Knightia

Knightia is an extinct genus of clupeid bony fish that lived in the freshwater lakes and rivers of North America and Asia during the Eocene epoch. The genus was erected by David Starr Jordan in 1907, in honor of the late University of Wyoming professor Wilbur Clinton Knight, "an indefatigable student of the paleontology of the Rocky Mountains."[1] It is the official state fossil of Wyoming,[2] and the most commonly excavated fossil fish in the world.[3]

For the plant genus, see Knightia (plant).

Knightia
Temporal range:
Knightia eocaena specimen
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Clupeiformes
Family: Clupeidae
Subfamily: Pellonulinae
Genus: †Knightia
Jordan 1907
Type species
Knightia eocaena
Jordan, 1907
Species
  • K. alta
    (Leidy, 1873)
  • "K. bohaiensis"
  • K. branneri
  • K. eocaena Jordan 1907
  • K. humulus
  • K. irregularis Longstaff, 1933
  • K. vetusta Grande, 1982
  • "?K. yuyanga"
Synonyms

Knightia belongs to the same taxonomic family as herring and sardines, and resembled the former closely enough that both Knightia alta and Knightia eocaena were originally described as species of true herring in the genus Clupea.

As with modern-day clupeids, Knightia spp. likely fed on algae and diatoms, as well as insects and occasionally smaller fish.[4]

Anatomy

In Knightia fish, rows of dorsal and ventral scutes run from the back of the head to the medial fins. They had heavy scales and small conical teeth. Their size varied by species: Knightia eocaena was the longest, growing up to 25 cm (10 in), though most specimens are no larger than 15 cm.[5] K. alta was shorter and relatively wider, with specimens averaging between 6 and 10 cm.[5]

Predators

A small schooling fish, Knightia made an abundant food source for larger Eocene predators. The Green River Formation has yielded many fossils of larger fish species preying on Knightia; specimens of Diplomystus, Lepisosteus, Amphiplaga, Mioplosus, Phareodus, Amia, and Astephus have all been found with Knightia in either their jaws or stomachs.[4]

Slab of fossilized Knightia eocaena from Fossil Butte National Monument
Digital artist's conception of Knightia sp.
Knightia fossils from Green River Formation of Wyoming

References
  1. Jordan, D. S. 1907. "The fossil fishes of California; with supplementary notes on other species of extinct fishes". Bulletin Department of Geology, University of California 5:136
  2. "Wyoming Secretary of State". Archived from the original on 2011-09-06. Retrieved 2011-01-22.
  3. Kelley, Patricia H.; Kowalewski, Michał; Hansen, Thor A. (2003). Predator-prey interactions in the fossil record. Springer. ISBN 0-306-47489-1.
  4. Grande, L. 1980. The paleontology of the Green River Formation, with a review of the fish fauna. Wyoming Geol. Surv., Bull. 63, pp. 85.
  5. Grande, Lance (June 7, 1982). "A Revision of the Fossil Genus †Knightia, With a Description of a New Genus From the Green River Formation (Teleostei, Clupeidae)" (PDF). American Museum Novitates. ISSN 0003-0082. OCLC 47720325. Archived from the original (PDF) on October 20, 2013. Retrieved November 12, 2011.
  • Data related to Knightia at Wikispecies
  • Media related to Knightia at Wikimedia Commons
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