Mammaliinien

Mammaliinien is a term found in some sources to denote the clade that includes all mammals, i.e., the class Mammalia. In standard taxonomy the widely accepted name is Mammalia, and Mammaliinien is not common in contemporary usage. When encountered, it is typically used to emphasize the broad mammalian lineage or to reflect a regional or historical naming practice.

Composition: Mammaliinien comprises three living lineages: Monotremata (monotremes such as the platypus and echidnas), Metatheria (the marsupials and their extinct relatives), and Eutheria (the placental mammals, including humans). Shared features include endothermy, hair or fur, mammary glands, and three middle ear bones. Reproduction varies: monotremes lay eggs; metatherians and eutherians give birth to relatively undeveloped young that complete development postnatally in a pouch or in the uterus.

Evolution and fossil record: The lineage that would become Mammaliinien/Mammalia arose from cynodonts in the late Triassic. Early mammaliforms appear in the Jurassic, with a richer fossil record in the Cretaceous. Crown-group mammals diversified markedly after the end-Cretaceous extinction, producing the breadth of forms seen today. Key early taxa include Morganucodon and Megazostrodon among the better-known mammaliaforms.

Ecology and diversity: Mammaliinien currently occupy a wide range of habitats, from oceans to deserts and forests. They range in size from small insectivores to the largest whales and occupy numerous ecological roles, including predators, herbivores, and pollinators. The clade exhibits varied life histories and social structures, reflecting a long evolutionary history and widespread geographic distribution.