Tiktaalik

Tiktaalik
Temporal range: Late Devonian (Frasnian), 375 Ma
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Cast of the Tiktaalik holotype in the Field Museum, Chicago
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Clade: Tetrapodomorpha
Clade: Elpistostegalia
Genus: †Tiktaalik
Daeschler, Shubin & Jenkins, 2006
Type species
†Tiktaalik roseae
Daeschler, Shubin & Jenkins, 2006

Tiktaalik (/tɪkˈtɑːlɪk/; Inuktitut ᑎᒃᑖᓕᒃ [tiktaːlik]) is a monospecific genus of extinct sarcopterygian (lobe-finned fish) from the Late Devonian Period, about 375 Mya (million years ago), having many features akin to those of tetrapods (four-legged animals).[1] Tiktaalik is estimated to have had a total length of 1.25–2.75 metres (4.1–9.0 ft) based on various specimens.[2]

Unearthed in Arctic Canada, Tiktaalik is a non-tetrapod member of Osteichthyes (bony fish), complete with scales and gills—but it has a triangular, flattened head and unusual, cleaver-shaped fins. Its fins have thin ray bones for paddling like most fish, but they also have sturdy interior bones that would have allowed Tiktaalik to prop itself up in shallow water and use its limbs for support as most four-legged animals do. Those fins and other mixed characteristics mark Tiktaalik as a crucial transition fossil, a link in evolution from swimming fish to four-legged vertebrates.[3] This and similar animals might be the common ancestors of all vertebrate terrestrial fauna: amphibians, reptiles, birds and mammals.[4]

The first Tiktaalik fossils were found in 2004 on Ellesmere Island in Nunavut, Canada. The discovery, made by Edward B. Daeschler of the Academy of Natural Sciences, Neil H. Shubin from the University of Chicago, and Harvard University Professor Farish A. Jenkins Jr., was published in the April 6, 2006 issue of Nature[1] and quickly recognized as a transitional form.

  1. ^ a b Daeschler, Edward B.; Shubin, Neil H. & Jenkins, Farish A. Jr. (6 April 2006). "A Devonian tetrapod-like fish and the evolution of the tetrapod body plan" (PDF). Nature. 440 (7085): 757–763. Bibcode:2006Natur.440..757D. doi:10.1038/nature04639. PMID 16598249.
  2. ^ Stewart, Thomas A.; Lemberg, Justin B.; Taft, Natalia K.; Yoo, Ihna; Daeschler, Edward B.; Shubin, Neil H. (2019). "Fin ray patterns at the fin-to-limb transition". Proceedings of the National Academy of Sciences. 117 (3): 1612–1620. doi:10.1073/pnas.1915983117. PMC 6983361. PMID 31888998.
  3. ^ "What has the head of a crocodile and the gills of a fish?". evolution.berkeley.edu. May 2006. Archived from the original on 2018-06-12. Retrieved 2018-06-06.
  4. ^ Shubin, Neil (2008). Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body. New York: University of Chicago Press. ISBN 978-0-375-42447-2.