The unexpected, recent history of horsetails in Australia

2019 ◽  
Author(s):  
Andrew C. Rozefelds ◽  
Mary E. Dettmann ◽  
Anita K. Milroy ◽  
Andrew Hammond ◽  
H. Trevor Clifford ◽  
...  
Keyword(s):  
Spatial Arrangement ◽  
Molecular Data ◽  
Leaf Sheath ◽  
Late Eocene ◽  
Fossil Flora ◽  
Fossil Plants ◽  
Outer Cortex ◽  
Early Oligocene ◽  
Extant Species ◽  
History Of

A new fossil flora from central Queensland, of late Eocene or early Oligocene age, has yielded a diverse assemblage of flowering plants and ferns, including the first evidence of horsetails (Equisetum L.) from the Cenozoic of Australia. The fossils assigned to Equisetum are based on a stem fragment, 2–3mm in diameter, and spreading leaf sheath and diaphragm. The leaf sheath is interpreted to consist of ~24–30 leaves. The spatial arrangement of regularly arranged depressions in a section of the outer cortex is interpreted as evidence of the leaf vascular traces, and indicates a similar number of vascular traces. This specimen provides the youngest evidence of the genus from Australia and indicates that Equisetum survived for at least another 50 million years after it was thought to be extinct in Australia. Whereas molecular data for extant species of Equisetum collectively suggest a comparatively recent origin and radiation, the fossil record of the genus indicates a significantly longer and more complex history. Fossils, such as the new specimen from Makowata, Queensland, will, therefore, play a key role in understanding the history and past distribution of Equisetum in Australia. A key challenge is to assemble and characterise the morphological traits of these living and fossil plants to better understand the origins, history and radiation of this remarkable group of euphyllophytes.

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.

scholarly journals III. Report on phyto-palæontological investigations of the fossil flora of Alum Bay

1880 ◽  
Vol 30 (200-205) ◽  
pp. 228-236
Keyword(s):  
Scientific Investigation ◽  
Fossil Flora ◽  
Fossil Plants ◽  
Detailed History ◽  
History Of ◽  
White Clay

The white clay of Alum Bay and the fossil plants included in it have been long known. The introduction to the “ Monograph on the British Eocene Flora,” Palæontographical Society, 1879, p. 12 gives a detailed history of this locality. The first scientific investigation of the fossil plants of Alum Bay were made by Dr. De la Harpe and Professor Oswald Heer who enumerated a Flora of about forty species, distributed in several genera.

scholarly journals Links between CO<sub>2</sub>, glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

2014 ◽  
Vol 10 (3) ◽  
pp. 2397-2416 ◽  
Author(s):  
J.-B. Ladant ◽  
Y. Donnadieu ◽  
C. Dumas
Keyword(s):  
Antarctic Circumpolar Current ◽  
Ice Sheet ◽  
Late Eocene ◽  
Early Oligocene ◽  
History Of ◽  
Potential Impact ◽  
Circumpolar Current ◽  
Set Up ◽  
The Antarctic ◽  
Exact Timing

Abstract. The timing of the onset of the Antarctic Circumpolar Current (ACC) is a crucial event of the Cenozoic because of its cooling and isolating effect over Antarctica. It is intimately related to the glaciations occurring throughout the Cenozoic from the Eocene–Oligocene (EO) transition (≈34 Ma) to the middle Miocene glaciations (≈13.9 Ma). However, the exact timing of the onset remains debated with evidence for a late Eocene set up contradicting others data pointing to an occurrence closer to the Oligocene–Miocene (OM) boundary. In this study, we show the potential impact of the Antarctic ice sheet on the initiation of a proto-ACC at the EO boundary. Our results reveal that the regional cooling effect of the ice sheet increases the sea ice formation, which disrupts the meridional density gradient in the Southern Ocean and leads to the onset of a circumpolar current and its progressive strengthening. We also suggest that subsequent variations in atmospheric CO2, ice sheet volumes and tectonic reorganizations may have affected the ACC intensity after the Eocene–Oligocene transition, which in turn may provide an explanation for the second initiation of the ACC at the Oligocene–Miocene boundary and may reconcile evidence supporting both early Oligocene and early Miocene onset of the ACC.

scholarly journals Links between CO<sub>2</sub>, glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

2014 ◽  
Vol 10 (6) ◽  
pp. 1957-1966 ◽  
Author(s):  
J.-B. Ladant ◽  
Y. Donnadieu ◽  
C. Dumas
Keyword(s):  
Antarctic Circumpolar Current ◽  
Middle Miocene ◽  
Ice Sheet ◽  
Late Eocene ◽  
Early Oligocene ◽  
History Of ◽  
Potential Impact ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Exact Timing

