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Figure 1:In mammals, the quadrate and articular bones are small and part of the middle ear; the lower jaw consists only of dentary bone.. While living mammal species can be identified by the presence of milk-producing mammary glands in the females, other features are required when classifying fossils, because mammary glands and other soft-tissue features are not visible in fossils.
Synapsida [a] is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant reptiles and birds).
A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia (/ m ə ˈ m eɪ l i. ə /). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones.
A = Anapsid, B = Synapsid, C = Diapsid. It was traditionally assumed that first reptiles were anapsids, having a solid skull with holes only for the nose, eyes, spinal cord, etc.; [10] the discoveries of synapsid-like openings in the skull roof of the skulls of several members of Parareptilia, including lanthanosuchoids, millerettids, bolosaurids, some nycteroleterids, some procolophonoids and ...
Evolution of dinosaurs – Archosaurian reptiles that dominated the Mesozoic Era. Evolution of birds – Derivation of birds from a dinosaur precursor; Evolution of mammals – Derivation of mammals from a synapsid precursor, and the adaptive radiation of mammal species Evolution of cetaceans
Synapsids are a clade that includes mammals and their extinct ancestors. The latter group are often referred to as mammal-like reptiles, but should be termed protomammals, stem mammals, or basal synapsids, because they are not true reptiles by modern cladistic classification.
Monotreme mammals are also testicond (like reptiles) and contain some, but not all (absent seminal vesicles) of the male reproductive glands observed in most metatherian and eutherian mammals. This combination of reptilian and mammalian structures within the monotreme reproductive tract has informed the evolution of the male reproductive tract ...
Therocephalia is an extinct clade of eutheriodont therapsids (mammals and their close relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores.