Protremaster, a new Lower Jurassic genus of asteroid from Antarctica

1985 ◽  
Vol 122 (4) ◽  
pp. 351-359 ◽  
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.

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

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

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.

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

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

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.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

scholarly journals Upper Karoo vertebrate assemblages (Late Triassic/Early Jurassic) of the Lake Kariba region, Zimbabwe

2017 ◽  
Author(s):  
Paul M Barrett ◽  
Tim Broderick ◽  
Kimberley Chapelle ◽  
Jonah Choiniere ◽  
Steve Edwards ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Southern Africa ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Type Locality ◽  
Late Triassic ◽  
Lake Kariba ◽  
Aquatic Fauna ◽  
Mudstone Facies

Southern Africa provides critical information on Late Triassic–Early Jurassic terrestrial tetrapod faunas. Most of the localities in this region are in South Africa and Lesotho, but preliminary work in Zimbabwe has revealed significant potential. Early Jurassic Zimbabwean localities have yielded the basal sauropodomorph Massospondylus, the early sauropod Vulcanodon and theropod material. Late Triassic localities are also known, but have yielded only fragmentary specimens thus far. In early 2017, a joint South African-Zimbabwean-UK team conducted fieldwork in the upper Karoo-aged deposits along the shores of Lake Kariba, northern Zimbabwe (Mid-Zambesi Basin). We relocated the Vulcanodon type locality on Island 126/127 and found that, contrary to previous reports suggesting a Toarcian age, the quarry was in a horizon pre-dating the onset of Drakensburg volcanism (= Batoka Basalts). It is situated instead within the earlier Lower Jurassic Forest Sandstone. This indicates that Vulcanodon is 10–15 million years older than thought previously, recalibrating several nodes within Sauropoda and indicating extensive overlap between true sauropods and 'prosauropods'. Other new vertebrate localities show that sauropodomorphs are present in the Forest Sandstone and upper Tashinga (Late Triassic) formations, but a grey mudstone facies within the Pebbly Arkose Member of the latter unit yields a more aquatic fauna, including lungfish and phytosaurs, but lacking sauropodomorphs. The phytosaur occurrence is the first in Africa south of the Sahara. Faunal and sedimentological evidence indicates that the Late Triassic and Early Jurassic sites in this region were deposited under more mesic environments than their lateral equivalents in South Africa.

Perspectives on the Evolution and Diversification of the Diatoms

2007 ◽  
Vol 13 ◽  
pp. 1-12 ◽  
Author(s):  
Matthew L. Julius
Keyword(s):  
Molecular Clock ◽  
Fossil Record ◽  
Early Jurassic ◽  
Late Triassic ◽  
Evolutionary Relationships ◽  
Data Sets ◽  
Diatom Species ◽  
Generic Level ◽  
Existing Data

The understanding of diatom evolution has progressed greatly over the last two decades. Existing data sets have been reanalyzed, new data sets have been generated, and new tools have been employed. Hindering progress is the seemingly endless number of diatom species remaining to be described and relative small number of investigators active in the field. This problem is further confounded by the dramatic reorganization of generic level classification in the group. Despite these problems, many conclusions can be made about prior hypotheses concerning the group's development. Most notably, the origin of the diatoms can be bracketed between the Late Triassic and Early Jurassic using fossil record and molecular clock estimates. This combination of techniques has also provided consensus and clarification to the origin and duration of specific lineages enhancing our understanding of the group's diversification, early ecology, and evolutionary relationships.

scholarly journals A rare case of an evolutionary late and ephemeral biomineralization: tunicates with composite calcareous skeletons

2020 ◽  
Vol 94 (4) ◽  
pp. 748-757
Author(s):  
Jobst Wendt
Keyword(s):  
New Species ◽  
New Genus ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Cambrian Explosion ◽  
New Order ◽  
Colonial Ascidian ◽  
New Family ◽  
The Family ◽  
Almost All

AbstractIn contrast to almost all other invertebrate phyla that constructed biomineralized skeletons during the “Cambrian explosion” and maintained them during the entire fossil record, ascidian tunicates evolved this protective and stabilizing advantage only during the Permian, although soft-bodied representatives of this subphylum made their first appearance already in the early Cambrian. It remains enigmatic why these compound calcareous skeletons persisted only until the Late Triassic, subsequently followed by less-rigid internal skeletons from the Lower Jurassic onwards, which consist of scattered isolated spicules only. In addition to recently described aragonitic ascidian exoskeletons from the Permian and Triassic, new discoveries of similar, but colonial ascidian compound endoskeletons in the lower Carnian exhibit a short-living branch of this group, which moreover contain the first indubitable calcareous spicules. The latter are embedded in the solid endoskeleton, which is composed of polygonal aragonitic plates with smooth outer and zigzag lined inner boundaries. They consist of irregular, parallel (orthogonal), or fan-shaped (clinogonal) arrangements of acicular aragonite crystals. The following taxa are described as new: order Cassianomorpha new order with the family Cassianosomidae new family and the genus Toscanisoma new genus with the species T. multipartitum new species and T. triplicatum new species.UUID: http://zoobank.org/03555353-cdab-42e8-8e99-9bfce15fa249

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

2016 ◽  
Vol 107 (2-3) ◽  
pp. 151-155 ◽  
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.

