EASY LIVING EATS : MASTER GLOBAL ESSAY

 

Small mammals often live fast and die young.  Rodents and shrews mature quickly, mate within months and usually go belly up in a year or two. Some giant rats kick the bucket in just six months.

But miniature mammals have not always burned out so quickly. Researchers recently analyzed a pair of fossilized skeletons belonging to a mouse - size mammal relative that lived among dinosaurs during the Jurassic period.

Their findings, published in the journal Nature,  reveal that these critters lived much longer and grew more slowly than their descendants of similar size.

The two specimens were discovered decades apart on the Isle of Skye in Scotland. This island was home to swampy lagoons fringed by dense forests 106 million years ago, Sauropod dinosaurs stomped across mud as pterosaurs flew overhead. Scurrying underfoot was a menagerie of Mesozoic mammal relatives.

Krusatodon kirtlingtonensis was among these ancestral mammals. The two newly described specimens provide a picture of Krusatodon,  which resembled a pint-size possum and weighed less than a hockey puck.

The larger of the Krusatodon specimens was found in the 1970. The another smaller Krusatodon was discovered in 2016 by Elsa Panciroli, a paleontologist at National Museums Scotland and the lead author of the new study,  and her team.

Dr. Panciroli said she was delighted '' to realize that the two of them were an adult and a juvenile of the same species.''

The team took high-resolution CT scans to compare the two fossil skeletons. To gauge how old each Kruatodon was when it died, the researchers analyzed rings of mineralized dental tissues called cementum.

The cementum hands revealed that the adult Krusatodon was around 7 years old when it died - a ripe old age, compared with living mammals of similar size.

The juvenile, which was roughly as large as the adult, was somewhere between 7 months and 2 years old.

Surprisingly, the Krusatodon was still replacing its baby teeth when it died.

'' We didn't expect it to be such an old juvenile,'' Dr. Panciroli said. Based on its size, '' you would expect it to replace its teeth within weeks or months, not two years.''

The World Students Society thanks Jack Tamisiea.