Abstract. The timing of the onset of the Antarctic Circumpolar Current (ACC) is a crucial event of the Cenozoic because of its cooling and isolating effect over Antarctica. It is intimately related to the glaciations occurring throughout the Cenozoic from the Eocene–Oligocene (EO) transition (&amp;approx; 34 Ma) to the middle Miocene glaciations (&amp;approx; 13.9 Ma). However, the exact timing of the onset remains debated, with evidence for a late Eocene setup contradicting other data pointing to an occurrence closer to the Oligocene–Miocene (OM) boundary. In this study, we show the potential impact of the Antarctic ice sheet on the initiation of a strong proto-ACC at the EO boundary. Our results reveal that the regional cooling effect of the ice sheet increases sea ice formation, which disrupts the meridional density gradient in the Southern Ocean and leads to the onset of a circumpolar current and its progressive strengthening. We also suggest that subsequent variations in atmospheric CO2, ice sheet volumes and tectonic reorganizations may have affected the ACC intensity after the Eocene–Oligocene transition. This allows us to build a hypothesis for the Cenozoic evolution of the Antarctic Circumpolar Current that may provide an explanation for the second initiation of the ACC at the Oligocene–Miocene boundary while reconciling evidence supporting both early Oligocene and early Miocene onset of the ACC.

Biostratigraphic, strontium isotopic, and geologic constraints on the landward movement and fragmentation of terranes within the Tofino Basin, British Columbia

2012 ◽  
Vol 49 (7) ◽  
pp. 819-856 ◽  
Author(s):  
Marjorie J. Johns ◽  
Julie A. Trotter ◽  
Christopher R. Barnes ◽  
Y. Roshni Narayan
Keyword(s):  
Late Eocene ◽  
Pacific Rim ◽  
Magnetic Data ◽  
Juan De Fuca Plate ◽  
Early Oligocene ◽  
The Pacific ◽  
Juan De Fuca ◽  
History Of ◽  
Oceanic Sediment ◽  
Middle Pliocene

Significant advancements in understanding the complex evolution of the Tofino Basin at a convergent accretionary margin are enabled by combining contextual geologic information with new isotopic and paleontological data. A high-resolution Cenozoic chronostratigraphy of the basin is constrained by strontium isotope ages (36.9–1.3 Ma) of Late Eocene to Pleistocene foraminifers together with a revised biostratigraphy (foraminifers and ichthyoliths) from six offshore wells and outcrop samples, new specimen thermal alteration values, and existing well log data. These data are integrated with archival multichannel seismic and magnetic data to interpret offshore well positions with relation to sub-basins and structural highs of the Pacific Rim and Crescent terranes, and other accreted strata. Six regions of the Tofino Basin are defined based on structure and depositional differences during the Eocene to Holocene history of accretion and fragmentation of the Crescent terrane and it underthrusting the Pacific Rim terrane. Subsequent oceanic sediment accretions and deposition of overlying sediments up to about 4000 m thick resulted as the Juan de Fuca plate subducted beneath Vancouver Island. Observations include different fragmentations and landward movements of the Crescent and Pacific Rim terranes in the regions and two fault styles in the Ucluelet and Carmanah regions where six new sub-basins are defined. Results, especially for the Ucluelet and Carmanah sub-basins, indicate periods of deformation during the Late Eocene, Late Oligocene, Middle–Late Miocene, and post middle Pliocene, whereas the Early Oligocene and Early Miocene had periods of relatively slow and less disturbed deposition.

scholarly journals Macroevolutionary analysis of the tempo of diversification in snappers and fusiliers (Percomorpha: Lutjanidae)

2017 ◽  
Vol 147 (1) ◽  
Author(s):  
Bruno Frédérich ◽  
Francesco Santini
Keyword(s):  
Habitat Preferences ◽  
Great Majority ◽  
Late Eocene ◽  
Morphological Data ◽  
Life History Strategies ◽  
Fish Family ◽  
Early Oligocene ◽  
Molecular Tree ◽  
Extant Species ◽  
Early Paleocene

The percomorph fish family Lutjanidae (snappers and fusiliers) includes about 135 reef-dwelling species, mainly confined to tropical and subtropical marine waters. The great majority of snappers are active predators feeding on fishes or crustaceans, even though some species, including the fusiliers (Caesioninae), have evolved zooplanktivory. Lutjanids show a great diversity of habitat preferences, based on depth segregation and distribution across reef and associated habitats (e.g., mangroves, seagrass beds, estuaries). In spite of their great ecological and economic importance little is known about the tempo of evolution in this group. The present study provides the most comprehensive molecular phylogeny to date for lutjanids, including 70% of extant species and 19 of the 21 currently described genera. We time-calibrated our molecular tree using the oldest described lutjanid fossils, and show how this group most likely originated during the Late Cretaceous or Early Paleocene. Lutjanids experienced a significant radiation during the Late Eocene and Early Oligocene, in contrast to a pattern of Late Oligocene/Miocene radiation observed in many other reef-associated groups. The time-tree allows us to investigate the tempo of diversification, and our results suggest a variation in the rate of speciation during the evolution of the major clade formed by “lutjanins and caesionins”. Variation in diet and life history strategies could explain this clade-specific dynamic, although future phylogenetic comparative studies combining additional ecological and morphological data are needed to test this hypothesis.

