Anaspida

Taxobox
name = Anaspida
fossil_range = early Silurian - Late Devonian


image_caption = "Jamoytius kerwoodi"
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Anaspida

:"For turtles, see Anapsida."

The Anaspida ("Without Shields") are stem gnathostomes,cite book |author=Ahlberg, Per Erik |authorlink= |editor= |others= |title=Major events in early vertebrate evolution: palaeontology, phylogeny, genetics, and development |edition= |language= |publisher=Taylor & Francis |location=Washington, DC |year=2001 |origyear= |pages= p188|quote= |isbn=0-415-23370-4 |oclc= |doi= |url=http://books.google.com/books?id=zeyRZNZl-74C&pg=PA188&dq=Anaspida+%22stem+gnathostomes%22&as_brr=3&ei=2KN-SNeSF6HOjgGr-NDHCA&sig=ACfU3U2_2PVl8IEP8mBW5PCch2Wr3OzTQw |accessdate=] and are classically regarded as the ancestors of lampreys.cite book |author=Patterson, Colin |authorlink= |editor= |others= |title=Molecules and morphology in evolution: conflict or compromise? |edition= |language= |publisher=Cambridge University Press |location=Cambridge, UK |year=1987 |origyear= |pages= p142|quote= |isbn=0-521-32271-5 |oclc= |doi= |url=http://books.google.com/books?id=DL_KQPX3AmIC&pg=PA142&dq=Anaspida+gnathostomes&ei=W6F-SO-2E5XCigHs-L2_CA&sig=ACfU3U203AXE0jY6Q46goxR6Jeiswg7P_A |accessdate=] Anaspids were small marine agnathans that lacked scales and paired fins. They first appeared sometime during the early Silurian, and flourished until the Late Devonian Extinction Event,cite book |author=Hall, Brian Keith; Hanken, James |authorlink= |editor= |others= |title=The Skull |edition= |language= |publisher=University of Chicago Press |location=Chicago |year=1993 |origyear= |pages= p131|quote= |isbn=0-226-31568-1 |oclc= |doi= |url= http://books.google.com/books?id=fB-hO7i50esC&pg=PA131&dq=Anaspida+gnathostomes&ei=W6F-SO-2E5XCigHs-L2_CA&sig=ACfU3U2Ztylrkp1nwc-wUCb4UF0rLqUF5w|accessdate=] during the late Devonian, where most species, save for lampreys, went extinct due to the environmental upheaval during that time. The gills opened as a row of holes along either side of the animal that typically numbered anywhere from from 6-15 pairs.

Notes