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North Pacific AKSR-NASR Anadyr-Koryak Verkhoyansk-Chukotka Okhotsk-Chukotka N. Alaska Yukon Chignik
Phytostratigraphy     Images of fossils characteristic of the Type Taphoflora


The Grebenka Phase of Floral Evolution

Samylina (1974), who originally distinguished the Grebenka phase “stratoflora”, considered it to be Turonian in age. Corresponding to this phase are the Grebenka flora of the Anadyr River middle reaches, which includes a series of taphofloras discovered on the right and left banks of this river, and the Middle Ginter taphoflora of the Ugol'naya Bay site. The taphoflora from the Krivorechenskaya Formation of the Yelisseev Locality in the Grebenka River middle reaches is the most diverse among them, being regarded as the type taphoflora of the phase (Shczepetov et al., 1992; Spicer et al., 2002, Herman, 2011a).

The boundary between the Early Ginter and Grebenka phases is substantiated by a succession of taphofloras in the Ginter Formation section at the Ugol'naya Bay site, where they are separated, however, by an interval of about 330 m thick lacking paleontological remains in the lower part and containing marine fossils of the middle Cenomanian Inoceramus pennatulus Zone in the upper part. Because taphofloras of the Grebenka phase from the Grebenka River basin correspond in age not only to the Cenomanian, but also to the late Albian (Spicer et al., 2002), the boundary between the two phases is most likely within the late Albian. The Grebenka phase is estimated to have been approximately 7 – 9 m.y. in duration.

The flora of the Grebenka phase is very diverse, consisting of at least 200 taxa. These taxa are listed in the panel to the right. Taphofloras typical of the phase are characterized by having angiosperms dominating the floral composition to the extent that they represent 35 – 40% of taxa. Ferns and conifers are also diverse comprising 20 – 25% of taxa, although fern impressions prevail in many local assemblages. Diverse and abundant Menispermites leaves belonging to at least eight species and platanoids represent a noticeable, though not dominant, component of the Grebenka flora. The platanoids, not being very diverse, largely belong to the genus Ettingshausenia. However one impression of the peltate Pseudoprotophyllum has been reliably identified (Yelisseev locality, collection of R.A. Spicer).

The presence of the genera Protophyllum and Credneria is doubtful. Angiosperms are fairly abundant and include entire-margined (Magnoliaephyllum, Myrtophyllum, Scheffleraephyllum, Dalbergites, etc.), lobed (Ettingshausenia, Cissites, Menispermites, Araliaephyllum, Dalembia) and compound (Scheffleraephyllum, Dalembia, Sorbites, etc.) leaves. Isolated specimens of Trochodendroides also occur.

Common among ferns are the genera Gleichenites, Birisia, Coniopteris, Hausmannia, Cladophlebis etc.; Birisia and Coniopteris remains are frequently very abundant in local assemblages. Caytonialeans (Sagenopteris) are relatively rare. Cycadophytes represented by leaves of Cycadites, Nilssonia (often forming accumulations of remains or ‘leaf mats’), Taeniopteris and by short shoots of Nilssoniocladus (Spicer and Herman, 1996) are common components in taphofloras of the Grebenka type. Ginkgoaleans include the genera Ginkgo, Baiera, and Sphenobaiera. The czekanowskialean genus Phoenicopsis is a very rare component. Conifers include the comparatively old, typically Early Cretaceous genera (Podozamites, Athrotaxopsis, Pagiophyllum, Pityophyllum) and remains of more advanced forms (Sequoia, Cupressinocladus, Cryptomeria); most common and frequently occurring species are Cephalotaxopsis intermedia, Araucarites anadyrensis, and Elatocladus smittiana associated with some remains with Sequoia aff. reichenbachii and Pagiophyllum triangulare.

Lebedev (1987) attributed a taphoflora from the Kondyreva River basin (right tributary of the Penzhina River) to the Grebenka phase of floral evolution. The Kondyreva River assemblage includes Onychiopsis psilotoides, Hausmannia sp., Cladophlebis (Birisia) oerstedtii, C. cf. frigida, Cladophlebis sp., Nilssonia alaskana, N. yukonensis, Cephalotaxopsis heterophylla, C. cf. intermedia, Araucarites anadyrensis, Menispermites sp., Celastrophyllum (?) sp., and Dicotyledones sp. (collection of Yu.M. Arsen'ev and E.A. Strizhko; determinations of E.L. Lebedev). The diversity of this flora is too low, however, to be confident that it is the Grebenka type and additional collecting is required before its affiliation can be confirmed.



Systematic composition of the Grebenka Phase flora
(AKSR, Late Albian – Cenomanian – Early Turonian)

Thallites sp. 1,
Thallites sp. 2,
Thallites sp. cf. Marchantites jimboi (Krysht.) Krysht.

Equisetites sp.

