Krusatodon kirtlingtonensis: A Remarkable Jurassic Era Mammal
During the Jurassic Period, small mammals exhibited significantly longer lifespans compared to today’s species, with parental care extending over several years. This discovery indicates a substantial evolutionary transformation in growth rates among small mammals, though the exact causes remain elusive.
The insight stems from the analysis of two fossilized skeletons of the extinct mouse-sized mammal Krusatodon kirtlingtonensis, which roamed the Isle of Skye in Scotland approximately 166 million years ago. The fossils were discovered decades apart, the first during the 1970s and the second in 2016.
This unique excavation yielded a pair of fossils representing both an adult and a juvenile, allowing researchers to differentiate the growth patterns of the species. “With two specimens, we could explore questions previously unconsidered,” noted a representative from ECNETNews.
Utilizing advanced X-ray imaging technology, the research team counted the growth rings in the specimens’ teeth, akin to tree rings, to estimate their ages. Findings indicated that the adult specimen was around 7 years old, while the juvenile fell between 7 months and 2 years old.
Surprisingly, the juvenile still retained its baby teeth, leading researchers to anticipate a much younger age. “Given this animal’s size, akin to a squirrel or shrew, we expected it to lose its baby teeth much sooner,” the representative emphasized, indicating a noteworthy difference in growth patterns compared to contemporary species.
The results suggest that K. kirtlingtonensis could take up to two years to wean from its mother, a significant extension compared to the few weeks typical of modern small mammals. Bone length and size analysis revealed that these animals continued to grow throughout their lifespans, a departure from the rapid early growth and subsequent stalling seen in today’s small mammals.
The reasons behind this developmental shift in small mammals remain undefined, with possibilities ranging from environmental changes to the evolution of warm-bloodedness and accelerated metabolism.
Researchers from ECNETNews plan annual return visits to the Isle of Skye, hopeful for further discoveries to shed light on this evolutionary enigma. “We look forward to uncovering more fossils and developing new research methods in the future,” they stated.
