A new study suggests that some prehistoric mammals were born nearly autonomous and grew up twice as quickly as their modern-day counterparts, providing them an advantage over other creatures after the extinction of the dinosaurs.
The discovery sheds light on how our early ancestors rose to prominence 62 million years ago and ruled lands formerly inhabited by Tyrannosaurus rex and others.
Scientists employed tooth analyses to determine the life history of Pantolambda bathmodon (P. bathmodon), a post-dinosaur herbivore roughly the size of a sheep.
According to their findings, P.bathmodon women were pregnant for around seven months and gave birth to single, well-developed infants with a full set of teeth.
The young, who were likely mobile from birth, nursed for about one to two months before attaining complete independence.
This early mammal lived and died more quickly than its contemporary counterparts, even though its gestation period was comparable to that of modern mammals of a similar size.
P. bathmodon were autonomous and sexually mature before their first birthday and survived only three to four years on average, although most animals of comparable size today live for at least 20 years.
The research was conducted by an international team led by the University of Edinburgh in partnership with the University of St Andrews, Carnegie Museum of Natural History, and New Mexico Museum of Natural History and Science.
Professor Steve Brusatte of the University of Edinburgh stated, “When the asteroid wiped off the dinosaurs 66 million years ago, some mammals survived and soon grew to fill the ecological niches vacated by T. rex, Triceratops, and other large dinosaurs.”
Being able to generate huge babies that grew for several months in the womb before birth allowed mammals to evolve from their mouse-sized predecessors that coexisted with dinosaurs to the broad array of species that exist today, including humans, elephants, and whales.
The scientists discovered that chemical alterations in the teeth revealed significant transitions in the early life of the organisms, such as high levels of zinc deposited at birth and barium enrichment throughout the nursing phase.
Dr. Gregory Funston, Royal Society Newton International Fellow at the University of Edinburgh and currently located at the Royal Ontario Museum in Toronto, is the study’s corresponding author. He stated, “Our research provides the most comprehensive view to date of the daily life of extinct mammals.
This exceptional amount of specificity demonstrates that the distinctive lifestyles of placental mammals developed early in their evolutionary history.
We believe that the prolonged gestation time of their infants may have fostered larger body sizes more quickly than other mammals, which may explain why they are the dominant mammals today.
