Beaver River (Silurian of Canada)

Where: Yukon, Canada (60.5° N, 125.8° W: paleocoordinates 5.2° N, 52.8° W)

• coordinate stated in text

When: Silurian (443.4 - 419.2 Ma)

• In summary, the vertebrates indicate either a Late Silurian or anEarlyDevonianage. TheinvertebratesidentifiedbyLenz(p.108) suggestanearlierdating. Themostsignificantofthemforcorrela- tion is the Monograptus dubius from beds overlying the vertebrate horizon. Thisspeciesisalong-livedoneinEurope,rangingfrom the Wenlock (zone 27 of the British section) into the Middle Ludlow

•(zone35or36). Theendofitsknownrangeoverlapsthesuggested vertebrate dating, and so Late Silurian, either Early or Middle Lud-

•low, may be taken tentatively as the probable age of this fauna, as estimated from the vertebrates. If this is correct it will extend

•downward the range of Homalaspidella and the Traquairaspididae, and suggest earlier specializations in certain Cyathaspididae.

Environment/lithology: marine; dolomite

Size class: macrofossils

Primary reference: R. H. Denison. 1963. New Silurian Heterostraci from Southeastern Yukon. Fieldiana Geology 14(7):105-141 [M. Uhen/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 185831: authorized by Mark Uhen, entered by Mark Uhen on 19.05.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Pteraspidomorpha
  - Ariaspididae
Ariaspis ornata n. gen. n. sp.
Ariaspis ornata n. gen. n. sp. Denison 1963
 Traquairaspidiformes -
Traquairaspis angusta n. sp. Denison 1963
 Cyathaspidida -
Homalaspidella borealis n. sp. Denison 1963
 Cyathaspidiformes - Cyathaspididae
Dikenaspis yukonensis n. gen. n. sp., Ptomaspis canadensis n. gen. n. sp., Vernonaspis major n. sp.
Dikenaspis yukonensis n. gen. n. sp. Denison 1963
Ptomaspis canadensis n. gen. n. sp. Denison 1963
Vernonaspis major n. sp. Denison 1963
Graptolithina
 Graptoloida -
Cyrtograptus cf. muchisoni graptoloid
var bohemicus
 Bireclinata - Monograptidae
Monograptus vomerinus graptoloid
var. gracilis
Monograptus acus graptoloid
"Monograptus spiralis" = Oktavites spiralis Geinitz 1842 graptoloid
 Bireclinata - Retiolitidae