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The egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. [1] Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals, monotremes (four species of echidna, and the platypus) are uniquely oviparous.
This feature, along with some other genetic similarities with birds, such as shared genes related to egg-laying, is thought to provide some insight into the most recent common ancestor of the synapsid lineage leading to mammals and the sauropsid lineage leading to birds and modern reptiles, which are believed to have split about 315 million ...
The viviparous lizard, or common lizard, (Zootoca vivipara, formerly Lacerta vivipara) is a Eurasian lizard.It lives farther north than any other species of non-marine reptile, and is named for the fact that it is viviparous, meaning it gives birth to live young (although they will sometimes lay eggs normally). [3]
Like other amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone ; the upper part is the domed carapace , while the underside is the flatter plastron or belly-plate.
Reptiles, from Nouveau Larousse Illustré, 1897–1904, notice the inclusion of amphibians (below the crocodiles). In the 13th century, the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians, and worms", as recorded by Beauvais in his Mirror of Nature. [7]
Females can build or dig several trial nests which appear incomplete and abandoned later. Egg-laying usually takes place at night and about 30–40 minutes. [88] Females are highly protective of their nests and young. The eggs are hard shelled, but translucent at the time of egg-laying. Depending on the species of crocodile, 7 to 95 eggs are laid.
In species in which eggs are laid then buried in sand, indentations in the sand can be a clue to imminent hatching. [9] In sea turtles, this usually occurs about 60 days after the laying of eggs, and often at night. [10] However, exposure to xenobiotic compounds, especially endocrine-disrupting compounds, can affect hatchling sex ratios as well ...
The gharial (Gavialis gangeticus), also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. . Mature females are 2.6 to 4.5 m (8 ft 6 in to 14 ft 9 in) long, and males 3 to 6 m (9 ft 10 in to 19 ft 8