Name: Enchodus
(Spear tooth).
Phonetic: En-coe-dus.
Named By: Louis Agazziz - 1835.
Synonyms: Esox lewesiensis, Eurypholis longidens,
Eurypholis major, Tetheodus.
Classification: Chordata, Actinopterygii,
Neopterygii, Salmoniformes, Enchodontoidei, Enchodontidae.
Species: E. zipapanensis (type), E.
amicrodus, E. annectens, E. brevis, E. dirus, E. faujasi, E. ferox, E.
gladiolus, E. gracilis, E. lamberti, E. libycus, E. lemonnieri, E.
lewesiensis, E. longidens, E. longipectoralis, E. major, E.
marchesettii, E. mecoanalis, E. oliveirai, E. parvus, E. petrosus, E.
pulchellus, E. saevus, E. shumardi, E. subaequilateralis, E. tineidae,
E. venator.
Diet: Carnivore/Piscivore.
Size: 1.5 meters long, fangs can reach to over
six centimetres long on the largest species, E. petrosus.
Other species smaller, as much as just a few centimetres long.
Known locations: Worldwide.
Time period: Late Cretaceous through to the Eocene.
Fossil representation: Huge number of fossils.
Usually the teeth are the most common fossils, but skulls and
partial post cranial remains are also known.
Although often referred to as the ‘Sabre-toothed herring’, Enchodus actually appears to be more closely related to salmon. The identifying characteristics of this and the binomal name are the large fang-like teeth in the mouth that often prove popular amongst fossil collectors. These teeth are perfect for biting into small slippery prey like fish as well as possibly cephalopods like squid and are situated in a mouth that has a wide gape.
Together these features reveal that while the teeth were great for prey capture they could not pull off smaller chunks of flesh. Instead once the prey had been speared by the teeth, Enchodus probably used a series of rapid jaw opening and closing movements to work its body over the prey. Additionally the downwards slant of the mouth would have facilitated this method of feeding as it would allow the lower jaw to open further and wider. As such prey was probably approached from behind and seized by the tail before being swallowed by a series of successive bites. The downwards slanting jaws might also indicate that Enchodus approached prey from a slight angle beneath them like in other fish with similar jaws that exhibit this behaviour.
Enchodus
appears to have held an intermediate placement in the oceanic food
chain as while it was a predator of other oceanic animals, Enchodus
itself was eaten by larger predators such as marine reptiles and
sharks. One well documented specimen (FHSM VP-2939) actually
reveals a tooth from the prehistoric
shark Squalicorax
with the skull of an
Enchodus along with further scrape marks that are
spaced in a manner
that look like they were caused by other teeth in the sharks jaw.
Enchodus
and predators similar to it form an important part of marine ecosystems
where they control the numbers of smaller predators and plankton
feeders so that they do not deplete the base food resources of the
ocean. In the process of doing this they form a large portion of the
oceans biomass which further supports a number of larger and more
diverse predators that cannot feed upon the smaller animals.
Further reading
- Review of the Vertebrata of the Cretaceous period found west of the
Mississippi River - Edward Drinker Cope - 1874.
- Vert�br�s fossiles du bassin du Niger [Fossil vertebrates of the
Niger basin] - C. Arambourg & L. Joleaud - 1943.
- A check list of North American Marine Cretaceous vertebrates
including fresh water fishes - D. A. Russel - 1988.
- Fossil fishes from the Cenomanian (Upper Cretaceous) of Namoura,
Lebanon. - P. L. Forey, L. Yi, C. Patterson & C. E. Davis -
2003.
- A New Species of Enchodus (Aulopiformes:
Enchodontidae) from the
Cretaceous (Albian to Cenomanian) of Zimap�n, Hidalgo, M�xico - C.
Fielitz & K. A. Gonzalez-Rodriguez - 2010.
- A new species of the neopterygian fish Enchodus from the Duwi
Formation, Campanian, Late Cretaceous, Western Desert, central Egypt. -
Acta Palaeontologica Polonica. 62 (3): 603–611. - Waymon L. Holloway,
Kerin M. Claeson, Hesham M. Sallam, Sanaa El-Sayed, Mahmoud Kora,
Joseph J.W. Sertich & Patrick M. O’Connor - 2017.