Taxonomy, phylogeny, and paleoecology of Eoseira wilsonii gen. et sp. nov., a Middle Eocene diatom (Bacillariophyceae: Aulacoseiraceae) from lake sediments at Horsefly, British Columbia, Canada

2005 ◽  
Vol 42 (2) ◽  
pp. 243-257 ◽  
Author(s):  
Alexander P Wolfe ◽  
Mark B Edlund
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Life Strategy ◽  
Centric Diatom ◽  
Evolutionary Trajectory ◽  
The Family ◽  
Freshwater Diatoms ◽  
Marine Realm ◽  
Diatom Genus ◽  
Early Cenozoic

A new centric diatom genus is described from laminated freshwater sediments of Middle Eocene age near Horsefly, British Columbia, Canada. This diatom, Eoseira wilsonii gen. et sp. nov., grew in filaments that constitute dense monospecific sub-horizons within the white couplets that represent summer deposition in the varved sequence. Although Eoseira clearly belongs within the Family Aulacoseiraceae, several features distinguish its valve structure from Aulacoseira. Gigantism of spines and the lack of geometric relationships between spine position and mantle areolae are the most conspicuous features of the genus. Eoseira is among the oldest freshwater diatoms known and one of relatively few extinct freshwater genera. In addition to serving as a potential biostratigraphic marker, Eoseira is a cornerstone to undertanding the evolutionary trajectory of the Aulacoseiraceae, likely the oldest family of freshwater diatoms. As such, it refines our understanding of early radiations from the marine realm in western North America. Furthermore, paleoecological inferences based on Eoseira life strategy pertain directly to limnological conditions during early Cenozoic hot-house conditions.

Eocene paleo-physiography and drainage directions, southern Interior Plateau, British Columbia

2005 ◽  
Vol 42 (2) ◽  
pp. 215-230 ◽  
Author(s):  
Selina Tribe
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Regional Scale ◽  
River Valley ◽  
Coast Mountains ◽  
Base Level ◽  
The North ◽  
Bedrock Geology ◽  
River Valleys ◽  
Early Cenozoic

A map of reconstructed Eocene physiography and drainage directions is presented for the southern Interior Plateau region, British Columbia south of 53°N. Eocene landforms are inferred from the distribution and depositional paleoenvironment of Eocene rocks and from crosscutting relationships between regional-scale geomorphology and bedrock geology of known age. Eocene drainage directions are inferred from physiography, relief, and base level elevations of the sub-Eocene unconformity and the documented distribution, provenance, and paleocurrents of early Cenozoic fluvial sediments. The Eocene landscape of the southern Interior Plateau resembled its modern counterpart, with highlands, plains, and deeply incised drainages, except regional drainage was to the north. An anabranching valley system trending west and northwest from Quesnel and Shuswap Highlands, across the Cariboo Plateau to the Fraser River valley, contained north-flowing streams from Eocene to early Quaternary time. Other valleys dating back at least to Middle Eocene time include the North Thompson valley south of Clearwater, Thompson valley from Kamloops to Spences Bridge, the valley containing Nicola Lake, Bridge River valley, and Okanagan Lake valley. During the early Cenozoic, highlands existed where the Coast Mountains are today. Southward drainage along the modern Fraser, Chilcotin, and Thompson River valleys was established after the Late Miocene.

scholarly journals Preface to 'Evolution, Extinction and Biogeography in Gondwana'

2001 ◽  
Vol 49 (3) ◽  
pp. I
Author(s):  
Robert S. Hill
Keyword(s):  
Middle Eocene ◽  
Long Distance ◽  
Plant Family ◽  
Widespread Distribution ◽  
Early Oligocene ◽  
Vegetation Disturbance ◽  
Late Paleocene ◽  
The Family ◽  
Dispersal Events ◽  
Early Cenozoic

The macrofossil record of the plant family Cunoniaceae in Australia is summarised and reviewed where necessary by using detailed studies of the morphology of extant genera. Eleven of the 26 Cunoniaceae genera are represented in the Australian macrofossil record and include leaves and leaf fragments, foliar cuticle and reproductive structures, and range from Late Paleocene to Quaternary in age. Macrofossils show that some genera had a different or more widespread distribution in Australia during the Cenozoic, with two genera (Weinmannia and Codia) having become extinct from the continent. Changes in climate, including increasing cold, frost, dryness, seasonality, or some combination of these, or a reduction in vegetation disturbance regimes (e.g. volcanism, uplifting, landslips), may be implicated in the regional or continental extinctions demonstrated by the macrofossil record. Many extant genera (Schizomeria, Vesselowskya, Callicoma, Ceratopetalum, Acsmithia, Codia) had evolved by the Early Oligocene or earlier (Eucryphia, Late Paleocene; Ceratopetalum, Middle Eocene), perhaps with generic diversification more or less complete by the end of the Early Cenozoic or earlier. A Cretaceous origin of the family is possible, and may account for its widespread distribution on Southern Hemisphere landmasses, although long-distance dispersal events are required to explain some modern geographic disjunctions.