scholarly journals New fossil flora from Palaeogene sediments near Bersin village (SW Bulgaria)

2021 ◽  
Vol 82 (3) ◽  
pp. 102-104
Author(s):  
Vladimir Bozukov ◽  
Milorad Vatsev ◽  
Dimiter Ivanov ◽  
Nikolay Simov
Keyword(s):  
Late Eocene ◽  
Fossil Flora ◽  
Fossil Plants ◽  
The Village

Data for new local palaeoflora near the village of Bersin (SW Bulgaria) are presented. Eight species of fossil plants have been identified. Eotrigonobalanus furcinervis is dominant over other species. The flora-bearing layers originate from the lower part of the Nevestino Formation, which is formed by alternating sandstone and mudstone sediments. Based on the established fossil macroflora, it can be assumed that the age of the flora-bearing sediments is late Eocene.

The evolutionary history and molecular systematics of the Musteloidea

2018 ◽  
Author(s):  
Klaus-Peter Koepfli ◽  
Jerry W. Dragoo ◽  
Xiaoming Wang
Keyword(s):  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Molecular Data ◽  
Morphological Data ◽  
Species Boundaries ◽  
Extant Species ◽  
Taxonomic History ◽  
History Of ◽  
A New Species

This chapter provides a review of the evolutionary and taxonomic history of the Musteloidea, which is the most species-rich superfamily of the Carnivora, containing approximately 30% of the extant species in the order. An up-to-date summary of knowledge on the evolutionary and taxonomic history and phylogenetic relationships of the Mephitidae, Ailuridae, Procyonidae and Mustelidae is provided. Multilocus DNA sequences have made a large impact on the understanding of phylogenetic relationships among the Musteloidea. Molecular data have revealed distinct families (Ailuridae and Mephitidae) within the Musteloidea and have illuminated new relationships based on tempo and patterns of evolution within the Procyonidae. Morphological data in conjunction with molecular data have been used to elucidate species boundaries within certain musteloid genera and have led to the discovery of a new species. Research studies published during the last 30 years have enriched and transformed our understanding of the evolution of musteloid biodiversity.

scholarly journals Genetic analysis identifies the Ostrea stentina/aupouria/equestris oyster species complex in Hawai‘i, and resolves its lineage as the western Pacific O. equestris

2020 ◽  
Author(s):  
Jolene T. Sutton ◽  
Jared Nishimoto ◽  
Jeremy Schrader ◽  
Keinan Agonias ◽  
Nicole Antonio ◽  
...  
Keyword(s):  
Species Complex ◽  
Taxonomic Status ◽  
Molecular Data ◽  
Western Pacific ◽  
Genetic Identification ◽  
Multiple Sources ◽  
Genomic Technologies ◽  
Extant Species ◽  
Commercial Species ◽  
History Of

AbstractBackgroundExtensive phenotypic plasticity in oysters makes them difficult to identify based on morphology alone, but their identities can be resolved by applying genetic and genomic technologies. In this study, we collected unknown oyster specimens from Hawaiian waters for genetic identification.MethodsWe sequenced two partial gene fragments, mitochondrial 16S ribosomal RNA (16S) and cytochrome c oxidase subunit I (COI), in 48 samples: 27 unidentified oyster specimens collected from two locations on O‘ahu, 13 known specimens from a hatchery in Hilo, Hawai‘i Island, and 8 known specimens from Hilo Bay, Hawai‘i Island.ResultsMolecular data identified approximately 85% of unknown samples as belonging to the Ostrea stentina/aupouria/equestris species complex, a globally distributed group with a history of uncertain and controversial taxonomic status. The remaining unknown samples were the native Dendostrea sandvichensis (G. B. Sowerby II, 1871), and nonnative Crassostrea gigas (Thunberg, 1793), the latter of which is a commercial species that was introduced to Hawai‘I from multiple sources during the 20th century. Phylogenetic analysis placed Hawai‘i Ostrea alongside samples from China, Japan, and New Zealand, grouping them within the recently classified western Pacific O. equestris. Until now, four extant species of true oyster have been documented in Hawai‘i. This study expands the known range of O. equestris by providing the first verification of its occurrence in Hawai‘i.

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