Temporal range: Late Devonian
Elpistostege is an extinct genus of tetrapod-like vertebrate that lived in the Late Devonian period (Late Givetian to Early Frasnian). Fossils of its skull and a part of its backbone have been found in rocks of the Escuminac Formation in Quebec, Canada. A complete specimen of the animal has since been found in the same formation. It has been proposed, by the palaeontologist Richard Cloutier at Université du Québec à Rimouski, that this species may dethrone its close relative Tiktaalik in the position of the most primitive stem-tetrapod, though phylogenetic analyses have shown them to be very close relatives. The fossil suggests that human hands likely evolved, eventually, from the fins of this fish, according to Cloutier, who claimed "It is the first time that digits, as seen in tetrapods, are found in a fin covered by scales and fin rays, as seen in fishes."
An analysis conducted by Swartz in 2012 found Elpistostege to be the sister taxon of Tiktaalik. Both were found to be primitive members of the group Stegocephalia, along with other primitive stem-tetrapods.
A 2020 paper instead recovers Elpistostege as the sister taxon of all tetrapods, crownward of Tiktaalik:
- Swartz, B. (2012). "A marine stem-tetrapod from the Devonian of Western North America". PLoS ONE. 7 (3): e33683. doi:10.1371/journal.pone.0033683. PMC 3308997. PMID 22448265.
- Cloutier, R.; Clement, A. M.; Lee, M. S. Y.; Noël, R.; Béchard, I.; Roy, V.; Long, J. A. (2020). "Elpistostege and the origin of the vertebrate hand". Nature. 579 (7800): 549–554. doi:10.1038/s41586-020-2100-8.
- Elpistostege at Palaeos
- History of Elpistostege
- Recent Discovery of an entire well-preserved fossil of Elpistostege watsoni
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