In 1828, Mary Anning in England found the first pterosaur genus outside Germany, by Richard Owen named as "Dimorphodon", also the first non-pterodactyloid pterosaur known. Later in the century, the Early Cretaceous Cambridge Greensand produced thousands of pterosaur fossils, that however, were of poor quality, consisting mostly of strongly eroded fragments. Based on these, nevertheless numerous genera and species would be named. Many were described by Harry Govier Seeley, at the time the main English expert on the subject, who also wrote the first pterosaur book, "Ornithosauria", and in 1901 the first popular book, "Dragons of the Air". Seeley thought that pterosaurs were warm-blooded and dynamic creatures, closely related to birds. Earlier, the evolutionist St. George Jackson Mivart had suggested pterosaurs were the direct ancestors of birds. Owen opposed the views of both men, seeing pterosaurs as cold-blooded "true" reptiles.