Jianianhualong
Name:
Jianianhualong
(Jianianhua dragon).
Phonetic: Je-an-e-an-hu-ah-long.
Named By: X. Xu, P. Currie, M. Pittman,
L. Xing, and Q.-J. Meng, J.-C., D.-Y. Hu &
C.-Y. Yu - 2017.
Classification: Chordata, Reptilia,
Dinosauria, Saurischia, Theropoda, Troodontidae.
Species: J. tengi (type).
Diet: Carnivore.
Size: Estimated reconstructed size of the holotype
individual about 1.12 meters long.
Known locations: China, Liaoning Province -
Yixian Formation.
Time period: Early Cretaceous.
Fossil representation: Almost complete individual
preserved flat on a slab, lacking only the tip of the tail. Feather
impressions are also preserved on the slab.
Jianianhualong
is a genus of troodontind
dinosaur that lived in China during the
early Cretaceous. The holotype individual has an almost perfect
state of preservation in the skeleton, and while some bones are not
too clearly distinguished, the only significant thing missing from it
is the tip of the tail. The whole animal from the tip of the
snout to where the tail is missing is one meter. Accounting for
additional vertebrae often seen in other troodontid dinosaurs has led
the original describers to determine that this Jianianhualong
was about
up to one hundred and twelve centimetres long in life (not
including the feathers). With the further observation that the
skeleton is formed in such a way that it was certainly an adult at the
time of death, Jianianhualong was towards the
smaller end of the size
scale for troodontid dinosaurs.
One
of the most exciting
discoveries concerning Jianianhualong is the
discovery of feather
impressions around the body, and particularly the tail. The tail
feathers of Jianianhualong have been confirmed as
being asymmetrical.
The 2017 description of Jianianhualong was the
first time that
such feathers had been observed in a troodontid dinosaur. Before the
description Jianianhualong other examples of
asymmetrical feathers were
usually seen in microraptoran dinosaurs, some of which have been
speculated to have been capable of at least gliding flight.
There
is no clear evidence to
suggest that Jianianhualong was a flier (or at
least a glider),
as the feathers of the arms are not fully preserved in the holotype,
meaning that the feather form of the arms is unknown. But just to
tease us, the asymmetrical feathers on the tail are formed in such a
way as to reduce drag, so that air flowed more smoothly over them
when moving forward.
Jianianhualong
is another of
a growing number of troodontid dinosaurs known from the Yixian
Formation, with other genera including Daliansaurus,
Mei,
Sinovenator,
Sinusonasus,
with even more related dromaeosaurs
also
present.
Further reading
- Mosaic evolution in an asymmetrically feathered troodontid dinosaur
with transitional features. - Nature Communications
8(14972). - X. Xu, P. Currie, M. Pittman, L.
Xing, and Q.-J. Meng, J.-C., D.-Y. Hu & C.-Y.
Yu - 2017.
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