Ancient mammals lived fast and died young, but this could be the reason for their evolutionary success

(ORDO NEWS) — By studying the chemical composition of the teeth of pantolambda, a relatively large mammal that lived 62 million years ago, scientists were able to describe in detail the stages of its life.

It turned out that pantolyambdas bore cubs for a long time, quickly grew up and died early.

Perhaps this is what allowed early mammals to quickly reach large sizes and occupy the ecological niches vacated after the extinction of the dinosaurs.

By studying the growth lines and chemical composition of the teeth of ancient mammals, scientists from the UK, the US and Canada have been able to accurately reconstruct their lives.

The object of the study was pantolambda ( Pantolambda bathmodon ), which lived about 62 million years ago in the territory of modern North America.

This animal was about the size of a sheep, and outwardly resembled modern cats, but was a herbivore. The new approach made it possible to determine exactly when the pantolambdas were born, how long they ate milk and at what age they died.

Scientists have made the thinnest sections of pantolambda fossil teeth and used a laser to vaporize their constituent substance and determine its chemical composition.

Growth lines on sections of teeth made it possible to divide the life of a mammal into clear time periods, sometimes equal to one day, and the chemical composition of the teeth showed changes in the diet and lifestyle of the animal.

For example, zinc levels are high at birth, and barium-rich enamel layers are deposited during breastfeeding. The study made it possible to learn more about the life of pantolambda than is known about the life of some modern mammals.

Ancient mammals lived fast and died young but this could be the reason for their evolutionary success 2
Reconstruction of the appearance of the pantolambda – adult and juvenile

It turned out that the pantolambdas carried offspring for a little less than seven months and gave birth to one well-developed cub with already formed teeth.

The cub, probably, could move independently already in the first days of life, fed on mother’s milk for only one or two months and reached puberty in about a year.

Such a long pregnancy is characteristic of placental mammals, in which, unlike marsupials and monotremes, the young grow inside the mother’s body, and their metabolism goes through the placenta.

Ancient mammals lived fast and died young but this could be the reason for their evolutionary success 3
Pantolambda teeth

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.

However, this speed may have given them and related mammals an advantage over other species, as it allowed them to evolve faster to spread around the planet after the extinction of the dinosaurs.

Dinosaurs disappeared 66 million years ago, after which the surviving mammals rapidly increased in size to fill the ecological niches vacated by large predators and herbivores.

The ability to give birth to large and independent young and the fast pace of life helped them to evolve from small creatures the size of a mouse into the huge number of species that we see today.

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