<i>Fedexia striegeli</i> Skull Views (IMAGE) Carnegie Museum of Natural History Caption This is the exquisitely preserved skull of <i>Fedexia striegeli</i>. <i>Fedexia</i>, described by researchers at Carnegie Museum of Natural History in Pittsburgh, Pa., provides evidence that the first widespread occurrence of terrestrial vertebrates 300 million years ago was in response to a brief episode of a globally warmer, drier climate. Credit Mark A. Klingler/Carnegie Museum of Natural History Usage Restrictions credit must be included 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.