title: Exceptionally preserved jellyfishes from the Middle Cambrian.
abstract: Cnidarians represent an early diverging animal group and thus insight into their origin and diversification is key to understanding metazoan evolution. Further, cnidarian jellyfish comprise an important component of modern marine planktonic ecosystems. Here we report on exceptionally preserved cnidarian jellyfish fossils from the Middle Cambrian (approximately 505 million years old) Marjum Formation of Utah. These are the first described Cambrian jellyfish fossils to display exquisite preservation of soft part anatomy including detailed features of structures interpreted as trailing tentacles and subumbrellar and exumbrellar surfaces. If the interpretation of these preserved characters is correct, their presence is diagnostic of modern jellyfish taxa. These new discoveries may provide insight into the scope of cnidarian diversity shortly after the Cambrian radiation, and would reinforce the notion that important taxonomic components of the modern planktonic realm were in place by the Cambrian period.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America.
authors.forename: Paulyn
authors.initials: P
authors.lastname: Cartwright
authors.forename: Susan L
authors.initials: SL
authors.lastname: Halgedahl
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Hendricks
authors.forename: Richard D
authors.initials: RD
authors.lastname: Jarrard
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Marques
authors.forename: Allen G
authors.initials: AG
authors.lastname: Collins
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Lieberman
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003063:Cnidaria / Q000033:anatomy & histology* / Q000502:physiology*; D017753:Ecosystem; D005580:Fossils; D005843:Geography; D008954:Models, Biological; D010163:Paleontology / Q000379:methods; D010802:Phylogeny; D010933:Plankton; D013997:Time Factors; D014589:Utah