New Zealand lizards tuataras helped scientists to qualify that the penis appeared in the evolution of amniotes (reptiles, birds, mammals) only 1 time, and all the variety of its forms (the bodies of the forked snake, solid - crocodiles, spiral birds) arose under the influence of different environmental conditions. The results of a new study presented in the journal Biology Letters.
Tuataras are "living fossils": the last adherents of the squad that became extinct together with the dinosaurs. They are remarkable including lack of the penis, in consequence, by studying them, we can understand, had preradical of hattery male genitals (and then lost them) or never had.
This issue can be checked by examining the eggs of lizards and traced the development of the embryo. The problem is that tuataras are endangered species and they reproduce very slowly. For puberty, they need about 10 years, and the females lay eggs only every two to five years. Each egg is extremely valuable and is under the control of new Zealand authorities.
But 1 of his colleagues managing research con Martin (Martin Cohn) remembered that in the vaults of Harvard's Museum of comparative Zoology preserved collection of histological sections, even including a few embryos hattery (they were made in 1909). Scientists were lucky: slices of one of the embryos treated directly to the stage of development when other reptiles begins the formation of the penis. Such forms on sections of an embryo tuataras would prove her ability to develop this body.
On the wonderfully surviving sections of the early twentieth century scientists turned to mount three-dimensional model of a fetus - and to find there the traces of the penis. Therefore, hattery male organ began to grow in the embryo stage, but after that, even before the birth of the egg, disappears. So prove the ability of all amniotes to form the penis, and the fact that modern diversity of forms arose over time, as the development of certain types.
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