scholarly journals O REGISTRO FÓSSIL DAS COBERTURAS SEDIMENTARES DO CRÁTON DO SÃO FRANCISCO EM MINAS GERAIS

2015 ◽  
Author(s):  
Jonathas S. Bittencourt ◽  
Matheus Kuchenbecker ◽  
André Gomide Vasconcelos ◽  
Karin E. B. Meyer
Keyword(s):  
Early Cretaceous ◽  
Fossil Record ◽  
Sedimentary Basins ◽  
Minas Gerais ◽  
The Other ◽  
Widespread Occurrence ◽  
Microbial Structures ◽  
Sedimentary Deposits ◽  
Fossil Preservation ◽  
Paleozoic Rocks

O registro fóssil dos depósitos sedimentares proterozoicos, paleozoicos e mesozoicos do Cráton do São Francisco inclui estruturas de origem microbiana (microbialitos, oncólitos), palinomorfos terrestres e marinhos, microfósseis silicosos e carbonáticos de origem marinha, metazoários neoproterozoicos, artrópodes, uma variedade de bioturbações, vertebrados actinopterígios, sarcopterígios e dinossauros. Com exceção dos microbialitos, que são amplamente distribuídos, os fósseis são relativamente escassos se comparados com a extensão geográfica dos depósitos e concentrados em alguns horizontes estratigráficos excepcionais. A raridade dos achados pode ser explicada pela falta de prospecção nas áreas mais distantes das localidades tradicionalmente conhecidas, e também ao baixo potencial de preservação dos fósseis em ambientes deposicionais do Meso e Neoproterozoico, ou de regimes climáticos extremos, i.e. glacial para o Paleozoico e desértico para as porções mesozoicas da Bacia Sanfranciscana. Trabalhos recentes de prospecção, no entanto, têm revelado um potencial significativo para novas descobertas, especialmente na região norte de Minas Gerais. Parte dos registros cenozoicos está distribuída em bacias restritas incluindo as de Gandarela e Fonseca (Eoceno-Mioceno), onde basicamente se preservou folhas de angiospermas e gimnospermas, palinomorfos e insetos, e a Bacia de Juatuba, com registro predominante de folhas de angiospermas O Quaternário constitui uma exceção do ponto de vista da diversidade e abundância de fósseis, especialmente devido à ampla ocorrência de mamíferos em sistemas cársticos. A descontinuidade dos depósitos sedimentares no Cráton do São Francisco mostram hiatos de cerca de 250 milhões de anos entre as seções fossilíferas paleozoicas e de cerca de 125 milhões de anos (Eocretáceo ao Pleistoceno) para a fauna de vertebrados. Palavras-chave: paleontologia, bacias sedimentares, registro fóssil, Proterozoico, Mesozoico, Cenozoico Abstract: THE FOSSIL RECORD OF THE SEDIMENTARY COVERS OF THE SÃO FRANCISCO CRATON IN MINAS GERAIS. The fossil record of the Proterozoic, Paleozoic and Mesozoic sedimentary deposits of the São Francisco Craton includes microbial structures (microbialites and oncoliths), terrestrial and marine palynomorphs, siliceous and calcareous marine microfossils, Neoproterozoic metazoans, arthropods, a variety of bioturbations, actinopterygians, sarcopterygians and dinosaurs. Except for the microbialites, which are widely distributed, the fossils are relatively scarce if compared with the geographic extension of the deposits and concentrated in some exceptional sedimentary horizons. The rarity of the findings can be explained by the lack of fieldwork far from the localities traditionally explored, and the low potential of fossil preservation in paleoenvironments of Paleo and Mesoproterozoic or those under extreme climatic regimes, i.e. glacial for the Paleozoic rocks and desertic for most of the Mesozoic rocks within the Sanfranciscana Basin. On the other hand, recent works have revealed a significant potential for new discoveries, especially in northern Minas Gerais. Part of the Cenozoic record is distributed across restrict basins, including Gandarela and Fonseca (Eocene-Miocene), where basically leaves of angiosperms and gymnosperms, palynomorphs and insects are preserved, and the Juatuba Basin, with predominant record of angiosperm leaves. The Quaternary is an exception of fossil diversity and abundance, due to the widespread occurrence of mammals in karstic deposits. The discontinuity of the sedimentary deposits in the São Francisco Craton shows gaps in the fossil record, which encompass c. 250 my between the Neoproterozoic and Paleozoic, and c. 125 my (Early Cretaceous to Pleistocene) for the vertebrate fauna. Keywords: paleontology, sedimentary basins, fossil record, Proterozoic, Mesozoic, Cenozoic

Foot scales in the Early Cretaceous bird Gansus from China provide evidences on the evolution of avian scales

2021 ◽  
Author(s):  
Tao Zhao ◽  
Zhiheng Li ◽  
He Zhang ◽  
Yanhong Pan
Keyword(s):  
Signaling Pathway ◽  
Early Cretaceous ◽  
Fossil Record ◽  
The Other ◽  
Signaling Modules

