scholarly journals Odonatan endophytic oviposition from the Eocene of Patagonia: The ichnogenus Paleoovoidus and implications for behavioral stasis

2009 ◽  
Vol 83 (3) ◽  
pp. 431-447 ◽  
Author(s):  
Laura C. Sarzetti ◽  
Conrad C. Labandeira ◽  
Javier Muzón ◽  
Peter Wilf ◽  
N. Rubén Cúneo ◽  
...  
Keyword(s):  
Circular Hole ◽  
Middle Eocene ◽  
Surface Pattern ◽  
Insect Damage ◽  
Early Eocene ◽  
Tissue Penetration ◽  
Considerable Similarity ◽  
Endophytic Oviposition ◽  
Plant Families

We document evidence of endophytic oviposition on fossil compression/impression leaves from the early Eocene Laguna del Hunco and middle Eocene Rio Pichileufu floras of Patagonia, Argentina. Based on distinctive morphologies and damage patterns of elongate, ovoid, lens-, or teardrop-shaped scars in the leaves, we assign this insect damage to the ichnogenus Paleoovoidus, consisting of an existing ichnospecies, P. rectus, and two new ichnospecies, P. arcuatum and P. bifurcatus. In P. rectus, the scars are characteristically arranged in linear rows along the midvein; in P. bifurcatus, scars are distributed in double rows along the midvein and parallel to secondary veins; and in P. arcuatum, scars are deployed in rectilinear and arcuate rows. In some cases, the narrow, angulate end of individual scars bear a darkened region encompassing a circular hole or similar feature indicating ovipositor tissue penetration. A comparison to the structure and surface pattern of modern ovipositional damage on dicotyledonous leaves suggests considerable similarity to certain zygopteran Odonata. Specifically, members of the Lestidae probably produced P. rectus and P. bifurcatus, whereas species of Coenagrionidae were responsible for P. arcuatum. Both Patagonian localities represent an elevated diversity of potential fern, gymnosperm, and especially angiosperm hosts, the targets of all observed oviposition. However, we did not detect targeting of particular plant families. Our results indicate behavioral stasis for the three ovipositional patterns for at least 50 million years. Nevertheless, synonymy of these oviposition patterns with mid-Mesozoic ichnospecies indicates older origins for these distinctive modes of oviposition.

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.

scholarly journals Maastrichtian–Rupelian paleoclimates in the southwest Pacific – a critical re-evaluation of biomarker paleothermometry and dinoflagellate cyst paleoecology at Ocean Drilling Program Site 1172

2021 ◽  
Vol 17 (6) ◽  
pp. 2393-2425
Author(s):  
Peter K. Bijl ◽  
Joost Frieling ◽  
Margot J. Cramwinckel ◽  
Christine Boschman ◽  
Appy Sluijs ◽  
...  
Keyword(s):  
Marine Sediments ◽  
State Of The Art ◽  
Middle Eocene ◽  
Potential Temperature ◽  
Critical Evaluation ◽  
Marine Biodiversity ◽  
Early Eocene ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Sw Pacific

Abstract. Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT'5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX86-based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX86-based SST and MBT'5me-based MAAT estimates remain without definitive explanation.

New Uintasoricine (?Primates, Plesiadapiformes) From the Earliest Bridgerian, Latest Early Eocene of Wyoming

2012 ◽  
Vol 86 (6) ◽  
pp. 973-978 ◽  
Author(s):  
Gregg F. Gunnell
Keyword(s):  
North America ◽  
New Genus ◽  
Middle Eocene ◽  
Field Work ◽  
Biodiversity Hotspot ◽  
Individual Species ◽  
Early Eocene ◽  
New Genus And Species ◽  
Body Weights ◽  
New Form

Uintasoricines are diminutive plesiadapiforms that are found in the latest Paleocene through middle Eocene, predominantly in North America. They are not a diverse group but individual species may be locally abundant and they are a persistent element of the plesiadapiform radiation in North America surviving over a span of approximately 16 million years. Recent field work in southern Wyoming at South Pass has led to the discovery of a new genus and species of uintasoricine. The new form is smaller in tooth dimensions compared to other known uintasoricines, being slightly smaller thanUintasorex montezumicusfrom California. Both the newly described taxon andU. montezumicusare among the smallest plesiadapiforms yet known with body weights estimated to be 20 to 25 g. The sediments of the Cathedral Bluffs Tongue of the Wasatch Formation at South Pass contain a unique upland fauna—the presence of a distinctive uintasoricine in this assemblage adds further evidence to support the notion that this upland environment was a biodiversity hotspot during the latest early Eocene.

