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These extended margins of thinned bone are called supratemporal fossae. Synapsids, including mammals, have one temporal fenestra, which is ventrally bordered by a zygomatic arch composed of the jugal and squamosal bones. This single temporal fenestra is homologous to the infratemporal fenestra, as displayed most clearly by early synapsids. [2]
Primitively, it is a flattened plate-like bone, but in many animals it is narrower in form, for example, where it forms the boundary between the two temporal fenestrae of diapsid reptiles. [8] The petrous and mastoid parts of the temporal bone, which derive from the periotic bone, formed from the fusion of a number of bones surrounding the ear ...
Humans are synapsids, as well. Most mammals are viviparous and give birth to live young rather than laying eggs with the exception being the monotremes. Triassic and Jurassic ancestors of living mammals, along with their close relatives, had high metabolic rates. This meant consuming food (generally thought to be insects) in much greater quantity.
The nares are retracted and the orbits are raised like in other aquatic mammals. Levels of stable isotopes in their tooth enamel suggest an aquatic diet and environment (carbon and oxygen) and fresh or brackish water (strontium). Their spongy bone structure is similar to that of cetaceans.
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.
Whales do not lay eggs. Since they are mammals, they give birth to live young. There are only five known monotremes, or egg-laying mammals, according to the Carnegie Museum of Natural History ...
Turtles have secondarily lost their fenestrae, and were traditionally classified as anapsids because of this. Molecular testing firmly places them in the diapsid line of descent. Post-cranial remains of amniotes can be identified from their Labyrinthodont ancestors by their having at least two pairs of sacral ribs , a sternum in the pectoral ...
1 occipital bone; 2 parietal bones; 1 sphenoid bone; 2 temporal bones; The ossicles (three on each side) are usually not included as bones of the neurocranium. [6] There may variably also be extra sutural bones present. Below the neurocranium is a complex of openings and bones, including the foramen magnum which houses