Anthracobunid Jaws and Horse Skull (IMAGE) PLOS Caption Pictured here are two jaws from anthracobunids recovered from 48 million year old sediments next to a horse skull. The study found that anthracobunids were an ancient relative of horses, rhinos, and tapirs. Credit Copyright Cooper Lab, NEOMED Usage Restrictions CC-BY 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.