The impact of the Toarcian Oceanic Anoxic Event (T-OAE) on the radiation of Early Jurassic dinoflagellate cysts in the Lusitanian Basin, Portugal

Dinoflagellates, together with diatoms and coccolithophores, form a major element of the marine eukaryotic phytoplankton, and are significant primary producers. Based on the fossil record, dinoflagellates appeared in Middle Triassic and during the Early Jurassic (late Pliensbachian) and underwent an important evolutionary radiation episode, with the occurrence of around 40 new species. The Lower Jurassic is particularly well-developed in the Lusitanian Basin of central western Portugal. This depocentre is filled mainly with marine Jurassic sediments, characterized by marl-limestone alternations. We analysed 214 samples from six Lower Jurassic sections in the Lusitanian Basin. The Pliensbachian–Toarcian succession in the Lusitanian Basin is characterised by relatively low dinoflagellate cyst diversity. Only fifteen taxa were recorded; these are assigned to seven genera. These are Luehndea, Mancodinium, Mendicodinium, Nannoceratopsis, Scriniocassis, Sentusidinium and Valvaeodinium. At the base of upper Pliensbachian (Amaltheus margaritatus ammonite biozone) the first dinoflagellate cyst appearances in the Lusitanian Basin are recorded, corresponding to the late Pliensbachian radiation event of this group. We identified the inceptions of Mancodinium semitabulatum, Luehndea spinosa, which belong to the family Mancodiniaceae, Nannoceratopsis gracilis and Nannoceratopsis senex, representing the family Nannoceratopsiaceae are also present. This family is confined to the Jurassic and the genus Nannoceratopsis is the only representative. These taxa became very common and abundant throughout the remaining late Pliensbachian and early Toarcian (Dactylioceras polymorphum ammonite biozone), before the T-OAE. The T-OAE in the Lusitanian Basin is expressed at the base of Hildaites levisoni ammonite biozone and is characterised by the apparent extinction of Luehndea spinosa and the disappearance of all dinoflagellate cyst taxa. During the remaining Toarcian only four new genera and families were identified and the abundance of this group is consistently very low. Apparently, the palaeoenvironmental changes associated with the T-OAE were more extensive in the Lusitanian Basin, compared with coeval basins in northern Europe. Hence, the T-OAE in this basin strongly affected the dinoflagellate cyst evolution patterns. Nevertheless, the late Toarcian of the Lusitanian Basin included an important evolutionary episode, namely the emergence of the first Gonyaulacaceae, due to the appearance of Sentusidinium. The family Gonyaulacaceae continued their diversification and became the most abundant family of cyst-forming dinoflagellates in the fossil record. In conclusion, the late Pliensbachian radiation of dinoflagellate cysts is well documented in the Lusitanian Basin and the T-OAE drastically affected the morphological experimentation period of this group during the remaining Early Jurassic.

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The impact of the Toarcian Oceanic Anoxic Event (T-OAE) on the radiation of Early Jurassic dinoflagellate cysts in the Lusitanian Basin, Portugal

10.7287/peerj.preprints.27953v1 ◽

2019 ◽

Author(s):

Vânia Fraguito Correia ◽

James B. Riding ◽

Luís V. Duarte ◽

Paulo Fernandes ◽

Zélia Pereira

Keyword(s):

Fossil Record ◽

Lower Jurassic ◽

Early Jurassic ◽

Dinoflagellate Cysts ◽

Dinoflagellate Cyst ◽

Oceanic Anoxic Event ◽

Eukaryotic Phytoplankton ◽

The Family ◽

The Impact ◽

Lusitanian Basin

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The effects of the Jenkyns Event on the radiation of Early Jurassic dinoflagellate cysts

Geological Society London Special Publications ◽

10.1144/sp514-2020-255 ◽

2021 ◽

pp. SP514-2020-255

Author(s):

Vânia F. Correia ◽

James B. Riding ◽

Luís V. Duarte ◽

Paulo Fernandes ◽

Zélia Pereira

Keyword(s):

Species Richness ◽

New Species ◽

Lower Jurassic ◽

Early Jurassic ◽

Dinoflagellate Cysts ◽

Oceanic Anoxic Event ◽

Anoxic Event ◽

Northern Regions ◽

Prolonged Recovery ◽

Lusitanian Basin

AbstractThis contribution is an overview of the Early Jurassic dinoflagellate cysts of the Lusitanian Basin in Portugal, with particular emphasis on the effects of the Jenkyns Event (Toarcian Oceanic Anoxic Event - T-OAE) on the evolution of this planktonic group. We review and discuss data from 214 samples from six Lower Jurassic successions (upper Sinemurian-upper Toarcian) in the Lusitanian Basin. The late Pliensbachian radiation of dinoflagellate cysts was well recognised in this basin. The pre-Jenkyns Event interval is highly productive, with maximum abundance and species richness values. However, this palaeoenvironmental perturbation severely affected the evolution of this group for the remainder of the Early Jurassic. The prolonged recovery of the dinoflagellates in the Toarcian following the Jenkyns Event is not typical of the northern regions (Arctic and Boreal realms), where new species began to evolve earlier compared with southern European basins.