Abstract Most modern birds have scales covering the foot, while our knowledge of early avian scales is limited, mainly due to the scarcity of fossil record. Here we characterize the morphological details of two types of scales preserved in IVPP V15077, a referred specimen of the Early Cretaceous bird Gansus. The scutellate and interstitial scales, which, in combination with previous discovery of scutate and reticulate scales in other Early Cretaceous birds, indicates that all four types present in modern birds have appeared in the Early Cretaceous. A phylogenetic context of fossilized scales suggests that the evolution of reticulate scales is conservative while that of the other types is more variable. It is consistent with the molecular hypothesis of the scales in modern birds and reptiles that most integumentary structures in amniotes are homologous with modified signaling modules to form various integumentary phenotypes, among which the reticulate scales may use the conserved signaling pathway.

scholarly journals The non-uniformity of fossil preservation

2016 ◽  
Vol 371 (1699) ◽  
pp. 20150130 ◽  
Author(s):  
Steven M. Holland
Keyword(s):  
Fossil Record ◽  
Primary Source ◽  
Sedimentary Basins ◽  
Probabilistic Methods ◽  
Depositional Facies ◽  
Empirical Estimates ◽  
Low Probability ◽  
Fossil Preservation ◽  
Long Timescales

The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’.

Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

2012 ◽  
Vol 39 (2) ◽  
pp. 217-233 ◽  
Author(s):  
J. David Archibald
Keyword(s):  
Fossil Record ◽  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Charles Darwin ◽  
The Other ◽  
Charles Lyell ◽  
Single Origin ◽  
Molecular Studies ◽  
Richard Owen ◽  
First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

scholarly journals Convergent evolution of ramified antennae in insect lineages from the Early Cretaceous of Northeastern China

2016 ◽  
Vol 283 (1839) ◽  
pp. 20161448 ◽  
Author(s):  
Taiping Gao ◽  
Chungkun Shih ◽  
Conrad C. Labandeira ◽  
Jorge A. Santiago-Blay ◽  
Yunzhi Yao ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Motion Detection ◽  
Lower Cretaceous ◽  
Fossil Record ◽  
Convergent Evolution ◽  
Chemical Cues ◽  
Northeastern China ◽  
Environmental Cues ◽  
Key Innovation ◽  
Temperature Levels

Antennae are important, insect sensory organs that are used principally for communication with other insects and the detection of environmental cues. Some insects independently evolved ramified (branched) antennae, which house several types of sensilla for motion detection, sensing olfactory and chemical cues, and determining humidity and temperature levels. Though ramified antennae are common in living insects, occasionally they are present in the Mesozoic fossil record. Here, we present the first caddisflies with ramified antennae, the earliest known fossil sawfly, and a scorpionfly also with ramified antennae from the mid-Lower Cretaceous Yixian Formation of Northeastern China, dated at 125 million years ago (Ma). These three insect taxa with ramified antennae consist of three unrelated lineages and provide evidence for broad structural convergence that historically has been best demonstrated by features such as convergent mouthparts. In addition, ramified antennae in these Mid-Mesozoic lineages likely do not constitute a key innovation, as they are not associated with significantly increased diversification compared with closely related lineages lacking this trait, and nor are they ecologically isolated from numerous, co-occurring insect species with unmodified antennae.

scholarly journals The oldest hexanchiform shark from the Southern Hemisphere (Neoselachii; Early Cretaceous, Antarctica)

2009 ◽  
Vol 21 (5) ◽  
pp. 501-504 ◽  
Author(s):  
Alberto Luis Cione ◽  
Francisco Medina
Keyword(s):  
Southern Hemisphere ◽  
Antarctic Peninsula ◽  
Early Cretaceous ◽  
The Other ◽  
James Ross Island

AbstractThe oldest record of the hexanchiform sharks from the Southern Hemisphere and the second chondrichthyan report known from Carboniferous to Early Cretaceous beds in Antarctica is given. The material was collected in late Aptian rocks of the Kotick Point Formation outcropping in the western part of James Ross Island, near Antarctic Peninsula. It consists of an isolated tooth assignable to a hexanchiform different from the other described genera. The tooth shows putative plesiomorphic cusp (few cusps, no serrations) and apomorphic root characters (relatively deep, quadrangular). It could be related to a species close to the origin ofHexanchus(unknown in beds older than Cenomanian).

