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1.
BMC Emerg Med ; 23(1): 64, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-37280527

RESUMO

INTRODUCTION: It has not yet been possible to ascertain the exact proportion, characterization or impact of low-acuity emergency department (ED) attendances on the German Health Care System since valid and robust definitions to be applied in German ED routine data are missing. METHODS: Internationally used methods and parameters to identify low-acuity ED attendances were identified, analyzed and then applied to routine ED data from two EDs of the tertiary care hospitals Charité-Universitätsmedizin Berlin, Campus Mitte (CCM) and Campus Virchow (CVK). RESULTS: Based on the three routinely available parameters `disposition´, `transport to the ED´ and `triage´ 33.2% (n = 30 676) out of 92 477 presentations to the two EDs of Charité-Universitätsmedizin Berlin (CVK, CCM) in 2016 could be classified as low-acuity presentations. CONCLUSION: This study provides a reliable and replicable means of retrospective identification and quantification of low-acuity attendances in German ED routine data. This enables both intra-national and international comparisons of figures across future studies and health care monitoring.


Assuntos
Serviço Hospitalar de Emergência , Triagem , Humanos , Estudos Retrospectivos
2.
BMC Neurol ; 22(1): 455, 2022 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-36476357

RESUMO

BACKGROUND AND AIMS: Myasthenia Gravis requires expert treatment from specialized neurologists. In Germany, this treatment is mainly provided by 18 Integrated Myasthenia Centers (iMZ) accredited by the German Myasthenia Gravis Association (DMG). The DMG is a large and well-organized patient organisation that is regarded as a trusted source for disease-specific information. The aim of this study was to analyse the type of requests that each of these institutions receives in order to identify any potential unmet needs regarding the availability of advice for patients and caregivers. This data can then be used in further research to tailor modern digital communication tools to the specific needs of MG patients. METHODS: Counselling requests sent via e-mail to both institutions were extracted for defined examination periods and divided into a period 'before COVID-19 pandemic' (01.07.2019-31.12.2019) and 'during COVID-19 pandemic' (01.07.2020-31.12.2020). Requests were then analysed using four main categories: medical requests, organisational issues, COVID-19 and social legislation inquiries. RESULTS: One thousand seven hundred eleven requests for advice were addressed to DMG and iMZ Charité. Most inquiries directed to the DMG (47%; n = 750) were related to medical issues, most frequently to side effects of medications (n = 325; 20%) and questions about treatment (n = 263; 16%), followed by inquiries regarding organisational issues (26%; n = 412). About half of the inquiries (n = 69; 58%) to the iMZ Charité were related to medical issues and almost one in three inquiries concerned organisational issues (n = 37; 30%). About one in ten inquiries concerned socio-legal matters (iMZ: n = 7; 6% and DMG: n = 177; 11%). During the pandemic, COVID-19 related issues accounted for 8% (n = 6) of inquiries at iMZ, and 16% (n = 253) at DMG. CONCLUSIONS: MG sufferers have a high demand for timely advice. In the current setting, they address their requests to both iMZs and the DMG via e-mail. Our findings confirm that the DMG is highly trusted by patients and caregivers and is used to obtain second opinions. A relevant proportion of requests to the iMZ could be answered more effectively through standardized responses or improved process management. The implementation of modern digital solutions, including telemedicine, for communication between patient and specialist should be evaluated in further research.


Assuntos
COVID-19 , Pandemias , Humanos , Estudos Retrospectivos , Alemanha/epidemiologia
3.
Proc Biol Sci ; 288(1953): 20210464, 2021 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-34157876

RESUMO

The biological pump is crucial for transporting nutrients fixed by surface-dwelling primary producers to demersal animal communities. Indeed, the establishment of an efficient biological pump was likely a key factor enabling the diversification of animals over 500 Myr ago during the Cambrian explosion. The modern biological pump operates through two main vectors: the passive sinking of aggregates of organic matter, and the active vertical migration of animals. The coevolution of eukaryotes and sinking aggregates is well understood for the Proterozoic and Cambrian; however, little attention has been paid to the establishment of the vertical migration of animals. Here we investigate the morphological variation and hydrodynamic performance of the Cambrian euarthropod Isoxys. We combine elliptical Fourier analysis of carapace shape with computational fluid dynamics simulations to demonstrate that Isoxys species likely occupied a variety of niches in Cambrian oceans, including vertical migrants, providing the first quantitative evidence that some Cambrian animals were adapted for vertical movement in the water column. Vertical migration was one of several early Cambrian metazoan innovations that led to the biological pump taking on a modern-style architecture over 500 Myr ago.