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Protremaster, a new Lower Jurassic genus of asteroid from Antarctica

Geological Magazine ◽

10.1017/s0016756800031794 ◽

1985 ◽

Vol 122 (4) ◽

pp. 351-359 ◽

Cited By ~ 6

Author(s):

Andrew B. Smith ◽

T. H. Tranter

Keyword(s):

Fossil Record ◽

Lower Jurassic ◽

Early Jurassic ◽

Late Triassic ◽

Morphological Diversification ◽

The Family

AbstractA new and well-preserved.asteroid, Protremaster uniserialis (gen. & sp.nov.) is described from the Lower Jurassic (Sinemurian) of Antarctica. This find extends the fossil record of the family Asterinidae and the subfamily Tremasterinae considerably and lends support to the idea that asteroids underwent an important morphological diversification in the late Triassic-early Jurassic.

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The oldest representative of the family Austropanorpidae (Mecoptera) from the Lower Jurassic of Siberia

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691017000214 ◽

2016 ◽

Vol 107 (2-3) ◽

pp. 151-155 ◽

Cited By ~ 2

Author(s):

Wiesław Krzemiński ◽

Agnieszka Soszyńska-Maj ◽

Katarzyna Kopeć ◽

Irena D. Sukatsheva

Keyword(s):

Lower Jurassic ◽

Early Jurassic ◽

Paleontological Institute ◽

Russian Academy Of Sciences ◽

The Family ◽

Academy Of Sciences

ABSTRACTThe family Austropanorpidae (Mecoptera) was described by Willmann in 1977 from the Eocene of Australia, based on one genus and species, Austropanorpa australis Riek, 1952. During a restudy of the collection of the Paleontological Institute, Russian Academy of Sciences in Moscow, a second and much older representative of this family was found. This specimen, described as Orthophlebia martynovae Sukatsheva, 1985 from Siberia (Russia), was considered until now to be a member of family Orthophlebiidae. We transfer this species to the Austropanorpidae, extending the age of this family back to the Early Jurassic. An updated diagnoses of the family Austropanorpidae and genus Austropanorpa are presented here.

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The impact of the Pliensbachian-Toarcian crisis on belemnite diversity and size distribution

10.5194/egusphere-egu2020-7873 ◽

2020 ◽

Author(s):

Kenneth De Baets ◽

Patrícia Rita ◽

Luís Vítor Duarte ◽

Pascal Neige ◽

Laura Piñuela ◽

...

Keyword(s):

High Resolution ◽

Species Turnover ◽

Adult Size ◽

Oceanic Anoxic Event ◽

Species Cluster ◽

Anoxic Event ◽

Major Bottleneck ◽

Scaling Analyses ◽

The Impact ◽

Lusitanian Basin

<p>The Pliensbachian&#8211;Toarcian transition has been considered a major bottleneck in the early evolution of belemnites, probably related to major palaeoenvironmental and climatic changes during the Early Toarcian. Previous research has focused on the study of belemnites from higher, temperate latitudes, while high-resolution studies on diversity and size of subtropical belemnite assemblages in the northwest Tethys are comparatively rare. The lack of high-resolution (ammonoid subzone) abundance data on diversity and size distributions of belemnite assemblages does not allow separating changes during the Pliensbachian&#8211;Toarcian boundary event from those during the Toarcian anoxic event. Sample standardized diversity analyses on new data from Iberian sections suggest the Pliensbachian&#8211;Toarcian corresponds to a slight decrease in diversity and an adult size decrease within dominant species. Cluster and non-metric multidimensional scaling analyses, however, indicate that the largest changes in diversity and palaeogeographic distribution of belemnite assemblages occurred during the Toarcian oceanic anoxic event (TOAE) rather than the Pliensbachian&#8211;Toarcian boundary. In southern basins like the Lusitanian Basin and Riff Mountains, belemnites even disappear entirely during the TOAE. More generally, the TOAE corresponds with an increase in body size of belemnite assemblages driven by species turnover. The lack of widespread anoxia in southern basins of the northwest Tethys indicates that direct impact of warming or increased pCO2 triggered by volcanism as well as indirect effects on nutrient availability and productivity might have played an important role during both crises.</p>

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Comment on “Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)” by Hesselbo S., Jenkyns H.C., Duarte L.V. and Oliveira L.C.V.

