Tests performed on ancient fossils have revealed that early mammals lived a lot longer in comparison to modern counterparts. Researchers analyzed fossilized teeth from Morganucodon and Kuehneotherium, insectivore mammals who lived during the early Jurassic period, in an area which can be found in South Wales.
While they have the size of contemporary shrews, the two mammals enjoyed a lifespan of up to 14 years, which is considerably longer than the lifespan of mice and shrews, who live up to two years in the wild.
It is worth noting that the high-quality fossils were recovered from caves and holes in which the tiny mammals fell as they were exploring the surrounding areas. Digital reconstructions of the teeth showed that the Morganucodon lived for up to 14 years, while the Kuehneotherium survived for up to 9, with the numbers being quite impressive.
Their skeletons show many similarities with one of the contemporary mammals. Shared traits include specialized chewing teeth which were used to consume prey. Skulls feature enough space for a relatively large brain, and it is likely that their bodies were covered in hair of thin fur.
Previous research has inferred that ancestors of mammals have started to become more warm-blooded since the start of the Late Permian era, more than 270 million years ago. However, after more than 70 million years, they were more similar to reptiles in comparison to modern mammals.
In the past, researchers used to believe that the key characteristics of mammals surfaced at the same time, but it seems that this is not the case. Observations of the blood tissues have also revealed that the blood flow was a bit faster in comparison to lizards with a similar size, but they lacked the energetic lifestyle of contemporary mammals.
The results are quite interesting, and the study has been published in a scientific journal.