Eunotia spp. (Bacillariophyceae) from Middle Eocene lake sediments and comments on the origin of the diatom raphe

2007 ◽  
Vol 85 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Peter A. Siver ◽  
Alexander P. Wolfe
Keyword(s):  
Lake Sediments ◽  
Northwest Territories ◽  
Middle Eocene ◽  
Valve Morphology ◽  
Progressive Degeneration ◽  
Extant Species ◽  
Freshwater Diatoms ◽  
Molecular Phylogenetic

Freshwater diatoms belonging to the genus Eunotia Ehrenberg 1837 are well preserved in Middle Eocene lake sediments from the Northwest Territories, Canada. Although two distinct valve morphologies are recognized, both have features that are entirely compatible with modern congeneric taxa, including dorsiventral valve morphology, striae spanning the valve face and extending onto the mantle, raphe structures on the mantle that extend distally onto the valve face, two helictoglossae per valve, and one apical rimoportula per valve. These findings establish that the genus Eunotia, and likely freshwater raphid diatoms as a whole, are more ancient than previously believed, dating back to at least 40 Ma. One of the observed morphotypes has a raphe spanning more than 80% of the valve length as well as a narrow hyaline area extending between proximal raphe endings and interrupting mantle striae. These features imply that the raphe system among certain ancient representatives of Eunotia was more developed relative to modern counterparts. The notion of progressive degeneration of the raphe within Eunotia is supported by several extant species. Collectively, these observations confirm molecular phylogenetic arguments that position Eunotia as a basal raphid diatom.

Falcatifolium (Podocarpaceae) macrofossils from paleogene sediments in south-eastern Australia: a reassessment

1998 ◽  
Vol 11 (6) ◽  
pp. 711 ◽  
Author(s):  
Robert S. Hill ◽  
Leonie J. Scriven
Keyword(s):  
Leaf Morphology ◽  
Middle Eocene ◽  
Late Eocene ◽  
South Eastern ◽  
Early Oligocene ◽  
Extant Species ◽  
Eastern Australia ◽  
South Eastern Australia

A re-investigation of macrofossils previously referred to the extantpodocarpaceous genus Falcatifolium Laubenfels shows thatno records can be sustained. Falcatifolium australisD.R.Greenwood from Middle Eocene sediments in Victoria bears littleresemblance to extant species in the genus and is transferred to the newfossil genus Sigmaphyllum R.S.Hill & L.J.Scriven.Specimens from Early Oligocene sediments in Tasmania previously assigned toFalcatifolium are described as a second species ofSigmaphyllum, S. tasmanensisR.S.Hill & L.J.Scriven, and specimens from mid to late Eocene sediments inTasmania previously assigned to Falcatifolium do notbelong to that genus, although their true generic affinities are uncertain.Dispersed cuticle specimens from Late Eocene–Oligocene sediments inSouth Australia referred to Falcatifolium are notreliable records of the genus and require further investigation. However,Dacrycarpus eocenica D.R.Greenwood, from Middle Eocenesediments in Victoria is transferred to Falcatifolium,and is similar to the extant species F. angustumLaubenfels, which has a leaf morphology unusual for the genus.Falcatifolium eocenica (D.R.Greenwood) R.S.Hill & L.J.Scriven is the only reliable record of the genus in the Australian fossilrecord to date.

Early Tertiary thermotectonic history of the northern Yukon and adjacent Northwest Territories, Arctic Canada

1997 ◽  
Vol 34 (10) ◽  
pp. 1366-1378 ◽  
Author(s):  
Paul B. O'Sullivan ◽  
Larry S. Lane
Keyword(s):  
Northwest Territories ◽  
Fission Track ◽  
Middle Eocene ◽  
Geothermal Gradient ◽  
Crystalline Rock ◽  
Early Eocene ◽  
Channel Formation ◽  
Rapid Cooling ◽  
Early Tertiary ◽  
History Of

