|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
Crossopterygii
Crossopterygii (class Osteichthyes) Subclass of bony fish comprising both fossil and living lobe-finned or tassel-finned fish, including the Coelacanthiformes and Rhipidistia. The former are well known from Palaeozoic and Mesozoic rocks, but were thought to have become extinct by the end of the Cretaceous until living specimens were netted this century in the Indian Ocean. The Rhipidistia did become extinct, although not before they gave rise, in the Devonian, to the amphibians. The Crossopterygii are characterized by the fact that all fins (except the tail-fin) are based on movable stalks or lobes. The tail fin is either heterocercal or diphycercal.
|
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Crossopterygii." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Crossopterygii." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O13-Crossopterygii.html AILSA ALLABY and MICHAEL ALLABY. "Crossopterygii." A Dictionary of Earth Sciences. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Crossopterygii.html |
|
Sarcopterygii
Sarcopterygii Subclass of fleshy-finned fish comprising two main groups (super-orders): the coelacanths (Crossopterygii), and the lungfish (Dipnoi). The Crossopterygii appeared in the Devonian, were widely distributed in the Mesozoic, and are now represented by a single genus, Latimeria. One order of the Crossopterygii, the Rhipidistia, is credited with being the root stock for more advanced vertebrates. The Dipnoi also appeared in the Devonian and are now represented by three species. They inhabit fresh water and have developed organs by which they can breathe atmospheric air.
|
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O13-Sarcopterygii.html AILSA ALLABY and MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Earth Sciences. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Sarcopterygii.html |
|
Sarcopterygii
Sarcopterygii The name given by some taxonomists to a group comprising the lobe-finned fish (subclasses Crossopterygii and Dipneusti). Others tend also to include the terrestrial vertebrates (Tetrapoda). See also CHOANICHTHYES; GNATHOSTOMATA.
|
|
|
Cite this article
MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Zoology. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Zoology. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O8-Sarcopterygii.html MICHAEL ALLABY. "Sarcopterygii." A Dictionary of Zoology. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Sarcopterygii.html |
|
Crossopterygii
Crossopterygii (Actinistia; class Osteichthyes) A subclass of bony fish that includes both fossil and living lobe-finned or tassel-finned fish, including the Coelacanthimorpha and Rhipidistia.
|
|
|
Cite this article
MICHAEL ALLABY. "Crossopterygii." A Dictionary of Zoology. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Crossopterygii." A Dictionary of Zoology. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O8-Crossopterygii.html MICHAEL ALLABY. "Crossopterygii." A Dictionary of Zoology. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Crossopterygii.html |
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
