Empetrum nigrum

Fletcher, T. L., Telka, A., Rybczynski, N. & Matthews, J. V., 2021, Neogene and early Pleistocene flora from Alaska, USA and Arctic / Subarctic Canada: New data, intercontinental comparisons and correlations, Palaeontologia Electronica (a 08) 24 (1), pp. 1-62 : 29-31

Empetrum nigrum L.

Rhamnaceae

Paliurus

Hypericaceae

Hypericum

Decodon globosus (E.M. Reid) Nikitin type

Mneme / Microdiptera type

Plantaginaceae

+ +

+ Hippuris + +

Haloragaceae

+ + + + + + Myriophyllum +

Araliaceae

Aralia

Apiaceae

+

+

Cicuta

Cornaceae + Cornus sericea subsp. sericea L. type + +

Cornus

Ericaceae

Andromeda

Arctostaphylos +

+

+ + + + + +

+ + + + +

+

Cassiope + + Chamaedaphne + + + + + +

Ledum

Oxycoccus ? +

+ + +

Vaccinium

Gentianaceae

Menyanthes trifoliata L. + +?

+ + +

+ + + + + + Menyanthes small form

Nymphoides

Verbenaceae

Verbena

Valerianaceae

Valeriana

Lamiaceae

Lycopus

Solanaceae

Solanum / Physalis type

Scrophulariaceae + + + +

+ + cf.

Linaria

Adoxaceae + Sambucus

Viburnum ? +

Decodon , another lythraceous genus, is often present in Neogene assemblages from northern North America. Though Decodon now grows in eastern North America, its last occurrence in Arctic regions was undoubtedly during the Pliocene. Wolfe and Tanai (1980) recorded foliar remains of Decodon from the Miocene Seldovia Point Formation of south-central Alaska, and we show here that it is present in mid-Miocene deposits in the Arctic.

Caprifoliaceae . Caprifoliaceae pollen, particularly Diervilla , is recorded in many Neogene pollen floras of North America and Eurasia. Macrofloral remains of both Diervilla and Weigela occur in Arctic Neogene assemblages, including those here, but to date Diervilla has only been found in presumed Miocene floras. On the other hand, Weigela macroremains occur in deposits ranging from mid-Miocene to Pliocene, and since its pollen cannot be distinguished from Diervilla , some of the Pliocene pollen reports of Diervilla may actually represent Weigela . This is further confused by phylogenetic studies that suggest Diervilla and Weigela diverged in the earliest Pliocene (Donoghue et al., 2001) and genetic studies (Kim and Kim, 1999) that suggest Weigela is not monophyletic, and should include Diervilla , despite morphological differences. Here, identification follows traditional morphological distinctions.

To date, Weigela has not been found in the Beaufort Formation on Meighen Island (15a,15b), but it does occur in the Beaufort Formation on northern Banks Island (11b) and in some of the Beaufort florules from Prince Patrick Island (12a; Matthews et al., 1990b; Fyles et al., 1994). A similar pattern is exhibited by Sambucus . Unless the fossils are rebedded from older deposits, any find of Sambucus or Weigela from a Subarctic/Arctic site is evidence for a pre-Quaternary age.

Taxa Cohorts

All the above comments regarding biostratigraphic implications are based on single taxa or groups of closely related taxa. Clearly, the power of conclusions relating to age and correlation is higher when several different types of fossils are used. This is why taxa cohorts are important. Cohorts differ from assemblages of fossils in that they represent certain collections of taxa that may form only a part of an assemblage. Enough sites have now been studied to allow recognition of several such cohorts.

For example, Aracites , Pinus (Strobus) , Myrica arctogale , Oxyria , and Dryas form a cohort. When it occurs in an assemblage it implies a Pliocene age. Insect fossils might well be considered as elements of such a cohort. Two forms that would be obvious constituents of the above-mentioned cohort are the extinct form Diacheila matthewsi Böcher, 1995 and Notiophilus cf. aeneus .