Name:
Pteranodon
(Toothless wing).
Phonetic: Teh-ran-oh-don (The 'P' is silent and
not
pronounced).
Named By: Othniel Charles Marsh - 1876.
Synonyms: Geosternbergia sternbergi, G.
walkeri, Ornithocheirus harpyia, O. umbrosus, Ornithochirus
harpyia, O. umbrosus, Ornithostoma ingens, O. umbrosum,
Pteranodon eatoni, P. (Geosternbergia) sternbergi, P.
(Geosternbergia) walkeri, P. (Longicepia) ingens, P.
(Longicepia) longicps, P. (Longicepia) marshi, P. marshi,
P. (Pteranodon) ingens, P. (Pteranodon) marshi, P.
(Occidentalia) eatoni, P. (Occidentalia) occidentalis, P.
(Sternbergia) sternbergi, P. (Sternbergia) walkeri, P.
walkeri, Pterodactylus occidentalis.
Classification: Chordata, Reptilia,
Pterosauria, Pterodactyloidea, Pteranodontidae.
Species: P. longiceps (type),
P.
stembergi.
Type: Piscivore.
Size: Males average wingspans of around 5.6 meters,
though largest males attain wingspans approaching 6.25 meters across.
Isolated
remains suggest an upper size of males of 7 meters though these fossils
might not be Pteranodon. Females much smaller with wingspans averaging
3.5 meters
Known locations: USA - Niobrara Formation,
Pierre Shale Formation.
Time period: Coniacian to Campanian of the
Cretaceous.
Fossil representation: Other a 1,000 known
specimens, although over half are of partial remains.
Multiple species and the
differences between male and female.
Much
like the pterosaurs
Pterodactylus
and Rhamphorhynchus,
Pteranodon has
suffered from the wastebasket taxon effect. This is because at the
time of its discovery it was the only known toothless pterosaur, and
as such any remains that suggested a toothless pterosaur were almost
automatically included into the genus. As such, an ever increasing
list of species names started to appear when in reality the fossils
were all representative of the same species.
Pteranodon
fossils display two distinct groups of small and large individuals with
quite a large degree of crest variation, although again, these
crests can also be broken down into individual groups. When these
fossils were first discovered they were taken as being examples of
different species and genus, but towards the end of the twentieth
century, new studies revealed that these differences were actually
evidence of sexual dimorphism.
The
more complete sets of remains that were attributed to the smaller
Pteranodon morph actually showed a proportionately
wider pelvis that
would have allowed for a much easier passage of eggs. The smaller
morphs also had different shaped crests than the larger examples of
Pteranodon, with the smaller members having more
triangular crests.
The larger Pteranodon specimens had crests that
curved upwards and
backwards, with some skulls showing signs of a second low crest that
ran towards the tip of the beak.
Piecing
all these bits together reveals that the crest in males was a sign of
sexual maturity and an aid in dominance displays. The smaller crests
in the smaller morphs were mostly representative of females, with the
exception of the remains with a narrower pelvis which probably
represented immature males that had yet to develop the head crest of
adulthood. This does of course mean that establishing the difference
between male and female in the smaller specimens can be difficult where
the pelvis has not been preserved.
Briefly
returning to the problem of multiple non-existent species, the new
studies allowed for the reduction of these names to the two distinct
species of P. longiceps and P.
stembergi. There are still other
species which are now considered to be Nomen dubium, and these
include Pteranodon comptus, P. ingens,
P.
occidentalis, P.
umbrosus, P. velox, Pterodactylus
ingens, P. umbrosus and
P. velox. There are also some sets of remains
that remain
attributed to different genera yet may yet be revealed to actually
belong to Pteranodon, and as such the list of
synonyms for Pteranodon
is likely to change and even grow with time.
Distinguishing features
The
head crest is by far the most distinctive feature of Pteranodon,
although many of the classic depictions of this pterosaur only seem to
depict a straight and narrow crest that angles back from the back of
the skull. Determining the full extent of the crest is reliant upon
the age of the individual and how well it has been preserved,
although there is a great degree of known variation from the standard
long and straight, to the highly ornate upwards pointing crests
that can be seen in remains of P. stembergi.
As
for practical function, it seems almost certain that the crest was
only for display as it is greatly reduced in specimens that are
confirmed female, and shows signs of still developing in immature
males. As a display device, it probably would not have been just a
case of large size and shape, but would probably been brightly
coloured to accentuate its presence to mates and potential rivals.
