Found "sister" of all living marsupials

North American marsupial species lived 32 million years ago

Skull of the Herpetotherium © Rosi Roth, Paleontological Institute of the University of Zurich
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An international research team has discovered new fossil finds as an important element in the evolution of marsupials: they identified a 32-million-year-old group of North American marsupials, the Herpetotherii, as the extinct sister group of all living Beutlers.

All living marsupials today, such as kangaroos, wombats, koala bears or opossums, have their origins on the former subcontinent Gondwana: they live on its present "remnants", in Australia and South America, or are - from the geologically short period of three million years ago - from the south - migrated to North America. However, marsupials were originally represented worldwide, as evidenced by the fossil record - the sum of all documented fossil occurrences described in publications.

Gaps in knowledge supplemented

However, the knowledge about the extinct genera today is still incomplete. Particularly fragmentary is the previous fossil record in the case of the originally native to North America Marsupial mammals: Here, it is based only on fragmentary tooth finds. New findings are now provided by the analyzes of Professor Marcelo Sánchez of the University of Zurich and his international research team from France, Great Britain, the USA and Germany. Their study was published in the scientific journal "Proceedings of the Royal Society, Biology Letters".

The study of several exceptionally well preserved fossil skulls and numerous skeletal material discovered in Wyoming, USA, provides information on the extremely important group of North American marsupials, the Herpetotherii. This group of baggers existed about 32 million years ago in the Oligocene of North America. So far it has been assumed that it is a primitive group of opossums.

Sister instead of subgroup

The current analyzes, however, show that the genus Herpetotherium differs significantly from the Opposum and that it does not form a subgroup, but the direct sister group to the entire spectrum of living marsupial mammals today. This group is therefore the ancestor of the extinct sisters of all living marsupials today. display

For the first time can be made statements about anatomy and lifestyle of this group. Thus, the investigation of the fossils, which was done among other things by computer tomography and microscopic evaluation of tooth structures, suggests a terrestrial lifestyle and a generalized food from insect and plant diet.

(University of Zurich, 17.04.2007 - NPO)