Lithornithidae  Lithornithidae is an extinct, possibly paraphyletic (but see below) clade of early paleognath birds. They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous representatives. All are extinct today; the youngest specimen is the currently unnamed SGPIMH MEV1 specimen from the mid-Eocene Messel Pit site. Lithornithids had long, slender, bills for probing. They closely resembled modern tinamous. They possessed a rhynchokinetic skull with relatively unfused cranial bones, a weakly fused pygostyle and a splenial. The unguals were more curved than in tinamous and probably allowed better perching in trees. The order Lithornithiformes was erected by Dr. Peter Houde in 1988. Initially, only three genera ("Lithornis", "Paracathartes", and "Pseudocrypturus") and eight named species were included. "Promusophaga" (Harrison & Walker, 1977) originally considered a stem-turaco, is considered synonymous with "Lithornis vulturinus". "Fissuravis" may also belong to the clade, and several unnamed remains are known. Lithornithiformes Houde, 1988  Several studies have shown conflicting status on the monophyly of the group. Some studies recover them as a paraphyletic assemblage leading to modern paleognaths, but more recent examinations group them in a single, natural group basal to the rest of Palaeognathae. Of issue is "Paracathartes", which differs radically from other lithornithids and has been suggested to more closely related to extant paleognaths, though it is recently recovered as a derived lithornithid. "Lithornis" itself may be paraphyletic in relation to "Paracathartes" and "Pseudocrypturus". In a study about ratite endocasts, "Lithornis" ranks among the taxa with well developed olfactory lobes. This is consistent with a nocturnal, forest-dwelling lifestyle, though as much all volant birds it retains large optical lobes. Unlike modern tinamous, at least "Lithornis" has toe claws and reversed halluxes that allow for efficient perching.