A collaborative effort among archaeologists and paleontologists has led to the discovery and identification of a previously unknown mammal species from the Maastrichtian age, representing a significant breakthrough in the understanding of prehistoric life. Detailed in their publication in Scientific Reports, the researchers emphasize the exceptional size of this newfound mammal, surpassing others of its kind from that era.
The fossilized remains, comprising a femur, tibia, hip, and hip socket, enabled the classification of the mammal within the Theria group, encompassing non-egg-laying mammals. Notably, the size of the discovered creature sets it apart, with the team naming it Patagomaia chainko. Unearthed in southern Patagonia, this medium-sized mammal, estimated to be about the size of an Andean fox, roamed the Earth approximately 70 million years ago.
Comparisons with contemporary mammals highlight the distinctive dimensions of Patagomaia chainko, suggesting an average weight range of 2 to 25 kilograms and a length of around one meter. Such proportions challenge the norm for mammals of that era, as prior research indicates most had a body mass below 100 grams, with only a fraction reaching 1 kilogram. The smallest estimates for P. chainko position it among the largest mammals of the Mesozoic Era.
Intriguingly, the researchers speculate about the creature's appearance, drawing parallels with a platypus, or perhaps a porcupine or badger. This conjecture adds an extra layer of curiosity to the understanding of the diversity in Mesozoic mammals.
The Mesozoic era typically hosted diminutive mammals, comparable in size to modern mice or shrews. Notably, the researchers observe a trend of larger body sizes among Mesozoic mammals residing in the southern hemisphere, compared to their northern counterparts—until the cataclysmic asteroid impact that precipitated the demise of the dinosaurs. The newly identified mammal, Patagomaia chainko, is anticipated to provide valuable insights into the evolution of southern hemisphere mammals during the Mesozoic Era, contributing to a more comprehensive understanding of prehistoric biodiversity.