Paenungulata
|
|
Paenungulata is a superorder that groups some remarkable mammals constituting three orders:
- Proboscidea (Elephants)
- Sirenia (Sea cows and manatees)
- Hyracoidea (Hyraxes, such as the African Rock Hyrax, Procavia habessinica)
All three still exist but the Paenungulata once had two additional orders, namely:
Both of these were as unique in their ways as the surviving orders. Embrithopods consist of elephant-sized rhino-lookalikes and desmostylians were odd semi-marine creatures that seem to have mainly fed on kelp.
George Gaylord Simpson, (Simpson 1945), working with traditional taxonomic techniques did succeed in grouping these spectacularly diverse mammals in the superorder he named Paenungulata, but there were many loose threads in unravelling their genealogy. The Hyraxes in his Paenungulata ("almost ungulates") offered hints that they might be connected to the perissodactyl ungulates— horses and rhinos and kin. Then genetic techniques were developed of inspecting the differences among amino acid differences among hemoglobin sequences. The most parsimonious cladograms depicted Simpson's Paenungulata as an authentic monophyletic clade and as one of the most anciently diversified among the placental mammals (Eutheria), that is, among the first group to diversify from the basal placental mammals. The hypothetical connections with Perissodactyls were not supported by the amino acid sequences.
Of the orders of Paenungulates mentioned above, hyraxes are the most basal, followed by embrithopods, sirenians and desmostylians, with elephants being the crown group. The latter three are grouped as the Thetytheria.
Paenungulata in its turn is part of Afrotheria, an ancient assemblage of mainly African mammals of great diversity. The other members of this superorder are Afrosoricidans (tenrecs and golden moles), elephant shrews (Macroscelidea) and aardvarks (Tubulidentata). Two mysterious, little-known fossil orders both represented by only one genus each, the Afredentata (Eurotamandua) and the Bibymalagasia (Plesiorycteropus) could represent two additional afrotherian groups.
External links
- Paleos.com: (http://www.palaeos.com/Vertebrates/Units/Unit530/530.100.html#Paenungulata) Vertebrates: Paenungulata
- Traute Kleinschmidt, John Czelusniak, Morris Goodman and Gerhard Braunitzer, "Paenungulata: A Comparison of the Hemoglobin Sequences from Elephant, Hyrax, and Manatee (http://mbe.library.arizona.edu/data/1986/0305/5klei.pdf)
References
- Simpson, G.G., "Classification," in Bulletin of the American Museum of Natural History vol. 85:1-350. 1945.
- McKenna, M. C. and Bell, S. K., editors, Classification of mammals; above the species level. Columbia University Press, New York, 1997.