|North Pacific||AKSR-NASR||Anadyr-Koryak||Verkhoyansk-Chukotka||Okhotsk-Chukotka||N. Alaska||Yukon||Chignik|
|Phytostratigraphy||Images of fossils characteristic of the Type Taphoflora|
The Early Ginter Phase of Floral Evolution
Characterizing this phase of floral evolution is relatively straightforward because it is represented by only one assemblage (Herman, 1999a). This is the taphoflora from the Ugol'naya Bay area, which is naturally the type flora of the Early Ginter phase. Despite the lack of other taphofloras it is reasonable to recognize this phase as distinct because the aforementioned taphoflora corresponds to the earliest epoch of floral genesis in the AKSR.
The remarkable features of this flora are: (1) the absence of angiosperms or any Late Cretaceous taxa among ferns and conifers; (2) the prevalence of Early Cretaceous genera and species (Hausmannia ex gr. bilobata Pryn., Cladophlebis aff. williamsonii (Brongn.) Brongn., Sagenopteris, Neozamites (?), Podozamites); (3) the presence of (apparently) only two cycadophyte genera. It cannot be excluded, however, that some of the distinctive features represent a consequence of taphonomic factors, but taken in combination, all the characteristics suggest that this flora is distinct, if not unique, and justifiably represents a phase of floral evolution that is markedly different from the somewhat younger Grebenka phase of floral evolution in this subregion. The Early Ginter flora seems to be correlative with floras of the Buor-Kemus type (Samylina, 1974) widespread in Northeastern Asia and North America. Accordingly, it determines the Early Ginter phytostratigraphic horizon, not only the beds with the taphoflora of the Ugol'naya Bay locality. Despite its limited correlation potential, the horizon can be considered as a subregional equivalent of the Buor-Kemus Horizon widespread in North Pacific.
The Early Ginter Horizon, with a problematic lower boundary, corresponds to part of the late Albian. Its similarity to the Buor-Kemus Horizon spanning the early–middle and partly late Albian means presumably that the lower boundary of the Early Ginter Phase (but not of the Ugol’naya Bay taphoflora, which is unlikely to be older than late Albian) can be positioned within the first half of the Albian Stage. Floras older than the one described are unknown in the AKSR.
Filippova (1998) was of the opinion that the taphoflora of the Ugol'naya Bay area is coeval with taphofloras from the Krivorechenskaya Formation sediments exposed along the Berezovaya, Srednyaya Orlovka and Malaya Grebenka rivers (right bank of the Anadyr River). Comparison between these and other floras from the Krivorechenskaya Formation suggests, however, that the three floras above represent impoverished floral assemblages (depleted primarily in angiosperm taxa) of more diverse taphofloras of the next Grebenka phase in flora evolution, which are somewhat younger than the Early Ginter taphoflora.