Apatite fission-track data from 16 sedimentary and crystalline rock samples indicate rapid regional Early Eocene denudation within the onshore Beaufort–Mackenzie region of northwestern Canada. Rocks exposed in the area of the Big Fish River, Northwest Territories, cooled rapidly from paleotemperatures of >80–110 °C to <6 0°C at ca. 56 ± 2 Ma, probably in response to kilometre-scale denudation associated with regional structuring. The data suggest the region experienced a geothermal gradient of ~28 °C/km prior to rapid cooling, with ~2.7 km of section having been removed from the top of the exposed section in the Moose Channel Formation and ~3.8 km from the top of the exposed Cuesta Creek Member. Farther to the west, rocks exposed in the headwaters of the Blow River in the Barn Mountains, Yukon Territories, were exposed to paleotemperatures above 110 °C in the Late Paleocene prior to rapid cooling from these elevated paleotemperatures due to kilometre-scale denudation at ca. 56 ± 2 Ma. Exposure of these samples at the surface today requires that a minimum of ~3.8 km of denudation occurred since they began cooling below ~110 °C. The apatite analyses indicate that rocks exposed in the northern Yukon and Northwest Territories experienced rapid cooling during the Early Eocene in response to kilometre-scale denudation, associated with early Tertiary folding and thrusting in the northern Cordillera. Early Eocene cooling–uplift ages for onshore sections are slightly older than the Middle Eocene ages previously documented for the adjacent offshore foldbelt and suggest that the deformation progressed toward the foreland of the foldbelt through time.

The Fossil Record of the Pancrustacea

2020 ◽  
pp. 21-52 ◽  
Author(s):  
Thomas A. Hegna ◽  
Javier Luque ◽  
Joanna M. Wolfe
Keyword(s):  
Fossil Record ◽  
Hydrothermal Vents ◽  
Molecular Phylogenetics ◽  
Imaging Techniques ◽  
Extant Species ◽  
Evolutionary Studies ◽  
Molecular Phylogenetic ◽  
Terrestrial Habitats ◽  
Molecular Phylogenetic Data

Fossils are critically important for evolutionary studies as they provide the link between geological ages and the phylogeny of life. The Pancrustacea are an incredibly diverse clade, representing over 800,000 described extant species, encompassing a variety of familiar and unfamiliar forms, such as ostracods, tongue worms, crabs, lobsters, shrimps, copepods, barnacles, branchiopods, remipedes, and insects. Having colonized nearly every environment on Earth, from hydrothermal vents to terrestrial habitats, they have a diverse fossil record dating back to the Cambrian (540–485 Ma). The quality of the fossil record of each clade is variable and related to their lifestyle (e.g., free-living versus parasitic, benthic versus pelagic) and the degree of mineralization of their cuticle. We review the systematics, morphology, preservation, and paleoecology of pancrustacean fossils; each major clade is discussed in turn, and, where possible, fossil systematics are compared with more recent data from molecular phylogenetics. We show that the three epic clades of the Pancrustacea—Allotriocarida, Multicrustacea, and Oligostraca—all have Cambrian roots, but the diversification of those clades did not take place until the Middle and Late Paleozoic. We also address the potential affinities of three “problematic” clades: euthycarcinoids, thylacocephalans, and cyclids. We conclude by assessing the future of pancrustacean paleobiology, discussing new morphological imaging techniques and further integration with growing molecular phylogenetic data.

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.

scholarly journals A fully resolved backbone phylogeny reveals numerous dispersals and explosive diversifications throughout the history of Asteraceae

2019 ◽  
Vol 116 (28) ◽  
pp. 14083-14088 ◽  
Author(s):  
Jennifer R. Mandel ◽  
Rebecca B. Dikow ◽  
Carolina M. Siniscalchi ◽  
Ramhari Thapa ◽  
Linda E. Watson ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Range Shift ◽  
Flowering Plant ◽  
Migration Routes ◽  
Biogeographic Patterns ◽  
Extant Species ◽  
The Family ◽  
History Of ◽  
Flowering Plant Species ◽  
Patterns And Processes