Assuntos
Evolução Biológica , Fósseis , Animais , Proteínas de Membrana Transportadoras , Oceanos e Mares
4.
Proc Natl Acad Sci U S A ; 113(16): 4410-5, 2016 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-27044103

RESUMO

The ∼430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities-that the tethered individuals represent a different epizoic or parasitic arthropod-appear less likely.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/fisiologia , Fósseis , Animais , Inglaterra
5.
Proc Biol Sci ; 284(1851)2017 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-28330926

RESUMO

Cascolus ravitis gen. et sp. nov. is a three-dimensionally preserved fossil crustacean with soft parts from the Herefordshire (Silurian) Lagerstätte, UK. It is characterized by a head with a head shield and five limb pairs, and a thorax (pereon) with nine appendage-bearing segments followed by an apodous abdomen (pleon). All the appendages except the first are biramous and have a gnathobase. The post-mandibular appendages are similar one to another, and bear petal-shaped epipods that probably functioned as a part of the respiratory-circulatory system. Cladistic analysis resolves the new taxon as a stem-group leptostracan (Malacostraca). This well-preserved arthropod provides novel insights into the evolution of appendage morphology, tagmosis and the possible respiratory-circulatory physiology of a basal malacostracan.


Assuntos
Crustáceos , Fósseis , Animais , Cabeça , Filogenia , Reino Unido
7.
BMC Evol Biol ; 16: 72, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-27056633

RESUMO

BACKGROUND: Paleozoic scorpions (Arachnida: Scorpiones) have been widely documented from the Carboniferous Period; which hosts a remarkable assemblage of more than sixty species including both putative stem- and crown-group fossils. By contrast the succeeding Permian Period is almost completely devoid of records, which are currently restricted to a trace fossil from the early Permian of New Mexico, USA and some limb fragments from the late Permian of the Vologda Region, Russia. RESULTS: ?Opsieobuthus tungeri sp. nov. from the Petrified Forest of Chemnitz, Germany represents the first complete body fossils of scorpions from the Permian. Explosive volcanism preserved these remarkable specimens in situ as part of the palaeosol horizon and bedrock of the Petrified Forest, immediately beneath the Zeisigwald tuff horizon. This dates to the early Permian (Sakmarian) or ca. 291 Ma. Intriguingly, the specimens were obtained from a palaeosol horizon with a compacted network of different-sized woody roots and thus have been preserved in situ in their likely life position, even within their original burrows. Differences in the structure of the comb-like pectines in the two fossils offer evidence for sexual dimorphism, and permit further inferences about the ecology and perhaps even the reproductive biology of these animals. CONCLUSIONS: As putative members of a Coal Measures genus, these fossils suggest that at least some Carboniferous scorpion lineages extended their range further into the Permian. This contributes towards a picture of scorpion evolution in which both basal and derived (orthostern) forms coexisted for quite some time; probably from the end of the Carboniferous through to at least the mid Triassic.


Assuntos
Evolução Biológica , Escorpiões/anatomia & histologia , Escorpiões/genética , Animais , Ecologia , Florestas , Fósseis , Alemanha , Escorpiões/classificação , Escorpiões/fisiologia
8.
Naturwissenschaften ; 103(3-4): 21, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26922777

RESUMO

Enosiaspis hrungnir gen. et sp. nov., a new species of marrellomorph arthropod from the Lower Ordovician (Tremadocian) Fezouata biota of Morocco, is described. This taxon is characterised by the possession of a cordiform dorsal carapace with an anterior notch and a doublure-like structure formed from fused marginal spines, covering the entire body. The head comprises at least five segments which bear an anterior pair of antenna, followed by three pairs of potentially biramous, geniculate appendages. The trunk possesses around 25 pairs of delicate, almost filamentous appendages, which decrease in size posteriorly. Similar features are also found in Xylokorys chledophilia from the Silurian of England, and Vachonisia rogeri from the Devonian of Germany, indicating acercostracan affinities for E. hrungnir. This was tested using a phylogenetic analysis which resolved this taxon as sister taxon to a group composed of the formerly mentioned taxa. The similarities between the ventral spinose carapace doublure of E. hrungnir and the mediolateral spines of marrellid marrellomorphs further support claims that the dorsal shield of acercostracans evolved from the fusion of spinose anlagen, akin to the formation of the carapace of crustaceans.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/classificação , Fósseis , Filogenia , Animais , Marrocos , Especificidade da Espécie
9.
Proc Natl Acad Sci U S A ; 109(39): 15702-5, 2012 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-22967511

