Jurassic mammals outlived modern counterparts, research reveals

Early mammals, which lived during the Jurassic period, when dinosaurs dominated the Earth, had much longer lifespans than their modern counterparts. These are the findings of a study published in the prestigious scientific journal "Science Advances."

Researchers conducted a detailed analysis of early mammal fossils from the Jurassic period, which allowed them to determine that these animals lived relatively long lives. A key element of this research was the analysis of growth rings in the teeth, which provided scientists with valuable information about the lifespan and growth rates of these mammals. This analysis also allowed them to determine the age at which these animals matured sexually.

The research, published on the University of Bonn's website, was conducted by teams of scientists from the University of Bonn in Germany and Queen Mary University of London in the United Kingdom.

As part of this research, scientists analysed fossils of various species of Jurassic mammals and their predecessors. These fossils were found in locations such as Portugal, Wales, and the United Kingdom (Oxfordshire). Among the analysed species were Dryolestes, which reached sexual maturity at the age of four years, and Haldanodon, which lived from eleven to fourteen years. These findings date back to between 200 million and 150 million years ago.

"We have never before been able to reconstruct the growth patterns of these early mammals with such precision," says Elis Newham from Queen Mary University of London.

The team of scientists utilised a technique known as synchrotron X-ray tomography. In this technique, electrons are accelerated to a speed close to the speed of light, which sets it apart from traditional X-ray imaging.

Thanks to this technique, scientists were able to obtain images of much higher quality than those achievable with conventional X-ray microtomography.

Scientists were able to visualise tiny growth rings in the bone tissue that anchors the teeth to the jaw. "These rings are similar to those found in trees, but they are much smaller and can only be seen under a microscope," explains Prof. Thomas Martin from the University of Bonn.

This research showed that the first signs of growth patterns characteristic of modern mammals, such as accelerated growth during adolescence, began to appear around 150 million years ago.

Early mammals grew much more slowly than their modern counterparts but lived much longer. Their lifespan ranged from eight to fourteen years, while today’s small mammals, like mice, typically live only one or two years. Early mammals, however, took several years to reach sexual maturity, whereas their modern counterparts reach it in just a few months.