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We report the first occurrence of microfossils in Ediacaran strata of the Camaquã Basin
The assemblage includes simple (Leiosphaeridia sp
predominantly) and ornamented acritarchs associated with microbial mats
They are related to the Ediacaran Complex Acanthomorph Palynoflora (ECAP) and Late Ediacaran Leiosphere Palynoflora (LELP) due to the similar morphology and time interval assigned to those assemblages
though the observed specimens are a lot simpler and less diversified
this case study reports Neoproterozoic cosmopolitan communities living in marine (basal unit) and lacustrine (middle units) settings
Fossils within non-marine strata in the Precambrian record are rare
this first finding of microfossils in the Camaquã Basin constitutes a new piece of the puzzle related to the history of the Panafrican-Brasiliano basins and shed some light on possible settings where the Ediacaran eukaryotes have evolved
Given the particular importance of Neoproterozoic biota for the comprehension of the spreading of life across diverse ecological niches
we register the first occurrence of Ediacaran
organic-walled microfossils preserved in fine-grained siliciclastic strata of the Camaquã Basin
most of the forms are simple and low-diversity
but related to both marine and lacustrine settings
hence representing cosmopolitan microorganisms
Photomicrograph of sedimentary features and microfossil content
(A) Fine-grained facies of Maricá Group seen under natural light showing a sphaeromorph acritarch (red arrow)
and carbonate cement around the grains; (B) Fine-grained facies form Maricá Group seen under polarized light showing a sphaeromorph acritarch (red arrow)
grains trapped (yellow arrows) by filamentous bacterial mats (blue arrows)
and carbonate cement around the grains (green arrows)
(C) Simple spherical microfossil (red arrow) and silt grains involved by filamentous bacterial mats (blue arrow) in the fine-grained facies of the Bom Jardim Group; (D) Siltstone of the Santa Bárbara Group displaying aligned grains of mica (yellow arrow) and opaque rounded microfossil (red arrow) inside a fossilized microbial mat
Described palynological slides are kept in the Museu de História Geológica do Rio Grande do Sul - MHGEO – Unisinos
Brazil – and assigned numbers according to the collection (ULVG – UNISINOS/Laboratório de História da Vida e da Terra - Lavigea)
Location and geographic coordinates for each sample are presented in the Supplementary File
One hundred forty nine complete specimens and dozens of fragments of sphaeromorphs were extracted from mudstones of the Maricá
Bom Jardim and Santa Bárbara outcrops (see Supplementary File - Table ST1)
commonly folded vesicles with smooth to shagrinate or granular wall surface
The Camaquã Basin palynomorphs includes more than one leiosphaerid species
but it is impossible to assert which species because the poor preservational quality precludes the identification of wall internal details and thickness
Based on the size of the recovered specimens it is possible to associate then with two potential species: L
the lack of diagnostic features about wall-thickness within this group of acritarchs makes difficult to ascribe them to species level
acid-resistant microfossils consisting of spherical to sub-spherical vesicle bearing numerous hollow
cylindrical processes distributed around the vesicle outline
The processes are more or less of equal size (in a single specimen)
differing in number between specimens and not very evenly distributed
Six complete and dozens of fragmented vesicles appear in palynological material extracted from mudstones of the Maricá
acid-resistant microfossils consisting of originally spherical to sub-spherical vesicles irregular in outline ornamented with long
Diameter ranging from 50 to 150 µm and spines ranging from 10 to 20 µm
The name derives from Latin irregularis – irregular
Type species Lophosphaeridium rarum Timofeev
Twenty-six entire and dozens of fragmented specimens extracted from mudstones of the Maricá
Compactional folds present on some specimens
The surface of the vesicle displays numerous tightly arranged
small conical spines that are visible as evenly small hairs distributed around the vesicle outline
Conical projections are approximately 10–15 µm long
but it not possible to ascribe them to species level
Type species Germinosphaera bispinosa Mikhailova
Forty-two microfossils extracted from mudstones of Maricá
acid-resistant spheroidal vesicles with one or more open-ended
tubular and occasionally branched processes that communicate freely with the vesicle
occasionally with a vase-shaped form with short or elongated processes
The fine-grained strata of the Maricá Group record a short-distance transport of immature
angular to sub-angular sediments deposited under wave action in a shallow marine setting (See Supplementary File)
No micro (hematite coating) or macroscopic (desiccation cracks) features related to subaerial exposure were identified
both Bom Jardim and Santa Bárbara groups also comprise immature
short-distance transported sediments deposited in a subaqueous realm
