scholarly journals A vanished history of skeletonization in Cambrian comb jellies

2015 ◽  
Vol 1 (6) ◽  
pp. e1500092 ◽  
Author(s):  
Qiang Ou ◽  
Shuhai Xiao ◽  
Jian Han ◽  
Ge Sun ◽  
Fang Zhang ◽  
...  
Keyword(s):  
Sense Organ ◽  
Early Evolution ◽  
Monophyletic Group ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Animal Groups ◽  
New Class ◽  
History Of ◽  
Ecological Importance

Ctenophores are traditionally regarded as “lower” metazoans, sharing with cnidarians a diploblastic grade of organization. Unlike cnidarians, where skeletonization (biomineralization and sclerotization) evolved repeatedly among ecologically important taxa (for example, scleractinians and octocorals), living ctenophores are characteristically soft-bodied animals. We report six sclerotized and armored ctenophores from the early Cambrian period. They have diagnostic ctenophore features (for example, an octamerous symmetry, oral-aboral axis, aboral sense organ, and octaradially arranged ctene rows). Unlike most modern counterparts, however, they lack tentacles, have a sclerotized framework, and have eight pairs of ctene rows. They are resolved as a monophyletic group (Scleroctenophora new class) within the ctenophores. This clade reveals a cryptic history and sheds new light on the early evolution of this basal animal phylum. Skeletonization also occurs in some other Cambrian animal groups whose extant members are exclusively soft-bodied, suggesting the ecological importance of skeletonization in the Cambrian explosion.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

scholarly journals Extraordinary fossils reveal the nature of Cambrian life: a commentary on Whittington (1975) ‘The enigmatic animal Opabinia regalis , Middle Cambrian, Burgess Shale, British Columbia’

2015 ◽  
Vol 370 (1666) ◽  
pp. 20140313 ◽  
Author(s):  
Derek E. G. Briggs
Keyword(s):  
British Columbia ◽  
Royal Society ◽  
Early Evolution ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Critical Interval ◽  
Middle Cambrian ◽  
Early Ordovician ◽  
History Of ◽  
350Th Anniversary

Harry Whittington's 1975 monograph on Opabinia was the first to highlight how some of the Burgess Shale animals differ markedly from those that populate today's oceans. Categorized by Stephen J. Gould as a ‘weird wonder’ ( Wonderful life , 1989) Opabinia , together with other unusual Burgess Shale fossils, stimulated ongoing debates about the early evolution of the major animal groups and the nature of the Cambrian explosion. The subsequent discovery of a number of other exceptionally preserved fossil faunas of Cambrian and early Ordovician age has significantly augmented the information available on this critical interval in the history of life. Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .

Origin and Early Evolution of Animals

2014 ◽  
Author(s):  
Kevin J. Peterson
Keyword(s):  
Complex System ◽  
Developmental Biology ◽  
Early Evolution ◽  
Cambrian Explosion ◽  
Static System ◽  
The Earth ◽  
Remarkable Event ◽  
History Of ◽  
To Come ◽  
The One

Coming at the end of one of the most intensive glaciation periods in Earth history (glaciers at sea level on the equator!), the explosive rise of animals 530 million years ago is one of the few major events in the history of life that combines the evolution of novel developmental regulatory circuitry with the emergence of unique environmental circumstances. This “Cambrian explosion” is truly a remarkable event in the history of life, as the Earth’s biota went from an essentially static system billions of years in existence to the one we enjoy today, a dynamic and awesomely complex system that forever changed the Earth’s biota, and ultimately the Earth itself. Part of the intrigue with the Cambrian explosion is that numerous phyla with very distinct body plans (whether arthropod, annelid, mollusk, echinoderm, or chordate) arrive on the scene in a geological blink of the eye, with little or no warning of what is to come in rocks that predate this interval of time. The abruptness of the transition between the “Precambrian” to the Cambrian was apparent early on with the publication of Murchison’s The Silurian System (1839), and is still apparent today. Indeed, the abruptness of the explosion has only gotten more pronounced since Murchison’s time as more and more of the Earth’s geological record has been explored, and accurate and precise dates have been placed on many of these outcrops. The books and papers in this article highlight the multifarious nature of the origin and early evolution of animals, ranging from morphology, to phylogeny, to paleontology, to developmental biology, and even to geochemistry and molecular biology.

scholarly journals The origin and early evolution of arthropods

2021 ◽  
Author(s):  
Cédric Aria
Keyword(s):  
Critical Role ◽  
Ecological Networks ◽  
Early Evolution ◽  
Cambrian Explosion ◽  
Full Potential ◽  
New Approaches ◽  
History Of ◽  
Patterns And Processes

The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pillars of the planet’s ecological networks. Forerunners of this epopee, exceptionally-preserved Palaeozoic fossils recently discovered or re-discovered thanks to new approaches and techniques have elucidated the precocious appearance of extant lineages at the onset of the Cambrian explosion, and pointed to the critical role of the plankton and hard integuments in early arthropod diversification. Despite new interpretative challenges, phylogenetic advances based on palaeontological evidence open the prospect of finally using the full potential of the most diverse animal phylum to investigate macroevolutionary patterns and processes.

