Fossil (IMAGE) University of Washington Caption Well-preserved fossils -- like this Yanoconodon allini (Specimen No.: NJU P06001; Formation: Yixian; Age: 122.2-124.6 million years ago; Provenance: China) -- enabled the team to infer ecology of these extinct mammal species, and look at changes in mammal community structure during the last 165 million years. Credit Meng Chen Usage Restrictions Must include credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.