Non User
Index: > A B C D E F G H I J K L M N O P Q R S T U V W X Y Z	Business Non User Industries Finance Tax

Home > Mammal

3.2 Molecular classification of Mammals

Molecular studies, based on DNA analysis, have revealed new relationships among mammal families over the last few years. The most recent classification systems based on molecular studies reveal four groups or lineages of placental mammals which diverged from early common ancestors in the Cretaceous. The Afrotheria, diverged first, from 110-100 million years ago ( mya), and evolved in the isolation of the African-Arabian continent; the Xenarthra, isolated in South America, diverged from the Boreoeutheria approximately 100-95 mya; and the Boreoeutheria split into the Laurasiatheria and Euarchontoglires between 95 and 85 mya; both of these groups differentiated on the northern continent of Laurasia. After tens of millions of years of relative isolation, Africa-Arabia collided with Eurasia, and the formation of the Isthmus of Panama linked South America and North America, facilitating the distribution of mammals seen today. With the exception of bats, no placental land mammals reached Australasia until the first human settlers arrived approximately 50,000 years ago.

• Group I: Afrotheria
  • • Order Macroscelidea: elephant shrews (Africa).
    • Order Afrosoricida
      • Family Tenrecidae: tenrecs (Madagascar) and otter-shrews (West and Central Africa).
      • Family Chrysochloridae: golden moles (Africa south of the Sahara).
    • Order Tubulidentata: aardvark (Africa south of the Sahara).
    • Order Hyracoidea: hyraxes, dassies (Africa, Arabia).
    • Order Proboscidea: elephants (Africa, Southeast Asia).
    • Order Sirenia
      • Family Dugongidae: dugong (East Africa, Red Sea, North Australia).
      • Family Trichechidae: manatees (tropical Atlantic coasts and adjacent rivers).
• Group II: Xenarthra
  • • Order Xenarthra: sloths and anteaters (Neotropical) and armadillos (Neotropical and Nearctic)
• Group III Euarchontoglires
  • Superorder Euarchonta
    • Order Scandentia: tree shrews (Southeast Asia).
    • Order Primates: lemurs, bushbabies, monkeys, apes (cosmopolitan).
    • Order Dermoptera: flying lemurs or colugos (Southeast Asia).
  • Superorder Glires
    • Order Lagomorpha: pikas, rabbits, hares (Eurasia, Africa, Americas).
    • Order Rodentia: rodents (cosmopolitan)
• Group IV: Laurasiatheria
  • • Order Insectivora
      • Family Solenodontidae: solenodons (Cuba, Hispaniola).
      • Family Erinaceidae: hedgehogs, moonrats (Eurasia, Africa).
      • Family Soricidae: shrews (Eurasia, Africa, North America to northern South America).
      • Family Talpidae: moles, shrew-moles, desmans (Eurasia, North America).
    • Order Chiroptera: bats (cosmopolitan)
    • Order Pholidota: pangolins, scaly anteaters (Africa, South Asia).
    • Order Carnivora: carnivorans (cosmopolitan)
    • Order Perissodactyla: odd-toed ungulates
      • Family Equidae: horses, zebras, donkeys (Africa, West and Central Asia).
      • Family Tapiridae: tapirs (Central and South America, Southeast Asia).
      • Family Rhinocerotidae: rhinoceroses (Africa, Southeast Asia).
    • Order Cetartiodactyla : cosmopolitan; includes former orders Cetacea (whales, dolphins and porpoises) and Artiodactyla (even-toed ungulates, including pigs, hippopotamus, camels, giraffe, deer, antelope, cattle, sheep, goats).

Politics	Business	Finance

Topics: Mammal *****family Mammals ***family ****family Classification...

---

MammalSubclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorp MammalogyIn biology, mammalogy is the study of mammals, a class of vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems. Three major subdivisions of mammals are monotremes, marsupials and placent Mammalian diving reflexSubmerging the face into water causes the mammalian diving reflex which is found in all mammals, but especially in marine mammals as for example whales and seals. This reflex puts the body into energy saving modus to maximize the time that can be spent un Mammal-like reptilesMammal-like reptiles is a term used to describe the prehistoric animals that appear to be the reptilian ancestors of mammals. Their scientific name is Therapsida, and the Cynodonts were the most mammal-like of the Therapsids. Mammalian embryonic diapauseDiapause in mammals is a condition where pre-implantation blastocysts are maintained in a state of dormancy, often due to environmental cues, until such time as the environment improves. Diapause occurs in over 100 species of mammals in distantly related