a much larger alluvial influence (relative to the Maricá Group)
and associated hyperpycnal turbidity currents
and rare (Bom Jardim Group) to common (Santa Bárbara Group) subaerial exposure of the depositional surface suggest continental
deep- to shallow lacustrine settings (See Photographs in Supplementary File)
eodiagenetic hematite coatings are widespread in both units
Acritarchs view under transmitted light microscopy
and (C) Santa Bárbara (sample ULVG 12511) groups; (D,E) Lophosphaeridium sp
from (D) Maricá (sample ULVG 12518) and (E) Bom Jardim (sample 12495) groups; (F)
Tanarium irregulare from Santa Bárbara Group (sample 12487); (G–J)
original opaque (G) and illuminated (H) image
and (J) Santa Bárbara (sample ULVG 12515) groups
Acritarchs view on scanning electron microscopy
from Maricá Group (sample ULVG 12509); (C,D) Leiosphaeridia sp
(D) with filamentous bacteria from Bom Jardim Group (sample ULVG 12506); (E,F) Germinosphaera sp
(F) from Santa Bárbara Group (sample ULVG 12508) with bacterial mats fragments
Note folded microfossils due to compaction (B,C images)
We demonstrate that the first find of body fossils in the Camaquã Basin add new information about the Ediacaran fossil record of South America and fill some gaps about microfossils existence and distribution in a Proto-Gondwana context
Several Ediacaran basins as Nama (Namibia)
Corumbá (Brazil) and others register body fossils related to ECAP and ELP assemblages
Even simpler and less diversified that those assemblages
the Camaquã Basin microfossils reported here include Camaquã Basin as hostess of Ediacaran life at southwestern Proto-Gondwana
This time interval is compatible with the Santa Bárbara Group
which reflect shallow-lacustrine conditions
The first finding of body fossils in the Camaquã Basin adds new evidence about the Ediacaran fossil record of South America
improves the dataset and complements the scenario of life within the Proto-Gondwana
Based on their similar morphology and assigned time interval the reported microfossils could be ascribed to the Ediacaran Complex Acanthomorph Palynoflora (ECAP) and Late Ediacaran Leiosphere Palynoflora (LELP)
even though the observed specimens are simpler and less diversified
The finding of microfossils in marine and lacustrine strata and the profusion of Leiosphaerids suggest that both habitats were already colonized by cosmopolitan eukaryotes by the Late Ediacaran
the lack of typical components of the Ediacara fauna suggest restrictive ecological conditions in both marine and lacustrine realms during the Camaquã Basin evolution
the close relationship between microfossils and bacterial mats suggest a possible link between both components of the Camaquã Basin biota and their living conditions
raw samples were mechanically disaggregated
they were digested with HCl and HF for carbonate and silicate removal
Boiling HCl was used for the removal of clay minerals
Strewed kerogen was oxidized with concentrated HNO3
After filtration (10 µm filter size) and swirling to separate heavy minerals
strew slides were prepared and examined under transmitted light microscope with interference contrast (Zeiss Axio Imager-A2)
SEM-EDS (scanning electron microscopy plus energy-dispersive X-ray spectroscopy) analyses were performed on gold-coated samples obtained from representative microfossil specimens
SEM studies were executed at Instituto Tecnológico de Micropaleontologia - itt FOSSIL - of the Universidade do Vale do Rio dos Sinos – UNISINOS (São Leopoldo City/Rio Grande do Sul State)
at Laboratório de Conformação Nanométrica – Instituto de Física of the Universidade Federal do Rio Grande do Sul – UFRGS (Porto Alegre/Rio Grande do Sul)
using a JIP-4500 MultiBeam SEM-FIB equipment and at Laboratório Nacional de Nanotecnologia – LNNano - of the Centro Nacional de Pesquisa em Energia e Materiais – CNPEM (Campinas/São Paulo)
All data generated or analysed during this study are included in this published article and in the Supplementary File
Stromatolites in Precambrian Carbonates: Evolutionary Mileposts or Environmental Dipsticks
Wrinkle structures: microbially mediated sedimentary structures common in subtidal siliciclastic settings at the Proterozoic Phanerozoic transition
Microbial mats in terminal Proterozoic siliciclastics: Ediacaran death masks
Preserved stable isotopic signature of subaerial diagenesis in the 1.2-b.y
central Arizona: Implications for the timing and development of a terrestrial plant cover
Palaeocology of a billion-year-old non-marine cyanobacterium from the Torridon Group and Nonesuch Formation
Life on land in the Proterozoic: evidence from the Torridonian rocks of northwest Scotland
The Geological Structure of the North-west Highlands of Scotland (eds Peach
plate LII (Memoirs of the Geological Society of Great Britain
New Pre-Paleozoic Nannofossils from the Stoer Formation (Torridonian)
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Preliminary report about trace fossils in Precabrian/Cambrian deposits of Southern Brazil
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A discussion and proposals concerning fossil dinoflagellates
