Shale-hosted biota from the Dismal Lakes Group in Arctic Canada supports an early Mesoproterozoic diversification of eukaryotes

2021 ◽  
pp. 1-25
Author(s):  
Corentin C. Loron ◽  
Galen P. Halverson ◽  
Robert H. Rainbird ◽  
Tom Skulski ◽  
Elizabeth C. Turner ◽  
...  

Abstract The Mesoproterozoic is an important era for the development of eukaryotic organisms in oceans. The earliest unambiguous eukaryotic microfossils are reported in late Paleoproterozoic shales from China and Australia. During the Mesoproterozoic, eukaryotes diversified in taxonomy, metabolism, and ecology, with the advent of eukaryotic photosynthesis, osmotrophy, multicellularity, and predation. Despite these biological innovations, their fossil record is scarce before the late Mesoproterozoic. Here, we document an assemblage of organic-walled microfossils from the 1590–1270 Ma Dismal Lakes Group in Canada. The assemblage comprises 25 taxa, including 11 morphospecies identified as eukaryotes, a relatively high diversity for this period. We also report one new species, Dictyosphaera smaugi new species, and one unnamed taxon. The diversity of eukaryotic forms in this succession is comparable to slightly older assemblages from China and is higher than worldwide contemporaneous assemblages and supports the hypothesis of an earlier diversification of eukaryotes in the Mesoproterozoic.

2015 ◽  
Vol 89 (1) ◽  
pp. 148-167 ◽  
Author(s):  
Romain Jattiot ◽  
Arnaud Brayard ◽  
Emmanuel Fara ◽  
Sylvain Charbonnier

AbstractGladius-bearing coleoids are rare in the fossil record. For the Cretaceous period, these cephalopods are mainly recorded in a few Lagerstätten in Lebanon (Haqel, Hajoula, En Nammoura, and Sahel Aalma). Here, we study 16 specimens of gladius-bearing coleoids from these Upper Cretaceous Lebanese Lagerstätten to investigate their taxonomic diversity. Besides two species that were already reported (Dorateuthis syriacaandGlyphiteuthis libanotica), one new species is identified in the Cenomanian site of Hajoula:Rachiteuthis acutalin. sp., as well as another form ofGlyphiteuthisfrom En Nammoura. Several studied specimens exhibit well-preserved soft-part characters. Among them, we document for the first time two transverse rows of sessile suckers inD.syriacaand we confirm the absence of tentacles, as well as the presence of a crop in this species. This strongly supports the phylogenetic proximity ofD.syriacawith modern vampyropods rather than with modern decabrachians. In turn, the similarity in gladius morphology between this taxon and modern squids is regarded as convergent.


2017 ◽  
Vol 188 (3) ◽  
pp. 19 ◽  
Author(s):  
Sylvain Charbonnier ◽  
Giorgio Teruzzi ◽  
Denis Audo ◽  
Maxime Lasseron ◽  
Carolin Haug ◽  
...  

Thylacocephalans (Euarthropoda, Thylacocephala) are characterized by their “bivalved” carapace and three anterior prehensile appendages. It is still not clear how they used to live, or what their evolutionary history is. This study focuses on new thylacocephalans from the Late Cretaceous Konservat-Lagerstätten of Lebanon, which yielded the youngest representatives of the group. Three new genera and species are described in the Cenomanian sublithographic limestones of Hakel and Hadjoula, and two new genera and one new species are described in the Santonian chalky limestones of Sahel Alma. Among the specimens from Hakel and Hadjoula, Paradollocaris vannieri, Thylacocaris schrami and Globulacaris garassinoi are the first reports of thylacocephalans in the Cenomanian of Lebanon. Paradollocaris and Thylacocaris are assigned to Dollocarididae based upon their large optic notches limited by rostral and antero-ventral processes, their hypertrophied eyes, and their posterior notches with dorsal and ventral spines. Moreover, Thylacocaris presents a very peculiar character: an optic notch with two strong optic spines protecting the eye. Globulocaris is assigned to Protozoeidae based upon its small carapace with a distinct dorsal notch anterior to a strong postero-dorsal spine. Among the specimens from Sahel Alma, Keelicaris deborae is a new form of thylacocephalans in the Santonian of Lebanon. It presents a very unusual keel-shaped carapace with terraces and punctuations, and is assigned to Microcarididae. The new genus Hamaticaris, presenting a very peculiar hooked rostrum, is also erected for Protozoea damesi Roger, 1946 (Roger J. 1946. Invertébrés des couches à poissons du Crétacé supérieur du Liban. Mémoires de la Société géologique de France (Nouvelle série) 51: 5–92). These two species add to the well-known thylacocephalans from Sahel Alma: Pseuderichtus cretaceus Dames, 1886 (Dames W. 1886. Ueber einige Crustaceen aus den Kreideablagerungen des Libanon. Zeitschrift der Deutschen Geologischen Gesellschaft 38: 551–575), Protozoea hilgendorfi Dames, 1886 and Thylacocephalus cymolopos Lange et al., 2001 (Lange S, Hof CHJ, Schram FR, Steeman FA. 2001. New genus and species from the Cretaceous of Lebanon links the Thylacocephala to the Crustacea. Palaeontology 44 (5): 905–912). The occurrence of such diverse fauna of thylacocephalans markedly increases the diversity of the group during the Late Cretaceous. The diversity and abundance of the Sahel Alma thylacocephalans pose also the problem of causes of their disappearance from the fossil record after the Santonian.


