2018-11-14 11:19:58
About thirty million years ago, in the early Oligocene, what is now the Fayoum oasis, southwest of Cairo, was a coastal swampy region surrounded by mangrove swamps and tropical rainforests. It would not be much different from the region of Uganda that borders Lake Victoria and the upper reaches of the Nile today. There lived, among other animals, giant tortoises, snakes, crocodiles, elephants, sirenians, hyraxes, rodents, elephant shrews, various birds, such as jacanas, storks, herons, flamingos, cormorants, eagles… and a wide variety of primates. Some mammals belong to extinct groups, such as the predatory creodonts, the hippopotamus-like anthracotheres, and the embryopods. Among the latter, which are distantly related to elephants, hyraxes, and manatees, the best known, as it is the only member of that group for which complete skeletons have been found, is Arsinoitherium.
The city of the same name is located in the Fayun oasis. The city of Fayun had various names throughout history: It was Shedet for the Egyptians and Crocodilopolis for the Greeks. In the century III BC, under the Ptolemaic dynasty, Pharaoh Ptolemy II Philadelphus renamed it after his sister and wife Arsinoe II, who was deified after his death. Near the ruins of the temple of Arsinoe was where the first fossils of Arsinoitherium were discovered, and for this reason she received the name of that Egyptian queen.
Arsinoitherium is a browsing herbivore resembling a rhinoceros. This is due, as we have seen on other occasions, to evolutionary convergence. The rhinoceros form is a good adaptation for a herbivore, as shown, in addition to Arsinoitherium and the rhinoceroses themselves, are the brontotherians, of which we have already discussed, and the uintaterians, and perhaps even the ceratopsian dinosaurs.
The species discovered in Fayun, Arsinoitherium zitteli, is the best known, and the first to be described. It was named in honor of the German paleontologist Karl Alfred von Zittel, a pioneer of paleontology in Egypt. It is six feet tall at the withers and three feet long, weighing up to two tons. There is another species, Arsinoitherium giganteum, which we only know of from teeth found in 2003 in northern Ethiopia, much larger than those of the Egyptian species. It is estimated that his height on the cross reached two and a half meters.
The head of Arsinoitherium is elongated, like that of rhinos. The brain is small and simple, similar to that of primitive sirenians. The dentition is complete, with 44 teeth, as in many primitive mammals, and does not present the typical gaps between the teeth that herbivores usually have. The molars are thick for crushing tough vegetation.
The skeleton is robust. The proportions of the body and legs resemble those of the elephant more than those of the rhinoceros. The relatively long, columnar legs have five fingers and provide support in the swampy environment in which it lives. Arsinoitherium is capable of running although, due to its large size, adults have nothing to fear from creodonts, the predators of the time.
The most characteristic feature of Arsinoitherium is the pair of huge flattened triangular horns that adorn its head. These horns are angled forward and slightly to the sides, and their base takes up most of the top of the skull, from above the eyes to the nasal bones. Another pair of small rounded horns starts immediately behind the first pair. With age, the horns on the snout become wider, longer, and more pointed.
Arsinoitherium horns are not made of hair like rhino horns, but rather hollow bone. The texture of the bone that forms the horns, with bifurcated neurovascular canals, longitudinal grooves and oblique holes, and roughness at the base of the horn, is reminiscent of bovine horns. In these, the horns are covered by a keratin sheath that provides resistance to impacts. We can assume then that the horns of Arsinoitherium also had a keratin sheath and that they were not a mere decoration, but were used in fights during courtship. With this sheath, the horns would have been even longer than the fossils show us. Which is not little; in some specimens, the bone horns reach a meter and a half in length.
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Reticular Infiltrator is the first novel in the trilogy The Saga of the Borelians. Do you want to see how it starts? Here you can read the first two chapters.
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