A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight

The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the...

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Bibliographic Details
Published in:PeerJ (San Francisco, CA) CA), 2019-07, Vol.7, p.e7247-e7247, Article e7247
Main Authors: Hartman, Scott, Mortimer, Mickey, Wahl, William R, Lomax, Dean R, Lippincott, Jessica, Lovelace, David M
Format: Article
Language:English
Subjects:
Avialae
Dinosauria
Dinosaurs
Earth science
Evolution
Evolutionary Studies
Flight
Hesperornithoides miessleri
Late Jurassic
Morphology
Morrison Formation
New species
Paleontology
Paraves
Phylogenetics
Phylogeny
Taxonomy
Vertebrae
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Summary:The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the origin of avialan flight. Here, we describe gen. et sp. nov., a new paravian theropod from the Morrison Formation (Late Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen comprising a partial, well-preserved skull and postcranial skeleton. Limb proportions firmly establish as occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close to , , and . Multiple alternative paravian topologies have similar degrees of support, but proposals of basal paravian archaeopterygids, avialan microraptorians, and being closer to Pygostylia than archaeopterygids or unenlagiines are strongly rejected. All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.
ISSN:2167-8359
2167-8359
DOI:10.7717/peerj.7247