|
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Evolution Of Mammalian Auditory Ossicles
The evolution of mammalian auditory ossicles was an evolutionary process that resulted in the formation of the mammalian middle ear, where the three middle ear bones or ossicles, namely the incus, malleus and stapes (a.k.a. "the anvil, hammer, and stirrup"), are a defining characteristic of mammals. The event is well-documented and important academically as a demonstration of transitional fossil, transitional forms and exaptation, the re-purposing of existing structures during evolution. The ossicles evolved from skull bones present in most tetrapods, including amphibians, sauropsids (which include extant taxon, extant reptiles and birds) and early synapsids (which include ancestors of mammals). The reptilian quadrate bone, quadrate, articular bone, articular and columella (auditory system), columella bones are homologs of the mammalian incus, malleus and stapes, respectively. In reptiles (and early synapsids by association), the eardrum is connected to the inner ear via a single ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
