Mammals are divided into three groups: placental, marsupial, and monotreme. Monotremes include only the platypus and four species of echidna. Placental mammals are dominant with over 5,500 species, while marsupials have only 334 species and are mostly found in Australia. Marsupials differ from placental mammals in their mode of reproduction, genitalia, and slightly lower blood […]
Placental mammals, the dominant terrestrial life form, have over 5,000 species including humans, dogs, cats, and horses. They are distinguished by their viviparousness and genitalia. They have occupied various ecological niches and have highly developed brains, with humans being the most successful. Placental mammals, also known as the infraclass Eutheria (from the Greek eu- “well(-developed)” […]
Mammals evolved from reptiles 175 million years ago and diversified after the extinction of dinosaurs. They have sweat glands, hair, and a neocortex, giving them superior intelligence. Most care for their young and have a more complex social structure than other organisms. Mammals are warm-blooded vertebrates that evolved in the Jurassic Period, about 175 million […]
Mammals evolved from synapsids, a group of non-amphibian tetrapods, branching off from reptiles in the Carboniferous period. Pelycosaurs were the first terrestrial amniotes of large size, evolving into therapsids, which evolved into true mammals over 70 million years. After the extinction of dinosaurs, mammals diversified and became the dominant land vertebrates. Mammals represent the last […]
Placental mammals are the dominant group of terrestrial vertebrates, with 20 orders in four superorders. The largest orders are Chiroptera, Rodentia, Carnivora, and Cetartiodactyla. Humans and their pets are the majority of placental mammals, causing extinction of many species through hunting and habitat destruction. The placental mammals, the infraclass Eutheria (which is Greek for “true/good […]
Most mammals have fur, but some have very short hair, including humans. The reasons for short hair are unclear, but for marine mammals, it helps with swimming, and for naked mole rats, it’s due to their underground lifestyle. The reason for human hair loss is unknown, but some theories suggest it’s related to a semi-aquatic […]
