Abstract
A new bird coracoid from the Uinta Formation in the Uinta Basin in Utah (USA) records the presence of the only known pangalliform from the middle Eocene of North America, occurring in a >15 million year gap in their history. This fossil represents a new taxon, informally termed the Uintan paraortygid, which is also currently the best-supported record of the extinct Paraortygidae in North America (and among the oldest records of the group in the world). The specimen exhibits a derived enlarged procoracoid prominence with a small procoracoid process, and concave elliptical scapular cotyle that are shared with the middle Eocene paraortygids, Xorazmortyx and Scopelortyx; however, the Uintan paraortygid also has a possibly autapomorphic (pneumatic) fossa adjacent to the scapular cotyle. The similarity in body size and morphology among these widely distributed early paraortygids suggests phylogenetic affinity among them. Given their occurrence in the United States, Uzbekistan, and Namibia during the middle Eocene, these birds likely were good fliers with an increased ability to disperse; and probably had a flexible biology or diet allowing them to occupy a diversity of habitats from coasts and forests to semi-arid savannah-like habitats. The problematic early records of Odontophoridae need to be reexamined as potential members of Paraortygidae and associates of these small-bodied taxa.
Highlights
Crown group Galliformes are a very familiar clade, with members such as megapodes, chachalacas, guineafowl, quail, and pheasants that are distributed on all continents, except Antarctica
The stem lineage leading to that diverse crown group is documented by a wide variety of Eocene, Oligocene, and early Miocene fossils, and extinct taxa from Africa, South America, North America, Asia, and Europe (e.g., [3,4,5,6,7,8,9,10])
A recent reanalysis of Sylviornis and related fossils suggests that at least one lineage of pangalliformes outside of Galliformes survived into the late Holocene of New
Summary
Crown group Galliformes are a very familiar clade, with members such as megapodes, chachalacas, guineafowl, quail, and pheasants (including the domestic chicken) that are distributed on all continents, except Antarctica. Eocene gap is global in its scope, though smaller than the North American gap (>5–10 million years vs >15 million years) This temporal dearth of specimens occurs between the youngest specimens of Gallinuloididae (Paraortygoides) from the early middle Eocene of Europe, and the oldest records of Quercymegapodiidae and Paraortygidae in the late Eocene of Europe [2,6,22]. The Asian stem galliform record currently is restricted to the early Eocene [4,9] and one other younger specimen [10] Narrowing this global gap is Scopelortyx klinghardtensis assigned to the Paraortygidae from the late middle Eocene (Bartonian; 38–41.3 Ma) of Namibia [16], and the paraortygid Xorazmortyx turkestanensis [10] from the latest Lutetian or Bartonian of Uzbekistan.
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