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Acritarchs from the type area of the Ordovician Caradoc Series
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This research was supported by the FAPERGS 01/2017 ARD Project entitled Geobiology of the Ediacaran Camaquã Basin (Brazil) (Grant Number 17/2551-0000 824-3)
The first author thanks CAPES for her scholarship (Grant Number 88887.150701/2017-00)
The third author acknowledges CNPq for the long-term support (Grant Number 308140/2014-1)
UFRGS and CNPEM for providing lab facilities (SEM and X-ray) and field equipment
Sebastian Willman (Uppsala University) for the discussions about the palynological material; Dr
for valuable assistance and review of a first draft of this MS
The authors also thank the editor for the assistance
Rodrigo Scalise Horodyski & Paulo Sérgio Gomes Paim
contributed with sedimentology and palaeontology research
contributed with palaeontology data and P.S.G.P
contributed with geology and sedimentology research and review
The authors declare no competing interests
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations
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The Brazilian Navy has finally confirmed the location of the Vital de Oliveiro
a Brazilian troop transport ship torpedoed and sunk by a Nazi submarine during World War II
The wreck was identified using advanced sonar imaging
lying about 65 kilometres off the coast of Rio de Janeiro
The Vital de Oliveiro was originally built in 1910 as a civilian ship named Itauba
It joined the Brazilian Navy in 1931 and became a troop transport during World War II
The ship was involved in transporting military personnel and supplies along the Brazilian coast during the war
the ship was torpedoed by the German submarine U-861
and 100 of the 270 crew members onboard lost their lives
Vital de Oliveiro became the only Brazilian military ship to be sunk by enemy forces during World War II
the ship’s exact location remained unknown until 2011
when it was first found by divers Jose Luíz and Everaldo Popermeyer Meriguete
The brothers had been called by a fisherman whose net had become stuck at the bottom of the ocean
and with the help of deep-sea diver Domingos Afonso Jório
it was confirmed that the net had caught on a cannon
the exact identification of the wreck remained unclear for years
the Brazilian Navy confirmed the wreck was indeed that of the Vital de Oliveiro
The Navy used multibeam and side-scan sonar technology aboard an oceanographic research vessel to conclusively identify the wreck
These sonar tools allowed researchers to visualise the hull and structural features of the ship
Lieutenant Captain Caio Cezar Pereira Demilio of the Brazilian Navy stated that shipwrecks and other submerged structures are crucial material records of Brazil’s maritime history
These discoveries help the country understand naval strategies
and events like military confrontations and maritime disasters
the Brazilian Navy lost two other warships during World War II
sank in 1945 after accidentally detonating its depth charges during gunnery practice
the research vessel that confirmed the wreck’s location was also named Vital de Oliveiro
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The southern region of Brazil is characterized by high species diversity and endemism of freshwater fishes distributed across geographically isolated river basins
Microglanis cottoideshas a widespread range across these river basins and occurs in sympatry with other endemic species of the genus (e.g
cottoides and presented for the first time information about the molecular phylogeny of species in the genus
cottoides currently forms a non-monophyletic group which includes populations endemic to the Uruguay River basin that are more closely related to M
Based on an integrative approach using morphological and molecular data
and the populations of the Uruguay River basin previously assigned to M
The time-calibrated phylogeny indicates that the separation between inland and the coastal clades occurred in the Tertiary period
and that the species within the coastal basins diverged in the Pliocene
which overlaps with the diversification times estimated for the two inland species as well
This pattern of diversification corroborates some previous studies with other fishes from the same region
30o54’5.6″S 52o05’18.9″W (Photo by O.A
Median-joining networks and Bayesian phylogenetic tree of Micriglanis obtained with COI data
(A) Median-Joining networks among haplotypes
Each circle represents a unique haplotype with circle sizes being proportional to their frequencies
The numbers between haplotypes correspond to mutational steps
Haplotypes: H1 = Ribeira; H2 = Guaratuba + Paranaguá + Itapocu; H3 = Paranaguá; H4 = Paranaguá; H5 = Madre; H6 = Araranguá; H7 = Araranguá; H8 = M
cibelae (Tramandaí); H10 = Patos (Camaquã); H11 = Negro + Uruguay; H12 = Uruguay; H13 = Uruguay; H14 = Microglanis sp
Node bars represent the threshold time for each cladogenetic event
The values above the branches indicate the posterior probability (pp)
* Individuals collected in their respective type locality
Link: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199963