The history of Cunoniaceae in Australia from macrofossil evidence

2001 ◽  
Vol 49 (3) ◽  
pp. 301 ◽  
Author(s):  
Richard W. Barnes ◽  
Robert S. Hill ◽  
Jason C. Bradford
Keyword(s):  
Middle Eocene ◽  
Long Distance ◽  
Widespread Distribution ◽  
Early Oligocene ◽  
Vegetation Disturbance ◽  
Late Paleocene ◽  
The Family ◽  
History Of ◽  
Dispersal Events ◽  
Early Cenozoic

The macrofossil record of the plant family Cunoniaceae in Australia is summarised and reviewed where necessary by using detailed studies of the morphology of extant genera. Eleven of the 26 Cunoniaceae genera are represented in the Australian macrofossil record and include leaves and leaf fragments, foliar cuticle and reproductive structures, and range from Late Paleocene to Quaternary in age. Macrofossils show that some genera had a different or more widespread distribution in Australia during the Cenozoic, with two genera (Weinmannia and Codia) having become extinct from the continent. Changes in climate, including increasing cold, frost, dryness, seasonality, or some combination of these, or a reduction in vegetation disturbance regimes (e.g. volcanism, uplifting, landslips), may be implicated in the regional or continental extinctions demonstrated by the macrofossil record. Many extant genera (Schizomeria, Vesselowskya, Callicoma, Ceratopetalum, Acsmithia, Codia) had evolved by the Early Oligocene or earlier (Eucryphia, Late Paleocene; Ceratopetalum, Middle Eocene), perhaps with generic diversification more or less complete by the end of the Early Cenozoic or earlier. A Cretaceous origin of the family is possible, and may account for its widespread distribution on Southern Hemisphere landmasses, although long-distance dispersal events are required to explain some modern geographic disjunctions.

New Dinopanorpidae (Insecta: Mecoptera) from the Eocene Okanagan Highlands (British Columbia, Canada and Washington State, USA)

2005 ◽  
Vol 42 (2) ◽  
pp. 119-136 ◽  
Author(s):  
S Bruce Archibald
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Hind Wing ◽  
Washington State ◽  
Large Species ◽  
Far Eastern Russia ◽  
The Family ◽  
Okanagan Highlands ◽  
Far Eastern ◽  
Maritime Province

Six new species of the extinct family Dinopanorpidae (Mecoptera) are described in the new genus Dinokanaga gen. nov. from five Early (and early Middle?) Eocene Okanagan Highlands localities in British Columbia and Washington State. These are Dinokanaga hillsi sp. nov., D. wilsoni sp. nov., D. dowsonae sp. nov., D. andersoni sp. nov., D. sternbergi sp. nov., and D. webbi sp. nov. The family Dinopanorpidae is previously known only from a hind wing of Dinopanorpa megarche Cockerell, and an undescribed species of Dinopanorpa, both from the Paleogene of Primorye (Maritime Province) in Pacific coastal far-eastern Russia. The family includes mostly large species, with forewings up to 43 mm in length. Dinopanorpidae is particularly distinguished by a long R1 vein in both the fore- and hind wings, extending almost to the wing apex and bending posteriad distally. Their wings are mostly dark with light bands and spots; have many to extremely dense crossveins; and an expanded costal space in the basal quarter of the forewing, which is more developed in larger species. The rostrum is extended; the medigynium is without tongue-shaped structures.

scholarly journals NEW AMBER DEPOSIT PROVIDES EVIDENCE OF EARLY PALEOGENE EXTINCTIONS, PALEOCLIMATES, AND PAST DISTRIBUTIONS

1999 ◽  
Vol 131 (2) ◽  
pp. 171-177 ◽  
Author(s):  
George Poinar ◽  
Bruce Archibald ◽  
Alex Brown
Keyword(s):  
British Columbia ◽  
North America ◽  
Chemical Analysis ◽  
Late Cretaceous ◽  
Middle Eocene ◽  
Life Forms ◽  
Tropical Regions ◽  
Terrestrial Invertebrates ◽  
The Family ◽  
Early Paleogene

AbstractA large, previously unstudied amber deposit in British Columbia dating from the Early to Middle Eocene (50−55 Ma) provides a noteworthy new source of terrestrial invertebrates and other life forms. This deposit contains what are likely the earliest unequivocal ants (members of the family Formicidae), including extinct representatives of Technomyrmex Mayr 1872, Leptothorax Mayr 1855, and Dolichoderus Lund 1831. Discovering Technomyrmex and a corydiinid cockroach, both of which are currently restricted to tropical regions, confirms earlier evidence of warm paleoclimates and past biogeographic distributions in the early Paleogene. Chemical analysis of the amber indicates that the source tree was an araucarian belonging to or near the genus Agathis Salisbury 1807, and demonstrates that this genus survived into the Tertiary in the Northern Hemisphere, since previous records revealed Agathis as a component only of the Cretaceous forests in North America. Comparing the Hat Creek fossil assemblages in this deposit with those from the well-studied western Canadian Late Cretaceous amber deposits offers a unique opportunity to study extinction and speciation events on both sides of the Cretaceous–Tertiary boundary.

