Alxasaurus
Name:
Alxasaurus
(Alxa lizard - after the Alxa desert).
Phonetic: Alks-ah-sore-us.
Named By: Dale Russel & Dong Zhiming -
1994.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Therizinosauroidea, Alxasauridae.
Species: A. elesitaiensis
(type).
Diet: Herbivore?
Size: About 3.8 meters long.
Known locations: Mongolia - Bayin-Gobi Formation.
Time period: Albian of the Cretaceous.
Fossil representation: 5 individuals of varying
levels of completeness.
Alxasaurus
was a very significant discovery since study of the bones of this
dinosaur reveal both specialised therizinosaur
morphs as well as more
standard’ theropod features. Combined with its appearance in the
early Cretaceous, Alxasaurus is firmly
established as a transitory
form that shows a stage of development between general theropods and
the later more advanced therizinosaurids. Alxasaurus
has a toothless
mouth that in life would have acted like a beak. This lack of
specialisation combined with its early appearance in therizinosaur
lineage means that there is a little doubt to what this dinosaur ate.
The
therizinosaurs were descended from the theropod dinosaurs, a group
vastly associated with the eating of meat, and since Alxasaurus
was
still changing, it is not entirely implausible that it was capable of
processing and digesting animal protein. However, Alxasaurus
like
all therizinosaurs were saurischian (lizard hipped) dinosaurs,
and one group of these, the sauropods, became some of the most
famous of plant eating dinosaurs of all time. Alxasaurus
also does
not have the build of a light weight and agile dinosaur, which a
predator would need to be in order to hunt. Also the support of a
‘pot belly’ for housing a longer gastrointestinal tract (a
requirement for animals that live on plants) is there in the
skeleton. Add to this the large finger claws on the hands which were
well adapted to reaching around tall branches so that more leaves could
be brought down to the mouth, and the odds are stacked in favour of
Alxasaurus being a plant eater. For the sake of
argument however,
if Alxasaurus and other therizinosaur genera ate
meat, they would
have almost certainly had to scavenge for it, and given their heavy
build, only rely upon it to supplement their existing diet of plants.
Further reading
- The affinities of a new theropod from the Alxa Desert, Inner
Mongolia, People’s Republic of China, Dale Russel & Dong
Zhiming - 1993 (released 1994).
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