Alexei B. Herman

Constant elevation of southern Tibet over the past 15 million years.

The uplift of the Tibetan plateau, an area that is 2,000 km wide, to an altitude of about 5,000 m has been shown to modify global climate and to influence monsoon intensity. Mechanical and thermal models for homogeneous thickening of the lithosphere make specific predictions about uplift rates of the Tibetan plateau, but the precise history of the uplift of the plateau has yet to be confirmed by observations. Here we present well-preserved fossil leaf assemblages from the Namling basin, southern Tibet, dated to ∼15 Myr ago, which allow us to reconstruct the temperatures within the basin at that time. Using a numerical general circulation model to estimate moist static energy at the location of the fossil leaves, we reconstruct the elevation of the Namling basin 15 Myr ago to be 4,689 ± 895 m or 4,638 ± 847 m, depending on the reference data used. This is comparable to the present-day altitude of 4,600 m. We conclude that the elevation of the southern Tibetan plateau probably has remained unchanged for the past 15 Myr.

Monocotyledons from the Early Campanian (Cretaceous) of Grünbach, Lower Austria

Abstract Four monocotyledons, Araciphyllites austriacus sp. nov., Pandanites trinervis (Ettingshausen) comb. nov., Sabalites longirhachis (Unger) comb. nov. and one unclassified monocotyledon leaf type are described from the Campanian of Grunbach in Austria mostly on the basis of leaf morphology. A new species of Araciphyllites is described and compared to recent representatives of the family Araceae. An emended diagnosis of the genus Pandanites is proposed and species Pandanites trinervis is revised on the basis of the detailed morphology and anatomy of its leaves. The unique construction of leaves of the Pandanaceae is discussed and used for comparison with recent and fossil representatives of the family. Sabalites longirhachis is characterised by costapalmate leaves, which are not dissected into segments. Relationship to similar species of the genus Sabalites is discussed. A fragmentary preserved leaf of an unnamed monocotyledon is included to show the diversity of monocotyledons in the Grunbach Campanian wetlands.

The Sensitivity of CLAMP to Taphonomic Loss of Foliar Physiognomic Characters

Abstract CLAMP (Climate Leaf Analysis Multivariate Program) is a powerful paleoclimate proxy with the ability to yield quantitative data on past temperatures, precipitation, growing season length, and humidity, as well as enthalpy (a property of a parcel of air that is useful in studies of paleoaltimetry). Commonly quoted uncertainties in CLAMP predictions relate to the statistical uncertainty inherent in the combined quality of the modern calibration data sets and the relationship of foliar architecture to the various climate parameters. This minimum uncertainty assumes that the fossil assemblage represents faithfully the foliar physiognomy of the source vegetation. Taphonomic processes degrade this physiognomic fidelity. Differential selection for size, shape, and species composition during transport and post-depositional processes biases the physiognomic profile of the fossil assemblage. The sensitivity of CLAMP precision to taphonomic filtering was assessed empirically using a modern data set from the Crimean Peninsula as a proxy fossil site. Elimination of leaf margin, apex, base, size, and shape character-state categories, singly and in combination, changed the predictive capability of CLAMP. Loss of margin characters had the greatest effect, particularly on temperature-related variables (mean annual, warm-month mean and cold-month mean temperatures, length of the growing season, and enthalpy). Taphonomic selection against large leaf sizes had little effect even on moisture-related estimates (precipitation during the growing season, mean monthly growing season precipitation, precipitation during the three wettest and driest months, relative humidity). Loss of taphonomically sensitive characters (apex, base, or shape) also had little effect on CLAMP predictions.

Foliar Physiognomic Record of Climatic Conditions during Dormancy: Climate Leaf Analysis Multivariate Program (CLAMP) and the Cold Month Mean Temperature

The extent to which the leaves of woody dicots encode in their physiognomy the climatic conditions that exist during dormancy was tested by sampling 20 sites along an approximately west‐east transect across European Russia, the Crimean Peninsula, Western Siberia, and central Eastern Siberia. This transect encompassed the most extreme mean annual temperature range recorded in the modern world where vegetation exists. Climate Leaf Analysis Multivariate Program (CLAMP) revealed little change in calibration of the warm month mean temperature compared with the PHYSG3AR data set derived from less extreme sites primarily in North America and Japan, but significant change with respect to the cold month mean temperature (CMMT) calibration. Although CLAMP underestimated the CMMT by up to 9°C in the coldest sites, the addition of the transect sites improved CLAMP’s performance at low temperatures. This suggests that winter cold is encoded in foliar physiognomy even though the leaves are functional only during the late spring and summer months. This increase in performance was, however, at the cost of decreasing precision. Precipitation predictive capabilities were only slightly affected, but calibration of key climatic variables such as enthalpy, used in determining palaeoaltitude, remained more or less unchanged after the inclusion of the cold transect samples.

