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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).
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 fertilized eggs within the female.
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 ...
Eggs laid by many different species, including birds, reptiles, amphibians, and fish, have probably been eaten by people for millennia. Popular choices for egg consumption are chicken, duck, roe, and caviar, but by a wide margin the egg most often humanly consumed is the chicken egg, typically unfertilized.
Many ancient reptile groups are known from egg fossils including crocodilians, dinosaurs, and turtles. [3] Some ancient reptiles, like ichthyosaurs [8] and plesiosaurs [9] are known to have given live birth and are therefore not anticipated to have left behind egg fossils. Dinosaur eggs are among the most well known kind of fossil reptile eggs. [3]
Several authors have suggested that terrestrial eggs evolved from amphibian eggs laid on land to avoid predation on the eggs and competition from other labyrinthodonts. [62] [63] The amniote egg would necessarily have had to evolve from one with an anamniote structure, as those found in fish and modern amphibians. [59]
The egg discovery was revealed the same day the Conservancy for Southwest Florida reported a 19-foot python found July 10 in Big Cypress National Preserve counted as a state record and possibly a ...
Some fish and amphibian eggs have thick, leathery coats, especially if they must withstand physical force or desiccation. These types of eggs can also be very small and fragile. [citation needed] While many reptiles lay eggs with flexible, calcified eggshells, there are some that lay hard eggs. Eggs laid by snakes generally have leathery shells ...