Beipiaosaurus
Name:
Beipiaosaurus
(Beipiao lizard).
Phonetic: Bat-pee-oh-sire-us.
Named By: Xu, tang, Wang - 1999.
Classification: Chordata, reptilia, Dinosauria,
Saurischia, Theropda, Therizinosauroidea.
Species: B. inexpectus
(type).
Type: Herbivore.
Size: 2.2 meters long.
Known locations: China, liaoning province -
Yixian Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: 2 individuals, one which
includes feathers.
As
a basal therizinosaur
Beipiaosaurus revealed some
surprising
characteristics, hence the species name inexpectus. One of these
characteristics is the underdeveloped inner toes, something that is
very different to later therizinosaurids which have all four toes
developed and in contact with the ground. This has been taken as an
indication of a three toed ancestor, the fourth being speculated as
being a dew claw that would regain contact with the ground in later
descendents. This partly fits with the discovery of features that
indicate coelurosaurian ancestry, the group that also gave rise to
the tyrannosaurs.
Arguably
the most significant discovery related to Beipiaosaurus
is not just the
presence of primitive feathers, but of two kinds of them. The first
is what is thought to have formed a downy covering for the purpose of
insulation and is a feature that would become increasingly common in
later small active theropods.
The
second kind of
feathers are larger and rise up through the downy layer. These
feathers are between ten and fifteen centimetres long and about three
millimetres wide. These feathers may have served more of a display
purpose than a practical function, but it is still not possible to
say with certainty.
Beipiaosaurus
was once the largest known feathered
dinosaur, a title it held on to until the description of the
carnivorous tyrannosaur
Yutyrannus
in 2012.
Further reading
- A therizinosauroid dinosaur with integumentary structures from China.
- Nature 399:350-354. - X. Xu, Z.-L. Tang - X.-L. Wang - 1999.
- Pygostyle-like structure from Beipiaosaurus
(Theropoda,
Therizinosauroidea) from the Lower Cretaceous Yixian Formation of
Liaoning, China - Acta Geologica Sinica 77 (3): 294–298. - X. Xu, Y.
Cheng, X. -L.Wang, C. Chang - 2003.
- Cranial osteology of Beipiaosaurus inexpectus
(Theropoda:
Therizinosauria). - Vertebrata PalAsiatica. 57 (2): 117–132. - C. -C.
Liao & X. Xu - 2019.
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