Toxodon
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Toxodon Temporal range: Late Pliocene to Late |
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| Skeleton of Toxodon in Buenos Aires | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Notoungulata |
| Family: | †Toxodontidae |
| Subfamily: | †Toxodontinae |
| Genus: |
†Toxodon Owen, 1837 |
| Type species | |
| †Toxodon platensis |
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| Species | |
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Toxodon (meaning "bow tooth") is an extinct mammal of the late Pliocene and epochs from about 2.6 million to 16,500 years ago. It is a member of Notoungulata, one of several now extinct orders of hoofed mammals indigenous to South America. It was among the largest and last members of its order, and was probably the most common large-hoofed South American mammal of its time.
Charles Darwin was one of the first to collect Toxodon fossils, after paying 18 pence for a T. platensis skull from a farmer in Uruguay. In The Voyage of the Beagle Darwin wrote "November 26th - I set out on my return in a direct line for Monte Video. Having heard of some giant's bones at a neighbouring farm-house on the Sarandis, a small stream entering the Rio Negro, I rode there accompanied by my host, and purchased for the value of eighteen pence the head of the Toxodon." Since Darwin discovered that the fossils of similar mammals of South America were different from those in Europe, he invoked many debates about the evolution and natural selection of animals.
Analysis of collagen sequences obtained from Toxodon as well as from Macrauchenia found that South America's native notoungulates and litopterns form a sister group to perissodactyls, making them true ungulates.
In 2014, a study identifying a new species of toxodontid resolved the phylogenetic relations of the toxodontids, including to Toxodon. The below cladogram was found by the study:
Rhynchippus spp.
Adinotherium spp.
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Wikipedia