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.

The oldest long-legged fly of the subfamily Medeterinae (Diptera: Dolichopodidae) from the Early Eocene of France

2020 ◽  
Vol 3 (2) ◽  
pp. 173-179
Author(s):  
VALERIE NGÔ-MULLER ◽  
ROMAIN GARROUSTE ◽  
ANDRÉ NEL
Keyword(s):  
Middle Eocene ◽  
Baltic Amber ◽  
Early Eocene

We describe Paleothrypticus eocenicus gen. et sp. nov., oldest and first Medeterinae from the Early Eocene Oise amber (France). Representatives of the tribes Medeterini and Systenini are recorded in the Middle Eocene Baltic amber and the Miocene amber of Mexico. These fossils show that this subfamily was already well diversified at the beginning of the Eocene.

scholarly journals Virtual endocasts of Eocene Paramys (Paramyinae): oldest endocranial record for Rodentia and early brain evolution in Euarchontoglires

2016 ◽  
Vol 283 (1823) ◽  
pp. 20152316 ◽  
Author(s):  
Ornella C. Bertrand ◽  
Farrah Amador-Mughal ◽  
Mary T. Silcox
Keyword(s):  
Surface Area ◽  
Brain Size ◽  
Middle Eocene ◽  
Brain Evolution ◽  
Early Eocene ◽  
Olfactory Bulbs ◽  
Ancestral Condition ◽  
Relative Brain Size ◽  
Endocranial Volume

Understanding the pattern of brain evolution in early rodents is central to reconstructing the ancestral condition for Glires, and for other members of Euarchontoglires including Primates. We describe the oldest virtual endocasts known for fossil rodents, which pertain to Paramys copei (Early Eocene) and Paramys delicatus (Middle Eocene). Both specimens of Paramys have larger olfactory bulbs and smaller paraflocculi relative to total endocranial volume than later occurring rodents, which may be primitive traits for Rodentia. The encephalization quotients (EQs) of Pa. copei and Pa. delicatus are higher than that of later occurring (Oligocene) Ischyromys typus , which contradicts the hypothesis that EQ increases through time in all mammalian orders. However, both species of Paramys have a lower relative neocortical surface area than later rodents, suggesting neocorticalization occurred through time in this Order, although to a lesser degree than in Primates. Paramys has a higher EQ but a lower neocortical ratio than any stem primate. This result contrasts with the idea that primates were always exceptional in their degree of overall encephalization and shows that relative brain size and neocortical surface area do not necessarily covary through time. As such, these data contradict assumptions made about the pattern of brain evolution in Euarchontoglires.

Geochronometry of the Eagle Plutonic Complex and the Coquihalla area, southwestern British Columbia

1992 ◽  
Vol 29 (4) ◽  
pp. 812-829 ◽  
Author(s):  
C. J. Greig ◽  
R. L. Armstrong ◽  
J. E. Harakal ◽  
D. Runkle ◽  
P. van der Heyden
Keyword(s):  
British Columbia ◽  
Late Jurassic ◽  
Middle Eocene ◽  
Timing Constraints ◽  
Early Eocene ◽  
East Side ◽  
Eastern Margin ◽  
Plutonic Complex ◽  
Southwestern Margin

