Carlson, Sandra J. Department of Geology, University of California, Davis, California.
- Additional Readings
A subphylum of inarticulated brachiopods having a bivalved calcitic shell with a laminar (tabular) secondary shell layer that is distinctly different from the microstructure of the calcareous articulated brachiopods. Together with Linguliformea and Rhynchonelliformea, Craniiformea is one of the three subphyla currently recognized in phylum Brachiopoda. It encompasses a single class Craniata, which is composed of three orders: Craniopsida, Craniida, and Trimerellida. Thirty-eight genera are currently recognized within Craniiformea, with 5 genera in Craniopsida, 16 genera in Craniida, and 17 genera in Trimerellida. Formerly considered to be a superfamily in order Acrotretida, Craniiformea has since been elevated to subphylum status based on the distinctive combination of a lack of tooth-and-socket hinge mechanism between the valves, the lack of a pedicle (a cuticle-covered stalklike appendage which emerges between the valves and attaches the brachiopod to the substrate), and the presence of a calcareous shell. See also: Acrotretida; Brachiopoda; Inarticulata; Lingulida; Rhynchonelliformea
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Its dedicated editorial team is led by Sagan Award winner John Rennie. Contributors include more than 9000 highly qualified scientists and 42 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 17,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information