4688 x 3593 px | 39,7 x 30,4 cm | 15,6 x 12 inches | 300dpi
Weitere Informationen:
The Perissodactyla and Artiodactyla make up the largest portion of ungulates, and also comprise the majority of large land mammals. These two groups first appeared during the late Paleocene and early Eocene (about 54 million years ago), rapidly spreading to a wide variety of species on numerous continents, and have developed in parallel since that time. Although whales and dolphins (Cetacea) do not possess most of the typical morphological characteristics of ungulates, recent discoveries have suggested that they are likely descended from early artiodactyls, and thus are directly related to other even-toed ungulates such as cattle and hippopotami. As a result of these discoveries, a new order of Cetartiodactyla has also been proposed to include the members of Artiodactyla and Cetacea, to reflect their common ancestry; however, strictly speaking, this is not necessary, as it is possible simply to recognize Cetacea as a subgroup of Artiodactyla. The Hyracoidea, Sirenia and Proboscidea are the Paenungulata. The Tubulidentata are also thought to be ungulates. The Macroscelidea have been interpreted as ungulates, and there is dental as well as genetic evidence supporting this interpretation. Some recent studies link Tubulidentata with the Paenungulata in the Pseudoungulata.[2] Genetic studies indicate that these animals are not closely related to the artiodactyls and perissodactyls. Instead, the closest relatives of pseudungulates are the Afrosoricida; the Pseudungulata and Afrosoricida make up the Afrotheria. Ungulate groups represented in the fossil record include the embrithopods, demostylians, mesonychids, "condylarths" and various South American and Paleogene lineages.