New U–Pb, K–Ar, and Rb–Sr dates from the Eagle Plutonic Complex and adjacent map units place timing constraints on intrusive and deformational events along the southwestern margin of the Intermontane Belt. U–Pb zircon minimum dates for Eagle tonalite and gneiss (148 ± 6, 156 ± 4, and 157 ± 4 Ma) document previously unrecognized Middle to Late Jurassic magmatism and syn-intrusive deformation along the eastern margin of the Eagle Plutonic Complex and the southwestern margin of the Intermontane terrane. Widespread mid-Cretaceous (Albian–Cenomanian) resetting of K–Ar and Rb–Sr isotopic systematics in Jurassic and older rocks is coeval and cogenetic with emplacement of plutons of the Fallslake Plutonic Suite (110.5 ± 2 Ma, U–Pb) which crosscut Jurassic plutons and structures but were themselves ductilely deformed along the Pasayten fault during sinistral, east-side-up, reverse displacement. K–Ar and Rb–Sr cooling dates for the Fallslake Suite of ca. 100 Ma, including dates from mylonites along the Pasayten fault, suggest that uplift, cooling, and unroofing of the Eagle Plutonic Complex occurred in mid-Cretaceous time along the Pasayten fault. Regional geologic evidence suggests that this thermal and unroofing event affected much of the southwest margin of the Intermontane Belt. Initial 87Sr/86Sr ratios and U–Pb geochronometry for the Fallslake Plutonic Suite suggest that it was derived, in part, from preexisting and relatively nonradiogenic Paleozoic to Mesozoic crust. K–Ar dating of several stocks demonstrates widespread Early Eocene plutonism in the Coquihalla area, and dating of the Needle Peak pluton indicates plutonism continued into Middle Eocene time.

scholarly journals Geometric morphometrics of endophytic oviposition traces of Odonata (Eocene, Argentina)

2020 ◽  
Vol 7 (12) ◽  
pp. 201126
Author(s):  
Eugenia Romero-Lebrón ◽  
Raquel M. Gleiser ◽  
Julián F. Petrulevičius
Keyword(s):  
Geometric Morphometrics ◽  
Linear Models ◽  
Middle Eocene ◽  
Evolutionary Constraint ◽  
Mixed Linear Models ◽  
Lower Eocene ◽  
Rio Negro ◽  
Endophytic Oviposition ◽  
The Individual ◽  
First Time

The insertion of the Odonata ovipositor in the plant tissue generates a scar that surrounds the eggs (trace). In insects, individual egg traces are known to vary in size, but their variation in individual shape is mostly unknown. Twenty-four specimens were obtained from the Laguna del Hunco (Lower Eocene, Chubut) and Río Pichileufú (Middle Eocene, Río Negro), Argentina, which had 1346 oviposition traces (MEF Collection). For the first time, a study of the shape and size of a large number of individual Odonata endophytic egg traces was carried out using traditional (general and mixed linear models) and geometric morphometrics (Fourier elliptical series) to elucidate whether there are changes in size or shape of the individual endophytic egg traces associated with the substrate used at the time of oviposition, if the Lower Eocene traces have varied in relation to those of the Middle Eocene, and if the ichnological classification ( Paleoovoidus arcuatus , P. bifurcatus and P. rectus ) reflects such variations. We found differences in size ( p < 0.05), but not in shape, in relation to the variables studied. This could reflect that the shape of Odonata eggs (inferred from the traces), unlike their size, could have a strong evolutionary constraint already observed since the Eocene.

scholarly journals Paleobiogeography of Eocene Radiolarians in the Southwest Pacific

2021 ◽  
Author(s):  
◽  
Kristina Michaela Pascher
Keyword(s):  
High Latitude ◽  
Middle Eocene ◽  
Late Eocene ◽  
Early Eocene ◽  
Low Latitude ◽  
Southwest Pacific ◽  
Early Oligocene ◽  
Climatic Optimum ◽  
Total Fauna ◽  
Radiolarian Assemblages

