A “mummy” in paleontology refers to an exceptionally preserved fossil that includes evidence of soft tissues, such as skin, muscles, or even internal organs, rather than just bones. These discoveries are rare, as soft tissues typically decay before fossilization. Such preservation offers a glimpse into the anatomy and appearance of ancient life, revealing details skeletal remains alone cannot. These fossils provide unique insights into prehistoric creatures and their environments.
Understanding Lystrosaurus
Lystrosaurus was a heavily built, herbivorous animal that lived from the late Permian to the early Triassic epochs, approximately 255 to 248 million years ago. It belongs to dicynodonts, a group of extinct mammal-like reptiles within the synapsid clade that includes modern mammals. Lystrosaurus had a distinctive pig-like appearance, with a horny beak and two prominent tusks extending downwards from its upper jaw, likely used for digging up plant roots.
Its size varied by species, ranging from that of a small dog to 2.5 meters (8 feet) long, averaging 0.9 meters (3 feet). Lystrosaurus moved with a semi-sprawling gait, and its robust forelimbs suggest it was a powerful digger, possibly nesting in burrows. This creature is notable for its survival of the Permian-Triassic extinction event, “The Great Dying,” which wiped out an estimated 70% of land vertebrates and 96% of marine animals. In the early Triassic, Lystrosaurus became the most common terrestrial vertebrate, making up as much as 95% of individuals in some fossil beds and dominating southern Pangaea for millions of years.
The “Mummy” Discovery
The Lystrosaurus “mummy” fossil is extraordinary due to the preservation of non-skeletal elements, such as skin impressions. Minerals replaced these soft tissues, creating a detailed stone replica. Such “mummified” fossils form when the body is protected from decay long enough for minerals to infiltrate and replace the soft tissues before they decompose.
This Lystrosaurus “mummy” was discovered in Antarctica, within the Fremouw Formation. Lystrosaurus fossils from this region were first found in 1969, with more abundant materials collected in subsequent years. The exceptional preservation likely involved rapid burial by wind-blown sand and mud, possibly after the animals died from drought around watering holes. This quick burial prevented typical decomposition, allowing for the impressions of pebbly skin and articulated bones to be preserved.
Insights from the Extraordinary Fossil
The Lystrosaurus “mummy” provides insights into the creature’s physiology and appearance. Preserved pebbly skin impressions offer direct evidence of its external texture. Articulated ribs still linked together suggest the skin was likely attached at burial, providing clues about its body structure.
These rare fossils contribute to understanding life during the early Triassic period and the recovery from the Permian-Triassic extinction. While scientists cannot definitively conclude Lystrosaurus underwent true hibernation, stress marks in the tusks of Antarctic specimens are analogous to those in modern hibernating animals. This suggests Lystrosaurus may have entered a hibernation-like state, or torpor, to cope with harsh environmental conditions near the South Pole, indicating such adaptations arose in vertebrates before mammals and dinosaurs evolved. The presence of multiple juvenile Lystrosaurus “mummies” found together suggests groups of young individuals may have huddled before dying, possibly due to recurring droughts after the mass extinction. This provides a clearer picture of their struggle for survival in the altered post-extinction environment.