Rock hyraxes, identified in southern Africa extra usually as “dassies,” are furry, thickset creatures with brief legs and no discernible tails. They spend a lot of their time sunning themselves on rocky outcrops.
One other factor they generally do is drag their butts alongside the bottom. Canine homeowners know that this habits generally is a signal of parasitic infections; in hyraxes the explanation appears to be much less clear, however this motion leaves distinctive traces in sandy areas.
Traces and tracks — historic, fossilized ones — are what we research on the African Centre for Coastal Palaeoscience by way of the Cape south coast ichnology undertaking. Over the previous few many years, we’ve got discovered nearly 400 vertebrate tracksites on this coast, some as previous as 400,000 years, in cemented dunes often called aeolianites from the Pleistocene epoch. This epoch lasted from about 2.58 million years in the past to about 11,700 years in the past.
We’re increase an image of the surroundings throughout that interval and the way the animals and vegetation of that point lived.
Amongst our newest finds are two fossilized traces that seem to have been made by rock hyraxes way back. One is a observe website and the opposite is a butt-drag impression with what could also be a fossilized dropping in it.
The possible observe website was delivered to our consideration from a website close to Walker Bay on the Cape south coast by an ardent tracker, Mike Fabricius. It’s round 76,000 years previous. We discovered the possible butt-drag impression east of Nonetheless Bay on the identical coast, and it’s most certainly round 126,000 years previous.
The butt-drag impression is the primary fossil of its sort to be described from wherever on this planet. As well as, these are the one doable fossilized hyrax tracks ever to be recognized. On the planet of paleontology, something this uncommon is essential and we really feel privileged to have the ability to interpret them.
Deciphering the drag mark
Relationship on our websites has been completed by way of a method often called optically stimulated luminescence, which works by analyzing when supplies like sand have been final uncovered to mild.
The butt-drag impression is 95 cm [37.4 inches] lengthy and 13 cm [5.1 inches] vast. It comprises 5 parallel striations. Its outer margins are barely raised, and inside it there’s a 2 cm-high [0.8 inch] raised characteristic, 10 cm by 9 cm [4 by 3.5 inches]. Clearly one thing was dragged throughout the floor when it consisted of free sand.
We thought-about doable causes aside from hyrax buttocks. These included a leopard or an ancestral human dragging prey, or maybe an elephant dragging its trunk. Firstly, nonetheless, these could be anticipated to depart tracks, and secondly in such interpretations the raised characteristic couldn’t be defined.
But when it was a hyrax, it could make sense, as a result of the buttock hint would have come after the tracks and wiped them out. And the raised characteristic could be a coprolite: a fused fossilized mass of hyrax droppings.
Outdated dung and urine
Rock hyraxes depart way more than simply tracks and butt-drag traces. As a result of they like rocky areas, their tracks will not be usually discovered, however they polish rock surfaces to a shiny end. That is much like what buffalo on the North American prairie do, creating “buffalo rubbing stones“.
Hyraxes additionally depart deposits of urine and dung. Urea and electrolytes are concentrated of their urine, and so they excrete massive quantities of calcium carbonate. This turns into cemented and kinds in depth whitish deposits on rock surfaces. Attributable to their communal habits, hyraxes usually urinate in the identical most popular localities over a number of generations.
Their urine and dung usually combine to type a substance often called hyraceum — a rock-like mass that may accumulate into in depth, darkish, tarry deposits. Hyraceum has been used as a conventional medicine to deal with quite a lot of illnesses, together with epilepsy, and for gynecological functions.
Hyraceum could also be tens of 1000’s of years previous, and will be thought to be a threatened, non-renewable useful resource. The middens, being delicate to environmental modifications and containing fossil pollen and different proof of historic life, type worthwhile pure archives for decoding previous climates, vegetation and ecology.
Considering of hyraceum as a hint fossil, one thing which apparently has not been completed earlier than, will help within the safety of this underappreciated useful resource.
Though fossilized urine is globally unusual, there’s a phrase to explain it: “urolite”, to tell apart it from “coprolite” (fossilized poop). Evidently hyraxes contribute the lion’s share of the world’s urolite. At paleontology conferences, college students will be seen sporting T-shirts that overtly state: “coprolite occurs”. In southern Africa, a extra acceptable time period could be “urolite occurs”.
By appreciating the significance of butt-drag impressions, urolites, coprolites and hyraceum, and studying concerning the surroundings of rock hyraxes and different animals throughout the Pleistocene, we’ll by no means view these endearing creatures in the identical mild once more.
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