Final answer:
Most other mammals have larger brain-to-body ratios, engage in considerable parental care, and encompass a diverse range of species from land to aquatic environments. They include viviparous species like chimpanzees and dolphins, as well as unique egg-laying monotremes such as the platypus. Mammals have successfully adapted to various habitats, with placentals being the most numerous and diverse.
Step-by-step explanation:
Research suggests that most other mammals have a range of characteristics that differentiate them from other animal groups. Mammals are known for their larger brain-to-body ratios, a characteristic advanced by increased cortical folding and surface area, which correlates with complex behavior. Specific examples such as chimpanzees and dolphins exhibit this trait, showing advanced social structures and behaviors.
Mammals provide extensive parental care, often investing a significant amount of their energy budget into their offspring, as demonstrated by species like humans, kangaroos, and pandas. These are examples of viviparous animals, which produce live young rather than laying eggs. Contrast this with monotremes like the platypus and echidnas, which still lay eggs.
In the mammalian kingdom, there are three types: monotremes, marsupials, and the eutherians or placentals. The latter group is the most numerous and widespread, with around 4,000 species exhibiting a myriad of adaptations. Mammals have successfully colonized a range of environments on land and in the ocean, highlighted by the transition of land-dwelling ancestors to aquatic lives as in the case of whales, dolphins, and porpoises.