Lystrosaurus was a genus of mammal-like reptiles that inhabited the Earth during the Paleozoic Era, during the well-known Permian period (approximately 250 million years ago). This genus has been classified within the group of the dicinodontic terapsids.
The existence of this genus occurred before the existence of the dinosaurs themselves, although its life was prolonged until it cohabited with the first genera. They are a strange genus and form a mixture between mammals and reptiles. It would have been one of the most common vertebrates during the Lower Triassic.
The dimensions of the Lystrosaurus are one meter long and one and a half meters high. In terms of weight it would have been about 90 to 100 kilograms. In addition, it would have had a fairly robust appearance with fangs protruding from its upper jaw.
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Lystrosaurus is undoubtedly a rather interesting genus. It is an animal that combines the characteristics of a reptile and a mammal. However, it is important to point out that although our page is mainly about dinosaurs, Lystrosaurus is not one of them. Having made this clear, let’s talk about the basic characteristics of Lystrosaurus.
- How long is it? – The length is approximately sixty centimeters up to two and a half meters.
- What is its height? – Approximately 1.5 meters.
- What’s its weight? – 1 to 100 kilograms.
- When did he live? – He inhabited our planet about 250 million years ago in the past.
- What is your order? – He belongs to the order of the Therapsids.
The taxonomy of the Lystrosaurus
Kingdom Animalia > Filo Chordata > Class Synapsida > Order Therapsida > Infraorden Dicynodontia > Family Lystrosauridae > Genus Lystrosaurus
Taxonomy does not end with the genus Lystrosaurus. The species that exist within the genus have not been mentioned and will be shown below. It should also be noted that at any time the number of species that exist may increase or decrease. We take care to keep this section fully updated to possible future changes.
The order: the terapsids
Lystrosaurus is a genus of mammals that are classified within the order of the Therapsids. That is why before going into more detail about them, it is convenient to know something else about their order. They are classified within that order because they adopt most of their characteristics. Next we will see the features and information about the order of the terapsids.
The origin of all modern-day mammals is found in the order of the terapsids. Most of the traits we see in today’s mammals are typical of the terapsids. One of the traits we are talking about would be the fact of having all four limbs coming out of the lower body and not sideways like reptiles.
Therapsids would have had limbs sticking out vertically from under their bodies, but they also had more symmetrical feet. They would have had four toes, the ones on the sides would have been short and the two in the middle somewhat longer. The latter reaffirms that they had legs that were more mammal-like than lizard-like.
The jaws of the terapsids were quite developed. They possessed a great range and above all the teeth were quite effective. They had front teeth that served to pinch and on the sides large teeth to bite and tear accompanied by molars capable of cutting and shearing food perfectly.
It is also interesting to note that they were endothermic animals. This means that they are animals that maintain a certain body temperature. They are the so-called “warm-blooded” and can be clearly distinguished from the reptiles which are poikilotherms or “cold-blooded”.
This has been deduced because they have erect limbs, vascularized bones, absence of growth rings and above all, a tail that has the necessary characteristics to preserve body heat.
History of Therapsids
This order of extinct reptiles comes from the pelicosaurs, specifically the Sphenacodonts. These evolved into the Therapsids, which managed to dominate the entire Permian region after the disappearance of the Pelicosaurs.
This order encompassed many genera and species of animals and to better differentiate between them has been subdivided into four major groups. These four clades are: the Anomodontia, Dinocepalia, Theriodontia and Biarmosuchia.
The first to disappear due to evolution were the Dinocephalia, which stopped inhabiting the planet at the end of the Permian. In the case we are talking about, the Lystrosaurus, they are the Anomodontia dicinodontes that managed to inhabit the planet for longer.
During the change from Permian to Triassic there was a great extinction. This affected a lot of species, families and even orders of animals that have been affected until they completely disappeared. In the case of the terapsids it is not much different, where the number of species and genera were drastically reduced.
Even so, what interests us, the dicinodon managed to survive the great Permian-Triassic extinction and thus inhabit the first moments of the Mesozoic Era.
Description of Lystrosaurus
Now we know a little more about the Therapsid Order to which the Lystrosaurus belongs. As we said, it adopts most of the characteristics of its order, although of course, it has certain differences with its brothers in the order.
For within the Therapsids it is situated in the subdivision of the Dicinodonts and from there it also differs slightly from the other Dicinodonts. That is why we will now talk about the characteristics and details of the Lystrosaurus.
Before talking about the physical features of this genre, there is a really interesting detail to be highlighted. It is quite a shocking fact, since this specimen came to dominate the planet completely. During a period of time within the Lower Triassic, the Lystrosaurus managed to be the dominant genus.