Arman’ Flora of the magadan region and development of floras in the North Pacific during the Albian-Paleocene

The Arman’ Flora from volcanogenic-sedimentary deposits in the Arman’ River basin and Naraula Formation in the Nel’kandzha-Khasyn interfluve includes 82 species of fossil plants comprising liverworts, horsetails, ferns, caytonealeans, cycadaleans, ginkgoaleans, czekanowskialeans, conifers, gymnosperms incertae sedis, and angiosperms. The Arman’ Flora appears to be of Turonian-Coniacian age, as it is close to the reliably dated Penzhina and Kaivayam floras from the Northwest Kamchatka and to Tyl’pegyrgynai Flora of the Pekul’nei Ridge. The dating is consistent with isotopic dates (40Ar/39Ar and U-Pb SHRIMP) characterizing the age of plant-bearing sequences. Based on the considered position of the Arman’ Flora in the scheme of Cretaceous florogenesis, a leading role in that florogenesis was played by the gradual invasion of floras by new, angiosperm dominated, plant communities. These communities initially populated unstable habitats in the coastal lowlands of Northeast Asia and Alaska, gradually invading with time the Asiatic intracontinental areas. The peculiar combination of Early and Late Cretaceous plants characteristic of the Arman’ Flora is strong evidence that Cenophytic plant communities dominated by angiosperms colonized areas still populated in the Late Cretaceous by Mesophytic communities. Absence of Mesophytic and Cenophytic taxa mixing in the Arman’ Flora burials suggests a replacement of plant communities as whole rather than of separate plants by more advanced taxa.

Infructescences of Friisicarpus nom. nov. (Platanaceae) and Associated Foliage of the Platanoid Type from the Cenomanian of Western Siberia

A new generic name, Friisicarpus N. Maslova et Herman, is proposed to replace Platanocarpus Friis, Crane, et Pedersen, 1988. Pistillate capitate inflorescences of Friisicarpus nom. nov. are reported from the Cenomanian of western Siberia for the first time. They are found in association with leaves of the typical Platanus-morphotype. Earlier, remains belonging to this genus were found to be associated with pinnatifid leaves of cf. Sapindopsis variabilis Fontaine (Crane et al., 1993).

Flora development in Northeastern Asia and Northern Alaska during the Cretaceous-Paleogene transitional epoch

Study of floral succession from the Cretaceous-Paleogene boundary interval in Russian Far East (Zeya-Bureya depression), Northeastern Russia (Koryak Upland), and Northern Alaska (Sagavanirktok River basin) is crucial for better understanding palaeoclimatic and palaeogeographic factors, which controlled events in vegetation evolution at that time. The succession of fossil floras in the Zeya-Bureya depression includes plant assemblages of the Santonian, Campanian, early Danian, Danian, and Danian-Selandian age. The early Danian Boguchan Flora keeps continuity in composition and dominating taxa with the Campanian Late Kundur Flora. The Koryak Flora of the Amaam Lagoon area (Northeastern Russia) is dated as late Maastrichtian based on correlation of plant-bearing beds with marine biostratigraphy, whereas the Early and Late Sagwon floras of Northern Alaska are dated back to the Danian-Selandian and early Paleocene based on palynological and macrofloristic data. The Early Sagwon Flora is most close to the late Maastrichtian Koryak Flora of the Amaam Lagoon area in composition and main dominants, while the Late Sagwon Flora is comparable with the Danian or Danian-(?) Selandian flora from the Upper Tsagayan Subformation of the Amur area. In a florogenic aspect, trans-Beringian plant migrations from northeastern Asia and southern palaeolatitudes of the Far East, which became possible due to Paleocene climate warming in Arctic, have played an important role in forming of the Paleocene floras of Northern Alaska. Floras of the Far East and high latitudes of Asia and North America show no evidence of catastrophic event at the Cretaceous-Paleogene boundary. Their development was most probably controlled by climate changes, plant evolution and migration.

Late paleocene flora of the northern Alaska Peninsula: the role of transberingian plant migrations and climatic change

For the first time, the Late Sagwon Flora is described from the upper beds of the Prince Creek Formation (Upper Paleocene) at the Sagavanirktok River (northern Alaska Peninsula). The flora is dominated by the angiosperm Tiliaephyllum brooksense Moiseeva et Herman sp. nov. and conifer Metasequoia occidentalis (Newb.) Chaney. The Late Sagwon Flora is most similar to the Danian or Danian-Selandian flora from the middle part of the Upper Tsagayan Subformation (Amur Region) and lower part of the Wuyun Formation (Heilongjiang Province, China). This similarity allows us to hypothesize that the genus Tiliaephyllum, which dominated in the Late Tsagayan Flora, migrated via the Bering Land Bridge from southern paleolatitudes of the Far East to high latitudes of the Arctic Pacific, due to the progressively warming climate of the Paleocene. Additional new angiosperm species are described from the Late Sagwon Flora: Archeampelos mullii Moiseeva et Herman sp. nov., Tiliaephyllum brooksense Moiseeva et Herman sp. nov., and Dicotylophyllum sagwonicum Moiseeva et Herman sp. nov.

