Colours of Wildlife: Vulpavus

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Vulpavus

Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Vulpavus by Willem


I go way back in time again. This is how I imagine the prehistoric critter Vulpavus palustris might have looked like in the flesh and fur. The scientific name means 'marsh-dwelling fox grandfather'. It was indeed an ancient ancestor, belonging to a group from which all of our modern-day carnivorans such as cats, dogs, bears, raccoons, badgers, otters, mongoose, genets, seals and walruses evolved.

Vulpavus itself lived from about 50 to 46 million years ago, and its fossils were found in North America. Several species are recognized within the genus. The type species, palustris, was about 60-90 cm in length, and weighed about 1.2 kg/2.6 lbs. In build, it was very similar to a modern genet with a lithe, long-tailed body and fairly short limbs. It seems to have walked mainly on the soles of its feet, rather than on its toes, as modern carnivorans do. It likely was a good climber. Living so long ago, it didn't leave many clues as to its nature and lifestyle. It inhabited moist, warm to hot forests, which back then covered much more of the Earth than is the case today. Even in what is today northern Canada, a subtropical climate reigned with lush vegetation spreading into the Arctic Circle. Vulpavus appears to have been a generalist predator, hunting critters like smaller mammals, birds, reptiles, amphibians, and some invertebrates. It would likely have eaten eggs if it could find it, and maybe a small amount of plant material such as berries and other fruits.


The context for understanding this little critter comes from the evolutionary history that lead up to it and onward from it. The non-avian dinosaurs went extinct about 66 million years ago, leaving a world in ecological chaos. No land-living animal larger than a cat survived that extinction event. Indeed, the mammals that survived tended to be a lot smaller than that. They inherited a world without any big herbivores or carnivores. A few kinds of versatile birds survived, as did tortoises, lizards, snakes, frogs and salamanders, and, amazingly, crocodiles. It took a few million years for the food webs to sort themselves out again. Initially the forests were filled by an abundance of small, scurrying and clambering critters, feeding mainly on fruit and soon on each other also. Our own ancestors, the primates, got their diversification in high gear. The first really large mammals soon evolved. At first, these were mainly herbivores, and belonged to groups now entirely vanished – rather plodding and ponderous forest and marsh dwellers feeding on soft vegetation. Into the 'Age of Mammals' climates all over the world became cooler and drier, and grasslands spread at the expense of forests. This development spurred new evolution in the mammals, leading to the modern types such as horses, deer and antelopes, that could cope with eating the tough grasses, and run rapidly over the plains.


Evolution of the herbivorous mammals also drove the evolution of the mammals that preyed on them. The first big plant-eaters embodied vast quantities of food for whatever was able to bring them down. But it took the predators quite a bit of time to reach that level. The first things that needed to evolve, was dentition that could deal with meat. The very earliest mammals had had numerous small, sharp teeth. These could deal with insects and other very small prey items. But the muscle meat of mammals is tougher to chew. The adaptation necessary for dealing with this, was shearing teeth, technically known as carnassials. These teeth have sharp, parallel ridges like blades, that shear past each other as the jaws are closed. The carnassials are the cheek teeth of predators; they also have the stabbing canine teeth, and cutting front teeth or incisors, which were already present in the distant ancestors of mammals living more than 250 million years ago.


Shearing teeth were evolved in several ancient groups of mammals. Most notably, there were the Hyaenodonts and the oxyaenodonts, both of which used to be joined into a group called the 'creodonts'. These soon included large members. But they were in many ways quite primitive. They were large-skulled, using mainly their teeth for killing. Their limbs weren't very versatile, and their brains and senses not very sophisticated. Some of them grew quite large quite soon, and they were the first predators able to deal with really large prey animals.


But, like the very first of the big herbivores, the first big carnivores were also not quite equipped for dealing with the ever-changing landscapes and climates. They were set to be replaced by new hordes of smarter, faster, more versatile predators. Enter our little Vulpavus and its kin. It had the shearing teeth for dealing with meat, a slender body with limbs that enabled it to creep, climb and dig. It had a more advanced brain and better senses. It was a generalist, able to exploit numerous different sources of food. This enabled it to thrive and to deal with many changes. These changes of course also drove additional evolution. So, while the 'primitive forest-dwelling predator' shape still exists in our present-day genets, civets and martens, added to that are all the new specialized forms that arose from it, such as the huge bears, the swimming otters and seals, the running wolves and cheetahs, and all the other successful carnivore types of later times.


Around when Vulpavus lived, about 50 million years ago, legions of very similar predatory mammals arose and filled the forests. Clearly the 'type' was very successful. So many different ones are known that it is quite an effort to sort out their relationships. One of the earliest groups of these ancient, small predators is known as the Viverravids, meaning the 'civet grandfathers'. They were present by 60 million years ago, and may already have been distinct 65 million years ago, just after the great extinction. They likely arose in North America. While having the typical shearing teeth, they nevertheless now seem to not have been true carnivorans. They are close, though, and so are called 'Carnivoramorphs' or 'carnivore forms'.


Alongside viverravids there were other small predators called Miacids. The miacids arose about 62 million years ago in North America and Europe. Actually back then, these continents were still linked, with the Atlantic Ocean only just starting to separate them. Miacids included a diversity of forms, though they were mostly rather small. But they were very successful, surviving for about 28 million years. Actually, Miacids are not a proper unit since some of them are just outside of the order containing the modern carnivorans, while others are within it. This basically means that carnivorans evolved from within the Miacids, with the ancestors of all those that exist today, being among their very similar relatives but distinct from them merely from the fact that they evolved into so many new types, while their fellows went extinct without leaving any progeny. The change into 'true' members of the order Carnivora happened about 42 million years ago, in the shape of the species Miacis or something very similar to it, and also to old Vulpavus. While looking like nothing special at the time, it had nevertheless hit the evolutionary jackpot, so to speak, and its descendants today are legion. Let us just hope that enough of them survive the present-day great extinction event that is ongoing as a result of the destructiveness of our own species, Homo sapiens.

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