Harvard University scientists revealed the time of origin of the earliest four-legged animals and found out that the tetrapeods acquired several new adaptive traits that allowed the vertebral to live on land and evolve the accelerated pace. Article researchers Published in the journal Nature Ecology and Evolution.
Specialists combined data on petrified remains and prints followed by early vertebrate animals, and also applied the Bayesian method for an accurate estimate of the time and pace of anatomical evolution during the appearance of tetrapeods. It turned out that the four-legged appeared 390 million years ago, which is 15 million years older than the oldest fossil belonging to the tetrapeods.
Researchers also found that most of the next relatives of four-legged fish had an exceptionally low rates of anatomical evolution, which suggests that these animals were quite well adapted to their water lifestyle. However, the evolutionary lines that led to the appearance of the first tetrapeods, on the contrary, differed by the high rates of evolution, which persisted within 30 million years.
All parts of the skeleton four-legged were under strong pressure directed selection for the development of new adaptive functions, but the skull and jaws developed faster than the rest of the body, including limbs. This is explained by the fact that the evolution of the limbs was more important in the late stage, when the animals were already adapted to life on land. Also, scientists found that, despite the high rates of evolution, the rate of formation of new animal species remained relatively low.