Most close relatives of birds neared the potential for powered flight
but few crossed its thresholds

Date:
August 11, 2020
Source:
The University of Hong Kong
Summary:
New research has resulted in an updated evolutionary tree of
early birds and their closest relatives to reconstruct powered
flight potential, showing it evolved at least three times. Many
ancestors of the closest bird relatives neared the thresholds of
powered flight potential, suggesting broad experimentation with
wing-assisted locomotion before flight evolved.



FULL STORY ========================================================================== Uncertainties in the evolutionary tree of birds and their closest
relatives have impeded deeper understanding of early flight in theropods,
the group of dinosaurs that includes birds. To help address this, an international study led by HKU Research Assistant Professor Dr. Michael
Pittman (Vertebrate Palaeontology Laboratory, Division of Earth and
Planetary Science & Department of Earth Sciences) and co-first-authored
by his former Postdoctoral Fellow Dr.

Rui Pei (now an Associate Professor at the Institute of Vertebrate
Paleontology and Paleoanthropology, Beijing), produced an updated
evolutionary tree of early birds and their closest relatives to
reconstruct powered flight potential, showing it evolved at least
three times. Many ancestors of the closest bird relatives neared the
thresholds of powered flight potential, suggesting broad experimentation
with wing-assisted locomotion before flight evolved.


==========================================================================
"Our revised evolutionary tree supports the traditional relationship
of dromaeosaurid ("raptors") and troodontid theropods as the closest
relatives of birds. It also supports the status of the controversial anchiornithine theropods as the earliest birds," said Dr. Pei. With
this improved evolutionary tree, the team reconstructed the potential
of bird-like theropods for power flight, using proxies borrowed from
the study flight in living birds. The team found that the potential for
powered flight evolved at least three times in theropods: once in birds
and twice in dromaeosaurids. "The capability for gliding flight in some dromaeosaurids is well established so us finding at least two origins
of powered flight potential among dromaeosaurids is really exciting,"
said Dr. Pittman. Crucially, the team found that many ancestors of
bird relatives neared the thresholds of powered flight potential. "This suggests that theropod dinosaurs broadly experimented with the use of
their feathered wings before flight evolved, overturning the paradigm
that this was limited to a much more exclusive club," added Dr. Pittman.

This study is the latest in the Vertebrate Palaeontology Laboratory's
long-term research into the evolution of early birds and their closest relatives (see Notes). Asked about future plans, Dr. Pittman replied:
"We have helped to better constrain the broader functional landscape of theropods just before flight evolved and in its earliest stages. We plan
to now focus on the dromaeosaurids and early birds that we have shown
to have the potential for powered flight to improve our understanding
of what it took to fly and why."

========================================================================== Story Source: Materials provided by The_University_of_Hong_Kong. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Rui Pei, Michael Pittman, Pablo A. Goloboff, T. Alexander Dececchi,
Michael B. Habib, Thomas G. Kaye, Hans C.E. Larsson, Mark
A. Norell, Stephen L. Brusatte, Xing Xu. Potential for Powered
Flight Neared by Most Close Avialan Relatives, but Few Crossed Its
Thresholds. Current Biology, 2020; DOI: 10.1016/j.cub.2020.06.105 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200811120215.htm

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