Palintropus is a prehistoric bird genus from the Late Cretaceous. A single species has been named (Palintropus retusus) based on a proximal coracoid from the Lance Formation of Wyoming, dated to the latest Maastrichtian, 66 million years ago.[verification needed] Coracoids and a proximal scapula of two unnamed species from the upper Campanian Dinosaur Park Formation of Alberta, dating to between 76.5 and 75 million years ago,[1] are also known.[2]
Initially it was placed in the wastebin genus "Cimolopteryx". Pierce Brodkorb assigned it its current name, first affiliating it with Apatornis in 1963, and establishing its current genus in 1970.[3]
Its relationships are not well determined, mainly due to the paucity of material. Several major theories have been established: Like many of the birds of the subtropical coastlands of the Western Interior Seaway - maybe a bit like eastern Australia today - it is sometimes believed to be an early member of the Charadriiformes (waders, gulls, auks, etc.; see also "Graculavidae").[3] However, an alternate theory is that it is a galliform, perhaps a quercymegapodiid.[2]
In 2009, Longrich and colleagues proposed that Palintropus is a primitive bird related to Apsaravis. They conducted the first [cladistic]] analysis of the remains, and found this to be the most likely hypothesis, suggesting Palintropus warrants inclusion in the newly established Palintropiformes.