Litopterna
- South America
- Antarctic
The Litopterna (Size: Litos = plain, smooth; ptérna = heel) are an extinct group of mammals that lived during the Cenozoic in South America and whose last representatives have become extinct at the end of the Pleistocene.
They are counted among the South American ungulates ( Meridiungulata ), a group of mammals, reached their representatives in geographically isolated South America during the Cenozoic a wide variety and a strong adaptive radiation have been through.
Features
The Litopterna are generally characterized by an extension of the limbs and a reduction in the number of toes, which meant that some representatives externally strongly reminiscent of camels or horses and probably also occupied similar ecological niches. The teeth were relatively simple and were in contrast to other South American ungulates no great specialization. The Litopterna ate probably of different plants.
History of development
The Litopterna are first documented in the Paleocene, Eocene, there are individual finds from the Antarctic continent that was still connected to South America and had a warmer climate than today. However, the most representative died out with the emergence of the Isthmus of Panama at the end of the Pliocene, as they were ousted by the superior camels, horses and deer, who immigrated from North America. Perhaps they were also the newly immigrated predators, which included dogs and cats, not grown. Only two genera of Litopterna, namely Windhausenia and Macrauchenia proved to be adaptable enough and survived until the end of the Pleistocene in South America.
System
The Litopterna can be divided into four families:
- The Protolipternidae, which were common in the upper Paleocene.
- The Notonychopidae, which also occurred in the upper Paleocene.
- The Proterotheriidae (Size: Proteros = front; Therion = mammal) that were distributed by the upper Paleocene to the upper Pleistocene. They showed a particularly strong reduction in the number of toes, and thus a resemblance to the horses. Known representatives are Diadiaphorus whose feet only with a hoof touched the ground and the side toes were stunted and Thoatherium whose legs ended just more like that of today's horse in a single hoof.
- The Macraucheniidae, which were also distributed from the upper Paleocene to the upper Pleistocene. These animals are a result of her long neck, elongated limbs and wide feet often described as similar to camel. But in contrast to these their feet ended in three toes. The best known representative of this group is Macrauchenia who may have had a short trunk and survived until the end of the Pleistocene.