2020 ◽  
Vol 63 (1) ◽  
pp. 33-42
Author(s):  
David K. Loydell

Examination of D.W.R. Wilson's PhD graptolite collection from the Howgill Fells, housed in the Lapworth Museum of Geology, University of Birmingham, reveals a high diversity (23 species) of middle Telychian graptolites from the uppermost Streptograptus crispus and Streptograptus sartorius (and possibly lowermost Monoclimacis griestoniensis) biozones. The collections include the first British records of Pseudoplegmatograptus hexagonalis and Pristiograptus pergratus. The stratigraphical range of P. pristinus is extended upwards, into the sartorius Biozone. One specimen of Stimulograptus clintonensis shows remarkable dorsal rhabdosome curvature proximally. Torquigraptus is particularly diverse in the sartorius Biozone with at least six species present: one new species, T. wilsoni, is described and two probable new species, one of which is very similar to the lower Telychian T. cavei, are left in open nomenclature.


2019 ◽  
Vol 53 (2) ◽  
pp. 255-278
Author(s):  
D. A. Chudaev

As a result of study of 18 samples, collected in Lake Teletskoye and inflowing rivers in 1992–1995, 34 diatom species of the genus Navicula Bory were found. Among them 21 taxa are new for the studied region, 7 species (Navicula arkona, N. hangaica, N. cf. pseudoreinhardtii, N. ricardae, N. scaniae, N. schweigeri, N. suecicarum) are recorded for the first time in Russia. One new species (N. pseudoharmoniae sp. nov.) is described. It is compared with N. harmoniae and N. digitoconvergens.


2015 ◽  
Vol 24 (1) ◽  
pp. 85-89
Author(s):  
Libin Ma ◽  
A.V. Gorochov

The genus Abaxitrella Gorochov, 2002 is recorded from China for the first time. Abaxitrella uncinata sp. nov. is discovered in the Chinese province Fujian; its description and illustrations as well as a key to Abaxitrella species are given.


2012 ◽  
Vol 21 (1) ◽  
pp. 131-144 ◽  
Author(s):  
A.G. Kirejtshuk ◽  
A. Nel

In the paper two new species of the genus Rhyzobius Stephens, 1829 (R. antiquus sp. nov. and R. gratiosus sp. nov.) and one new species of the genus Nephus Mulsant 1846 (N. subcircularis sp. nov. without a certain subgeneric placement) from the Lowermost Eocene amber of Oise are described. A short review of known fossil records of the family Coccinellidae is given.


2020 ◽  
Vol 63 (5) ◽  
pp. 469-478
Author(s):  
Sally C. Fryar ◽  
Kevin D. Hyde ◽  
David E. A. Catcheside

AbstractA survey of driftwood and mangrove wood in South Australia revealed a high diversity of marine fungi. Across eight sites there were 43 species of marine fungi, of which 42 are new records for South Australia, 11 new records for Australia and 12 taxa currently of uncertain status likely to be new species. Sites had distinctive species compositions with the largest difference attributable to substrate type (beach driftwood vs. mangrove wood). However, even between mangrove sites, species assemblages were distinctly different with only the more common species occurring at all mangrove sites. More intensive surveys across a broader range of habitats and geographic locations should reveal significantly more species.


Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 420
Author(s):  
María Eugenia Salgado Salomón ◽  
Carolina Barroetaveña ◽  
Tuula Niskanen ◽  
Kare Liimatainen ◽  
Matthew E. Smith ◽  
...  

This paper is a contribution to the current knowledge of taxonomy, ecology and distribution of South American Cortinarius (Pers.) Gray. Cortinarius is among the most widely distributed and species-rich basidiomycete genera occurring with South American Nothofagaceae and species are found in many distinct habitats, including shrublands and forests. Due to their ectomycorrhizal role, Cortinarius species are critical for nutrient cycling in forests, especially at higher latitudes. Some species have also been reported as edible fungi with high nutritional quality. Our aim is to unravel the taxonomy of selected Cortinarius belonging to phlegmacioid and myxotelamonioid species based on morphological and molecular data. After widely sampling Cortinarius specimens in Patagonian Nothofagaceae forests and comparing them to reference collections (including holotypes), we propose five new species of Cortinarius in this work. Phylogenetic analyses of concatenated rDNA ITS-LSU and RPB1 sequences failed to place these new species into known Cortinarius sections or lineages. These findings highlight our knowledge gaps regarding the fungal diversity of South American Nothofagaceae forests. Due to the high diversity of endemic Patagonian taxa, it is clear that the South American Cortinarius diversity needs to be discovered and described in order to understand the evolutionary history of Cortinarius on a global scale.


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