Basal Cambrian microfossils from the Yangtze Gorges area (South China) and the Aksu area (Tarim block, northwestern China)

2009 ◽  
Vol 83 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Lin Dong ◽  
Shuhai Xiao ◽  
Bing Shen ◽  
Chuanming Zhou ◽  
Guoxiang Li ◽  
...  
Keyword(s):  
Geographic Distribution ◽  
South China ◽  
Northwestern China ◽  
Cambrian Explosion ◽  
Filamentous Cyanobacteria ◽  
Primary Producers ◽  
Tarim Block ◽  
Eukaryotic Phytoplankton ◽  
History Of ◽  
Wide Geographic Distribution

The basal Cambrian marks the beginning of an important chapter in the history of life. However, most paleontological work on the basal Cambrian has been focused on skeletal animal fossils, and our knowledge about the primary producers—cyanobacteria and eukaryotic phytoplankton (e.g., acritarchs)—is limited. In this research, we have investigated basal Cambrian acritarchs, coccoidal microfossils, and cyanobacteria preserved in phosphorites and cherts of the Yanjiahe Formation in the Yangtze Gorges area (South China) and the Yurtus Formation in the Aksu area (Tarim Block, northwestern China). Our study confirms the occurrence in these two formations of small acanthomorphic acritarchs characteristic of the basal CambrianAsteridium–Comasphaeridium–Heliosphaeridium(ACH) assemblage. These acritarchs include abundantHeliosphaeridium ampliatimi(Wang, 1985) Yao et al., 2005, commonYurtusia uniformisn. gen. and n. sp., and rareComasphaeridium annulare(Wang, 1985) Yao et al., 2005. In addition, these basal Cambrian successions also contain the clustered coccoidal microfossilArchaeophycus yunnanensis(SonginLuo et al., 1982) n. comb., several filamentous cyanobacteria [Cyanonema majusn. sp.,Oscillatoriopsis longaTimofeev and Hermann, 1979, andSiphonophycus robustum(Schopf, 1968) Knoll et al., 1991], and the tabulate tubular microfossilMegathrix longusL. Yin, 1987a, n. emend. Some of these taxa (e.g.,H. ampliatum, C. annulare, andM. longus) have a wide geographic distribution but occur exclusively in basal Cambrian successions, supporting their biostratigraphic importance. Comparison between the stratigraphic occurrences of microfossils reported here and skeletal animal fossils published by others suggests that animals and phytoplankton radiated in tandem during the Cambrian explosion.

scholarly journals Elucidation of Early Evolution of HIV-1 Group M in the Congo Basin Using Computational Methods

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 517
Author(s):  
Marcel Tongo ◽  
Darren P. Martin ◽  
Jeffrey R. Dorfman
Keyword(s):  
Genetic Relatedness ◽  
Early Evolution ◽  
Congo Basin ◽  
Global Epidemic ◽  
The Past ◽  
History Of ◽  
Cold Spots ◽  
Genomic Regions ◽  
Basin Region ◽  
Hiv 1

The Congo Basin region is believed to be the site of the cross-species transmission event that yielded HIV-1 group M (HIV-1M). It is thus likely that the virus has been present and evolving in the region since that cross-species transmission. As HIV-1M was only discovered in the early 1980s, our directly observed record of the epidemic is largely limited to the past four decades. Nevertheless, by exploiting the genetic relatedness of contemporary HIV-1M sequences, phylogenetic methods provide a powerful framework for investigating simultaneously the evolutionary and epidemiologic history of the virus. Such an approach has been taken to find that the currently classified HIV-1 M subtypes and Circulating Recombinant Forms (CRFs) do not give a complete view of HIV-1 diversity. In addition, the currently identified major HIV-1M subtypes were likely genetically predisposed to becoming a major component of the present epidemic, even before the events that resulted in the global epidemic. Further efforts have identified statistically significant hot- and cold-spots of HIV-1M subtypes sequence inheritance in genomic regions of recombinant forms. In this review we provide ours and others recent findings on the emergence and spread of HIV-1M variants in the region, which have provided insights into the early evolution of this virus.

3D printing technology in musical instrument research: reviewing the potential

2018 ◽  
Vol 24 (9) ◽  
pp. 1511-1523 ◽  
Author(s):  
Antreas Kantaros ◽  
Olaf Diegel
Keyword(s):  
Additive Manufacturing ◽  
Design Methodology ◽  
Musical Instrument ◽  
Musical Instruments ◽  
Wind Instruments ◽  
Content Type ◽  
New Class ◽  
History Of ◽  
New Applications ◽  
Practical Implications

