2019-03-22 11:36:55
A century and a half ago, in the middle of the century XIX, ranchers in Sioux County, in the northwestern corner of Nebraska, began to find some strange half-buried structures that they called “devil’s corkscrews.” These were vertical spirals of rock, thicker than an arm and up to ten feet high, that erosion was exposing on the sides of the hills. In some places, the corkscrews of the devil appeared grouped together forming “forests”.
In 1891, one such rancher, James Cook, found several of these corkscrews on his property on the banks of the Niobrara River. That same year, geologist and paleontologist Erwin Hinckley Barbour had come to the University of Nebraska as head of the Department of Geology and was appointed State Geologist by the governor. Thanks to the donations of Charles Henry Morrill, a member of the university council, Barbour organized scientific expeditions throughout the state every summer to enrich the collections of the university museum. On the first of these expeditions, that same year of 1891, Barbour’s group happened to pass through the vicinity of Cook’s property, and Cook alerted him to the devil’s corkscrews. Barbour excavated some of them and discovered that they were whitish tubes with a fibrous appearance filled with calcified roots, sand and sediment; These were not rocks, but fossils, which Barbour called Daemonhelix, Latin for “devil’s propeller”.
The following year, Barbour proposed that they were freshwater sponges, since the sediments in which they were found had been deposited during the Miocene, about twenty million years ago, at the bottom of extensive lakes. Or so it was believed then. When new investigations revealed that these sediments corresponded more to semi-arid grasslands, Barbour suggested that Daemonhelix was a giant land plant.
Meanwhile, paleontologists had found rodent bones inside some corkscrews. In 1893, the American Edward Drinker Cope and the Austrian Theodor Fuchs independently proposed that Daemonhelix were the remains of ancient burrows, built and inhabited by those rodents. Barbour would not budge, maintaining that the propellers were too perfect to have been built by a burrowing animal. But the discovery of scratches inside the tubes ended the controversy; They showed that an animal had dug them up.
In 1905, the corkscrew maker was finally identified: an extinct species of beaver called Palaeocastor, which had been described by Joseph Leidy in 1869 and which inhabited the North American wastelands during the Oligocene and part of the Miocene, thirty years ago. and twenty-three million years.
Palaeocastor, with an elongated body about a foot in length, is smaller and more slender than living beavers. It has large claws, a short tail, small eyes and ears, and long incisors that, as in all rodents, grow throughout life to compensate for wear.
Like many primitive beavers, Palaeocastor was not an aquatic animal. It lived in family groups and, unlike most rodents, the pairs had few young, in whose care they invested considerable time and resources. Like today’s prairie dogs, they formed colonies; in some sites groups of up to two hundred burrows have been found.
At its lower end, the spiral ends in a set of chambers where beavers sleep and care for their young; in some of them there are deeper spaces that could function as water drains or latrines. In certain burrows, the chambers have a sloped floor to prevent the accumulation of water. The scratches on the inner walls, which were at first interpreted as claw marks, were actually made by the incisors; Palaeocastor dug with its teeth.
It is not known for sure why Palaeocastor built its corkscrew-shaped burrows. It can be to make access difficult for predators, to control the circulation of air inside and prevent the entry of air that is too hot or humid, to facilitate the extraction of earth thanks to the lesser inclination of the tunnel, to increase the surface of the burrow and thus improve drainage in the event of possible flooding, or simply to explore the subsoil in search of the most favorable area for the construction of the lower chamber.
Palaeocastor’s bones are not the only ones found inside devil’s corkscrews; in one of them the fossil remains of Zodiolestes appeared, a burrowing mustelid that must have been one of the main predators of Palaeocastor.
Palaeocastor became extinct as the humid Oligocene gave way to the Miocene, with a drier, grassland-dominated climate. But theirs are not the only spiral burrows we know of. Already in the Permian, 260 million years ago, the Diictodon therapsid, a relative of mammals, half a meter long, with a large head, a horny beak, a pair of long fangs in the upper jaw and strong legs with sharp claws. , built burrows up to two meters deep. And even today, lizards of the species Varanus panoptes, lizards between three feet and five feet long that inhabit northern Australia and southern New Guinea, live in burrowing colonies even more complex than those of Palaeocastor. : these burrows begin with a straight, slightly inclined tunnel, followed by a helical section of up to eight turns, sometimes with changes in the direction of twist, and end in an egg-laying chamber, which can be as deep as three meters and a half Complex behaviors are not unique to mammals.
CONSTRUCTION OF GERMAN FERNÁNDEZ:
reticular infiltrate
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.
The Karnak file. Ed.Rubeo
The hanged man and other fantastic tales. Ed.Rubeo
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