A NOTE ON THE BIOLOGY OF ANOPLIUS TENUICORNIS (TOURNIER) IN NORTH AMERICA (HYMENOPTERA: POMPILIDAE)

1987 ◽  
Vol 119 (1) ◽  
pp. 103-103
Author(s):  
S. Koponen ◽  
M.S. Wasbauer
Keyword(s):  
North America ◽  
The Other ◽  
Biological Information ◽  
Broad Distribution ◽  
Widespread Occurrence ◽  
Rotten Wood ◽  
Holarctic Species

Anoplius tenuicornis (Tournier) is a holarctic species with a broad distribution both in Europe (Wolf 1967) and North America (Wasbauer and Kimsey 1985). Despite the widespread occurrence of the species, individuals are not frequently encountered, so it is not surprising that biological information on it has not been available for North America and very little for Europe. Richards and Hamm (1939) gave two fragmentary reports of some significance on A. tenuicornis in England, reported as A. piliventris (Morawitz). In one case, cocoons of the wasp were found in dead thistle stems. In the other, an old burrow of Ectemnius continuus (Fabricius) (Sphecidae) (reported as Solenius) in rotten wood contained a series of wasp cocoons and fragments of clubionid spiders, the presumed prey.

scholarly journals The complex vocalization of Scinax cardosoi (Anura: Hylidae), with comments on advertisement calls in the S. ruber Clade

2015 ◽  
Vol 14 (2) ◽  
pp. 127 ◽  
Author(s):  
Thiago Ribeiro de Carvalho ◽  
Lucas Borges Martins ◽  
Ariovaldo Antonio Giaretta
Keyword(s):  
Original Description ◽  
Minas Gerais ◽  
The Other ◽  
Single Type ◽  
Southeastern Brazil ◽  
Advertisement Calls ◽  
Call Duration ◽  
Phenotypic Characters ◽  
Acoustic Data ◽  
Lower Amplitude

The complex vocalization of Scinax cardosoi (Anura: Hylidae), with comments on advertisement calls in the S. ruber Clade. The complex vocalization of Scinax cardosoi from a population of Minas Gerais in southeastern Brazil is described and compared with available acoustic data for the other species of the S. ruber Clade. Three distinct types of high-pitched, pulsed calls were identified, and are referred to as “short,” “long,” and “trilled” calls. Short calls (16–66 ms) resemble squeaks, and consist of a pulsed signal (8–28 pulses/call) with regular amplitude modulations throughout their duration; the amplitude peak occurs at about the midpoint of the call duration. Long calls (268–518 ms) resemble giggles, and have lower amplitude than short calls; typically, they consist of pulsed note series (1–6 notes/call). Trilled calls resemble insect chirps and have the lowest amplitude of the three call types; they consist of long (1.1–3.0 s) pulsed note series (9–25 notes/call). Acoustic data are taxonomically informative in the Scinax ruber Clade and provide phenotypic characters diagnosing S. cardosoi in addition to those features proposed in its original description. The vocalization repertoire of S. cardosoi resembles the complex vocal repertoires (i.e., multiple call types emitted in variable combinations) of members of the S. catharinae Clade more than some species of the S. ruber Clade, which tend to have simpler call structures (i.e., a single type of multipulsed note).

Stratigraphic biases in the analysis of taxonomic survivorship

Paleobiology ◽  
1975 ◽  
Vol 1 (4) ◽  
pp. 343-355 ◽  
Author(s):  
J. John Sepkoski
Keyword(s):  
Simple Model ◽  
Lognormal Distribution ◽  
Fossil Record ◽  
The Other ◽  
Time Intervals ◽  
Survivorship Analysis ◽  
Other Hand ◽  
Incomplete Sampling ◽  
Biologic Factors

Taxonomic survivorship curves may reflect stratigraphic as well as biologic factors. The approximately lognormal distribution of lengths of Phanerozoic time intervals produces an error in the estimation of taxonomic durations that is also lognormally distributed. As demonstrated by several simulated examples, this error may cause concave taxonomic survivorship curves to appear linear, especially if the maximum durations involved are relatively short. The error of estimation also makes highly concave taxonomic survivorship curves virtually unrecognizable. Incomplete sampling of the fossil record, on the other hand, may not be a serious problem in survivorship analysis. Simulated paleontological sampling employing a simple model suggests that survivorship curves tend to retain their original shapes even when as few as 20% of the taxa have been discovered. However, concave taxonomic survivorship curves tend to lose their concavity as efficiency of sampling declines.

scholarly journals Mass contents of natural radioactive elements in the main types of rocks of the Mesozoic sediments of the West-Siberian Plate and their comparative assessment with the contents in the deposits of some sedimentary basins of the former USSR

2020 ◽  
Vol 177 ◽  
pp. 02004
Author(s):  
Viacheslav Turyshev
Keyword(s):  
Western Siberia ◽  
Sedimentary Rocks ◽  
Sedimentary Basins ◽  
Comparative Assessment ◽  
Radioactive Elements ◽  
The West ◽  
Sedimentary Deposits ◽  
Former Ussr

The average and boundary contents of natural radioactive elements in sandy, aleuritic, argillaceous, mixed and carbonaceous types of sedimentary rocks of the main groups of productive strata of the Jurassic-Cretaceous age of Western Siberia are estimated; a comparison of the obtained values of the contents of radioelements with their contents in sedimentary deposits of some regions of the former USSR is performed.

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