However, a work published by Phil Senter in 2007 following the description of Tanycolagreus found it and Coelurus to be closely related at the base of Tyrannosauroidea. Senter proposed that Coelurus and Tanycolagreus were the only coelurids and were actually tyrannosauroids, but the phylogenetic analysis of Turner et al. (2007b) found that Coelurus was a basal coelurosaur, although more derived than the tyrannosaurids. Zanno in 2010 recovered Coelurus as a basal maniraptoran. Coelurus is sometimes put into its own family, Coeluridae, although the membership of the family has not been stable. Before the use of phylogenetic analyses, Coeluridae and Coelurosauria were taxonomic wastebaskets used for small theropods that did not belong to other groups; thus, they accumulated many dubious genera. As late as the 1980s, popular books recognized over a dozen "coelurids", including such disparate forms as the noasaurid Laevisuchus and the oviraptorosaurian Microvenator, and considered them descendants of the coelophysids. A wastebasket Coeluridae lingered into the early 1990s in some sources (and appears in at least one 2006 source) but since then it has only been recognized in a much reduced form. Coeluridae received a formal phylogenetic definition in 2015, when it was defined as all species more closely related to Coelurus fragilis than to Proceratosaurus bradleyi, Tyrannosaurus rex, Allosaurus fragilis, Compsognathus longipes, Ornithomimus edmontonicus, or Deinonychus antirrhopus by Hendrickx, Hartman and Mateus. It remains unclear whether or not this group contains any species other than Coelurus itself, and while Tanycolagreus is often included, support for this relationship has been weak in most of the studies that recovered it. Below is a cladogram placing Coelurus in Coelurosauria by Cau et al. in 2015. Paleobiology and paleoecology Provenance and occurrence The type specimen of Coelurus agilis, YPM 2010 (now considered a synonym of Coelurus fragilis) was recovered in the Brushy Basin member of the Morrison Formation, in Albany County, Wyoming. The specimen was collected by Reed in gray sandstone and brown/green claystone that were deposited during the Kimmeridgian stage of the Jurassic period, approximately 157 to 152 million years ago. This specimen is housed in the collection of the Yale Peabody Museum in New Haven, Connecticut. Fauna and habitat The Morrison Formation is interpreted as a semiarid environment with distinct wet and dry seasons, and flat floodplains. Vegetation varied from river-lining forests of conifers, tree ferns, and ferns, to fern savannas with rare trees. It has been a rich fossil