Recent molecular data, both from rRNA and from mtDNA as well as embryological data strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic.
12.
Most of the ostracoderms, such as thelodonts, osteostracans, and galeaspids, were more closely related to the gnathostomes than to the surviving agnathans, known as cyclostomes.
13.
Dohrn claimed cyclostomes such as lampreys are degenerate fish as there is no evidence their jawless state is an ancestral feature but is the product of environmental adaptation due to parasitism.
14.
The original scheme groups hagfish and lampreys together as cyclostomes ( or historically, Agnatha ), as the oldest surviving class of vertebrates alongside gnathostomes ( the now-ubiquitous jawed vertebrates ).
15.
Little is known about predation specifically on cyclostomes although it is likely that they are preyed upon by the nudibranchs ( sea-slugs ), pycnogonids ( sea-spiders ), echinoids and fishes which consume other marine bryozoans.
16.
Mertz obviously isn't simple-minded, not with published articles under his belt such as " The Cyclostome Bryozoan Crisiid eburnea and Idmonea atlantica in the Modern Reefs of the Bermuda Complex : Comparative Data of Paleoecology and Paleobryozoology ."
17.
The appearance of the early vertebrate jaw has been described as " a crucial innovation " and " perhaps the most profound and radical evolutionary step in the vertebrate history " . cyclostomes, the jawless hagfishes and lampreys that did survive, have yielded little insight into the deep remodelling of the vertebrate skull that must have taken place as early jaws evolved.
18.
Up until recently ( 2008 ) there were " inadequately known and misunderstood type species belonging to the Cyclostome Bryozoan family Oncousoeciidae . " ( Taylor, Zaton 2008 ) Modern research and experiments have been done using low-vacuum scanning electron microscopy of uncoated type material to critically examine and perhaps revise the taxonomy of three genera belonging to this family, including " Oncousoecia ", " Microeciella ", and " Eurystrotos ".
