In a paper published in the journal Communications Biologya team of U. The discovery was enabled by high-resolution of incremental growth marks preserved in the fossilized tusks of Lystrosaurus from Antarctica. Image credit: Victor O. Leshyk, www. Lystrosaurus is a type of dicynodonta major group of primarily herbivorous vertebrates underklader for man date sidor were common during underklader for man date sidor Permian and Triassic periods.

The ancient creature was between 1. The fossilized remains of Lystrosaurus are known from China, Europe, India, South Africa and Antarctica and this geographic distribution was one of the early pieces of evidence used in support of the large supercontinent Pangea. The Lystrosaurus fossils from the Fremouw Formation of Antarctica are the oldest evidence of a hibernation-like state in a vertebrate animal and indicate that torpor — a general term for hibernation and similar states in which animals temporarily lower their metabolic rate to get through a tough season — arose in vertebrates even before mammals and dinosaurs evolved.

Megan Whitneya postdoctoral researcher at Harvard University. It is an ancient one. The Lystrosaurus tusks made the study possible because, like elephants, their tusks grew continuously throughout their lives. The paleontologists compared cross-sections of tusks from six Antarctic Lystrosaurus to cross-sections of four Lystrosaurus from South Africa.

The underklader for man date sidor from the two regions showed similar growth patterns, with layers of dentine deposited in concentric circles like tree rings. The Antarctic fossils, however, held an additional feature that was rare or absent in tusks farther north: closely-spaced, thick rings, which likely indicate periods of less deposition due to prolonged stress. Whitney said. The researchers cannot definitively conclude that Lystrosaurus underwent true hibernation.

The stress could have been caused by another hibernation-like form of torpor, such as a more short-term reduction in metabolism. Evidence of torpor in the tusks of Lystrosaurus from the Early Triassic of Antarctica. Commun Biol 3, ; doi: Source Link.

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