Rahonavis
Name: Rahonavis
(Cloud Bird).
Phonetic: Rae-hoe-nay-viss.
Named By: Forster et al - 1998.
Synonyms: Rahona ostromi.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Dromaeosauridae, Unenlagiinae.
Species: R. ostromi (type).
Type: Carnivore.
Size: 70 centimeters long.
Known locations: Madagascar - Maevarano
Formation.
Time period: Maastrichtian of the Cretaceous.
Fossil representation: One partial articulated
skeleton.
As
a creature that displays both dinosaurian and avian features, it is
not known for certain how Rahonavis fits in with
the evolution of birds
from dinosaurs. This is problem shared with other discoveries such as
Xiaotingia
and even Archaeopteryx
as the difining line of when
a bird
becomes a bird and not a dinosaur is very hard to establish. One
theory which is quite plausible is that flight evolved several times to
be lost again in later descendents, whose descendents in turn would
regain the ability, the pattern continuing until the establishment of
the line towards Modern birds.
Although
sometimes conceived as a bird, it’s possible that Rahonavis
was
more like a dromaeosaurid
dinosaur. Again the possibility of
Rahonavis evolving from flying ancestors is quite
possible and the term
secondarily flightless is often applied. Still some consider
Rahonavis as being capable of flight as evidenced by
the long fore
limbs and attachments for ligaments to the shoulder that prove
Rahonavis had the necessary degrees of wing motion
for flight.
Considering that the holotype specimen was found within the remains of
a titanosaurid
dinosaur, Rahonavis may have
flown around Mesozoic
Madagascar looking for carrion.
Rahonavis
has been accused of being a fossil chimera, the remains of more than
one animal being constructed into a single incorrect representation.
However this claim has been strongly refuted on the grounds that the
main skeleton was found articulated with parts of the wing and shoulder
bones all found within the same small area to one another, indicating
they all belonging to one animal.
Further reading
- The theropod ancestry of birds: new evidence from the Late Cretaceous
of Madagascar. - Science 279:1915-1919. - C. A. Forster, S. D. Sampson,
L. M. Chiappe & D. W. Krause - 1998.
- Genus correction. - Science 280(5361):185. - C. A. Forster, S. D.
Sampson, L. M. Chiappe & D. W. Krause - 1998.
----------------------------------------------------------------------------
Random favourites
 |
 |
 |
 |