room for hair to grow, and unless the tooth was supported by being in contact with the flange, it would have defeated its supposed purpose. (I should add that the dirk-toothed felids like Smilodon didn’t have the flange. This is such fun.)

I want to note that things will be changing here at Olduvai George soon. I’ll have an announcement next week about some exciting new developments that will help me to post more often and include more new illustrations. New old whales are coming.

I was hoping to have Kutchicetus up this week but I haven’t nailed the look yet as the new work is based on material I hadn’t seen until last week. 2007 promises to be a very busy year.