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2007.04.055 ◽

2007 ◽

Vol 259 (3-4) ◽

pp. 634-639 ◽

Cited By ~ 21

Author(s):

J.M. McArthur

Keyword(s):

Carbon Isotope ◽

Fossil Wood ◽

Early Jurassic ◽

Oceanic Anoxic Event ◽

Marine Carbonate ◽

Anoxic Event ◽

Isotope Record ◽

Lusitanian Basin

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A new early-branching armoured dinosaur from the Lower Jurassic of southwestern China

10.1101/2021.11.24.469951 ◽

2021 ◽

Author(s):

Xi Yao ◽

Paul Barrett ◽

Lei Yang ◽

Xing Xu ◽

Shundong Bi

Keyword(s):

Fossil Record ◽

Evolutionary History ◽

Yunnan Province ◽

Morphological Diversity ◽

Lower Jurassic ◽

Early Jurassic ◽

New Taxon ◽

Unique Combination ◽

Geographic Spread ◽

History Of

The early evolutionary history of the armoured dinosaurs (Thyreophora) is obscured by its patchily distributed fossil record and by conflicting views on the relationships of its Early Jurassic representatives. Here, we describe an early-diverging thyreophoran from the Lower Jurassic Fengjiahe Formation of Yunnan Province, China, on the basis of an associated partial skeleton that includes skull, axial, limb and armour elements. It can be diagnosed as a new taxon based on numerous cranial and postcranial autapomorphies and is further distinguished from all other thyreophorans by a unique combination of character states. Although the robust postcranium is similar to that of more deeply nested ankylosaurs and stegosaurs, phylogenetic analysis recovers it as either the sister taxon of Emausaurus or of the clade Scelidosaurus and Eurypoda. This new taxon, Yuxisaurus kopchicki, represents the first valid thyreophoran dinosaur to be described from the Early Jurassic of Asia and confirms the rapid geographic spread and diversification of the clade after its first appearance in the Hettangian. Its heavy build and distinctive armour also hint at previously unrealised morphological diversity early in the clade history.

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Orbital pacing and secular evolution of the Early Jurassic carbon cycle

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1912094117 ◽

2020 ◽

Vol 117 (8) ◽

pp. 3974-3982 ◽

Cited By ~ 14

Author(s):

Marisa S. Storm ◽

Stephen P. Hesselbo ◽

Hugh C. Jenkyns ◽

Micha Ruhl ◽

Clemens V. Ullmann ◽

...

Keyword(s):

Carbon Cycle ◽

Lower Jurassic ◽

Early Jurassic ◽

Oceanic Anoxic Event ◽

Secular Evolution ◽

Igneous Provinces ◽

Orbital Cycles ◽

Orbital Tuning ◽

Comparable Amplitude

Global perturbations to the Early Jurassic environment (∼201 to ∼174 Ma), notably during the Triassic–Jurassic transition and Toarcian Oceanic Anoxic Event, are well studied and largely associated with volcanogenic greenhouse gas emissions released by large igneous provinces. The long-term secular evolution, timing, and pacing of changes in the Early Jurassic carbon cycle that provide context for these events are thus far poorly understood due to a lack of continuous high-resolution δ13C data. Here we present a δ13CTOC record for the uppermost Rhaetian (Triassic) to Pliensbachian (Lower Jurassic), derived from a calcareous mudstone succession of the exceptionally expanded Llanbedr (Mochras Farm) borehole, Cardigan Bay Basin, Wales, United Kingdom. Combined with existing δ13CTOC data from the Toarcian, the compilation covers the entire Lower Jurassic. The dataset reproduces large-amplitude δ13CTOC excursions (>3‰) recognized elsewhere, at the Sinemurian–Pliensbachian transition and in the lower Toarcian serpentinum zone, as well as several previously identified medium-amplitude (∼0.5 to 2‰) shifts in the Hettangian to Pliensbachian interval. In addition, multiple hitherto undiscovered isotope shifts of comparable amplitude and stratigraphic extent are recorded, demonstrating that those similar features described earlier from stratigraphically more limited sections are nonunique in a long-term context. These shifts are identified as long-eccentricity (∼405-ky) orbital cycles. Orbital tuning of the δ13CTOC record provides the basis for an astrochronological duration estimate for the Pliensbachian and Sinemurian, giving implications for the duration of the Hettangian Stage. Overall the chemostratigraphy illustrates particular sensitivity of the marine carbon cycle to long-eccentricity orbital forcing.

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