RESUMO

The basic arrangement of limbs in euarthropods consists of a uniramous head appendage followed by a series of biramous appendages. The body is divided into functional units or tagmata which are usually distinguished by further differentiation of the limbs. The living horseshoe crabs are remnants of a much larger diversity of aquatic chelicerates. The limbs of the anterior and posterior divisions of the body of living horseshoe crabs differ in the loss of the outer and inner ramus, respectively, of an ancestral biramous limb. Here we report a new fossil horseshoe crab from the mid-Silurian Lagerstätte in Herefordshire, United Kingdom (approximately 425 Myr B.P.), a site that has yielded a remarkably preserved assemblage of soft-bodied fossils. The limbs of the new form can be homologized with those of living Limulus, but retain an ancestral biramous morphology. Remarkably, however, the two limb branches originate separately, providing fossil evidence to suggest that repression or loss of gene expression might have given rise to the appendage morphology of Limulus. Both branches of the prosomal limbs of this new fossil are robust and segmented in contrast to their morphology in Cambrian arthropods, revealing that a true biramous limb was once present in chelicerates as well as in the mandibulates.


Assuntos
Estruturas Animais/anatomia & histologia , Estruturas Animais/fisiologia , Evolução Biológica , Caranguejos Ferradura/anatomia & histologia , Caranguejos Ferradura/fisiologia , Animais , Fósseis
10.
Phys Occup Ther Pediatr ; 35(1): 73-87, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25529409

RESUMO

BACKGROUND: Physical activity is recognized as a rehabilitation approach for individuals with motor disabilities. OBJECTIVES: To determine whether community fitness programs were accommodating children and youth with motor disabilities, and to understand family perspectives on important outcomes related to fitness programs. DESIGN: Telephone survey and qualitative interviews. PARTICIPANTS AND SETTINGS: Representatives of 61 fitness programs/facilities and 13 parents of children with motor disabilities. METHODS: Telephone survey (facilities) and qualitative interviews (parents). RESULTS: 24.6% of programs reported lack of wheelchair accessibility. Only 9.8% of programs and facilities required their staff to have training to support individuals with disabilities. Parents discussed barriers, including lack of staff support and challenges with finding information about community programs. Parents focused on the social benefits of fitness programs. CONCLUSIONS/SIGNIFICANCE: Additional efforts toward reducing access barriers are needed. Parents' focus on social outcomes has direct implications on the design and evaluation of fitness programs.


Assuntos
Serviços de Saúde Comunitária/provisão & distribuição , Crianças com Deficiência/reabilitação , Terapia por Exercício , Aptidão Física , Alberta , Criança , Feminino , Grupos Focais , Acessibilidade aos Serviços de Saúde , Humanos , Entrevistas como Assunto , Masculino , Limitação da Mobilidade
11.
Proc Biol Sci ; 281(1778): 20132986, 2014 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-24452026

RESUMO

A new arthropod, Enalikter aphson gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Lagerstätte of the UK. It belongs to the Megacheira (=short-great-appendage group), which is recognized here, for the first time, in strata younger than mid-Cambrian age. Discovery of this new Silurian taxon allows us to identify a Devonian megacheiran representative, Bundenbachiellus giganteus from the Hunsrück Slate of Germany. The phylogenetic position of megacheirans is controversial: they have been interpreted as stem chelicerates, or stem euarthropods, but when Enalikter and Bundenbachiellus are added to the most comprehensive morphological database available, a stem euarthropod position is supported. Enalikter represents the only fully three-dimensionally preserved stem-group euarthropod, it falls in the sister clade to the crown-group euarthropods, and it provides new insights surrounding the origin and early evolution of the euarthropods. Recognition of Enalikter and Bundenbachiellus as megacheirans indicates that this major arthropod group survived for nearly 100 Myr beyond the mid-Cambrian.


