Enchodus

Extinct genus of ray-finned fishes From Wikipedia, the free encyclopedia

Enchodus (from Greek: ἔγχος enchos, 'spear' and Greek: ὀδούς odoús 'tooth')[2] is an extinct genus of aulopiform ray-finned fish related to lancetfish and lizardfish. Species of Enchodus flourished during the Late Cretaceous, where they were a widespread component of marine ecosystems worldwide, and there is some evidence that they may have survived to the Paleocene or Eocene; however, this may just represent reworked Cretaceous material.[3][4][5]

Phylum:Chordata
Class:Actinopterygii
Order:Aulopiformes
Family:†Enchodontidae
Quick facts Scientific classification, Type species ...
Enchodus
Temporal range: Albian-Maastrichtian
~105–66 Ma Possible Barremian & Paleogene records
E. petrosus mounted skeleton cast, Rocky Mountain Dinosaur Resource Center
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Aulopiformes
Family: †Enchodontidae
Genus: †Enchodus
Agassiz, 1835
Type species
†Esox lewesiensis
Mantell, 1822
Species

~26+, see text

Synonyms[1]
  • Isodus Heckel, 1849
  • Phasganodus Leidy, 1857
  • Ischyrocephalus von der Marck, 1858
  • Solenodon Kramberger, 1881 (preocc.)
  • ?Tetheodus Cope, 1874
  • Holcodon Kramberger, 1885
  • Eurygnathus Davis, 1887 (preocc.)
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Description

Enchodus species were small to medium in size, with E. zinensis reaching 172.2 centimetres (67.8 in) long.[6] One of the genus' most notable attributes are the large "fangs" at the front of the upper and lower jaws and on the palatine bones, leading to its misleading nickname among fossil hunters and paleoichthyologists, "the saber-toothed herring". These fangs, along with a long sleek body and large eyes, suggest Enchodus was a predatory species.[7]

E. petrosus, with standard length around 76.7 centimetres (30.2 in)[6] and sometimes over 1 metre (3 ft 3 in),[8] is known from common remains coming from the Niobrara Chalk, the Mooreville Chalk Formation, the Pierre Shale, and other geological formations deposited within the Western Interior Seaway and the Mississippi Embayment. Large individuals of this species had fangs measuring over 6 centimetres (2.4 in) in length, giving its skull an appearance somewhat reminiscent of modern deep-sea fishes, such as anglerfish and viperfish. Other species, such as E. parvus, were considerably smaller, measuring only some centimetres (a few inches) long.[9]

Despite being a formidable predator, remains of Enchodus are commonly found among the stomach contents of larger predators, including sharks, other bony fish, mosasaurs, plesiosaurs and seabirds such as Baptornis advenus.[citation needed]

Distribution

Enchodus fossils have been found all over the world. In North America, Enchodus remains have been recovered from most US states with fossiliferous Late Cretaceous rocks, including Kansas, Nebraska, Colorado, Alabama, Mississippi, Georgia, Tennessee, Wyoming, Texas, California, North Carolina, and New Jersey. Fossils also have been found in the Aguja and El Doctor Formations of Mexico and the Ashville, Vermillion River and Dinosaur Park Formations, and Brown Bed Member of Canada. The taxon is also known from coeval strata in Mexico, South America (Tiupampan Santa Lucía Formation and Maastrichtian El Molino Formation of Bolivia, Paraíba, Pernambuco and Sergipe states of Brazil, as well as Argentina, Chile, and Peru[10]), Africa (Egypt, Morocco, the Congo, Angola, Niger, and Equatorial Guinea), the Middle East (Saudi Arabia, Lebanon, Israel, Palestine and Jordan), Europe (England, France, the Netherlands, Belgium, Spain, Italy, Germany, Sweden, the Czech Republic, Slovenia, Greece, Ukraine[11] and Russia), India, and Japan.[12][1] Potentially the latest Enchodus remains are known from the earliest Eocene of Barmer, India.[4] However, it has also been suggested that all post-Cretaceous Enchodus records are just reworked material.[5]

Taxonomy

Species of Enchodus are generally classified into two different clades, the North American and the Mediterranean. It has been proposed that this distinction is the result of several isolated events between the two populations over the Late Cretaceous.[13] The earliest known species is E. zimapanensis from the late Albian or earliest Cenomanian of Mexico.[14] Potentially earlier remains are known from the late Barremian/early Aptian of Brazil (Morro de Chaves Formation), but these specimens are too fragmentary to confidently assign to this genus.[15][16]

Species

Specimen of E. gracilis
Reconstructed school of E. petrosus
Specimen of E. faujasi

Enchodus was a diverse, long-lived genus with many species known throughout its temporal and geographic range. The following valid species are known:[12][1][15][17]

Many other dubious species based on insufficient remains have been described throughout its range. Even most of the valid Enchodus species are based on only isolated teeth and bones.[15] The genus Parenchodus, considered to be the sister genus of Enchodus, has been synonymized with this genus based on some studies.[15] However, more recent studies have found it to be a valid genus distinct from Enchodus.[13][18]

Phylogeny

Enchodus[13]
Enchodus

E. marchesettii

Parenchodus

E. brevis

E. lewesiensis

E. gracilis

E. venator

E. shumardi

E. petrosus

E. zipapanensis

E. faujasi

E. gladiolus

E. tineidae

E. dirus

Phylogeny of the genus with some species

Gallery

  • Restoration of E. petrosus
    Restoration of E. petrosus
  • E. lewesiensis skull
    E. lewesiensis skull
  • Teeth of E. elegans from Khouribga
    Teeth of E. elegans from Khouribga
  • Teeth of E. libycus from Khouribga
    Teeth of E. libycus from Khouribga

References

Further reading

External links

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