Dorygnathus
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Name:
Dorygnathus
(Spear jaw).
Phonetic: Dor-e-nay-fus (the 'g' is silent).
Named By: Johann Andreas Wagner - 1860.
Synonyms: Dorygnathus mistelgauensis,
Parapsicephalus.
Classification: Chordata, Reptilia,
Pterosauria, Rhamphorhynchoidea, Rhamphorhynchidae.
Species: D. banthensis
(type).
Type: Piscivore.
Size: Up to 1.5 meter wingspan, although older
individuals may have been slightly larger, as evidenced by remains
with a wingspan measuring 169 centimetres. Skull up to 16
centimetres long.
Known locations: Germany, Bavaria - Posidonia
shale. France, Nancy. United Kingdom.
Time period: Toarcian of the Jurassic.
Fossil representation: Over 50 individual
specimens.
Dorygnathus
is typical of the basal rhamphorhynchoid group of pterosaurs
which
include Rhamphorhynchus
itself. This includes Dorygnathus having a
similar overall morphology including a long tail that was held stiff by
a network of tendons. Although no one knows if the tail of
Dorygnathus had a vane on the end like in Rhamphorhynchus,
one
specimen seems to show evidence of hairs, or more correctly
'pycnofibres' that extended from the tail.
The
teeth of Dorygnathus have quite a special
arrangement, with the front
teeth of the lower jaw not just pointing forwards but outwards. The
other teeth in the lower jaw just point upwards, as do the teeth in
the upper, and both sets of teeth get smaller the further back they
ago. When closed the teeth intermeshed making for an effective prey
trap.
By
having the front teeth fanning out from the lower jaw, Dorygnathus
would have certainly been an effective fish hunter. The lower teeth
in this arrangement would have significantly increased the 'catch'
area, kind of like if you wore a baseball glove instead of just
relying upon your hand to catch a baseball. The arrangement may also
suggest a preference for smaller fish species as larger ones would not
have required the special adaptation.
The
wings of Dorygnathus are quite short when compared
to some other
pterosaurs, and it has been speculated that Dorygnathus
may have been
more restricted to coastal waters rather than flying out many
kilometres and spending extended periods over open water.
When
first discovered in 1830, Dorygnathus was
thought to have
potentially been similar to Dimorphodon,
then attributed to
Pterodactylus.
This opinion continued until 1858 when Richard
Owen described two Dimorphodon specimens that
actually had their
skulls, and in so doing creating the genus Dimorphodon
and splitting
it from Pterodactylus in the process. With this
new description it
became instantly clear that Dorygnathus was
actually very different to
Dimorphodon and so was given its own group.
A
second species of Dorygnathus was once named in
1971 as D.
mistelgauensis, after Mistelgau in Bavaria where it was
discovered.
This specimen was split into a separate species on the grounds that it
was larger than most other species in fact it was about half as big
again as the average. This was accepted until 2008 when Kevin
Padian referenced a confirmed D. banthensis
specimen that was even
larger than D. mistelgauensis. Since the second
specimen could
no longer be separated on the basis of size alone the result was that
D. mistelgauensis became a synonym to D.
banthensis.
Another
pterosaur called Campylognathoides
has also been
found, albeit in
smaller numbers, in the same areas as Dorygnathus.
These specimens
have also been found to date to the same time period making it highly
probable that Dorygnathus and Campylognathoides
shared the same skies
and possibly feeding grounds as one another.
Further reading
- Studies of Liassic Pterosauria, I. The holotype and referred
specimens of the Liassic Pterosaur Dorygnathus banthensis (Theodori) in
the Petrefaktensammlung Banz, Northern Bavaria. - K. Padian &
R. Wild - 1992.
- The Early Jurassic Pterosaur Dorygnathus Banthensis(Theodori, 1830) -
Kevin Padian - 2008.
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