Protosphyraena
Name:
Protosphyraena
(Early Sphyraena).
Phonetic: Pro-to-s-fy-ray-nah.
Named By: J. Leidy - 1857.
Classification: Chordata, Osteichthyes,
Actinopterygii, Pachycormiformes, Pachycormidae.
Species: P. perniciosa, P.
bentoniana, P. nitida.
Diet: Piscivore/Carnivore.
Size: Specimens range in size beween 2 and 3
meters in length. Largest known species is P. perniciosa.
Known locations: Canada, Manitoba - Vermilion
River Formation, Saskatchewan - Ashville Formation. England
- West Melbury Marly Chalk Formation. France. Jordan. Spain
- La Cabana Formation. USA, Alabama - Mooreville Chalk
Formation, Colorado - Greenhorn Limestone Formation, Kansas
- Greenhorn Limestone Formation, Niobrara Formation, South
Dakota - Greenhorn Limestone Formation, Texas - Eagle Ford
Formation.
Time period: Most fossils range from the Cenomanian
to the Santonian of the Cretaceous, though some fossils are now
confirmed as being Campanian in age.
Fossil representation: Remains on multiple
individuals ranging from partial jaws, snouts and teeth, but
partial post cranial skeletons are also known.
Protosphyraena
means ‘early Sphyraena’, a reference to the
Sphyraena genus
which includes the modern day barracuda. This all came down to the
original interpretation of the first fossils which were very much like
those of barracuda. However, later fossil examples of
Protosphyraena revealed it to be more swordfish-like
in appearance,
though it must be noted that today Protosphyraena
is not considered to
be a relative of either barracuda or swordfish.
Protosphyraena
is a predatory fish that was built for high speed, either steady
cruising or sudden bursts after prey. The body is long and
streamlined with high forks to the tail that provide an efficient large
area to push against the water. The pectoral fins are also very long
as well which is also an indicator of high swimming speeds as they act
as hydroplanes to keep the body level when swimming forward. The
faster the movement forward, the larger the pectoral fins need to be
to counter this effect.
Aside
from acting as hydroplanes, the pectoral fins of Protosphyraena
may
have also been killing weapons in their own right. The fins of
Protosphyraena perniciosa particularly were
reinforced with a hard
keratinous substance, could grow to over a meter in length and also
had a serrated edge on the anterior (frontal) plane. They would
for a lack of a better term been almost like a pair of swords.
Protosphyraena
also had a long yet robustly formed snout and under this a mouth which
housed large, forward pointing teeth. One popular view of
Protosphyraena hunting is that it rammed into the
flanks of large
aquatic creatures (much like as has been speculated for the ancient
shark Edestus)
like mosasaurs,
as postulated in the Hunting
Dinosaurs on the Red Deer River, Alberta, Canada by
Charles
Sternberg. In this example Protosphyraena would
spear the animal with
its snout, burying its head up to its eyeballs while lashing at the
sides with its sword-like pectoral fins.
As
dramatic as that sounds, it perhaps is not very likely, after all
mosasaurs themselves were predators, and while smaller ones like
Platecarpus,
may have been threatened by such fish, especially if
hunting in shoals, larger ones like Tylosaurus
would be more inclined
to take the opportunity of a quick snack. Modern sword fish use their
long snouts to lash out at fish, stunning and wounding them so that
they cannot swim away, and while the snout of Protosphyraena
was not
as long as modern swordfish, it could still have been combined with
the pectoral fins to lash out at several fish in a ‘bait ball’ so
that a few injured ones could then be picked off.
It
should also be noted however that the pectoral fins between different
species of Protosphyraena differed in length and
form, with those of
P. nitida being notably shorter than those of P.
perniciosa. The
pectoral fins of P. perniciosa may have also
served a defensive
purpose, making it very difficult for an apex predator such as a
large mosasaur to swallow a Protosphyraena without
the fins getting
stuck in the throat.
Further reading
- On an extinct genus of saurodont fishes. - Proceedings of the
Academy of Natural Sciences of Philadelphia 24: 280–281. -
Edward Drinker Cope - 1873.
- On two new species of Saurodontidae. - Proceedings of the
Academy of Natural Sciences of Philadelphia 25:337-339. - Edward
Drinker Cope - 1873.
- Remarks on Saurocephalus and its allies. -
Transactions of the
American Philosophical Society 11: 91–95. - J. Leidy -
1857.
- A contribution to the knowledge of the ichthyic fauna of the Kansas
Cretaceous. - Kansas University Quarterly 7(1):22-29, pl.
I, II. - A. Stewart - 1898.
- Notice of three new Cretaceous fishes, with remarks on the
Saurodontidae Cope. - Kansas Univ. Quar. 8(3):107-112. -
A. Stewart - 1899.
- Biostratigraphic distribution of species of Protosphyraena
(Osteichthyes: Actinopterygii) in the Niobrara and Pierre
Formations of Kansas. - Proceedings of the Nebraska Academy of
Sciences and Affiliated Societies, 89th Annual Meeting, p.
51-52. - J. D. Stewart - 1979.
- The stratigraphic distribution of late Cretaceous Protosphyraena
in
Kansas and Alabama, Geology, by J. D. Wilson. In,
aleontology and biostratigraphy of western Kansas: Articles in honor
of Myrl V. Walker, Fort Hays Studies, 3(10):80-94. - M.
E. Nelson (ed).
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