scholarly journals Impact of mid Eocene greenhouse warming on America’s southernmost floras

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Damián A. Fernández ◽  
Luis Palazzesi ◽  
M. Sol González Estebenet ◽  
M. Cristina Tellería ◽  
Viviana D. Barreda
Keyword(s):  
Middle Eocene ◽  
Pollen Grains ◽  
Late Eocene ◽  
Significant Rise ◽  
Spores And Pollen ◽  
Deep Time ◽  
Nonparametric Estimators ◽  
Southern Patagonia ◽  
Marine Realm ◽  
High Diversity

AbstractA major climate shift took place about 40 Myr ago—the Middle Eocene Climatic Optimum or MECO—triggered by a significant rise of atmospheric CO2 concentrations. The biotic response to this MECO is well documented in the marine realm, but poorly explored in adjacent landmasses. Here, we quantify the response of the floras from America’s southernmost latitudes based on the analysis of terrestrially derived spores and pollen grains from the mid-late Eocene (~46–34 Myr) of southern Patagonia. Robust nonparametric estimators indicate that floras in southern Patagonia were in average ~40% more diverse during the MECO than pre-MECO and post-MECO intervals. The high atmospheric CO2 and increasing temperatures may have favored the combination of neotropical migrants with Gondwanan species, explaining in part the high diversity that we observed during the MECO. Our reconstructed biota reflects a greenhouse world and offers a climatic and ecological deep time scenario of an ice-free sub-Antarctic realm.

Fossil Mosses from the Bisaccate Zone of the Mid-Eocene Allenby Formation, British Columbia

1974 ◽  
Vol 11 (3) ◽  
pp. 409-421 ◽  
Author(s):  
Marian Kuc
Keyword(s):  
British Columbia ◽  
Middle Eocene ◽  
Plant Tissues ◽  
Plant Remains ◽  
Lake Bottom ◽  
White Colour

New fossil taxa (Ditrichites fylesi, Muscites maycocki, M. ritchiei, Palaeohypnum jovet-asti and P. steerei); unnamed moss and moss-like fossils, detrital fragments of various plant tissues, and paleobotanical evidence of the bisaccate zone are described from the Middle Eocene Allenby Formation near Princeton, British Columbia. These remains occur in laminated, tuffaceous, silty and pyroclastic shale, deposited under lacustrine conditions.Detailed examination of the various laminae indicates that beds of white colour and composed of coarser silt grains are poor in fossils and could be related to periods of decreasing bioproduction; less silty and darker coloured beds are rich in macro- and microfossils and could be related to periods of extensive bioproduction. The rock features, lamination, and distribution of macrofossils indicate the slow and undisturbed accumulation of plant remains on a lake bottom.

Cymatosirella Dąbek, Witkowski & Sabbe gen. nov., a new marine benthic diatom genus (Bacillariophyta) belonging to the family Cymatosiraceae

Phytotaxa ◽  
2014 ◽  
Vol 183 (2) ◽  
pp. 120
Author(s):  
PRZEMYSŁAW DĄBEK ◽  
KOEN SABBE ◽  
ANDRZEJ WITKOWSKI ◽  
COLIN ARCHIBALD ◽  
KRZYSZOF J. KURZYDŁOWSKI ◽  
...  
Keyword(s):  
New Genus ◽  
Light And Electron Microscopy ◽  
Benthic Diatom ◽  
Western Cape ◽  
Western Cape Province ◽  
Line Drawings ◽  
The Family ◽  
Diatom Genus ◽  
Electron Microscopical ◽  
First Time

We present a new marine benthic diatom genus Cymatosirella gen. nov. The genus belongs to the family Cymatosiraceae and has been assigned to the subfamily Extubocelluloideae on the basis of ultrastructural cell wall features. It has isovalvate cells with undulate valves and is characterized by the absence of tubular processes and the occurrence of hollow spines which are observed for the first time in the Cymatosiraceae. The new genus contains four species, two of which are transferred from the genus Cymatosira, viz. Cymatosirella capensis comb. nov. and Cymatosirella minutissima comb. nov., and two which are new to science, viz. Cymatosirella benguelensis sp. nov. and Cymatosirella taylorii sp. nov. Cymatosirella capensis is chosen as the generitype. The new genus includes a group of very small taxa inhabiting the intertidal zone of the Atlantic Ocean with three species in South Africa and one in Europe. C. capensis was originally described by Giffen from Langebaan Lagoon (a shallow marine inlet in the southern part of Saldanha Bay, Western Cape Province), on the basis of light microscopy only, and has to date only been illustrated by line drawings. C. minutissima, so far only known from the Westerschelde estuary (The Netherlands), has previously been documented in more detail using both light and electron microscopy. Here, we present the results of detailed light and electron microscopical investigations of C. capensis, both from its original type material and from recently collected samples from the type locality and neighboring littoral areas in the Western Cape Province, and of the new species C. benguelensis and C. taylorii, also from Western Cape localities. All species are compared with similar small taxa belonging to the Cymatosiraceae, subfamily Extubocelluloideae.

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