The sunflower family, Asteraceae, comprises 10% of all flowering plant species and displays an incredible diversity of form. Asteraceae are clearly monophyletic, yet resolving phylogenetic relationships within the family has proven difficult, hindering our ability to understand its origin and diversification. Recent molecular clock dating has suggested a Cretaceous origin, but the lack of deep sampling of many genes and representative taxa from across the family has impeded the resolution of migration routes and diversifications that led to its global distribution and tremendous diversity. Here we use genomic data from 256 terminals to estimate evolutionary relationships, timing of diversification(s), and biogeographic patterns. Our study places the origin of Asteraceae at ∼83 MYA in the late Cretaceous and reveals that the family underwent a series of explosive radiations during the Eocene which were accompanied by accelerations in diversification rates. The lineages that gave rise to nearly 95% of extant species originated and began diversifying during the middle Eocene, coincident with the ensuing marked cooling during this period. Phylogenetic and biogeographic analyses support a South American origin of the family with subsequent dispersals into North America and then to Asia and Africa, later followed by multiple worldwide dispersals in many directions. The rapid mid-Eocene diversification is aligned with the biogeographic range shift to Africa where many of the modern-day tribes appear to have originated. Our robust phylogeny provides a framework for future studies aimed at understanding the role of the macroevolutionary patterns and processes that generated the enormous species diversity of Asteraceae.

A new Symphoromyia in the Middle Eocene Baltic amber (Diptera: Rhagionidae)

Zootaxa ◽  
2020 ◽  
Vol 4820 (2) ◽  
pp. 373-378
Author(s):  
VALERIE NGO-MULLER ◽  
ANDRE NEL
Keyword(s):  
Middle Eocene ◽  
Baltic Amber ◽  
Fossil Species ◽  
Extant Species

Symphoromyia clerci sp. nov. is described from the Eocene Baltic amber. Even if it has nearly all the characters of the extant species of Symphoromyia subgenus Symphoromyia, it differs from these flies in the short scape, as long as the pedicel (at least twice as long in extant taxa). This fossil is twice as large as those that were previously described from the same amber. These taxa need to be revised to verify their generic attribution. Symphoromyia clerci sp. nov. is the second fossil species attributable to this genus on the basis of ‘modern’ characters. The extant Symphoromyia are frequently hematophagous on mammals, suggesting a similar biology for the Eocene representatives of this genus.

The ant genus Tapinoma Förster (Formicidae: Dolichoderinae) in Miocene amber of Peru

2019 ◽  
Vol 2 (6) ◽  
pp. 585-590
Author(s):  
VINCENT PERRICHOT ◽  
RODOLFO SALAS-GISMONDI ◽  
PIERRE-OLIVIER ANTOINE
Keyword(s):  
Invasive Species ◽  
Middle Eocene ◽  
Argentine Ant ◽  
Early Eocene ◽  
Crown Group ◽  
Phylogenetic Studies ◽  
Major Species ◽  
Group Evolution ◽  
Molecular Phylogenetic ◽  
India And China

On the 17 extant subfamilies of ants, Dolichoderinae is one of the four major species-rich clades (with Formicinae, Ponerinae, and Myrmicinae), and a cosmopolitan group including some of the world’s most invasive species such as the Argentine ant and white-footed ant. It comprises currently 846 species in 28 extant and 20 extinct genera (Bolton, 2019). Most of the fossils are Cenozoic in age, which accords with the timeline of the Dolichoderinae as proposed by molecular phylogenetic studies (Ward et al., 2010; Moreau & Bell, 2013; Borowiec et al., 2019). According to these studies, crown-group dolichoderines arose sometime between 66 and 53 million years ago. Thus, around or after the Cretaceous–Paleogene transition, although this would have been preceded by approximately 30 million years of stem group evolution. Cretaceous dolichoderines are exceedingly rare indeed, and the only two known genera—Eotapinoma Dlussky, and Chronomyrmex McKellar, Glasier & Engel, from Canadian Campanian amber (79–78 Ma)—although originally placed in the Tapinomini and Leptomyrmecini, respectively, have been suggested to be stem dolichoderines (Dlussky, 1999; McKellar et al., 2013; Boudinot et al., 2016). Another fossil dolichoderine was reported from “Cretaceous amber” of Ethiopia (LaPolla et al., 2013: suppl. fig. 5) but this amber is now known to be much younger in age, likely Miocene (Perrichot et al., 2016, 2018). The first definitive crown-group dolichoderines are thus currently from the middle Eocene (50–45 Ma) of Europe and North America, belonging to various extinct species of the genera Dolichoderus, Iridomyrmex, Liometopum, and Tapinoma (see Barden, 2017). Some earlier crown-group dolichoderines may be present in early Eocene (55–52 Ma) ambers from France, India, and China (Perrichot, pers. observ.), but these have yet to be formally described.

