Aurornis
Name: Aurornis
(Daybreak bird).
Phonetic: Or-ror-niss.
Named By: Pascal Godefroit, Andrea Cau, Hu
Dong-Yu, François Escuillié, Wu Wenhao & Gareth Dyke -
2013.
Classification: Chordata, Avialae.
Species: A. xui (type).
Diet: Insectivore/Carnivore.
Size: About 50 centimetres long.
Known locations: China, Liaoning Province -
Tiaojishan Formation? See main text.
Time period: Oxfordian of the Jurassic? See main
text.
Fossil representation: Single individual preserved
on a slab.
Just
after its description and at the time of writing, there is some
uncertainty as to exactly how old Aurornis are.
The type specimen was
acquired from a fossil dealer in China and was labelled as coming from
the Tiaojishan Formation which is Oxfordian (late Jurassic) in
age. However the describers now recognise the possibility that the
holotype may have actually come from the Yixian Formation which is
Barremian/Aptian (early Cretaceous) in age.
If
the original description of Aurornis as a Jurassic
organism is correct
then it may hint at an earlier bird evolution than previously thought.
If it comes from the Oxfordian then Aurornis were
similar to but
appeared ten million years before the world famous Archaeopteryx,
a
genus that many choose to use to mark the dividing line between where
dinosaurs turned into birds. However, there is still a lot of
on-going debate about Archaeopteryx, with some
labelling them as a
bird like dinosaurs while others treat them as the first birds.
One
key difference between Archaeopteryx and Aurornis
is that Aurornis had
a much more primitive bone structure, which means that is was less
likely to have the ranges of motion necessary for ‘flight
strokes’. Aurornis also had a covering of
feathers all over the
body, but lacked larger flight capable feathers. This in turn
suggests that the feathers on Aurornis served an
insulatory and display
purpose.
At
fifty centimetres long Aurornis were fairly big for
a potential bird
ancestor, but still quite small when compared to predatory dinosaurs
in the same ecosystem. Given their size, Aurornis
may have hunted
for smaller invertebrates like insects and worms that lived amongst the
litter of the forest floor.
Further reading
- A Jurassic avialan dinosaur from China resolves the early
phylogenetic history of birds, Pascal Godefroit, Andrea Cau, Hu
Dong-Yu, François Escuillié, Wu Wenhao & Gareth Dyke -
2013.
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