Sinodelphys is the oldest known mammal of the Metatheria infrared class, which also includes contemporary pedigrees.
This animal lived 125 million years ago (Barrion of the Chalk Age) and Sinodelphys has been found in the Yixian formation, the famous fossil venue in the northern Chinese province of Liaoning. In this area, other mammals like Eomaia, Repenomamus and multituberculates also lived. Feathered dinosaurs like Sinosauropteryx and Microraptor have also been found in Liaoning. Sinodelphys were 15-20 cm tall and about 30g heavy. This animal looked like an opossum. The skeleton indicates that Sinodelphys was a good climber and probably the omnivore that ate both fruits and insects. As with other mammals from the Yixian formation, besides a virtually complete skeleton, fur coat and body parts have been preserved from Sinodelphys.
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