Mass occurrence of hokkaidoconchid gastropods in the Upper Jurassic methane seep carbonate from Alexander Island, Antarctica

AbstractThe Tithonian (Upper Jurassic) methane seep carbonate of the Gateway Pass Limestone Bed (Alexander Island, Antarctica) yields enormous numbers of the minute gastropod mollusc, Hokkaidoconcha hignalli sp. nov. together with an unidentified limpet gastropod and occasional protobranch and lucinid bivalves. This assemblage constitutes one of the most abundant (by means of the specimen number) records of Jurassic chemosynthesis-based communities. The gastropod family Hokkaidoconchidae is extremely common in Cretaceous hydrocarbon seep carbonates from Japan and is known also from Upper Jurassic/Cretaceous hydrocarbon seep carbonates in California. It is an extinct family closely related to modern seep and vent dwelling Provannidae. This is the first confirmed record of this family in the Southern Hemisphere, indicating its surprisingly early and widespread distribution reaching high latitudes.

Download Full-text

Evolutionary Genetics and Biogeography of Galaxiid Fishes (Teleostei: Galaxiiformes: Galaxiidae)

Diversity ◽

10.3390/d13040153 ◽

2021 ◽

Vol 13 (4) ◽

pp. 153

Author(s):

Graham P. Wallis

Keyword(s):

Southern Hemisphere ◽

Evolutionary Genetics ◽

Widespread Distribution

Since the dawn of the discipline, biogeographers have wondered at the widespread distribution of galaxiid fishes throughout temperate regions of the Southern Hemisphere [...]

Download Full-text

Interannual variability of precipitable water

Annales Geophysicae ◽

10.1007/s00585-996-0464-1 ◽

1996 ◽

Vol 14 (4) ◽

pp. 464-467 ◽

Cited By ~ 1

Author(s):

R. P. Kane

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Precipitable Water ◽

Radiosonde Data ◽

High Latitudes ◽

Zonal Winds ◽

Low Latitudes ◽

Linear Trends

Abstract. The 12-month running means of the surface-to-500 mb precipitable water obtained from analysis of radiosonde data at seven selected locations showed three types of variability viz: (1) quasi-biennial oscillations; these were different in nature at different latitudes and also different from the QBO of the stratospheric tropical zonal winds; (2) decadal effects; these were prominent at middle and high latitudes and (3) linear trends; these were prominent at low latitudes, up trends in the Northern Hemisphere and downtrends in the Southern Hemisphere.

Download Full-text

Interannual Variability of Stratospheric Final Warming in the Southern Hemisphere and its Tropospheric Origin

Journal of Climate ◽

10.1175/jcli-d-20-0945.1 ◽

2021 ◽

pp. 1-59

Author(s):

Soichiro Hirano ◽

Masashi Kohma ◽

Kaoru Sato

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Reanalysis Data ◽

Stationary Waves ◽

High Latitudes ◽

Wave Source ◽

Barotropic Model ◽

Stratospheric Final Warming ◽

Zonal Wavenumber ◽

Favorable Conditions

AbstractThe relation between interannual variability of stratospheric final warming (SFW) and tropospheric circulation in the Southern Hemisphere (SH) is explored using reanalysis data and a linear barotropic model. The analysis is focused on quasi-stationary waves with zonal wavenumber 1 (s = 1 QSWs; s is zonal wavenumber), which are the dominant component of the SH extratropical planetary waves.First, interannual variability of SFW is investigated in terms of amplitudes of stratospheric and tropospheric s = 1 QSWs, and wave transmission properties of the mean flow from the late austral winter to spring. Upward Eliassen–Palm flux due to s = 1 QSWs is larger from the stratosphere down to the middle troposphere in early-SFW years than late-SFW years. More favorable conditions for propagation of s = 1 stationary waves into the stratosphere are identified in early-SFW years. These results indicate that the amplification of tropospheric s = 1 QSWs and the favorable conditions for their propagation into the stratosphere lead to the amplification of stratospheric s = 1 QSWs, and hence earlier SFWs.Next, numerical calculations using a linear barotropic model are performed to explore how tropospheric s = 1 QSWs at high latitudes amplifies in early-SFW years. By using tropical Rossby wave source and horizontal winds in the reanalysis data as a source and background field, respectively, differences in s = 1 steady responses between early- and late-SFWs are examined at high latitudes. It is suggested that the larger amplitudes of tropospheric s = 1 QSWs in early-SFW years are attributed to differences in wave propagation characteristics associated with structure of the midlatitude jets in austral spring.

