''Yuknessia'' is an early pterobranch, known from the

Burgess shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fos ...

, the Chengjiang and the

Wheeler shale The Wheeler Shale (named by Charles Walcott) is a Cambrian ( 507 Ma) fossil locality world-famous for prolific agnostid and ''Elrathia kingii'' trilobite remains (even though many areas are barren of fossils) and represents a Konzent ...

. Long, unbranched fronds emerge from a central holdfast-like body covered in small conical plates. 23 specimens of ''Yuknessia'' are known from the Greater

Phyllopod bed The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess Shale fossil ''Lagerstätte''. It was quarried by Charles Walcott from 1911–1917 (and later named Walcott Quarry), and was ...

, where they comprise < 0.1% of the community. The genus contains two species: the type species ''Y. simplex'' and ''Y. stephenensis''. It was originally interpreted as a

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

, and has since been reinterpreted it as a colonial pterobranch.

References

External links

"Yuknessia simplex"
Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. (Burgess Shale species 136)

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ...

Prehistoric hemichordate genera Wheeler Shale Burgess Shale animals Cambrian genus extinctions {{paleo-invertebrate-stub