Purpose This paper aims to discuss additive manufacturing (AM) in the context of applications for musical instruments. It examines the main AM technologies used in musical instruments, goes through a history of musical applications of AM and raises the questions about the application of AM to create completely new wind instruments that would be impossible to produce with conventional manufacturing. Design/methodology/approach A literature research is presented which covers a historical application of AM to musical instruments and hypothesizes on some potential new applications. Findings AM has found extensive application to create conventional musical instruments with unique aesthetics designs. It’s true potential to create entirely new sounds, however, remains largely untapped. Research limitations/implications More research is needed to truly assess the potential of additive manufacturing to create entirely new sounds for musical instrument. Practical implications The application of AM in music could herald an entirely new class of musical instruments with unique sounds. Originality/value This study highlights musical instruments as an unusual application of AM. It highlights the potential of AM to create entirely new sounds, which could create a whole new class of musical instruments.

scholarly journals Decoupled evolution of soft and hard substrate communities during the Cambrian Explosion and Great Ordovician Biodiversification Event

2016 ◽  
Vol 113 (25) ◽  
pp. 6945-6948 ◽  
Author(s):  
Luis A. Buatois ◽  
Maria G. Mángano ◽  
Ricardo A. Olea ◽  
Mark A. Wilson
Keyword(s):  
Late Ordovician ◽  
Hard Substrate ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Continuous Increase ◽  
Late Cambrian ◽  
Unconsolidated Sediment ◽  
Underlying Causes ◽  
Hard Substrates ◽  
Shed Light

Contrasts between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE) have long been recognized. Whereas the vast majority of body plans were established as a result of the CE, taxonomic increases during the GOBE were manifested at lower taxonomic levels. Assessing changes of ichnodiversity and ichnodisparity as a result of these two evolutionary events may shed light on the dynamics of both radiations. The early Cambrian (series 1 and 2) displayed a dramatic increase in ichnodiversity and ichnodisparity in softground communities. In contrast to this evolutionary explosion in bioturbation structures, only a few Cambrian bioerosion structures are known. After the middle to late Cambrian diversity plateau, ichnodiversity in softground communities shows a continuous increase during the Ordovician in both shallow- and deep-marine environments. This Ordovician increase in bioturbation diversity was not paralleled by an equally significant increase in ichnodisparity as it was during the CE. However, hard substrate communities were significantly different during the GOBE, with an increase in ichnodiversity and ichnodisparity. Innovations in macrobioerosion clearly lagged behind animal–substrate interactions in unconsolidated sediment. The underlying causes of this evolutionary decoupling are unclear but may have involved three interrelated factors: (i) a Middle to Late Ordovician increase in available hard substrates for bioerosion, (ii) increased predation, and (iii) higher energetic requirements for bioerosion compared with bioturbation.

Towards Parallel Cable-Driven Pantographs

2011 ◽  
Author(s):  
Simon Perreault ◽  
Philippe Cardou ◽  
Cle´ment Gosselin
Keyword(s):  
Low Cost ◽  
Output Link ◽  
Static Balancing ◽  
New Class ◽  
Nonlinear Springs ◽  
Preliminary Validation ◽  
Important Challenge ◽  
History Of ◽  
Working Principle ◽  
Two Degree Of Freedom

We propose a new class of pantographs, i.e., of mechanisms that allow the reproduction of the displacements of an input link, the master, with an output link, the slave. The application we envision for these devices is the telemanipulation of objects from small distances, at low cost, where magnetic fields or other design constraints prohibit the use of electromechanical systems. Despite the long history of pantographs, which were invented in the 17th century, the class of pantographs proposed here is new, as it relies on parallel cable-driven mechanisms to transmit the motion. This allows the reproduction of rigid-body displacements, while previous pantographs were limited to point displacements. This important characteristic and others are described in the paper. One important challenge in the design of the proposed systems is that the cables must remain taut at all time. We address this issue by introducing nonlinear springs that passively maintain a minimum tension in the cables, while approximating static balancing of the mechanism over its workspace. Approximating static balancing allows the forces applied at the slave to reflect more accurately at the master, and vice versa. As a preliminary validation, a two-degree-of-freedom parallel cable-driven pantograph is designed. A prototype of this apparatus that does not include approximate static balancing is built, which demonstrates the working principle of these mechanisms.

scholarly journals Discovery, development and application of drugs targeting BCL-2 pro-survival proteins in cancer

2021 ◽  
Author(s):  
Erinna F. Lee ◽  
W. Douglas Fairlie
Keyword(s):  
Structural Biology ◽  
Protein Interactions ◽  
Basic Science ◽  
Great Success ◽  
Protein Protein Interactions ◽  
New Class ◽  
Success Stories ◽  
History Of ◽  
Approved Drugs ◽  
Close Relatives

The discovery of a new class of small molecule compounds that target the BCL-2 family of anti-apoptotic proteins is one of the great success stories of basic science leading to translational outcomes in the last 30 years. The eponymous BCL-2 protein was identified over 30 years ago due to its association with cancer. However, it was the unveiling of the biochemistry and structural biology behind it and its close relatives’ mechanism(s)-of-action that provided the inspiration for what are now known as ‘BH3-mimetics’, the first clinically approved drugs designed to specifically inhibit protein–protein interactions. Herein, we chart the history of how these drugs were discovered, their evolution and application in cancer treatment.

Sign in / Sign up

Export Citation Format

Share Document