|
Pyrotheria is an order of extinct meridiungulate mammals. These mastodon-like ungulates include the genera ''Baguatherium'', ''Carolozittelia'', ''Colombitherium'', ''Gryphodon'', ''Propyrotherium'', ''Proticia'', and ''Pyrotherium''. They had the appearance of large, digitigrade, tapir-like mammals with relatively short, slender limbs and five-toed feet with broad, flat phalanges. Their fossils are restricted to Paleocene through Oligocene deposits of Brazil, Peru and Argentina. Some experts place the clade Xenungulata (which contains several genera, including ''Carodnia'') within Pyrotheria, even when dentition, although bilofodont in both orders, is very different. For most scholars, the two orders remain separated. The dentition is complete with strong, procumbent, chisel-shaped incisors, strong sharp-pointed canines, and low-crowned cheek teeth with bilophodont molars. The affinities of the Xenungulata remain uncertain. Affinities with the Dinocerata are strongly supported by the dental characteristics. Initial study of the structure of the tarsus suggested that the xenungulates had a common ancestry with typical pyrotheres, such as ''Pyrotherium'', but a more recent examination of the tarsus of ''Pyrotherium'' failed to support this, instead showing some traits shared by ''Pyrotherium'' and the Embrithopoda. It remains to be seen which of these views will turn out to be right. This means that the Pyrotheria can be members of no less than three major cladistic branches of placential mammals: Meridiungulata (if xenungulates are the closest relatives), Laurasiatheria (if dinoceratans are the closest relatives) and Afrotheria (if embrithopods are the closest relatives). ==Classification== *Colombitheriidae * *''Proticia'' * *''Colombitherium'' *Pyrotheriidae * *''Pyrotherium'' * *''Griphodon'' * *''Propyrotherium'' * *''Carolozittelia'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pyrotheria」の詳細全文を読む スポンサード リンク
|