Assuntos
Artrópodes/classificação , Fósseis , Filogenia , Animais , Artrópodes/anatomia & histologia
12.
Naturwissenschaften ; 101(12): 1065-73, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25296691

RESUMO

The morphology of the arthropod Sanctacaris uncata, from the Middle Cambrian Burgess Shale of Canada, is reinterpreted based on a restudy of previously described material. Although originally considered a chelicerate-like arthropod, these affinities were dismissed based primarily on interpretations of the anterior appendages and hypotheses which considered the megacheirans ('great-appendage' arthropods) as putative ancestors of chelicerates. The similarities between megacheirans and chelicerates appear to be overstated however, and this study instead reaffirms the identity of putative chelicerate feature in S. uncata and similar arthropods such as Sidneyia and Emeraldella, both also from the Middle Cambrian Burgess Shale. Newly interpreted features, including the presence of pediform exites, multi-partite trunk exopods, and a trunk differentiated into an anterior limb-bearing area and a differentiated posterior limbless abdomen, were coded into an extensive phylogenetic data set of fossil and recent arthropods. In all analyses, Sanctacaris resolved as the basal-most member of total-group Euchelicerata (the least inclusive group including horseshoe crabs and arachnids but not pycnogonids), thus making it the oldest chelicerate in the fossil record. The vicissicaudates (including Sidneyia, Emeraldella, aglaspidids, and cheloniellids--all of which have previously been allied to chelicerates) resolved as sister-taxon to crown-group Chelicerata. This topology indicates that many purported chelicerate features, such as lamellar gills, and a differentiated posterior abdomen evolved sequentially in the chelicerate stem-lineage.


Assuntos
Artrópodes/classificação , Fósseis , Filogenia , Animais , Artrópodes/anatomia & histologia , Canadá
14.
Front Sports Act Living ; 6: 1408887, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38993696

RESUMO

Sport management leadership research has predominantly focused on leadership behaviours, particularly transformative leadership, without fully acknowledging the complex, multifaceted nature of leadership within the sports context. This perspective overlooks the reality that sports leaders operate within complex organizations and varied contexts that significantly influence their behaviours. Leadership in sports demands core capabilities in decision-making, communication, and strategic thinking, and a mindset that influences perception, decision-making, and behaviour. Consequently, a singular focus on transformative leadership may undervalue the importance of other attributes. This paper thus argues for a comprehensive leadership framework that integrates behaviours, roles, capabilities, and mindset, and draws insights from business management. By proposing this framework organized across four domains-Context, Roles, Capabilities, and Mindset-this paper aims to foster a deeper understanding of sports leadership dynamics, highlighting the necessity of a holistic approach that considers the interconnectedness of these elements.

15.
Psychol Sport Exerc ; 71: 102570, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38008392

RESUMO

Adapted recreation programs involving the entire family may offer ways to enhance relationships in families with a child living with a disability because they enable participating together in new and potentially empowering experiences. This study examined family members' perspectives on their lived experiences with their relationships within their family and how they perceived they were affected by their participation in an adapted summer camp for families with a child living with a disability. We conducted a collective case study with five families who participated in a week-long camp. A focus group was conducted with each family and analyzed using reflexive thematic analysis. Participation in the camp impacted family relationships by reducing isolation for mothers; alleviating stress and anxiety which helped families bond; providing shared experience which led to mutual understanding, communication, and support; improving independence and confidence of the child living with a disability; facilitating sibling bonding and parent comfort with giving siblings more responsibility; and enhancing families' confidence to participate in family activities beyond the camp. These findings elucidate how participation in this type of program can impact relationships in families that include a child living with a disability and inform future program design.


Assuntos
Pais , Irmãos , Criança , Feminino , Humanos , Mães , Relações Familiares , Pesquisa Qualitativa
16.
Cladistics ; 29(1): 15-45, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34814371

RESUMO

The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of undetermined affinities, is re-examined in the context of the major Cambrian and Ordovician lamellipedian arthropod groups. A cladistic analysis of ten genera of aglaspidids sensu stricto, six aglaspidid-like arthropods and 42 Palaeozoic arthropod taxa indicates that Xenopoda, Cheloniellida, Aglaspidida sensu lato and Trilobitomorpha form a clade (Artiopoda Hou and Bergström, 1997) nested within the mandibulate stem-lineage, thus discarding previous interpretations of these taxa as part 'of the chelicerate stem-group (Arachnomorpha Heider, 1913). The results confirm an aglaspidid identity for several recently described arthropods, including Quasimodaspis brentsae, Tremaglaspis unite, Chlupacaris dubia, Australaglaspis stonyensis and an unnamed Ordovician Chinese arthropod. The problematic Bohemian arthropod Kodymirus vagans was recovered as sister taxon to Beckwithia typa, and both form a small clade that falls outside Aglaspidida sensu stricto, thus discarding eurypterid affinities for the former. The analysis does not support the phylogenetic position of Kwanyinaspis maotianshanensis at the base of Conciliterga as proposed in recent studies, but rather occupies a basal position within Aglaspidida sensu lato. The results indicate a close association of aglaspidid arthropods with xenopods (i.e. Emeraldella and Sidneyia) and cheloniellids (e.g. Cheloniellon, Duslia); the new clade "Vicissicaudata" is proposed to encompass these arthropods, which are characterized by a differentiated posterior region. The phylogenetic position of aglaspidid arthropods makes them good outgroup candidates for analysing the internal relationships within the groups that form Trilobitomorpha. This work provides a much clearer picture of the phylogenetic relationships among Lower Palaeozoic lamellipedians.

