Article
Article
Phymosomatoida
Article By:
Smith, Andrew B. Department of Paleontology, Natural History Museum, London, United Kingdom.
Last reviewed:January 2020
DOI:https://doi.org/10.1036/1097-8542.513400
An extinct order of regular sea urchins (class Echinoidea) characterized by having a large monocyclic apical disk that forms a ring indented by periproctal plates. Members of the Phymosomatoida have compound ambulacral plating with three or more elements bound together by a single large tubercle. Their jaw apparatus is of the stirodont design, having teeth that are keeled and unfused epiphyses. They comprise two families, one with perforate tubercles and the other with imperforate tubercles, the former being the ancestor to the latter. They first appeared in the Lower Jurassic and became extinct at the end of the Eocene. The morphology of Phymosomatoida suggests that they were epifaunal grazers and lived in shallow shelf seas. See also: Echinodermata; Echinoidea
The content above is only an excerpt.
About AccessScience
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. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles 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 19,000 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
