Name: Xiphactinus
(Sword Ray).
Phonetic: Zif-ack-tih-nus.
Named By: Joseph Leidy - 1870.
Classification: Chordata, Actinopterygii,
Osteoglossomorpha, Ichthyodectiformes, Ichthyodectidae,
Ichthyodectinae.
Species: X. audax, X. vetus.
Type: Carnivore/Piscivore.
Size: 4 to 6 meters long.
Known locations: USA, Alabama, Georgia,
Kansas. Europe. Australia. Canada.
Time period: Coniacian through to the Maastrichtian
of the Cretaceous.
Fossil representation: Many specimens from across
the globe.
The
broad range of fossils discovered around the world suggests that the
bony fish Xiphactinus had a cosmopolitan
distribution. A comparable
similar fish with regards to appearance is the modern day Tarpon.
Although Tarpon are not related to the ancient Xiphactinus,
their
streamlined bodies and strongly upturned mouths bear a striking
resemblence.
One
important difference between the two fish are the enlarged teeth
present in Xiphactinus fossils. If Xiphactinus
failed to swallow its
prey in one go, the teeth would have dug in preventing its prey from
escaping, allowing Xiphactinus to steadily slide
its prey into its
mouth, one bite at a time.
The
discovery of a two meter Gillicus
arcuatus inside the fossil of a
Xiphactinus twice its size is proof that it was a
formidable predator,
although it is thought that the Xiphactinus may
have died from
internal injury due to the Gillicus struggling
inside of it,
explaining why the Gillicus was not digested. Xiphactinus
was
however also preyed upon by other larger predators as evidenced in a
fossil of the shark Cretoxyrhina
at least one specimen of which has been found with a large Xiphactinus
inside of it. Another shark active in the Western Inland Seaway,
Squalicorax,
also exhibits Xiphactinus remains inside of its
own.
Further reading
- Notices of remains of extinct vertebrated animals of New Jersey,
collected by Prof. Cook of the State Geological Survey under the
direction of Dr. W. Kitchell. - Proceedings of the Academy of Natural
Sciences of Philadelphia 8:220-221. - J. Leidy - 1856.
- [Remarks on ichthyorudiolites and on certain fossil Mammalia]. -
Proceedings of the Academy of Natural Sciences of Philadelphia
22(1):12-13 - J. Leidy - 1870
- Xiphactinus vetus and the Distribution of Xiphactinus
Species in the
Eastern United States. - Journal of Vertebrate Paleontology. 17 (3):
610–15. - D. R. Schwimmer, J. D. Stewart & G. Dent Williams -
1997.