Weird Nature

Lystrosaurus, The Prehistoric Animal That Took Over The World  

Eric Luis
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Most people are likely unfamiliar with the Lystrosaurus, an unassuming, mammal-like reptile that has been extinct for roughly 250 million years. This lack of knowledge is unfortunate, since the history of the Lystrosaurus is one of the most interesting of any ancient creature. At one time, Lystrosaurus managed to effectively thrive all over the planet, including Antarctica and parts of Asia and South Africa. In relation to other prehistoric wildlife, Lystrosaurus were comparatively small and defenseless, making their achievement even more impressive.

What exactly was the Lystrosaurus, and how did the species manage to become the dominant land animals of the early Triassic? The story is complex, but it manages to showcase the luck of evolution and provide new perspectives on how creatures can adapt to a dangerous environment. While they may not be as impressive as other dinosaurs of the Triassic period, these facts about Lystrosaurus demonstrate that there was more to them than meets the eye.

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Photo: R. Hadian/Wikimedia Commons/Public Domain

Approximately 95% of all species on Earth were wiped out following the end-Permian extinction. About 250 million years ago, the continents combined to form the super-landmass of Pangaea. When a supervolcano on the northern tip of Pangaea erupted, one of the largest chain reactions in geological history was set in motion.

The area called Siberian Traps spewed enormous quantities of lava, ash, and other toxins. An estimated 43,000 gigatons of carbon were absorbed by the atmosphere, creating a harmful habitat and causing the acidification of the world’s oceans. Amazingly, several species survived, and the most successful of these was the Lystrosaurus

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Photo:  Dmitry Bogdanov/Wikimedia Commons/CC BY-SA 3.0

Lystrosaurus not only survived a cataclysmic event; they used it to become the most common terrestrial animal on Earth. Scientists found only one Lystrosaurus fossil that predates the Permian extinction, but after the cataclysm, the species's numbers grew exponentially.

Lystrosaurus became so prevalent, their skeletons comprised 95% of the fossils found in many sites from the time. As a result, the Lystrosaurus became the dominant land vertebrate of that period.

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Photo:  Ghedoghedo/Wikimedia Commons/CC BY-SA 3.0

For years, Lystrosaurus' methods of survival in a highly toxic environment were unclear. One theory proposed that Lystrosaurus had already adapted to eating the simple plants that survived the Permian extinction. Another popular theory claimed that they had large lungs, which evolved to adapt to plunging oxygen levels. Some believe that Lystrosaurus, similar to crocodiles, led a semi-aquatic lifestyle.

Scientists at the the University of Utah believe they have discovered the secret of Lystrosaurus' survival. After comparing growth rates in Lystrosaurus fossils from before and after the extinction event, they discovered the post-extinction skeletons were much smaller and perished at much younger ages. Animals that once lived up to 13 or 14 years were now only living between two and three. They were also producing offspring at much earlier ages.

This lifestyle allowed the species to survive while simultaneously reducing the quality of life for individual Lystrosaurus. While the strategy wasn't perfect, it was effective enough to make Lystrosaurus some of the most dominant land animals of all time.

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Photo:  FunkMonk/Wikimedia Commons/CC BY-SA 3.0

Lystrosaurus, a name meaning shovel lizard, shared a similar anatomy to many burrowing animals. Their adaptations to a semi-subterranean lifestyle most likely played a vital role in their survival of an apocalyptic environment. Their front legs were larger and more muscular than their hind legs, leading scientists to believe that they were adept at digging and hiding in underground dens.

Instead of teeth, Lystrosaurus sported a sharp, beak-like jaw and two protruding tusks. Research suggested they used their heads to dig up roots, an underground food source that was less affected by the toxic air than aboveground vegetation.