Palaeontology: 75 million-year-old burrow contains fossilised rodents snuggled-up together 

US palaeontologists made the find - the oldest evidence of social behaviour among mammals - in a famous dinosaur nesting site called Egg Mountain, in Montana. https://www.dailymail.co.uk/sciencetech/article-8908923/Palaeontology-75-million-year-old-burrow-contains-fossilised-rodents-snuggled-together.html?ns_mchannel=rss&ns_campaign=1490&ito=1490