Taxonomic diversity estimation using rarefaction

Paleobiology ◽  
1975 ◽  
Vol 1 (4) ◽  
pp. 333-342 ◽  
Author(s):  
David M. Raup
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Sample Size ◽  
Fossil Record ◽  
World Wide ◽  
Taxonomic Diversity ◽  
Early Jurassic ◽  
Late Triassic ◽  
Geologic Time ◽  
Large Samples

Benthic ecologists have successfully applied rarefaction techniques to the problem of compensating for the effect of sample size on apparent species diversity (= species richness). The same method can be used in studies of diversity at higher taxonomic levels (families and orders) in the fossil record where samples represent world-wide distributions of species or genera over long periods of geologic time.Application of rarefaction to several large samples of post-Paleozoic echinoids (totaling 7,911 species) confirms the utility of the method. Rarefaction shows that the observed increase in the number of echinoid families since the Paleozoic is real in the sense that it cannot be explained solely by the increase in numbers of preserved species. There has been no statistically significant increase in the number of families since mid-Cretaceous, however. At the order level, echinoid diversity may have been nearly constant since late Triassic or early Jurassic.

Revision of the bizarre Mesozoic scorpionflies in the Pseudopolycentropodidae (Mecopteroidea)

2005 ◽  
Vol 36 (4) ◽  
pp. 443-458 ◽  
Author(s):  
David Grimaldi ◽  
Alexandr Rasnitsyn ◽  
Zhang Junfeng ◽  
Nicholas Fraser
Keyword(s):  
New Species ◽  
Late Jurassic ◽  
Hind Wing ◽  
Early Jurassic ◽  
Western Hemisphere ◽  
Late Triassic ◽  
Similar Species ◽  
Antennal Flagellum ◽  
The Family

AbstractThe Mesozoic family Pseudopolycentropodidae presently consists of seven described species from the mid-Triassic to the Late Jurassic of Europe and Asia. Pseudopolycentropus prolatipennis Whalley, from the Early Jurassic of England, is revised based on re-examination of the type. Four new species are described herein that add significant distributional and stratigraphic extensions to the family. Pseudopolycentropodes virginicus Grimaldi and Fraser, gen. n., sp. n. from the Late Triassic (Carnian) of Virginia USA is the first species of the family from the Western Hemisphere. Pseudopolycentropus daohugouensis Zhang, sp. n. from the Late Jurassic of China is very similar to P. latipennis Martynov, 1927 from the Late Jurassic of Kazakhstan. Four specimens belonging to two very similar species in mid-Cretaceous amber from northern Burma (Myanmar), Parapolycentropus burmiticus Grimaldi and Rasnitsyn, gen. n., sp. n. and P. paraburmiticus Grimaldi and Rasnistyn, sp. n., are the only specimens of the family from the Cretaceous. The amber species are exceptional, with the hind wing reduced to a minute lobe, the antennal flagellum modified into an arista, labial palps are lost, and – like the Late Jurassic species — the laciniae and what are probably mandibles are modified into a long, stylet-like proboscis. What the species with long proboscides fed upon is ambiguous, but it was doubtfully blood. Complete preservation in amber of morphological details, particularly the female terminalia, confirms previous views that this unusual group is phylogenetically basal to Recent Mecoptera.

scholarly journals Earwigs (Dermaptera) from the Mesozoic of England and Australia, described from isolated tegmina, including the first species to be named from the Triassic

2016 ◽  
Vol 107 (2-3) ◽  
pp. 129-143 ◽  
Author(s):  
Richard S. Kelly ◽  
Andrew J. Ross ◽  
Edmund A. Jarzembowski
Keyword(s):  
New Taxa ◽  
Early Cretaceous ◽  
Early Jurassic ◽  
Late Triassic ◽  
Incertae Sedis ◽  
The Family

ABSTRACTDermaptera (earwigs) are described from the Triassic of Australia and England, and from the Jurassic and Cretaceous of England. Phanerogramma heeri (Giebel) is transferred from Coleoptera and it and Brevicula gradus Whalley are re-described. Seven new taxa are named based on tegmina: Phanerogramma australis sp. nov. and P. dunstani sp. nov. from the Late Triassic of Australia; P. gouldsbroughi sp. nov. from the Triassic/Jurassic of England; Brevicula maculata sp. nov. and Trivenapteron moorei gen. et sp. nov. from the Early Jurassic of England; and Dimapteron corami gen et sp. nov. and Valdopteron woodi gen. et sp. nov. from the Early Cretaceous of England. Phanerogramma, Dimapteron and Valdopteron are tentatively placed in the family Dermapteridae, and Trivenapteron is incertae sedis. Most of the specimens of Phanerogramma heeri are from the Brodie Collection and labelled ‘Lower Lias'; however, some were collected from the underlying Penarth Group, thus this species spans the Triassic/Jurassic boundary. The palaeobiogeography of the Late Triassic and Early Jurassic of England is discussed.

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