<p>This thesis investigates the effect of climatic and oceanographic changes on the distribution of fossil radiolarian assemblages from the early Eocene to early Oligocene (~56–30 Ma) in the Southwest Pacific. Radiolarian assemblages have been analysed from a series of archived cores collected by the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP). The selected cores form a latitudinal transect designed to investigate the ecological change associated with the transition from the warm ‘greenhouse’ climate of the Eocene into the cooler Oligocene, when continental-scale glaciation is believed to have intiated in Antarctica. High-latitude sites were sampled on the Campbell Plateau (DSDP Site 277), Tasman Rise (DSDP sites 280 and 281) and the Tasman Sea (DSDP Site 283 and ODP Site 1172), while mid-latitude sites were sampled both to the west of New Zealand (DSDP sites 207, 206, 592) and east of New Zealand (ODP Site 1123). New foraminifer oxygen (δ¹⁸O) and carbon (δ¹³C) stable isotope data from DSDP sites 277, 207 and 592 are presented and provide additional age control and insights in the climatic and oceanographic changes in the Southwest Pacific during the early Eocene to early Oligocene.  This thesis contributes a comprehensive taxonomic review of Eocene radiolarian taxa with the intention of standardising nomenclature and to resolve synonymies. 213 out of 259 counting groups have been reviewed and assigned to species or subspecies level and 7 new species are yet to be described. All sites have been correlated to the Southern Hemisphere radiolarian zonation, from the upper Paleocene to upper Oligocene (RP6SH to RP17SH). Alternative datums for the base of RP10SH (LO of Artobotrys auriculaleporis) and the base of RP12SH (LO of Lophocyrtis longiventer) are proposed.  The early Eocene climatic optimum (EECO, ~53–49 Ma) can be identified by a negative excursion in foraminiferal δ¹⁸O values at Site 207. The radiolarian assemblages at sites 207 (paleolatitude ~46°S) and 277 (paleolatitude ~55°S) during the EECO are dominated by taxa with low-latitude affinities (Amphicraspedum spp. represents up to 89% of total fauna), but many typical low-latitude genera (e.g. Thyrsocyrtis, Podocyrtis, Phormocyrtis) are absent. Following the EECO, low-latitude taxa decrease at Site 207 and disappear at Site 277. Radiolarians are abundant and very diverse at mid-latitude sites 207 and 206 (paleolatitude ~42°S) during the middle Eocene, and low-latitude taxa are common (up to ~15% of the total fauna at Site 207 and ~10% at Site 206). The middle Eocene climatic optimum (MECO, ~40 Ma), although truncated by poor drilling recovery at Site 277, is identified by a negative shift in foraminiferal δ18O values at this site and is associated by a small increase in radiolarian taxa with low-latitude affinities (up to ~5% of total fauna).  Early in the late Eocene (~37 Ma), a positive shift in δ¹⁸O values at Site 277 is correlated with the Priabonian oxygen isotope maximum (PrOM). Within this cooling event, radiolarian abundance, diversity and preservation, as well as diatom abundance, increase abruptly at Site 277. A negative δ¹⁸O excursion above the PrOM is correlated to a late Eocene warming event (~36 Ma) and is referred to as the late Eocene climatic optimum (LECO). The LECO is identified using stable isotopes at sites 277 and 592. Radiolarian abundance and diversity decline within this event at Site 277 although taxa with low-latitude affinities increase (up to ~10% of total fauna). At Site 592, radiolarian-bearing sediments are only present during this event with up to ~6% low-latitude taxa. Apart from the LECO, late Eocene radiolarian assemblages at Site 277 are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and Oligocene (~38–27 Ma) at DSDP sites 280, 281, 283, and ODP sites 1172 and 1123 and are associated with very high diatom abundance.  Radiolarian assemblages are used for reconstructing the evolution of oceanic fronts. The composition of the assemblages suggests that the oscillation between warm subtropical and cool subtropical conditions can be explained by the varying influence of the warm proto-East Australian Current and cold proto-Ross Gyre. In contrast to temperature reconstructions based on geochemical proxies (TEX₈₆, UK’₃₇ and Mg/Ca), which indicate tropical temperatures throughout most of the Eocene, radiolarians indicate warm subtropical conditions during the EECO. Warm surface water masses may have been transported by the proto-East Australian Current to ~55°S during the EECO. During the middle to late Eocene, cool subtropical conditions prevailed in the Southwest Pacific. Localised occurrences of abundant diatoms indicate upwelling areas close to the Tasman Rise in the middle Eocene. The proliferation of radiolarian assemblages and expansion of high-latitude taxa onto the Campbell Plateau in the latest Eocene is explained by a northward expansion of proto-Ross Gyre. In the early Oligocene (~32 Ma), there is an overall decrease in radiolarian abundance and diversity on the Campbell Plateau (Site 277) and diatoms disappear. Major hiatuses in the region indicate intensified bottom-water currents associated with the establishment of the Antarctic Circumpolar Current. A frontal system similar to present day developed in the early Oligocene, with nutrient-depleted subantarctic waters bathing the southern Campbell Plateau, resulting in a more restricted radiolarian assemblage at Site 277.</p>

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