Haplocheirus
Name:
Haplocheirus
(Simple hand).
Phonetic: Hap-low-ky-rus.
Named By: J. N. Choiniere, X. Xu, J. M.
Clark, C. A. Forster, Y. Guo & F. Han - 2010.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Alvarezsauroidea.
Species: H. sollers (type).
Diet: Insectivore?
Size: 2 meters long.
Known locations: China, Junggar Basin -
Shishugou Formation.
Time period: Oxfordian of the Jurassic.
Fossil representation: Almost complete individual on
slab.
At
the time of its description Haplocheirus was the
oldest known
alvarezsaur
by an impressive sixty-three million years before the
previous record holder. This places Haplocheirus
firmly within the
Oxfordian stage of the Jurassic revealing that the alvarezsaurs began
at least this far back rather than the early Cretaceous period as
previously thought. On a side note, Haplocheirus
also happened to
predate the famous ‘dino-bird’ Archaeopteryx by
fifteen million
years, further confirming the idea that while Archaeopteryx
was the
first feathered bird like dinosaurs discovered, it was not the first
to have feathers.
Haplocheirus
was a primitive alvarezsaur, something that is not just revealed by
its early appearance its features as well. First is the sheer size of
Haplocheirus which at around two meters is bigger
than the known later
and more refined forms. Second is that the more advanced forms of the
Cretaceous have a single specially developed digit on each hand.
Haplocheirus also has a well-developed thumb, but
it also retains
the use of two additional fingers on each hand. It seems that in time
as the alvarezsaurs became more specialised these two fingers still
present in Haplocheirus became redundant to the
point that they became
vestigial appendages.
As
a small dinosaur Haplocheirus would have had to of
been careful not to
end up being a meal for Jurassic era Asian theropods such as Sinraptor
and Monolophosaurus,
both known from the same formation as
Haplocheirus.
Further reading
- A basal alvarezsauroid theropod from the early Late Jurassic of
Xinjiang, China. - Science 327(5965):571-574. - J. N. Choiniere, X. Xu,
J. M. Clark, C. A. Forster, Y. Guo & F. Han - 2010.
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