Name:
Pterodactylus
(Winged finger).
Phonetic: Teh-roe-dack-till-us (The P is silent
and not pronounced).
Named By: Georges Cuvier -1809.
Synonyms: Diopecephalus kochi,
Macrotrachelus longirostris, Ornithocephalus antiquus, O.
brevirostris, O. kochi, O. longirostris, O. meyeri, O.
redenbacheri, Ptenodracon brevirostris, Pterodactylus
brevirostris, P. crocodilocephaloides, P. kochi, P.
longirostris, P. meyeri, P. micronyx, P.
nettecephaloides, P. pulchellus, P. redenbacheri, P.
scolopaciceps, P. spectabilis, P. suevicus, Rhamphorhynchus
scolopaciceps.
Classification:Chordata, Reptilia, Pterosauria,
Pterodactyloidea, Euctenochasmatia.
Species: P. antiquus (type).
Type: Piscivore/Insectivore.
Size: About 1 meter wingspan.
Known locations: Europe. Africa.
Time period: Early Tithonian of the Jurassic.
Fossil representation: Dozens of specimens, some
showing complete skeletons with some even including impressions of soft
tissue.
Pterodactylus
has the honour of being the first pterosaur
known to science,
although the type of creature that it really was, was still largely
unknown at the time of its discovery. Many scientists inferred that
it was more like a bat, or something between a bat and a bird. Some
even put forward the suggestion that it was actually a marine creature
and suggested that the wings were actually flippers.
Time,
along with new discoveries and further research eventually
confirmed Pterodactylus as a flying reptile, but
continuing
incomplete knowledge and understanding of the group during the
nineteenth century resulted in many discoveries being attributed to
Pterodactylus as different species of the genus.
To cause even
further confusion, it was also not known that Pterodactylus
individuals varied considerably with age, with the result that
Pterodactylus juveniles and sub adults were
incorrectly named as
different species.
Studies
towards the end of the twentieth century have not only
successfully reduced the number of species, they have also identified
clear yearly growth cycles. Currently the only universally accepted
species is the type Pterodactylus antiquus. The
only other strong
contender is P. longicollum which represents a
larger and longer
necked individual that also has fewer teeth. P.
longicollum may yet
represent a separate genus, meaning that its future inclusion as a
Pterodactylus species is by no means certain.
Other
species that remain are considered Nomen dubium and these include
Pterodactylus arningi, P. cerinensis,
P. grandipelvis, P.
manseli, P. maximus, P.
pleydelli and P. suprajurensis.
These are pretty much only known from scant fossil material, and
their inclusion in either Pterodactylus or indeed
another pterosaur
genus is difficult to establish with certainty. These problems with
multiple names are not unique to Pterodactylus,
and another Jurassic
pterosaur, Rhamphorhynchus,
has also
had similar trouble with its
taxonomic history.
As
noted above, new study of Pterodactylus remains
also revealed
yearly growth cycles with have allowed for fossils to be divided into
classes. The first year class obviously represents the youngest
individuals, and typically have skull lengths between fifteen and
forty-five millimetres long. The second year individuals are
larger with skulls fifty-five to ninety-five millimetres long. The
third year specimens are the largest and include the type species
remains for P. antiquus.
Perhaps
the most interesting thing about these revelations is that none
of the specimens represent an adult specimen, meaning that the true
adult form of Pterodactylus is either still
unknown, or has already
been attributed to another genus. Also the slow and steady growth is
more indicative of a pattern as seen in today’s crocodiles than
modern birds. On a related note, the debate about whether
pterosaurs were warm or cold blooded is not easy to settle, although
such a growth pattern is more indicative of a cold blooded animal.
The
beak of Pterodactylus was straight and not curved
like so many
other pterosaurs. The number of teeth can also be used to establish
the age of the individuals with younger specimens having around only
fifteen teeth, while the larger and older specimens have closer to
ninety and ran through the entire length of both jaws. The teeth are
also larger towards the tips of the jaws, possibly to help facilitate
prey capture, and in older specimens, are proportionately narrower
than their younger kin.
The
changing dentition may also be indicative of a feeding strategy
that changed with age, with younger Pterodactylus
feeding upon
insects while older ones also including fish and maybe even small
animals into their diets. This would also have reduced feeding
competition between the different age groups. Study of the scleral
rings has also revealed a diurnal adaptation, meaning that
Pterodactylus would have been active during the
daytime. In contrast
some other pterosaurs such as the aforementioned Rhamphorhynchus
had
nocturnal lifestyles as indicated by study of their scleral rings.
Another
indicator of age is what appears to be a short rounded crest
that grew from the back of the skull. Aside from only becoming
developed in larger individuals, it may have also been a display and
potential sign of sexual dimorphism, most probably more pronounced in
males. Since a confirmed adult Pterodactylus
fossil is still
unknown, the extent to which this crest grew cannot be precisely
known.
Soft
tissue impressions have been preserved in a specimen of
Pterodactylus, and these impressions reveal the
presence of both a
throat pouch that extended from the middle of the mandible to the upper
neck, and the presence of pycnofibres on the neck. The throat pouch
was almost certainly an aid for feeding, perhaps allowing
Pterodactylus to scoop up a large amount of water
with its prey, and
then letting it drain out while its teeth prevented its prey from
escaping.
Pycnofibres
are usually seen as a sign of insulation but so far they
are only known on the neck area. What they may have been for in this
case is to serve as a kind of splash guard. Assuming that
Pterodactylus fed from the water, when its beak
went into the water
it would have undoubtedly caused some splash back, potentially
spraying water against the neck. If the water made contact with the
skin, Pterodactylus would have suffered a greater
amount of heat loss
through the water evaporation, just like what happens when you
sweat. By having a layer of pycnofibres, it may have prevented the
splash from making direct contact with the skin, and would have been
of even more use had Pterodactylus been a cold
blooded creature.
Further reading
- (Pterodactylus longirostris) - Isis von Oken, 1126
und 1788, Jena -
G. Cuvier - 1819.
- Year-classes of pterosaurs from the Solnhofen Limestone of Germany:
Taxonomic and Systematic Implications - Journal of Vertebrate
Paleontology 16 (3): 432–444. - S, C, Bennet - 1996.
- Soft tissue preservation in a specimen of Pterodactylus
kochi
(Wagner) from the Upper Jurassic of Germany - Neues Jahrbuch f�r
Geologie und Pal�ontologie, Abhandlungen 210: 421–441. - E. Frey
& D. M. Martill - 1998.
- Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit
Morphology - Science 332 (6030): 705–8. - L. Schimtz & R,
Motani - 2011.
- New information on body size and cranial display structures of
Pterodactylus antiquus, with a revision of the genus
- Christopher S.
Bennet - 2013.