Acanthodes

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Acanthodes
Temporal range: 409–284Ma
Early Devonian to Early Permian
Acanthodes BW.jpg
Acanthodes bronni from the Early Permian of Germany
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Acanthodii
Order: Acanthodiformes
Genus: Acanthodes
Fossil of Acanthodes. Exhibit in the National Museum of Nature and Science, Tokyo, Japan.

Acanthodes (meaning spiny base or thorny base) is an extinct genus of spiny shark.[1] Fossils have been found in Europe, North America, and Australia.

Compared with other spiny sharks, Acanthodes was relatively large, at 30 centimetres (12 in) long. The genus had no teeth,[2] instead gills. Because of this, it is presumed to have been a filter feeder, filtering plankton from the water.[3] The Acanthodes has been found to have only a couple of skull bones. It was covered in scales that were cubical in shape.

It also had fewer spines than many of its relatives. Each of the paired pectoral and pelvic fins had a spine, as did the single anal and dorsal fins, giving it a total of just six, less than half that of many other species.[3]+ A fossil discovered near Hamilton, Kansas, and published in 2014 as Acanthodes bridgei was so well-preserved that traces of its eye tissue were sufficient to establish that Acanthodes had both rod and cone photoreceptor cells, and thus profited from color vision.[4]

The scientific classification of acanthodians is still a subject of great dispute, due to the fact that they share qualities of both bony fish (osteichthyes) and cartilaginous fish (chondrichthyes). A recent study has suggested that Acanthodes may have been an early common ancestor to all cartilaginous and bony fish, including humans.[5][6]

Notes[edit]

  1. ^ Royal Physical Society of Edinburgh (1880). "Proceedings of the Royal Physical Society of Edinburgh" V. p. 115. 
  2. ^ Nicholson, Henry Alleyne; Richard Lydekker (1889). A Manual of Palaeontology. p. 966. 
  3. ^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 30–31. ISBN 1-84028-152-9. 
  4. ^ NewsScienceMag, "Three hundred million year old fossil fish still has traces of eye tissue", 23 December 2014: accessed 23 December 2014.
  5. ^ Article on Acanthodes as ancestor of Man, http://www.sci-news.com/paleontology/article00396.html, accessed 15 June 2012
  6. ^ Journal article on Acanthodes, http://www.nature.com/nature/journal/v486/n7402/full/nature11080.html, accessed 15 June 2012
  • Parker, Steve. Dinosaurus: the complete guide to dinosaurs. Firefly Books Inc, 2003. Pg. 60

External links[edit]