Colours of Wildlife: Euchambersia
Created | Updated Apr 21, 2019
Euchambersia
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!"
Another prehistoric animal for you today. Euchambersia mirabilis, or 'Chambers' true wonderful critter', is known from a couple of skulls found in South Africa. They date from the Late Permian, about 256-255 million years ago. The first skull was discovered in the nineteen thirties by famed palaeontologist Robert Broom, and named after Scottish evolutionary thinker Robert Chambers. Chambers published, anonymously, a book called 'Vestiges of the Natural History of Creation', a work that spoke about evolution well before Charles Darwin's 'The Origins of Species'. Back to Euchambersia. This animal was a Therocephalian, a group I've already devoted much writing to. This one merits an article of its own! Like other therocephalians, it was an advanced pre-mammal, but not on the main branch that led to the true mammals. It already had many advanced features of its skeleton, likely had a fast metabolism, and perhaps was coated in hair or fur. It was not large, going by the skulls that we have: about the size of a cat or small dog. The rest of the body not being known, I based it on that of other known therocephalians: a fairly compact body, shortish and sturdy limbs, and a short tail. It likely held its body well off the ground. While not a speedy runner by the standards of modern-day animals like gazelles or cheetah, it was likely fast and agile for its time, able to catch many other critters of a size similar to itself. Like other proto-mammals of its time, it might have been partly or fully nocturnal.
The environment in which Euchambersia lived was a floodplain crossed by many rivers, their banks supporting tall trees that were likely ancestral to modern gymnosperm or cone-bearing plants. The climate had distinct moist and dry seasons. The fauna included many other therocephalians, as well as gorgonopsians, biarmosuchians, dicynodonts, and cynodonts. These were all proto-mammals, groups I have discussed here in some detail. There were also other reptilian creatures, including distant ancestors of the archosaurs, the group that later evolved into the dinosaurs and which today still includes the birds and the crocodiles. Other more primitive reptile-like things still abounded, as did amphibians. Again, these 'amphibians' were perhaps not directly ancestral to modern frogs, toads, newts and salamanders. They were somewhat salamander-like, but included some hefty-sized creatures. All in all, it was already an ecologically diverse and rich region in which old Euchambersia roamed and hunted.
Groovy Teeth and Face Glands
The amazing feature of Euchambersia is immediately visible in its skull. The skull was comparatively short, broad and deep. Like with many other therocephalians, it doesn't have teeth behind its canines in its upper jaw. But it also had something else: immediately behind the upper canines there was a big hollow on each side of the jaw, opening upwards towards the eye. This hollow must have been filled by some kind of soft tissue in life. Also, the canine, which is long and sharp, has a groove along its front surface. This suggests that there was a gland in the face, and perhaps one that secreted some liquid onto the canine tooth, which would have run down the groove towards the tip of the tooth. The hollow containing this possible gland also had external openings; scans of the skull showed that these were the ends of channels in the bones that contained nerves and blood vessels leading to the teeth and mouth tissue, probably to support the glands and their secretions, and/or to conduct the secretion to the tooth. To scientists thinking about such things, one possibility leaped out: venom! If the gland contained poison, which was then injected into a wound inflicted by the canine teeth, then Euchambersia would have had a great advantage as a hunter. Like modern venomous animals, it could have inflicted a quick bite, and then waited for its prey to succumb to the venom, upon which it could feed on it at leisure.
This has by no means been proved yet. The groove on the tooth was apparently not as deep as initially supposed, more like a shallow ridge, so the canines were nothing like the hollow venom-delivering fangs of snakes. But even an inefficient system would still have been a start. At least one other therocephalian, Ichibengops, is also suspected of having been venomous. The time at which they lived, the Late Permian, was one of massive experimentation with new anatomic and metabolic features, and ways of life, especially among the proto-mammals. It is by no means impossible for these early animals to have started on the venom path. Sadly, this initial experiment was cut short. The massive extinction at the end of the Permian wiped out almost all of the proto-mammals; only some cynodonts, dicynodonts and a few therocephalians (but not Euchambersia) survived. From there, it took a lot of evolution to produce new venomous animals. There might be many we don't know about – even some of the dinosaurs may have been venomous. But venomous snakes only came into existence relatively late, perhaps in the Cretaceous. It's possible that venomous lizards, similar to the modern Gila Monster and the Komodo Dragon, preceded them. No bird ever developed active venom, though a few kinds are toxic. In mammals, we today have venom in the Duck-Billed Platypus (though used only for defense), in some shrews, and in a related kind of insectivore called a Solenodon. These are all mammals that can in some way be called rather primitive; they shared a common ancestor living in the early Jurassic. This is long after Euchambersia's time, and yet it shows that it's not such a far stretch to suppose that venom evolved quite early in the game. What is perhaps puzzling is why, when in many ways it seems to be an ideal method for hunting, it is not used by many more mammalian predators today.
I must stress that we don't actually know if Euchambersia was truly venomous or not. No venom survived the fossilization; no glandular tissue either, only petrified bones. So it is possible that the hollows in each side of the skull contained some other kind of gland or thing. It's difficult to work out what else it might have been, other than a venom gland. Yet, something else it might indeed have been. This just highlights the difficulty of figuring out the full anatomies and lifestyles of extremely ancient living things, from the bits and pieces that ultimately come down to us after hundreds of millions of years. It is actually quite astonishing that we have so much and in such a good state of preservation. It would help if we found more material of Euchambersia, including some of the skeleton behind the head.