Gleichenia pseudocrenata E. Lebedev,
Gleichenites zippei (Corda) Seward,
Gleichenites asiatica Philippova,
Gleichenites microphylla Philippova,
Birisia jelisejevii (Krysht.) Philippova,
Birisia ochotica Samylina,
Birisia (?) oerstedtii (Heer) E. Lebedev,
Birisia sp.,
Coniopteris anadyrensis Philippova,
Coniopteris (Birisia ?) grebencaensis Philippova,
Coniopteris sp.,
Adiantopteris (?) sp.,
 Arctopteris penzhinensis E. Lebedev,
Asplenium dicksonianum Heer,
Asplenium rigidum Vassilevskaya,
Onychiopsis elongata (Geyl.) Yok.,
Hausmannia bipartita Samyl. et Shczep.,
Hausmannia (?) sp., Schizea sp.,
Cladophlebis cf. frigida (Heer) Sew.,
Cladophlebis ex gr. haiburnensis (L. et H.) Brong.,
Cladophlebis aff. septentrionalis Hollick,
Cladophlebis ubiencaensis Philippova,
Cladophlebis sp. 1-4,
Sphenopteris sp. 1-2

Ginkgoales: Ginkgo ex gr. adiantoides (Unger) Heer,
Ginkgo ex gr. lepida Heer,
Ginkgo sp.,
Baiera cf. gracilis (Bean) Bunb.,
Sphenobaiera vera Samylina et Shczepetov,
Desmiophyllum (Sphenobaiera ?) sp.,
Pseudotorellia (?) sp.;

Leptostrobales: Phoenicopsis ex gr. angustifolia Heer;

Sagenopteris variabilis (Velenovsky) Velenovsky,
Sagenopteris (?) sp.;

Cycadites hyperborea (Krysht.) E. Lebedev,
Nilssonia alaskana Hollick,
Nilssonia serotina Heer,
Nilssonia yukonensis Hollick,
Nilssonia cf. yukonensis Hollick,
Nilssonia sp.,
Nilssoniocladus chukotensis Spicer et Herman,
Taeniopteris ex gr. lundgreni Nathorst,
Taeniopteris sp. 1-2;

Cephalotaxopsis ex gr. heterophylla Hollick,
Cephalotaxopsis intermedia Hollick,
Taxites (Florinia ?) sp.,
Florinia borealis Sveshn. et Budantsev,
Florinia (?) sp.,
Cephalotaxus (?) sp.,
Araucarites anadyrensis Krysht.,
“Araucarites” sp.(cone),
Pagiophyllum triangulare Prynada,
Podozamites lanceolatus (Lindl. et Hutton) Braun,
 Pseudolarix (?) sp., Picea (?) sp.,
Pityophyllum ex gr. nordenskioldii (Heer) Nath.,
Pityophyllum ex gr. staratschinii (Heer) Nath.,
Pityospermum aff. piniformis Samylina,
Pityospermum semiovale Samylina,
Pityostrobus sp. 1-3,
Pityolepis sp.,
Pityocladus sp.,
Athrotaxopsis cf. expansa Fontaine,
Sequoia fastigiata (Sternb.) Heer,
Sequoia cf. minuta Sveshnokova,
Sequoia ex gr. reichenbachii (Geinitz) Heer,
Sequoia sp. (cone),
Sequoia sp. (cone scale),
Cryptomeria subulata (Heer) Sveshnikova,
Tollia sp.,
Parataxodium aff. wigginsii Arnold et Lowther,
Cupressinocladus cretaceus (Heer) Seward,
Elatocladus gracillimus (Hollick) Sveshnikova,
Elatocladus smittiana (Heer) Seward,
Elatocladus sp.;

Magnoliaephyllum alternans (Heer) Seward,
“Cocculus” cf. extinctus Velenovsky,
 Cocculophyllum cf. furcinerve Krassilov,
Menispermites ginterensis Herman,
Menispermites grebenkaensis E. Lebedev,
Menispermites ex gr.sibiricus (Heer) Golovneva
Menispermites marcovoensis Philippova,
Menispermites minutus (Krysht.) Herman,
 Menispermites aff. reniformis Dawson,
Menispermites ex gr. septentrionalis Hollick,
Menispermites sp.,
Ettingshausenia louravetlanica (Herman) Herman,
Ettingshausenia sp. (E. ex gr. embicola (Vachr.) Herman),
Anadyricarpa altingiosimila N. Maslova et Herman,
Pseudoprotophyllum cf. boreale (Dawson) Hollick,
Platanofoliagen. indet., 
“Diospyros” aff. steenstrupi Heer,
Sorbites asiatica Philippova,
Myrtophyllum acuminata (Philippova) Herman,
Celastrophyllum latifolium Fontaine,
Celastrophyllum sp. 1-2,
“Araliaephyllum” dentatum Philippova,
Araliaephyllum medium (Philippova) Herman,
Araliaephyllum devjatilovae Philippova,
Araliaephyllum polevoii (Krysht.) Krassilov,
Araliaephyllum (?) sp.,
Scheffleraephyllum venustum (Philippova) Philippova,
Scheffleraephyllum sp.,
Trochodendroides arctica (Heer) Berry,
Trochodendroides sp., “Zizyphus” sp.,
Crataegites (Cissites ?) sp.,
Dalbergites elegans Efimova,
Dalbergites sp.,
Cissites orbiculatus Philippova,
Cissites sp. 1-4,
Dalembia vachrameevii E. Lebedev et Herman,
Grebenkia anadyrensis (Krysht.) E. Lebedev,
cf. Palaeonuphar nordenckioldii (Heer) Bell,
Dicotylophyllum (Lindera ?) sp.,
Dicotylophyllum (Cissites ?) sp.,
Dicotylophyllum (Menispermites ?) sp.,

Dicotylophyllum sp. 1-8, Carpolithes sp. 1-3.



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