What family are reptiles in?

Which distinguishing characteristic allowed the amniotes to venture onto land?

The distinguishing characteristic of amniotes, a shelled egg with an amniotic membrane, allowed them to venture onto land. The amniotes include reptiles, birds, and mammals; shared characteristics between this group include a shelled egg protected by amniotic membranes, waterproof skin, and rib ventilation of the lungs.

What are the 4 living clades of reptiles?

Class Reptilia, amniotes that are neither mammals nor birds, has four living clades: Crocodilia, Sphenodontia, Squamata, and Testudine. Reptile are amniotes that lay their eggs on land; they have scales or scutes and are ectothermic.

What are the classes of amniotes?

In the past, the most common division of amniotes has been into the classes Mammalia, Reptilia, and Aves. Birds are descended, however, from dinosaurs, so this classical scheme results in groups that are not true clades.

How did the early amniotes split into two main lines?

The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids and sauropsids. Synapsids include all mammals, including extinct mammalian species.

How did the early amniotes differ from their amphibian ancestors?

While the early amniotes resembled their amphibian ancestors in many respects, a key difference was the lack of an otic notch at the back margin of the skull roof. In their ancestors, this notch held a spiracle, an unnecessary structure in an animal without an aquatic larval stage.

How did amniotes evolve from small lizards?

The eggs could also “breathe” and cope with wastes, allowing the eggs and individuals to evolve into larger forms. The first amniotes, referred to as “basal amniotes”, resembled small lizards and evolved from the amphibian reptiliomorphs about 312 million years ago, in the Carboniferous geologic period.

What are amniotes classified as?

Amniotes are a clade of tetrapod vertebrates that comprise sauropsids (including reptiles and birds) and synapsids (including mammals). They are distinguished by a membrane (amnion) protecting the embryo and a lack of a larval stage.

How are the amniotes distinguished from amphibians?

The amniotes are distinguished from amphibians by the presence of a terrestrially adapted egg protected by four extra-embryonic membranes. The amniotes include reptiles, birds, and mammals. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids (mammals) and sauropsids.

How did the first amniotes evolve?

The first amniotes evolved from amphibian ancestors approximately 340 million years ago during the Carboniferous period. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids and sauropsids.

What are the different types of amniotes?

The amniotes include reptiles, birds, and mammals. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids (mammals) and sauropsids. Sauropsids can be further divided into anapsids and diapsids (crocodiles, dinosaurs, birds, and modern reptiles).

How are amniotes different from amphibians?

Unlike amphibian species amniotes were completely adapted to land and had no reliance on aquatic environments even for reproductive purposes. You may have never heard of the term amniotes before, but they are a family which contains birds, mammals and reptiles.

What is the evolutionary history of amniotes?

Evolution of Amniotes The first amniotes evolved from amphibian ancestors approximately 340 million years ago during the Carboniferous period. The early amniotes diverged into two main lines soon after the first amniotes arose. The initial split was into synapsids and sauropsids.

How did reptiles evolve from amniotes?

The amniotes split into two main groups. One of those groups were the Sauropsids, which developed scaled skin and all the other features we associate with reptiles. The first reptiles evolved over 300 million years ago, and would ultimately diversify into turtles, lizards, crocodiles, and all the other crazy varieties of reptiles we know of.

What is the function of the amniotic membrane?

amnion: the innermost membrane of the fetal membranes of amniotes; the sac in which the embryo is suspended; protects the embryo from shock and carries out hydration The amniotes, reptiles, birds, and mammals, are distinguished from amphibians by their terrestrially-adapted egg, which is protected by amniotic membranes.

How did the evolution of amniotic membranes affect the development of embryos?

The evolution of amniotic membranes meant that the embryos of amniotes were now provided with their own aquatic environment, which led to less dependence on water for development, allowing the amniotes to branch out into drier environments.

What are amniotes and how are they classified?

Amniotes are often described and grouped by the number of openings (fenestrae) that are present in the temporal region of their skull. The three groups that have been identified on this basis include the anapsids, diapsids, and synapsids. Anapsids have no openings in the temporal region of their skull.

What is the difference between amniotes and mammals?

Very shortly after the first amniotes appeared, a lineage called Synapsida split off; this group was characterized by a temporal opening in the skull behind each eye to give room for the jaw muscle to move. These are the “mammal-like amniotes”, or stem-mammals, that later gave rise to the true mammals.

What is the difference between amniote and amphibian embryos?

Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes. In eutherian mammals (such as humans), these membranes include the amniotic sac that surrounds the fetus. These embryonic membranes and the lack of a larval stage distinguish amniotes from tetrapod amphibians.

What is the difference between amnion and amniotes?

They differ from amniotes, or “higher vertebrates” (reptiles, birds, and mammals), which deposit their eggs on land or keep the fertilized egg within the mother. The term “amnion” refers to an embryonic membrane generated during amniotes’ fetal development that functions to carry oxygen into the egg and expel carbon dioxide.

Why did the amniotic sac evolve in mammals?

It evolved due to the need for animals to have offspring while being able to be completely terrestrial. The amniotic sac is able to house the growing offspring, provide nutrients, oxygen though the placenta and fluid for protection. The first mammals were egg-laying.

What do amphibians reptiles and mammals have in common?

Amphibians, reptiles, and mammals all are tetrapods; they have true limbs. Reptiles and mammals (as well as birds, or feathered reptiles) have amniotic eggs; in conjunction with internal fertilization, the amniotic egg allows these classes to reproduce without the necessity of water to protect and support the egg.

What is the function of the four membranes of the amniote?

Together, these four membranes protect the embryo and prevent its drying out. They are also responsible for the control of gas exchange and for providing nutrients for the developing embryo. The presence of the chorion, allantois, yolk sac, and amnion leads to the identification of an organism as an amniote.

What is the function of the amnion membrane?

Amnion Definition. The amnion is an extraembryonic membrane that surrounds a developing amniote embryo. It acts as a protective sac along with three other extraembryonic membranes: the chorion, the yolk sac, and the allantois. The membranes are then enclosed further by a shell (in birds, reptiles, and some mammals) or in a uterus (in most mammals).

What is the function of the amnion and chorion in the embryo?

D is correct. The amnion acts to protect the developing embryo against mechanical shock. The chorion and the allantois are involved in gas exchange of oxygen and carbon dioxide, while the allantois transports nutrients to, and waste from, the embryo.