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).
Size: 2 meters long.
Known locations: China, Junggar Basin - Shishugou Formation.
Time period: Oxfordian of the Jurassic.
Fossil representation: Almost complete individual on slab.
the time of its description Haplocheirus was the
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
years, further confirming the idea that while Archaeopteryx
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.
- 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.