Exceedingly well-preserved bird fossil specimens dating 50 million years represent a new species that is a previously unknown relative of the modern-day ostrich, according to a new paper co-authored by Sterling Nesbitt of Virginia Tech's College of Science and part of the university's Global Change Center.
The bird fossils were found more than a decade ago, completely intact with bones, feathers, and soft tissues in a former lake bed in Wyoming. Nesbitt cannot hide a grin as he calls the fossil a once-in-a-lifetime discovery for paleontologists.
"This is among one of the earliest well-represented bird species after the age of large dinosaurs," said Nesbitt, an assistant professor in the Department of Geosciences.
"You can definitely appreciate how complete these fossil are," added Nesbitt of the remains, the focus of a research paper co-authored by Nesbitt and newly published in the Bulletin of the American Museum of Natural History.
A new skeleton of Palaeosinopa didelphoides (Mammalia, Pantolesta) from the early Eocene Fossil Butte Member, Green River Formation (Wyoming), and skeletal ontogeny in Pantolestidae
Authors:
Rose et al
Abstract:
A new subadult partial skeleton of a pantolestid is reported from the late early Eocene Fossil Butte Member of the Green River Formation. Although the specimen displays a full permanent dentition, the presence of unfused elbow epiphyses (typically the first epiphyses to close), together with a short skull, shallow dentaries, and incompletely erupted third molars, indicates that it was a young juvenile. This adds to evidence that pantolestids had relatively early eruption of permanent premolars and late epiphyseal closure. Based on molar size and morphology, including presence of a well-developed paraconid, the specimen is attributed to Palaeosinopa didelphoides. Despite differences in skeletal size and robustness among the three known Fossil Butte pantolestid skeletons, all of which are skeletally subadult, similarity in molar size (and morphology, to the extent that it is visible) suggests that the three skeletons represent three growth stages of P. didelphoides. If this interpretation is correct, it has implications for recognition of fossil species based on such traits as jaw depth, presence/absence of diastemata, and relative robustness of skeletal features.
