Perhaps the most familiar example of an evolutionary radiation is that of placental mammals immediately after the extinction of the dinosaurs at the end of the Cretaceous, about 66 million years ago.
The luteal phase is the latter phase of the menstrual cycle (in humans and a few other animals) or the earlier phase of the estrous cycle (in other placental mammals).
Xist (X-inactive-specific transcript) is a long ncRNA gene on the X chromosome of the placental mammals that acts as major effector of the X chromosome inactivation process forming Barr bodies.
The patella has convergently evolved in placental mammals and birds; most marsupials have only rudimentary, non-ossified patellae although a few species possess a bony patella.
Antibodies to Ross River virus have been found in a wide variety of placental and marsupial mammals, and also in a few bird species.
Eutheria |