Practical
functionality of the crest still remains an active topic with the most
popular theory explaining the crest as a rudder to help steering,
pretty much like in a modern aeroplane, although at the front and
with a greater degree of potential movement. It is also thought by
some that it may have supported a growth of skin between its head and
its back, perhaps not just to increase its surface area, but also
to create a form of display structure that could be erected when it
pitched its head forward.
Although
the crest is regarded by most to have been for display, as noted in
the difference between female, male and immature male specimens, it
should not be forgotten that such a structure would have invariably had
an impact upon the aerodynamics of Pteranodon. It
may even have had a
negative impact on a males ability to hunt for fish, reducing the
amount of time a male could stay in his prime, increasing the chance
of genetic variation as males replaced one another, and also going
some way to explain the greater abundance of female and immature male
specimens over the remains of males that would be regarded as being at
the peak of their masculinity.
Aside
from the crest, the most prominent feature of Pteranodon
is the
toothless beak which at the time of discovery was unknown in pterosaurs
as all other species before its discovery had teeth. This means that
instead of relying upon teeth to seize its prey, Pteranodon
may have
used a scooping motion instead.
Flight ability
Pteranodon
was long considered to be just a huge glider, its size making it
impossible to flap its wings making it reliant upon strong up draughts
present at coastal locations. However this is now considered to be an
out dated and erroneous view of Pteranodon's flight
capabilities.
Studies of the wing strength compared to body weight have revealed
that flapping would have certainly been possible, and indeed
necessary when lifting off from the ground.
Pteranodon
is often associated with the Albatross because of similarities with
wing proportions, and this coupled with further studies has brought
the summarisation that Pteranodon flew like large
sea birds do today
like the just mentioned Albatross. This means that when flying over
the ocean looking for fish, Pteranodon used a
method of flight that
is referred to as dynamic soaring.
Dynamic
soaring is where a flying creature such as an Albatross flies into the
trough formed by two waves and into the lee of a passing wave. The
lee is the change that results in stronger air pressure that occurs as
the wave moves along, and this pressure results in air moving
faster over the wings, and increasing their lift. The animal in
question can then turn around sharply, a process called
'wheeling', and then head back towards the trough with a back wind
that further increases speed. Lee waves are also formed around land
objects such as mountains and are sometimes exploited by glider pilots
to keep their aircraft in the air for longer.
By
utilising this method of flight, Pteranodon could
indeed fly for
extended periods without flapping, although this would be more a case
on energy conservation as opposed to inability. It also means that
Pteranodon likely flew for extended periods while
looking for food and
maybe at range too. How migratory Pteranodon
was in uncertain,
although because the remains seem to be attributed to the Western
interior seaway, it may have had a limited global distribution.
When
not flying, Pteranodon is now thought to have
been bipedal like other
known pterosaurs, supporting itself by leaning forward onto its
wings. This is different from many early views that had Pteranodon
reared up on its hind legs with its wings well away from the ground.
Although no hard evidence exists for quadrupedal locomotion in
Pteranodon, it does exist for a number of other
pterosaurs. Also,
there is no evidence that Pteranodon was only
bipedal, and until
such evidence can be proven to exist, the quadrupedal method remains
the most likely.
Diet
As
for diet, the remains of fish including the scales and bones make it
certain that the diet of Pteranodon was mostly if
not exclusively
fish. The actual feeding strategy is still unknown and subject to
debate but includes three distinct possibilities. The first and most
widely accepted view is that Pteranodon flew low
over the water and
scooped up fish with its beak while it was still in flight. The
second involves Pteranodon actually landing on the
water and then
snatching fish up as it bobbed around on the surface. The third makes
the suggestion that Pteranodon would plunge into
the water from a
height and use its velocity to dive deep under water, increasing the
chance of prey capture. The final theory comes from the observation
that the head and shoulders of Pteranodon had a
robust construction
similar to today's diving birds.
Relationships
The
number of remains attributed to female Pteranodon
greatly outweighs the
known males, and this has brought the suggestion that Pteranodon
was
a polygynous animal. This means that males would mate with several
females as opposed to just forming a mating pair. Comparison with
animals that are known to be polygynous today would suggest that
dominant Pteranodon males would take up territories
in prominent
locations. The Pteranodon with the largest and
perhaps also the most
vividly coloured head crest would keep away other males that did not
have such an elaborate display.
