Evolution of Major Groups of Living Mammals
There are currently vigorous debates between traditional paleontologists and molecular phylogeneticists about how and when the modern groups of mammals diversified, especially the placentals. Generally the traditional paelontologists date the appearance of a particular group by the earliest known fossil whose features make it likely to be a member of that group, while the molecular phylogeneticists suggest that each lineage diverged earlier (usually in the Cretaceous) and that the earliest members of each group were anatomically very similar to early members of other groups and differed only in their genetics. These debates extend to the definition of and relationships between the major groups of placentals — the controversy about Afrotheria is a good example.
Read more about this topic: Evolution Of Mammals
Famous quotes containing the words evolution of, evolution, major, groups and/or living:
“What we think of as our sensitivity is only the higher evolution of terror in a poor dumb beast. We suffer for nothing. Our own death wish is our only real tragedy.”
—Mario Puzo (b. 1920)
“By contrast with history, evolution is an unconscious process. Another, and perhaps a better way of putting it would be to say that evolution is a natural process, history a human one.... Insofar as we treat man as a part of nature—for instance in a biological survey of evolution—we are precisely not treating him as a historical being. As a historically developing being, he is set over against nature, both as a knower and as a doer.”
—Owen Barfield (b. 1898)
“The more you stay in this kind of job, the more you realize that a public figure, a major public figure, is a lonely man.”
—Richard M. Nixon (1913–1995)
“As in political revolutions, so in paradigm choice—there is no standard higher than the assent of the relevant community. To discover how scientific revolutions are effected, we shall therefore have to examine not only the impact of nature and of logic, but also the techniques of persuasive argumentation effective within the quite special groups that constitute the community of scientists.”
—Thomas S. Kuhn (b. 1922)
“Life yields only to the conqueror. Never accept what can be gained by giving in. You will be living off stolen goods, and your muscles will atrophy.”
—Dag Hammarskjöld (1905–1961)