Download Full-text

Organic-walled microfossils and palynodebris in cold seep carbonate deposits: The Upper Jurassic–Lower Cretaceous Agardhfjellet Formation on Svalbard (Arctic Norway)

Norwegian Journal of Geology ◽

10.17850/njg96-2-01 ◽

2016 ◽

Cited By ~ 1

Author(s):

Thine Sanne Dalseg ◽

Hans Arne Nakrem ◽

Morten Smelror

Keyword(s):

Lower Cretaceous ◽

Upper Jurassic ◽

Cold Seep ◽

Seep Carbonate ◽

Carbonate Deposits

Download Full-text

Temperate Forests of the Southern Andean Region

The Physical Geography of South America ◽

10.1093/oso/9780195313413.003.0021 ◽

2007 ◽

Cited By ~ 2

Author(s):

Thomas T. Veblen

Keyword(s):

South America ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Boreal Forests ◽

Temperate Forests ◽

High Latitudes ◽

Andean Region ◽

Southern South America ◽

The Andes ◽

Evergreen Conifers

Although most of the continent of South America is characterized by tropical vegetation, south of the tropic of Capricorn there is a full range of temperate-latitude vegetation types including Mediterranean-type sclerophyll shrublands, grasslands, steppe, xeric woodlands, deciduous forests, and temperate rain forests. Southward along the west coast of South America the vast Atacama desert gives way to the Mediterranean-type shrublands and woodlands of central Chile, and then to increasingly wet forests all the way to Tierra del Fuego at 55°S. To the east of the Andes, these forests are bordered by the vast Patagonian steppe of bunch grasses and short shrubs. The focus of this chapter is on the region of temperate forests occurring along the western side of the southernmost part of South America, south of 33°S. The forests of the southern Andean region, including the coastal mountains as well as the Andes, are presently surrounded by physiognomically and taxonomically distinct vegetation types and have long been isolated from other forest regions. Although small in comparison with the extent of temperate forests of the Northern Hemisphere, this region is one of the largest areas of temperate forest in the Southern Hemisphere and is rich in endemic species. For readers familiar with temperate forests of the Northern Hemisphere, it is difficult to place the temper temperate forests of southern South America into a comparable ecological framework owing both to important differences in the histories of the biotas and to contrasts between the broad climatic patterns of the two hemispheres. There is no forest biome in the Southern Hemisphere that is comparable to the boreal forests of the high latitudes of the Northern Hemisphere. The boreal forests of the latter are dominated by evergreen conifers of needle-leaved trees, mostly in the Pinaceae family, and occur in an extremely continental climate. In contrast, at high latitudes in southern South America, forests are dominated mostly by broadleaved trees such as the southern beech genus (Nothofagus). Evergreen conifers with needle or scaleleaves (from families other than the Pinaceae) are a relatively minor component of these forests.

Download Full-text

Southern-Hemisphere high-latitude stratospheric warming revisit

Climate Dynamics ◽

10.1007/s00382-019-05083-7 ◽

2019 ◽

Vol 54 (3-4) ◽

pp. 1671-1682

Author(s):

Yan Xia ◽

Weixuan Xu ◽

Yongyun Hu ◽

Fei Xie

Keyword(s):

Southern Hemisphere ◽

High Latitude ◽

Recent Decade ◽

Warming Trend ◽

High Latitudes ◽

Stratospheric Warming ◽

Amundsen Sea ◽

Maximum Warming ◽

Dipole Pattern ◽

The Western Pacific

AbstractPrevious studies showed significant stratospheric warming at the Southern-Hemisphere (SH) high latitudes in September and October over 1979–2006. The warming trend center was located over the Southern Ocean poleward of the Western Pacific in September, with a maximum trend of about 2.8 K/decade. The warming trends in October showed a dipole pattern, with the warming center over the Ross and Amundsen Sea, and the maximum warming trend is about 2.6 K/decade. In the present study, we revisit the problem of the SH stratospheric warming in the recent decade. It is found that the SH high-latitude stratosphere continued warming in September and October over 2007–2017, but with very different spatial patterns. Multiple linear regression demonstrates that ozone increases play an important role in the SH high-latitude stratospheric warming in September and November, while the changes in the Brewer-Dobson circulation contributes little to the warming. This is different from the situation over 1979–2006 when the SH high-latitude stratospheric warming was mainly caused by the strengthening of the Brewer-Dobson circulation and the eastward shift of the warming center. Simulations forced with observed ozone changes over 2007–2017 shows warming trends, suggesting that the observed warming trends over 2007–2017 are at least partly due to ozone recovery. The warming trends due to ozone recovery have important implications for stratospheric, tropospheric and surface climates on SH.

