A breakthrough fossil shows what a dinosaur-era pig would have looked like

According to the researchers, the fossils discovered in the Karoo desert represent an extremely rare discovery because a few of the dead Lystrosaurus happen to have preserved parts of their skin on them.

Lystrosaurus was an incredible survivor

Eleven years have passed since the first Lystrosaurus fossil discovery took place in the Karoo desert. A total of 170 prehistoric specimens have been found at the site since then, including the remains of eight Lystrosauruses. Surprisingly, two of those animals were found buried with parts of their skin intact even after millions of years of their death.

It is believed that extremely dry conditions like draughts would have caused the death and fast fossilization of the discovered Lystrosauruses. However, it is because of the dryness that some parts of their skin dried so much that they got mummified along with the bones. The fossils from the Karoo desert suggest that many Lystrosauruses may have gathered at the place in search of food and water before their death.

One of the most fascinating things about Lystrosaurus as a species is that it had characteristics of both mammals and reptiles. This is why they are classified as Therapsids, direct ancestors of mammals, also known as protomammals.

Interestingly, the species also managed to survive a large catastrophic event during their existence. For instance, the researchers claim that 252 years ago, over 70% of terrestrial animals on Earth went extinct due to mass-scale extinction events mainly triggered by the eruption of large volcanoes in Siberia.

Mass extinction couldn’t kill them, but hunger and thirst did

Lystrosauruses remained alive for a long time after those events probably because they were hibernating during the period of destruction. They are also considered one of the very first animals that had the ability to undergo hibernation. Moreover, Lystrosaurus inhabited not only Africa but parts of Asia (India, China) and Antarctica as well.

In the years that followed after the mass extinction, the Earth went through various phases of climate change. Lystrosaurus were mainly affected by droughts that led to the scarcity of food and water. The repeated occurrence of droughts adversely affected their population and eventually made them extinct.

"As we are observing today with global warming, it seems that (global warming) increases the likelihood of extreme events. That may have been what was happening in the earliest Triassic, that there were these repeated drought events happening more frequently," a paleontologist at Field Museum in Chicago and one of the authors of the study, Pia Viglietti told Live Science,

The study is published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Abstract:

The sedimentology and taphonomy of in-situ fossils from earliest Triassic strata (Induan) in the southern Karoo Basin of South Africa is presented as evidence for episodes of drought-induced mass death of the resident tetrapods. Abundant skeletons are preserved in a 2 m-thick tabular silty-sandstone capping a multi-storeyed low-sinuosity channel sandstone interpreted as a wide shallow channel that became progressively abandoned, with more ephemeral flow regime than in the underlying channels and subjected to intermittent flows of low-density sediment-laden floodwaters. Stratigraphic and planimetric distribution of 170 in-situ tetrapod fossils shows several clusters of up to eight closely-spaced articulated Lystrosaurus skeletons preserved in prone and spread-eagled body position. These are interpreted as drought-stricken carcasses that collapsed and died of starvation in and alongside dried-up water sources. Two of the specimens display an unusual micritic envelope with a distinctive pustular texture interpreted as permineralised mummified skin indicative of rapid desiccation after death. Bonebeds of disarticulated bones of multiple juvenile Lystrosaurus occur in shallow depressions within the rubified mudstones. Layering of different skeletal elements suggests some hydraulic sorting but the initial aggregation was likely a behavioural response to drought. Osteohistology of spread-eagled Lystrosaurus (L. declivis and L. murrayi species) skeletons show that they represent early juvenile stage which is in accordance with previous findings that throughout Pangaea Early Triassic Lystrosaurus died relatively young due to environmental stressors. Our results support the hyperthermal hypothesis that ∼252 Mya increased continental aridity, already a consequence of the coalescence of Pangaea, was critically intensified by volcanogenic greenhouse gasses from the Siberian traps. We propose that in the aftermath of the End-Permian mass extinction event, a succession of climatic drying episodes orchestrated a series of fully-functioning terrestrial ecosystems that were markedly different to those of the pre-extinction, and likely had a profound and lasting influence on the evolution of tetrapods.