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After internal fertilization and the habit of laying eggs in terrestrial environments became a reproduction strategy amongst the amniote ancestors, the next major breakthrough appears to have involved a gradual replacement of the gelatinous coating covering the amphibian egg with a fibrous shell membrane. This allowed the egg to increase both ...
Cladistically included but traditionally excluded taxa. Amniotes. The anamniotes are an informal group of craniates comprising all fish and amphibians, which lay their eggs in aquatic environments. They are distinguished from the amniotes (reptiles, birds and mammals), which can reproduce on dry land either by laying shelled eggs or by carrying ...
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals).
Anurans are the amphibians lacking a tail such as frogs and toads. [16] Anurans are commonly used as a model organism for amphibians, because of the large, easy to manipulate eggs, fast developmental rate, high fecundity rate, no parental involvement, and external fertilization. Males will congregate near a lake or pond and establish calling ...
Eggs of various birds, a reptile, various cartilaginous fish, a cuttlefish and various butterflies and moths. (Click on image for key) Diagram of a fertilized chicken egg in its ninth day. Membranes: allantois, chorion, amnion, and vitellus/yolk. An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote ...
The characteristic quivering abdomen caused by movement of tadpoles within a pregnant female Limnonectes larvaepartus. Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos ...
List of amphibians. The temnospondyl Eryops had sturdy limbs to support its body on land. Red-eyed tree frog (Agalychnis callidryas) with limbs and feet specialised for climbing. Japanese giant salamander (Andrias japonicus), a primitive salamander. The bright colours of the common reed frog (Hyperolius viridiflavus) are typical of a toxic species.
Reptiliomorpha (meaning reptile-shaped; in PhyloCode known as Pan-Amniota[ 2 ][ 3 ]) is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians (lissamphibians). It was defined by Michel Laurin (2001) and Vallin and Laurin (2004) as the largest clade that includes ...