Panderichthys

Taxobox
name = "Panderichthys"
fossil_range = Fossil range|380Late Devonian

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image_width = 250px
image_caption = Reconstruction of "Panderichthys"
regnum = Animalia
phylum = Chordata
classis = Sarcopterygii
ordo = Panderichthyida
familia = Panderichthyidae
genus = "Panderichthys"
binomial = "Panderichthys rhombolepis"
binomial_authority = Gross, 1941

"Panderichthys" is a 90–130 cm long fish from the Devonian period 380 million years ago, (Frasnian epoch) of Latvia. It has a large tetrapod-like head. "Panderichthys" exhibits transitional features between lobe-finned fishes and early tetrapods such as "Acanthostega". The evolution from fish to land dwelling tetrapods required many changes in physiology, most importantly the legs and their supporting structure, the girdles. Well preserved fossils of "Panderichthys" clearly show these transitional formsref|Evolution, making "Panderichthys" a rare and important find in the history of life.

Fish like "Panderichthys" were the ancestors of the first tetrapods, air-breathing, terrestrial animals from which the land vertebrates, including humans, are descended. The most notable characteristic of "Panderichthys" was its spiracle, a vertical tube used to breathe water through the top of its head, while its body was submerged in mud. This spiracle is a transitional organ that led, through evolution, to the development of the stirrup bone, one of the three bones (stirrup, hammer, and anvil) in the human middle ear.

[http://www.news.com.au/dailytelegraph/story/0,22049,24381533-5016574,00.html Recent reexamination] of existing Panderichthys fossils using a CT scanner shows four very clearly differentiated distal radial bones at the end of the fin skeletal structure. These finger-like bones do not show joints and they are quite short, but nonetheless show an intermediate form between fully fish-like fins and tetrapods.

References

*
* [http://www.nature.com/nature/journal/v438/n7071/edsumm/e051222-13.html The pelvic fin and girdle of Panderichthys and the origin of tetrapod locomotion]

See also

" – exhibited a sequence of adaptations:

• "Panderichthys", suited to muddy shallows;
• "Tiktaalik" with limb-like fins that could take it onto land;
• Early tetrapods in weed-filled swamps, such as:
  • "Acanthostega" which had feet with eight digits,
  • "Ichthyostega" with limbs.

Descendants also included pelagic lobe-finned fish such as coelacanth species.]

* "Eusthenopteron"
* "Elpistostege"

External links

* [http://pharyngula.org/index/weblog/comments/panderichthys_rhombolepis Pharyngula]
* [http://www.devoniantimes.org/Order/re-panderichthys.html Devonian Times - Panderichthys]