A new fossil psyllid, Cacopsylla trigona sp. nov. (Hemiptera: Psylloidea: Psyllidae), from the Miocene of China

2019 ◽  
Vol 2 (5) ◽  
pp. 413-417
Author(s):  
TINGYING ZHANG ◽  
XINYU LUO ◽  
YUNZHI YAO ◽  
DONG REN
Keyword(s):  
Northern Hemisphere ◽  
Phylogenetic Analyses ◽  
Extant Species ◽  
Molecular Phylogenetic

Psyllinae, a subfamily of Psyllidae, currently includes 29 genera (Burckhardt & Ouvrard, 2012; Ouvrard, 2018), of which Cacopsylla Ossiannilsson, 1970 is the most species-rich genus, distributed mainly in the Northern Hemisphere (Li, 2011; Ouvrard, 2018). In China, more than 300 extant species of Cacopsylla have been reported (Yang et al., 2004; Li, 2011; Luo et al., 2012, 2016). Based on recent molecular phylogenetic analyses, Cacopsylla in its current sense is a polyphyletic genus (Percy et al., 2018; Cho et al., 2019).

Discovery of a new species of the Cretaceous genus Microphorites Hennig, 1971 (Diptera: Dolichopodidae s. lat.) in Paleogene amber from eastern Moravia (Czech Republic)

2016 ◽  
Vol 47 (2) ◽  
pp. 181-193 ◽  
Author(s):  
Michal Tkoč ◽  
André Nel ◽  
Jakub Prokop
Keyword(s):  
Czech Republic ◽  
New Species ◽  
Middle Eocene ◽  
Wing Venation ◽  
Extant Species ◽  
Radial Vein ◽  
Complete Cell ◽  
Geochemical Analyses ◽  
Extinct Genus ◽  
A New Species

A new species of the extinct genusMicrophoritesHennig, 1971 (Dolichopodidae s. lat.: Microphorinae) is described from a single female preserved in Študlov amber (Moravia, Czech Republic), currently dated from the Paleocene to the middle Eocene.Microphorites moravicussp. n. has the typical wing venation of the genus, e.g., three radial veins, crossvein r-m, crossvein bm-cu complete, cell dm, two medial veins and vein CuA1. It differs from the other species ofMicrophoritesby the long antenna, with prolonged and laterally compressed first flagellomere and presence of a pterostigma at the fusion of the first radial vein and costa. A comparison ofM. moravicuswith all other species ofMicrophorites, as well as fossil and extant species ofMicrophorMacquart, 1827 is given. The age and source plant of Študlov amber is discussed in terms of newly performed geochemical analyses.

scholarly journals Geochemical data for lake sediments and surface waters, Abitau Lake area, Northwest Territories (NTS 75-B)

2016 ◽  
Author(s):  
M W McCurdy ◽  
S J Pehrsson ◽  
H Falck ◽  
S J A Day ◽  
J E Campbell
Keyword(s):  
Lake Sediments ◽  
Northwest Territories ◽  
Surface Waters ◽  
Geochemical Data ◽  
Lake Area
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