The North America of the Cretaceous Period approximately 100 to 66 million years ago was a far cry from the North America of today. Not only was the continent split into two separate landmasses, Laramidia in the west and Appalachia in the east; it was also dominated by a variety of dinosaur species, some of which bared a striking resemblance to the modern ostrich.
According to a paper published in PLOS ONE, the analysis of fossils from an ancient formation of rock in northern Mississippi has now revealed two new species of these ostrich-like dinosaurs, one of which was among the largest in the world. The analysis has also advanced scientists' understandings of dinosaur diversity in the Appalachian section of Cretaceous North America.