Ichthyostega
Ichthyostega | |
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Reconstructed skeleton in Moscow Paleontological Museum | |
Skeletal reconstruction | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Sarcopterygii |
Clade: | Tetrapodomorpha |
Clade: | Stegocephali |
Family: | †Ichthyostegidae Säve-Söderbergh, 1932 |
Genus: | †Ichthyostega Säve-Söderbergh, 1932 |
Type species | |
†Ichthyostega stensioei Säve-Söderbergh, 1932
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Other species[1][2] | |
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Synonyms | |
Genus synonymy
Species synonymy
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Ichthyostega (from
History
In 1932
Description
Ichthyostega was a fairly large animal for its time, as it was broadly built and about 1.5 m (4.9 ft) long. The skull was low, with dorsally placed eyes and large
Postcranial skeleton
The legs were large compared to contemporary relatives and it
The
Ichthyostega is related to
Classification
Traditionally, Ichthyostega was considered part of an order named for it, the "
Elpistostegalia |
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Paleobiology
Early limbed vertebrates like Ichthyostega and Acanthostega differed from earlier
Its massive ribcage was made up of overlapping ribs and the animal possessed a stronger skeletal structure, a largely fishlike spine, and forelimbs apparently powerful enough to pull the body from the water. These anatomical modifications may have evolved to handle the lack of buoyancy experienced on land. The hindlimbs were smaller than the forelimbs and unlikely to have borne full weight in an adult, while the broad, overlapping ribs would have inhibited side-to-side movements.[8] The forelimbs had the required range of movement to push the body up and forward, probably allowing the animal to drag itself across flat land by synchronous (rather than alternate) "crutching" movements, much like that of a mudskipper[3] or a seal.[9][10] It was incapable of typical quadrupedal gaits as the forelimbs lacked the necessary rotary motion range.[3]
See also
- Evolutionary history of life
- Hynerpeton
- List of transitional fossils
- List of prehistoric amphibians
- Ymeria
References
- ^ Haaramo, Mikko. "Taxonomic history of the genus †Ichthyostega Säve-Söderbergh, 1932". Mikko's Phylogeny Archive. Blom, 2005. Retrieved 24 October 2015.
- ^ "Ichthyostega". Paleofile. Retrieved 24 October 2015.
- ^ S2CID 3127857.
- ^ ISBN 8200376605.
- ISBN 0-412-78580-3, p. 262
- ^ S2CID 4370488.
- PMID 22448265.
- ^ Devonian Times – Tetrapods Answer
- ^ Williams, James J. (May 24, 2012). "Ichthyostega, one of the first creatures to step on land, could not have walked on four legs, say scientists". BelleNews. Retrieved 4 November 2013.
- ^ Mosher, Dave (May 23, 2012). "Evolutionary Flop: Early 4-Footed Land Animal Was No Walker?". National Geographic News. Archived from the original on May 25, 2012. Retrieved 4 November 2013.
Further reading
- Blom, H (2005). "Taxonomic Revision Of The Late Devonian Tetrapod Ichthyostega from East Greenland". Palaeontology. 48 (1): 111–134. .
- Westenberg, K (1999). "— From Fins to Feet". National Geographic. 195 (5): 114–127.
- ISBN 9780253356758.
External links
- Tree of Life Site on early tetrapods
- Getting a Leg Up on Land Scientific American Nov. 21, 2005, article by Jennifer A. Clack.
- BBC News: Ancient walking mystery deepens
- 3D computer model, forelimb maximal joint range, and hindlimb maximal joint range of Icthyostega on YouTube, videos by Stephanie E. Pierce, Jennifer A. Clack, & John R. Hutchinson