Definition of amniote Amniote

am•ni•ote

We found 4 definitions of amniote from 4 different sources.

What does amniote mean?

Noun Plural: amniotes
amniote - any member of the Amniota
		craniate, vertebrate animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium
		amniota higher vertebrates (reptiles, birds and mammals) possessing an amnion during development
		amnion, amnios, amniotic sac thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)

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amniote (Noun)
Any of the Amniota group of vertebrates having an amnion during the development of the embryo; mammals, birds and reptiles.

The amniotes are a taxonomical family of animals. They are a group of tetrapod vertebrates that include the Synapsida (mammals and mammal-like reptiles) and Sauropsida (reptiles and dinosaurs, including birds). The embryos of amniotes are either laid as eggs or carried by the female. These embyros are protected by several membranes. In humans, these membranes include the amniotic sac that surrounds the fetus. These embryonic membranes are why amniotes are different from other tetrapods, the amphibians.

The first amniotes looked similar to small lizards. They evolved 340 million years ago. Their eggs could survive out of the water. This let amniotes move into environments that had less water. The amniotes moved across the Earth. Almost all vertebrates that live mainly on land are amniotes.