Fish to Tetrapod
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Fish to Tetrapod
An intermediate between limbed-vertebrates and lobe-finned fish helps us to better understand the
evolution of the tetrapod body plan.
http://palaeos.com/paleozoic/devonian/frasnian.htm
Switch From Fish to Tetrapod
During this transition:1. The skull was
remodeled2. The bones
connecting the head to the shoulder were lost
3. The middle ear was modified
4. Robust limbs with digits evolved
5. Shoulder girdle & pelvis were altered
6. Ribs were expanded
7. The bony connections between vertebrae developed
(De Souza, M; 2009)
http://eurwentala.deviantart.com/art/Fish-Fishapod-Tetrapod-185103242
Tiktaalik Lived in Shallow Waters and Subaerial Habitats
http://evolutionjustatheory.blogspot.ca/2009_09_01_archive.html
In response to this new environment, Tiktaalik developed:1. New mechanisms of
head movement2. New mechanisms of
body support3. New mechanisms of
respiration
New Mechanisms of Head Movement
Loss of opercular,
subopercular and the
extrascapular effectively decoupled the head
from the the pectoral girdle.
These changes are also associated
with new patterns of locomotion and
feeding.
http://www.devoniantimes.org/opportunity/tetrapodsAnswer.html
Daeschler et al. 2006
New Mechanisms of Respiration
http://guardianlv.com/2014/01/extinct-land-walking-fish-tiktaalik-roseae-possessed-robust-hips/
Changes in respiration mechanisms allowed Tiktaalik to exploit both aquatic and terrestrial environments.
New Mechanisms of Body Support
Rib support allowed Tiktaalik to remain supported in shallow water and when on land.
Panderichthys, Elpistostege, and Tiktaalik Form a Paraphyletic
Assemblage of Elpistostegalian Fish
http://en.wikipedia.org/wiki/Eusthenopteron
http://www.richannel.org/finding-tiktaalikDaeschler et al., 2006
Implications for Vertebrate Biology
• Changes in the rear skill preceeded those in the lower jaw and palate.
• Loss of opercular, subopercular, and the extrascapular series series occurs before the loss of the gulars, submandibulars, and the supracleithral series.
Insight Into the Order in Which Derived Characters Evolved
BibliographyDaeschler, Edward B. and Shubin, Neil H. and Jenkins, Farish A. (2006). A Devonian tetrapod-like fish and the evolution of the tetrapod body plan. Nature, 440(7085), 757–763.
De Souza, M. (2009). Just a Theory [Website]. Retrieved January 16th, 2015, from http://evolutionjustatheory.blogspot.ca/2009_09_01_archive.html
Eurwentala (2010). Fish, Fishapod, Tetrapod [Website]. Retrieved January 16th, 2015, from http://eurwentala.deviantart.com/art/Fish-Fishapod-Tetrapod-185103242
James Fenner (2014). Extinct Land-Walking Fish Tiktaalik roseae Possessed Robust Hips [Website]. Retrieved January 18th, 2015, from http://guardianlv.com/2014/01/extinct-land-walking-fish-tiktaalik-roseae-possessed-robust-hips/
Murphy, M.C (2006). Tetrapod Answers [Website]. Retrieved January 18th, 2015, from http://www.devoniantimes.org/opportunity/tetrapodsAnswer.html
Neil Shubin (2015). Your Inner Fish [Website]. Retrieved January 18th, 2015, from http://avonapbiology.wikispaces.com/Nick+Tan+Your+Inner+Fish
Unknown (2013). A Few Selected Transitional Fossils [Websites]. Retrieved January 16th, 2015, from http://www.transitionalfossils.com
Unknown (December 27th, 2014). Eusthenopteron [Website]. Retrieved January 17th, 2015, from http://en.wikipedia.org/wiki/Eusthenopteron
White, T. (2002). The Frasnian [Website]. Retrieved January 16th, 2015, from http://palaeos.com/paleozoic/devonian/frasnian.htm
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