Download Full-text

Talbragarus averyi gen. et sp. n., the first Jurassic weevil from the southern hemisphere (Coleoptera: Curculionoidea: Nemonychidae)

Zootaxa ◽

10.11646/zootaxa.3478.1.25 ◽

2012 ◽

Vol 3478 (1) ◽

pp. 256-266 ◽

Cited By ~ 11

Author(s):

ROLF G. OBERPRIELER ◽

STEFANIE K. OBERPRIELER

Keyword(s):

Southern Hemisphere ◽

Plant Species ◽

New South ◽

Upper Jurassic ◽

Plant Association ◽

Dominant Plant Species ◽

The Family

The first authentic weevil fossils known from Australia, and the oldest known from the southern hemisphere, are describedand illustrated on the basis of two specimens recovered from the Upper-Jurassic Talbragar Fish Bed in New South Wales.Talbragarus averyi gen. et sp. n. is classified in the family Nemonychidae based on the presence of scutellary strioles onthe elytra, the length and insertion of the antennae and the shape of the eyes, prothorax, legs and overall body. Anassignment of Talbragarus to a subfamily of Nemonychidae is not possible due to the lack of preservation of crucialcharacters, but it may represent the subfamily Rhinorhynchinae, which is still extant in Australia. Talbragarus wasprobably associated with the dominant plant species found in the Talbragar Fish Bed, the araucariaceous Podozamitesjurassica, and may have fed on its pollen as adults and larvae as extant Australian Nemonychidae do, indicating that this insect-plant association may have survived in Australia from Jurassic times.

Download Full-text

A newPliosaurusspecies (Sauropterygia, Plesiosauria) from the Upper Jurassic of Patagonia: new insights on the Tithonian morphological disparity of mandibular symphyseal morphology

Journal of Paleontology ◽

10.1017/jpa.2017.82 ◽

2018 ◽

Vol 92 (2) ◽

pp. 240-253 ◽

Cited By ~ 9

Author(s):

José P. O’Gorman ◽

Zulma Gasparini ◽

Luis A. Spalletti

Keyword(s):

New Species ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Upper Jurassic ◽

Occipital Condyle ◽

Mandibular Symphysis ◽

Morphological Disparity ◽

Vaca Muerta ◽

Vaca Muerta Formation ◽

A New Species

AbstractMost species of the genusPliosaurusOwen, 1842 come from the Northern Hemisphere, however, a growing number of new specimens are now available from the Southern Hemisphere. Here, a new species ofPliosaurusis described, the second for the genus from the Southern Hemisphere, collected from the upper Tithonian (Jurassic) levels of the Vaca Muerta Formation, Neuquén Province, Patagonia.Pliosaurus almanzaensisnew species is characterized by two autapomophies: the angular participating in the mandibular symphysis and the occipital condyle without a notochordal pit or several, irregularly arranged grooves. Additionally,P.almanzaensisn. sp. can be differentiated from otherPliosaurusspecies by the following characters: trihedral teeth, nine or more symphyseal alveoli, 15–17 post-symphyseal alveoli, and the parasphenoid without a ventral keel.Pliosaurus almanzaensisn. sp. shows thatPliosaurusspecies with nine or more symphyseal alveoli persisted until the late Tithonian, contrary to previous assumptions that only species with six symphyseal alveoli were present.

Download Full-text

Dynamical evolution of a minor sudden stratospheric warming in the Southern Hemisphere in 2019

10.5194/acp-2021-444 ◽

2021 ◽

Author(s):

Guangyu Liu ◽

Toshihiko Hirooka ◽

Nawo Eguchi ◽

Kirstin Krüger

Keyword(s):

Southern Hemisphere ◽

Vertical Component ◽

Polar Vortex ◽

Planetary Waves ◽

High Latitudes ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Zonal Wavenumber ◽

Westerly Winds ◽

A Minor

Abstract. This study analyzes the Japanese 55-year Reanalysis (JRA-55) dataset from 2002 to 2019 to examine the sudden stratospheric warming event that occurred in the Southern Hemisphere (SH) in 2019 (hereafter referred to as SSW2019). Strong warming at the polar cap and decelerated westerly winds were observed, but since there was no reversal of westerly winds to easterly winds at 60° S in the middle to lower stratosphere, the SSW2019 is classified as a minor warming event. The results show that quasi-stationary planetary waves of zonal wavenumber 1 developed during the SSW2019. The strong vertical component of the Eliassen–Palm flux with zonal wavenumber 1 is indicative of pronounced propagation of planetary waves to the stratosphere. The wave driving in September 2019 shows that the values are larger than those of the major SSW event in 2002 (hereafter referred to as SSW2002). Since there was no pronounced preconditioning (as in SSW2002) and the polar vortex was already strong before the SSW2019 occurred, a major disturbance of the polar vortex was unlikely to have taken place. The strong wave driving in SSW2019 occurred in high latitudes. Waveguides (i.e., positive values of the refractive index) are found at high latitudes in the upper stratosphere during the warming period, which provided favorable conditions for quasi-stationary planetary waves to propagate upward and poleward.

Download Full-text