![]() It is useful to show again the climate change graph from the last article.Ħ5 million years of climate change, from Wikimedia CommonsĪt the beginning of the Tertiary Period, climates were warm and forests spread across all the continents. They are the most divers and wide-ranging of contemporary mammals. Placental mammals, such as humans, protect their young within the mother’s body. Marsupials, such as kangaroos and koalas, do not lay eggs, but their young are born underdeveloped and must be protected in the mother’s pouch as they grow and develop. Remote ancestors of mammals all laid eggs and these still do. Monotremes are rather rare egg-laying mammals, such as the platypus. Three orders of mammals which survived are still around today. producing milk to feed their young (in mammary glands).bearing their young alive (in most cases).being endothermic, or warm-blooded, which allows them to adjust their body temperatures according to external conditions, an advantage for adaptation to different climates.having differentiated teeth, i.e., teeth differently shaped to fulfill different functions in different parts of the mouth (e.g., incisors, canines and molars).The number of mammals and mammal species underwent an extraordinary increase. Be that as it may, after the dinosaurs died out, surviving mammals could creep out of their holes to occupy the old econiches as well as new ones. Possibly both processes – and others – contributed. Animals which depended on plants for food (or on animals dependent on plants) died out, whereas those which ate organisms like insects or worms, which in turn fed on detritus, survived. Perhaps a more likely suggestion is that particles in the air, whether from asteroid impact or volcanic activity, reduced incident sunlight so that photosynthesis was diminished. In this case, the heat would have had to pass quickly. One theory, based on the hypothesis that dinosaurs were killed by extreme heat after a huge asteroid struck the Earth, would have it that mammals stayed safe either in their burrows or under the sea until the worst heat had passed. It Is not clear how mammals managed to survive. ![]() Paleocene Epoch, 65 MyaĪlthough the earliest true mammals evolved during the late Triassic, they remained small and relatively inconspicuous until around 65 Mya, the time of the K-T extinction and the disappearance of the dinosaurs. We will now take up where we left off after the K-T extinction and the beginning of the first epoch of the Cenozoic Era. In numbers they still do, but they are not alone.
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