|North Pacific||AKSR-NASR||Anadyr-Koryak||Verkhoyansk-Chukotka||Okhotsk-Chukotka||N. Alaska||Yukon||Chignik|
|Phytostratigraphy||Images of fossils characteristic of the Type Taphoflora|
The Tuluvak Phase of Floral Evolution
Floras of this phase are known only from the Lower Colville-Chandler area, where assemblages have been discovered in non-marine deposits of the Tuluvak Formation. These deposits, contain the type flora of the phase. The beds are of Coniacian age, because they overlie marine deposits of the Seabee Formation, which bear remains of the Turonian mollusks and foraminifers, and underlie, with partial replacement along strike, the Schrader Bluff Formation comprised of marine sediments containing the late Santonian–early Campanian inoceramids in the lower part (Brosgé and Wittington, 1966; Herman and Spicer, 1997b; Mull et al., 2003). The Tuluvak phase was approximately 3.2 m.y. in duration.
Plant taxa of the Tuluvak flora are listed in the panel to the right. Ferns and conifers, with Parataxodium wigginsii most frequent among the latter, are of low diversity in the Tuluvak flora (Herman and Spicer, 1997b, 1997c). Relatively rare ginkgoaleans are represented only by the species Ginkgo ex gr. adiantoides. A characteristic aspect of the flora is the prevalence of angiosperms dominated by platanoids, frequently large-leaved, and by Trochodendroides forms occurring in association with fruits Trochodendrocarpus. Unusual three-lobed forms (Dicotylophyllum triangulare) and leaves with emarginate apex (Dalbergites simplex, Dalbergites sp.) have been detected among impressions of entire-margined leaves.
In comparison to the Kaolak flora, the flora of the Tuluvak phase is nearly 1.5 times more diverse. On the other hand, both floras are dominated by angiosperms, primarily by platanoids and Trochodendroides forms. However, peculiar aspects of the Tuluvak flora are evident from the abundance of angiosperms with entire-margined leaves (Magnoliaephyllum cf. alternans, Magnoliaephyllum sp., Laurophyllum sp., Dalbergites simplex, Dalbergites sp., Leguminosites sp., Sapotacites sp., Dicotylophyllum triangulare, etc.) and from appearance of plant remains typical of the Senonian floras in the North Pacific (Cupressinocladus cretaceus, Magnoliaephyllum cf. alternans, Paraprotophyllum ignatianum, Cissites beljaevii, Zizyphus smilacifolia, Z. ex gr. kujiensis, Quereuxia angulata).