Zhenyuanlong
Name:
Zhenyuanlong
(Zhenyuan’s dragon).
Phonetic: Zen-yu-an-long.
Named By: Junchang Lü & Stephen L.
Brusatte - 2015.
Classification: Chordata, Reptilia, Dinosauira,
Theropoda, Maniraptora, Dromaeosauridae.
Species: Z. suni (type).
Diet: Carnivore.
Size: Holotype individual estimated to be about
1.65 meters long at the time of death (not including feathers).
Known locations: China, Liaoning Province -
Yixian Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: Partial skull and partial
skeletal remains.
Zhenyuanlong
is an interesting genus of dromaeosaurid
dinosaur. To start
Zhenyuanlong has some of the proportionately
shortest arms in relation
to leg lengths of any dromaeosaurid, and at the time of the
description of the genus in 2015, only Austroraptor
and Mahakala
are known to have been even more extreme. The radius bone of the
forearm of Zhenyuanlong is by proportion the
thinnest of any previously
described theropod dinosaur.
From
these arms however large pennaceous feathers (the kind with
well-developed quills) grew and attained lengths of over twice the
length of the humerus (upper arm bone). These feathers resulted
in what would have looked like a wing, however researchers are
certain that Zhenyuanlong was incapable of flight.
For a start on the
preserved skeleton there are no attachments that support the presence
of strong flapping muscles like those seen in birds, and the size and
possible weight of the Zhenyuanlong holotype
individual would have also
made extended gliding unlikely.
The
purpose of the large ‘wing; feathers was probably that of display,
though it is not impossible that the wings may have been held out to
improve stability and balance when Zhenyuanlong was
running and
cornering at speed. The rest of the body of Zhenyuanlong
seems to
have been covered in fluffy downy feathers that probably served and
insulatory purpose, though secondarily also may have been coloured
for display. One area of curiosity about Zhenyuanlong
is that the
rear legs don’t show the presence of large feathers similar to the
arms, something quite unusual given that Zhenyuanlong
has been
identified as being similar to other genera such as Microraptor
which
do. However, the authors describing Zhenyuanlong
also noted that no
feathers, not even insulatory ones were preserved on the hind
quarters. This raises the prospect that Zhenyuanlong
either had an
unusual feathering pattern, or that the hind quarter feathers on the
first known individual were simply not preserved.
Zhenyuanlong
is one of a growing number of dromaeosaurs that have been discovered in
Liaoning Province with other genera including Microraptor,
Graciliraptor,
Sinornithosaurus,
Tianyuraptor
and Changyuraptor.
It is not yet known if all of these genera coexisted at the same time
as one another, yet all of them show specific specialisations,
indicating perhaps a high degree of niche partitioning amongst China’s
dromaeosaurids that would allow for a fairly high number of genera to
co-exist in the same ecosystems. Out of these genera Zhenyuanlong
is
noted as being very similar to Tianyuraptor in
body, while the
skull of Zhenyuanlong is similar to both Tianyuraptor
and
Sinornithosaurus in skull form.
Further reading
- A large, short-armed, winged dromaeosaurid (Dinosauria:
Theropoda) from the Early Cretaceous of China and its implications
for feather evolution. - Scientific Reports 5: Article number
11775. - Junchang Lü & Stephen L. Brusatte - 2015.
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