In a new research paper published in the journal "Naturwissenschaft" provides information about the opening of fossil reptiles, living about 120 million years ago, which proves that some lizards do not lay eggs, but give birth to live young.
The fossil was found Susan Evans (Susan Evans), a professor from the Department of Cellular and Evolutionary Biology, University College London, in Jehol (Jehol) north-east of China. In this area were also found hundreds of dinosaurs, amphibians, reptiles, fish, birds, mammals and invertebrates, as well as fossils of various plants.
Lizard in this case was identified as a species Yabeinosaurus, as scientists assume that is related to geckos belonging to the family Gekkonidae. Researcher Ivas initially did not attach much importance to fossil when it was discovered, but Yuan Wang (Yuan Wang) from the Chinese Academy of Sciences studied in detail the fossil and discovered it 15 small fossil embryos.
The embryos are almost completely formed and the researchers believe that the mother length of about 30 centimeters died just days before she was to give birth to offspring.
This finding clearly shows that some lizards give birth to live young during the Early Cretaceous period. Preceding the opening of some marine fossil lizards have already indicated that they were viviparous reptile, but it is opening for the first time demonstrated that this feature was peculiar play and terrestrial lizards.
"We previously thought that lizards adapted to give birth to live young after mammals, but now it is obvious that it happened at about the same time period. This pattern, which is the oldest of those that we have seen, refers to the fact that such a physiological adaptation, as a necessary blood supply to the embryos and very thin shells or no shells at all, to access the oxygen evolved at a very early period, "- said Professor Susan Evans.
For lizards extra weight during the entire embryonic period may restrict their movement and ability to escape from predators. It is assumed that the lizard, whose fossils have been discovered recently, lived on the river bank or in a place nearby to the water to in times of danger, so was it easier and faster to run away and hide from predators in the water.
"We know that this lizard lived near the water, and so we assume that probably lizards could swim, even if they originally lived on the land. This was very important to them, as a pregnant lizard, more restricted in his movements, in mean gestation of offspring could always hide in the water when approaching a hungry dinosaur! " - Concluded Evans.
Original: Physorg Translation: M. Potter