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Basal Deinonychosauria (Theropoda) aerial ability (free pdf)
Ben Creisler
bcreisler@gmail.com
A new paper in the 2014 issue of the open access Japanese journal
Bulletin of the Gunma Museum of Natural History:
Boris Sorkin (2014)
Aerial ability in basal Deinonychosauria.
Bulletin of the Gunma Museum of Natural History 18: 21-34
http://www.gmnh.pref.gunma.jp/research/no_18/bulletin18_4.pdf
Previously proposed hypothesis that flightless derived members of the
maniraptoriform clade Deinonychosauria (Dinosauria : Theropoda)
evolved from volant ancestors is evaluated by reviewing relevant
publications subsequent to that of the hypothesis. Functional
morphology and computer and physical modeling indicate that basal
Dromaeosauridae microraptorine Microraptor and unenlagiine Rahonavis
were volant, the former being capable of gliding and powered flight
utilizing long pennaceous feathers on fore and hind limbs and
scansorial locomotion, supporting the hypothesis that the more derived
flightless dromaeosaurids evolved from volant ancestors. Phylogenetic
relationships between the shortarmed basal dromaeosaurids Tianyuraptor
and Mahakala and the longer-armed dromaeosaurids and troodontids
indicate that short fore limbs and inferred lack of aerial and
scansorial ability of the former are autapomorphies and do not
contradict the above conclusion.
Functional morphology indicates that basal Troodontidae Anchiornis and
Xiaotingia were capable of gliding flight utilizing long pennaceous
feathers on both fore and hind limbs and scansorial locomotion,
supporting the hypothesis that the more derived flightless troodontids
evolved from volant ancestors. Functional morphology indicates that
microraptorine Sinornithosaurus and unenlagiine Buitreraptor and basal
troodontid (or more basal paravian) Eosinopteryx represent
transitional forms between the volant and scansorial basal
dromaeosaurids and troodontids (or more basal paravians) and the more
derived flightless and terrestrial ones. Scansorial and four-winged
gliding ability in basal members of both Dromaeosauridae and
Troodontidae and morphology of basal paravians Pedopenna and
Archaeopteryx suggest that the most recent common ancestors of both
Deinonychosauria and Paraves were also scansorial four-winged gliders.
Morphology and phylogenetic position of yet unknown members of the
maniraptoriform clade Oviraptorosauria whose future discovery would
support or falsify previously proposed hypothesis that known
flightless oviraptorosaurs evolved from volant ancestors are
speculated on.