vertebrae were short and massive, even in the neck. The neck was relatively short, consisting of at least 13 massive vertebrae. The torso was relatively short. The wings were vestigial, with the upper wing-bones small and highly reduced, similar in proportion to the wings of the cassowary. Classification Gastornis and its close relatives are classified together in the family Gastornithidae, and were long considered to be members of the order Gruiformes. However, the traditional concept of Gruiformes has since been shown to be an unnatural grouping. Beginning in the late 1980s with the first phylogenetic analysis of gastornithid relationships, consensus began to grow that they were close relatives of the lineage that includes waterfowl and screamers, the Anseriformes. A 2007 study showed that gastornithids were a very early-branching group of anseriformes, and formed the sister group to all other members of that lineage. Recognizing the apparent close relationship between gastornithids and waterfowl, some researchers classify gastornithids within the anseriform group itself. Others restrict the name Anseriformes only to the crown group formed by all modern species, and label the larger group including extinct relatives of anseriformes, like the gastornithids, with the name Anserimorphae. Gastornithids are therefore sometimes placed in their own order, Gastornithiformes. A simplified version of the family tree found by Agnolin et al. in 2007 is reproduced below. Today, at least five species of Gastornis are generally accepted as valid. The type species, Gastornis parisiensis, was named and described by Hébert in two 1855 papers. It is known from fossils found in western and central Europe, dating from the late Paleocene to the early Eocene. Other species previously considered distinct, but which are now considered synonymous with G. parisiensis, include G. edwardsii (Lemoine, 1878) and G. klaasseni (Newton, 1885). Additional European species of Gastornis are G. russeli (Martin, 1992) from the late Paleocene of Berru, France, and G. sarasini (Schaub, 1929) from the early-middle Eocene. G. geiselensis, from the middle Eocene of Messel, Germany, has been considered a synonym of G. sarasini, however, other researchers have stated that there is currently insufficient evidence to synonymize the two, and that they should be kept separate at least pending a more detailed comparison of all gastornithids. The supposed small species G. minor is considered to be a nomen dubium. Gastornis gigantea (Cope, 1876), formerly Diatryma, dates from the middle Eocene of western North America. Its junior synonyms include Barornis regens