„Þríbrotar“: Munur á milli breytinga

| fossil_range = Ár[[kambríum]]<ref name="lieberman02">{{Citation |last=B. S. |first=Lieberman |title=Phylogenetic analysis of some basal early Cambrian trilobites, the biogeographic origins of the eutrilobita, and the timing of the Cambrian radiation |journal=[[Journal of Paleontology]] |volume=76 |edition=4 |pages=692–708 |year=2002 |doi=10.1666/0022-3360(2002)076<0692:PAOSBE>2.0.CO;2 |issue=4}}</ref><ref name=Fortey00a>{{citation|title=Trilobite!: Eyewitness to Evolution|first=Richard|last=Fortey|author-link=Richard Fortey |year=2000|isbn=978-0-00-257012-1|publisher=HarperCollins|location=London}}</ref><ref name=Fortey00a>{{citation|title=Trilobite!: Eyewitness to Evolution|first=Richard|last=Fortey|author-link=Richard Fortey |year=2000|isbn=978-0-00-257012-1|publisher=HarperCollins|location=London}}</ref> – [[permtímabilið|síðperm]]