Editing Cephalaspidomorphi (section)

==Biology and morphology==
[[File:Cephalaspis Lyellii.jpg|thumb|254px|left|Reconstruction of ''[[Cephalaspis]] lyelli'']]
Cephalaspidomorphs possessed armored plates on the exterior of their bodies. The head shield was particularly well developed, protecting the head, [[gill]]s and the anterior section of the [[viscera]]. The body was in most forms well armored as well. The head shield had a series of grooves over the whole surface, forming an extensive [[lateral line]] organ. The eyes were rather small and placed on the top of the head. There was no [[jaw]], and instead the mouth opening was surrounded by small plates, making the lips flexible, but without any ability to bite.<ref name=Colbert&Morales>{{cite book|last=Morales|first=Edwin H. Colbert, Michael|title=Evolution of the vertebrates : a history of the backboned animals through time|year=1991|publisher=Wiley-Liss|location=New York|isbn=978-0-471-85074-8|edition=4th}}</ref>

No internal skeleton is known, outside of the head shield. If they had a [[vertebral column]] at all, it would have been [[cartilaginous|cartilage]] rather than bone. Likely, the [[axial skeleton]] consisted of an unsegmented [[notochord]]. A fleshy appendage emerged laterally on each side, behind the head shield, functioning as [[pectoral fin]]s. The tail had a single, wrap-around tail-fin. Modern fishes with such a tail are rarely quick swimmers, and the Cephalaspidomorphs were not likely very active animals. They probably spent much of their time semi-submerged in the mud. They also lacked a [[swim bladder]], and would not have been able to keep afloat without actively swimming. The head shield provided some lift though and would have made the Cephalaspidomorphs better swimmers than most of their contemporaries.<ref name=Colbert&Morales/> The whole group were likely algae- or filter-feeders, combing the bottom for small animals, much like the modern armored bottom feeders, such as [[Loricariidae]] or ''[[Hoplosternum]]'' catfish.<ref>{{cite book|last=Lucas|first=F.A.|title=Animals of the past : an account of some of the creatures of the ancient world|year=1922|publisher=American Museum of Natural History|location=New York}}</ref>