(ORDO NEWS) — Early mammals often died at a young age, but this may have been part of an evolutionary strategy. An article about this was published in Nature.
The authors of the work studied pantolambda, an ancient mammal that lived in North America about 62 million years ago. Outwardly, it vaguely resembled a large cat, but at the same time led a herbivorous lifestyle.
To study the life of an individual, scientists cut its teeth into thin layers, and analyzed the growth lines. This made it possible to obtain a time scale of life accurate to the day.
Then the layers were evaporated with a laser and the chemical composition was analyzed using a spectrometer, which made it possible to find out what condition the animal was in at different periods of life.
For example, at birth, there is a lot of zinc in the teeth, and a high proportion of barium is characteristic of the time of breastfeeding.
As it turned out, the gestation period reached seven months, the cub was born with teeth and, probably, with the ability to walk from the first days. Milk feeding lasted 1-2 months, and by the end of the first year, the individual reached sexual maturity.
It came as a surprise to the scientists that most pantolambdas studied died at about four years of age, with the oldest individuals living to 11 years of age.
This pace of life is much faster than that of modern mammals. Pantolambdas lived, on average, half as long as one would expect, based on the size of their bodies.
Probably, this was the advantage of these animals and other mammals over other species, since the rapid change of generations leads to accelerated evolutionary adaptation.
Most likely, this is what made it possible for mammals to occupy many evolutionary niches after the extinction of giant lizards.
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