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Toxodon – one of the strangest animals

Toxodon

Charles Darwin described Toxodon as “one of the strangest animals ever discovered”. What is the uniqueness of this mighty Pleistocene mammal? Certainly not one, but several features made Darwin himself impressed with the skull he had bought for 18p from a farmer. Let’s try to get to know these features and see if the English naturalist was telling the truth.

Classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: †Notoungulata
  • Family: †Toxodontidae
  • Subfamily: †Toxodontinae
  • Genus: †Toxodon
  • Species:
    • †Toxodon platensis
    • †Toxodon burmeisteri
    • †Toxodon chapalmalensis
    • †Toxodon darwini
    • †Toxodon ensenadensis
    • †Toxodon expansidens
    • †Toxodon gracilis
Toxodon

Dating and occurrence

It is estimated that this large mammal lived on our planet from about 3 million (11.6 million?) to 11 thousand years ago, that is, from the Late Miocene to Holocene.

Its remains were discovered in South America, incl. in Argentina and Uruguay. Charles Darwin wrote about it, who incidentally was one of the first discoverers of Toxodon fossils.

Toxodon

Anatomy

Toxodon was similar in size and proportion to modern rhinoceros, but in the past, it was thought to have features of hippos and even elephants.

The skull found is massive, suggesting that the Toxodons were very heavy animals. The arrangement of the bones of the feet also suggests that they had short stout legs with plantigrade feet – this way of walking (on the whole feet, not only on the toes) may confirm the thesis that the animal was heavy (although on the other hand, elephants do not mind it – they walk on their toes :)).

A broad, squat body suggests that the digestive system was very extensive, similar to today’s large herbivores. The hind limbs were longer than the front limbs, so the silhouette tilted forward. This would mean that the head was close to the ground from which the mammal could easily pick up plant food.

The protrusions on the anterior dorsal vertebrae were probably enlarged so that the neck muscles supporting the heavy skull could attach to them. It is possible, however, that on the back, instead of the muscles, there was a hump that acted as an energy store in times of crop failure.

Toxodon

An aquatic animal?

Many reconstructions of Toxodon present it as a semi-aquatic animal, similar to hippos. A large, heavy animal, immersed in water, moved more easily and obtained food more efficiently, e.g. aquatic plants. From the twentieth century, however, gradually began to depart from this theory.

The main reason for this is the fact that during the reign of Toxodons in South America, the climate was very dry, creating steppes and grassy savannas. In addition, an animal with a head as low as Toxodon, would have a hard time keeping it above the surface of the water.

Diet

The width of the mouth indicated that the animal has been able to maintain a diverse plant diet that included grasses, leaves, shrubs and low trees. So far, however, these are only assumptions. Scientists speculate that Toxodon may have had prehensile lips. If this were true, Toxodon would be able to adapt to a variety of environmental conditions. It would eat whatever was currently available.

Toxodon

Extinction

Toxodons may have been one of South America’s most widespread herbivores. However, they lived in times of major changes, because during the formation of the Panama Isthmus (not to be confused with the Panama Canal ;)), which today connects North and South America. This process has made it possible for previously isolated species to travel to other continents.

It is unlikely that Toxodons would fall victim to large flightless birds of the Phorusrhacidae family, as these dangerous birds had already died out before the appearance of Toxodons. However, this extinction could have had a lot to do with North American predators that crossed the land bridge and entered South America. One of these dangerous predators was certainly the smilodons. It is possible that the saber-toothed tigers that came to South America, with time specialized in killing large Toxodons.

Man had a significant influence on the extinction of the Toxodon genus.  Arrowheads have been found along with Toxodon bones, which may indicate that the people who came to those lands hunted for them fiercely. Certainly, however, the increased hunting by the first humans was not the main cause of the genus extinction. It is suspected that, like the rest of the representatives of the Pleistocene megafauna, Toxodons disappeared from the surface of the Earth due to climate change, diseases, and perhaps as a result of a comet impact.

Toxodon

Detailed data / dimensions (size)

Toxodon

  • Body length: 2.7 m (8.9 ft)
  • Height at the withers: 1.5 m (4.9 ft)
  • Potential weight: 1,500 kg (3,300 lb)
  • Temporal range: (11.6 million?) 3 million – 11 thousand years ago (Late Miocene-Holocene)
  • Distribution: South America, Uruguay and Argentina
Toxodon

Toxodon – interesting facts

  • The name Toxodon means “bow tooth”. It refers to strongly curved upper incisors, which interested Richard Owen – the creator of the description of Toxodon.
  • Toxodon, like rhinos today, could gallop while escaping from attackers. It is possible that he also deterred enemies in this way. It, therefore, seems that its greatest weapon against predators was its large size.
  • The man who found the first bones of Toxodon, including the skull, was Charles Darwin. The 22-year-old scientist was then on a 5-year journey on the HMS Beagle.
  • Darwin acquired the Toxodon skull not by excavation, but … by a commercial transaction. The scientist bought it from an Uruguayan farmer for 18p and then sent it to Richard Owen, who analyzed the find.
Toxodon

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