For a time, 95% of terrestrial vertebrate animals belonged to this group and it is the only case where a terrestrial animal came to dominate the Earth on such a scale.
The skull of the Lystrosaurus is quite peculiar. It is relatively strong for its lightness and has large openings in the jaw to make room for the large muscles it had for its jaw.
However, the front of the skull and its lower jaw are quite narrow. The back of the mouth has a horny beak very similar to that of today’s tortoises. The snouts are relatively short and they have no teeth.
The curious thing about their beaks is that they are quite similar to those of turtles. They are ideal for chewing on vegetation which, with the help of the secondary palate, would grind up the food when it was closed. The jaw itself was quite fragile, and could not open and close tightly.
To chew, they would have used a backward and forward movement, in the form of a shear.
The body of this genus is quite small and robust. Its body had the shape of a barrel, similar to that of today’s pigs, and its limbs were robust. The two forelimbs would have been bent at the elbow area while the hind limbs were kept completely straight.
In addition, it had a tail that was only a few centimeters long. It moved in a semi-expansion manner, its front legs being considerably more robust than the hind legs. The possibility that it would have been a digging animal and that its home would have been burrows is considered.
When did the Lystrosaurus live?
Lystrosaurus is a really ancient genus of reptile-mammal and if we wanted to see one in action we would have to go back many millions of years. This specimen is so old that it lived with the first dinosaurs and even existed before them.
This genus inhabited our planet a lot of years ago, specifically in the late Permian and early Early Triassic. This coincides with the transition from the Permian Age to the Mesozoic Age (traditionally known as the age of the dinosaurs).
Unfortunately, this genus did not inhabit the entire era of dinosaurs, and it was only a few million years old. The Mesozoic Era spanned from 251 million years ago to 65 million years ago in the past. The genus we are referring to “only” was on the planet from 255 million to about 245 million years ago.
During the transition from the Permian era to the early Triassic, the genus Lystrosaurus became almost extinct. Fortunately, at least one species of Lystrosaurus was able to survive the mass extinction of the late Permian. The little competition of herbivorous animals and especially the absence of predators favored the survival of this genus.
Why did they survive the late Permian extinction?
There is no doubt that the late Permian extinction took a lot of living beings with it. Few species and genera managed to survive this great extinction, as is the case with Lystrosaurus. The survival of this genus brought with it many doubts and with it some theories that try to explain the reasons.
The fact is that during this period there was a great reduction of oxygen in the atmosphere and with it the presence of carbon dioxide increased. This increase in CO2 made it very difficult for the animals to breathe and few were able to survive.
The most accepted theory is that the Lystrosaurus was able to cope with this change due to its anatomy. It had large barrel-shaped breasts where it could easily accommodate large lungs and short nostrils, allowing air to reach the lungs quickly.
Despite this, there are other animals with similar characteristics that unfortunately could not survive. That is why probably more factors intervened such as the size of its body, the fact that it is an amphibious animal, the posture of the animal and perhaps a little bit of luck.
Where did the Lystrosaurus live?
It is not known for sure all the places where this animal lived, although it has been possible to deduce some of its areas. Quite a few remains have been found in the area of present-day Antarctica, South Africa and India. That is why we can mention that the Lystrosaurus was inhabiting these geographical areas in the past.
The area in which it would have inhabited is quite extensive, it would have been all over the south of Pangaea. This area coincides with today’s Antarctica, India and South Africa. This area corresponded to an area with both a land and an aquatic environment. In this area of the great Pangaea there were large lakes that favoured the life of the Lystrosaurus, which as mentioned was a semi-aquatic animal.
What did the Lystrosaurus feed on?
Now that we know much more about our dear friend, let us turn to what the Lystrosaurus ate. Many might think that because it was the most abundant animal on earth, it would have fed on other animals in order to eliminate them and in turn survive. That is why it is really surprising that this animal was a boiling animal.
As we have seen before, there were many species of Lystrosaurus. Still, not all of them met the same fate and not all of them could survive. What determined which species would continue and which would cease to exist was the vegetation.
The fact is that Lystrosaurus would have fed on plants such as Dicroidium, which were very abundant throughout the Lower Triassic. The vegetation that was abundant during this period was not very high, and it was an impediment for the large-sized herbivores.
The Lystrosaurus maccaigi was one of these large hervibores that fed on vegetation similar to Glossopteris. Glossopteris and other large vegetation could not survive the extinction at the end of the Permian, and with it many species of large hervibores.
We hope that this entry with information about Lystrosaurus has helped you. If you have any doubt, suggestion or contribution concerning this animal, please do not hesitate to use our comment box, we will be happy to read your contributions and solve any possible doubts!