Further reading
- The Vertebrata of the Cretaceous formations of the West - Report, U.
S. Geological Survey of the Territories (Hayden), 2: 302 pp., 57 pls. -
E. D. Cope - 1875.
- Notice of a new sub-order of Pterosauria - American Journal of
Science, Series 3 11 (65): 507–509. - O. C. Marsh - 1876a.
- Principal characters of American pterodactyls - American Journal of
Science, Series 3 12 (72): 479–480. - O. C. Marsh - 1876b.
- The characters of Pteranodon. - American Journal
of Science, ser. 4,
16(91):82-86, pl. 6-7. - G. F. Eaton - 1903.
- The characters of Pteranodon (second paper). -
American Journal of
Science, ser. 4, 17(100):318-320, pl. 19-20. - G. F. Eaton - 1904.
- Stomach stones and the food of plesiosaurs - Science 20 (501):
184–185 - B. Brown - 1904.
- The skull of Pteranodon. - Science (n. s.) XXVII
254-255. - G. F.
Eaton - 1908.
- Osteology of Pteranodon. - Memoirs of the
Connecticut Academy of Arts
and Sciences, 2:1-38, pls. i-xxxi. - G. F. Eaton - 1910.
- Ein Lebensbild von Pteranodon ingens auf
flugtechnischer Grundlage. -
Nova Acta Leopoldina, N.F., 12(83): 16-32 - D. von Kripp - 1943.
- Pteranodon sternbergi, a new fossil pterodactyl
from the Niobrara
Cretaceous of Kansas. - Proceedings South Dakota Academy of Science
45:74-77. - J. C. Harksen - 1966.
- The taxonomy of the Pteranodon species from
Kansas - Kansas Academy
of Science, Transactions 74(1):1-19. - H. W. Miller - 1971.
- A skull of Pteranodon (Longicepia) longiceps
Marsh associated with
wing and body parts. - Kansas Academy of Science, Transactions
74(10):20-33. - H. W. Miller - 1971.
- Biomechanics of Pteranodon. - Philosophical
Transactions Royal
Society B, 267 - C. D. Bramwell & G. R. Whitfield - 1974.
- Dynamic analysis of Pteranodon ingens: a
reptilian adaptation to
flight - Journal of Paleontology 49: 534–548. - R. S. Stein - 1975.
- A functional analysis of flying and walking in pterosaurs -
Paleobiology 9 (3): 218–239. - K. Padian - 1983.
- The aerodynamics of Pteranodon and Nyctosaurus,
two large pterosaurs
from the Upper Cretaceous of Kansas. - Journal of Vertebrate
Paleontology 3(2):84-124. - J. C. Brower - 1983.
- Sexual dimorphism of Pteranodon and other
pterosaurs, with comments
on cranial crests - Journal of Vertebrate Paleontology 12 (4): 422–434
- S. C. Bennet - 1992.
- Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon
(Pterosauria, Pterodactyloida) - Occasional Papers of the Natural
History Museum, University of Kansas 169: 1–70. - S. C. Bennet - 1994.
- The Pterosaurs of the Niobrara Chalk. - The Earth Scientist, 11(1):
22-25. - S. C. Bennet - 1994.
- An early occurrence of Pteranodon sternbergi from
the Smoky Hill
Member (Late Cretaceous) of the Niobrara Chalk in western Kansas -
Kansas Academy of Science, Transactions 18(Abstracts):27. - M. J.
Everhart - 1999.
- Inferring stratigraphic position of fossil vertebrates from the
Niobrara Chalk of western Kansas. - Current Research in Earth Sciences:
Kansas Geological Survey Bulletin, 244(Part 1): 26 pp. - S. C. Bennet -
2000.
- The osteology and functional morphology of the Late Cretaceous
pterosaur Pteranodon. General description of
osteology -
Palaeontographica, Abteilung A 260: 1–112 - S. C. Bennet - 2001.
- The osteology and functional morphology of the Late Cretaceous
pterosaur Pteranodon. Part II. - Functional
morphology.
Palaeontographica, Abteilung A, 260:113-153. - S. C. Bennet - 2001.
- Pteranodont claw morphology and its implications for aquatic
locomotion - Master's Thesis, Michigan State University. - A. C. Smith
- 2007.
- Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea) with
the description of two new species. - Anais da Academia Brasileira de
Ci�ncias. 82 (4): 1063–1084. - A. W. A. Kellner - 2010.