Late Early–Late Cretaceous floras of the North Pacific Region: florogenesis and early angiosperm invasion

Abstract During the early–middle Albian, a single uniform flora existed in the North Pacific Region. In the middle Albian, structural and landscape modification of the region resulted in its subdividing into several floristic-palaeogeographic subregions. Latest Albian and Late Cretaceous floras of coastal plains of North-eastern Asia and Alaska were dominated by angiosperms, whereas within the Asiatic continental interior depressions and the highlands of the Okhotsk–Chukotka volcanogenic belt angiosperm-dominated floras coexisted with floras dominated by ferns and gymnosperms. The observed phenomenon can be explained by the early angiosperm ability to colonise disturbed coastal plain environments due to their abbreviated reproductive cycle and generalised methods of pollination and seed dispersal. In North-eastern Asia and Alaska the first angiosperm remains were found in deposits of an alluvial–deltaic origin. During the early–middle Albian these plants probably occupied disturbed near-channel environments. Within the coastal plains and lowlands of the North Pacific Region, repeating transgressions and regressions and lateral river channel migration constantly disturbed environments and provided fresh sedimentary surfaces that were colonised by angiosperms more readily than by other plants. Climatic fluctuations and proximal volcanic eruptions probably contributed to the formation of habitats favourable for early angiosperms. Angiosperm-rich plant communities gradually invaded the Asiatic continental interiors along river valleys and other disturbed habitats and replaced previous fern–conifer-dominated mature climax vegetation. The data presented here do not support the hypothesis of the initial dispersal of early Cretaceous angiosperms along mountain ranges but support the hypothesis of angiosperm dispersal around coastal margins and into continental interiors along disturbed river habitats.

Albian-Paleocene flora of the north pacific: Systematic composition, palaeofloristics and phytostratigraphy

Principal attention is focused on phytostratigraphy and comparative palaeofloristics of the Anadyr-Koryak (AKSR) and Northern Alaska (NASR) subregions of the North Pacific Region. The high-resolution Upper Albian-Paleocene phytostratigraphic schemes of these subregions are based on perceived stages of their floral evolution. In the AKSR the scheme includes seven subdivisions of subregional extent: the Early Ginter (upper Albian), Grebenka (upper Albian-Cenomanian-lower Turonian), Penzhina (upper Turonian), Kaivayam (Coniacian), Barykov (Santonian-lower to ?middle Campanian), Gornorechenian (?upper Campanian-lower Maastrichtian), and Koryak (lower to upper Maastrichtian-?Danian) phytostratigraphic horizons. The phytostratigraphic scheme of the NASR includes three subregional phytostratigraphic horizons and five plant-bearing beds. These are the Kukpowruk (?lower to middle-?upper Albian), Niakogon (upper Albian-Cenomanian), Kaolak (Turonian) horizons and beds with the Tuluvak (Coniacian), Early Kogosukruk (upper Santonian-Campanian), Late Kogosukruk (Campanian-Maastrichtian), Early Sagwon (Danian-Selandian), and Late Sagwon (Selandian-Thanetian) floras. The comparative analysis of coeval (or close in age) floras distinguished in the AKSR and NASR shows that they are either similar to each other (floras Early Ginter and Kukpowruk, Grebenka and Niakogon, Penzhina and Kaolak, Koryak and Early Sagwon) or different in systematic composition (floras Kaivayam and Tuluvak, Gornorechenian and Kogosukruk). Similarities between the floras imply that plant assemblages of two subregions evolved under comparable climatic conditions and freely intercommunicated via the Bering Land Bridge during the Albian-Turonian and terminal Maastrichtian-Paleocene. Floras of the AKSR and NASR, which are of different composition, existed in particular intervals of geological history when trans-Beringian plant migrations were limited or even ceased because of palaeoclimatic difference between the subregions. Floras of the AKSR and NASR survived crisis at the Cretaceous-Paleogene boundary without essential evolutionary consequence which does not support a hypothesis of a global ecological crisis at this boundary. From the analysis of the Arctic end-Cretaceous flora and palaeoclimate we conclude that the large Northern Alaskan dinosaurs were driven by lack of resources (food and shelter) to migrate 1200–1300 kilometres to the South to find forage, warmer temperatures and better light conditions before winter set in. A scenario of the Albian-Late Cretaceous florogenesis in the North Pacific Region is proposed. A primary driver of Albian-Late Cretaceous florogenesis was the gradual invasion by novel angiosperm-rich plant communities into the Asiatic continental interiors and a replacement of pre-existing vegetation dominated by ancient ferns and gymnosperms. Plant fossils representing Mesophytic and Cenophytic communities usually do not mix in the individual assemblages.