17.
Disabil Rehabil ; : 1-10, 2023 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-37357366

RESUMO

PURPOSE: Children and adolescents with developmental challenges may rely on their parents for assistance with everyday tasks to a greater extent than typically developing children. The objective of this study was to examine family members' perspectives regarding family relationships related to participation in an adapted summer camp for children and adolescents living with a disability. MATERIALS AND METHODS: A collective case study was conducted with eleven families who had a child living with a disability who participated in an adapted physical activity (PA) summer camp. A focus group was conducted with each family and thematically analyzed. RESULTS: Families experienced changes in perspectives and pride surrounding adapted PA, more family conversations about disability, less parental worry, more independence of the child living with a disability, and enhanced family bonds through PA. The children who participated in the camp saw impacts on their self-confidence and independence. COVID-19-related program suspension was associated with frustration, worry, and strained family relationships. CONCLUSIONS: These findings elucidate how participation in adapted PA for children and youth with disabilities can impact family relationships. Future interventions allow for space for family interactions and create opportunity for children and adolescents with disabilities to be independent.


Practitioners could make sure they have resources to recommend and be aware of programs that are available for this population.Practitioners could talk to families about benefits of recreation programs for both children and families in terms of benefits for children and family relationships and parental stress.Knowing the potential benefits to the family as a whole may impact parents' decisions about their child participating in recreation programs.Practitioners could talk to families about benefits of physical activity participation in terms of experiencing independence.Understanding potential benefits regarding independence may give children living with a disability a better understanding of how recreation programs may impact their lives.

18.
R Soc Open Sci ; 10(8): 230661, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37538743

RESUMO

A new arthropod, Carimersa neptuni gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Konservat-Lagerstätte, UK. The head bears pedunculate eyes and five pairs of appendages. Triflagellate antennae are followed by two pairs of uniramous limbs each with an endopod bearing a pronounced gnathobasic basipod. The posterior two pairs of head limbs and all trunk limbs bear an endopod, exopod and filamentous exite. The trunk consists of 10 appendage-bearing segments followed by an apodous abdomen of four segments. The arthropod resolves as sister taxon to Kodymirus and Eozetetes + Aglaspidida. It is the first representative of Vicissicaudata reported from the Herefordshire Lagerstätte and the first Silurian example with well-preserved appendages. The preservation of a cluster of radiolarians apparently captured by the trunk appendages is the first direct association of predator and prey discovered in the Herefordshire fauna, and suggests that Carimersa was a nektobenthic form that used its gnathobasic basipods in microdurophagy.

19.
Front Neurol ; 14: 1307627, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38162439

RESUMO

Background: Myasthenia gravis (MG) is a rare autoimmune disease and chronic condition that necessitates specialized care. Patients experience a significant burden of disease affecting various aspects of their lives. The aim of this study was to investigate the impact of MG on family planning, challenges associated with pregnancy, childcare responsibilities and the extent to which MG patients perceive and utilize social support. Methods: This analysis used data from our main data of a large cross-sectional study built on a questionnaire-based survey encompassing 1,660 MG patients and members of the German Myasthenia Association (Deutsche Myasthenie Gesellschaft), and focused on sociodemographic, clinical and family planning relevant data points. Results: Decisions regarding family planning were significantly impacted for individuals with MG when MG symptoms started either before or during their family planning (men: n = 19 and 29.7%; women: n = 156 and 58.4%). In this subgroup a substantial proportion opted against parenthood due to MG (men: n = 8 and 50.0%; women: n = 54 and 38.0% and/or another n = 12 and 8.4% of female participants encountered partner-related refusals). In the subgroup of female SP with MG starting before or during family planning who have reported ever been pregnant the self-reported miscarriage rate was 29.0% (n = 51). MG patients with medium incomes or moderate disease severity reported lower levels of perceived social support. 42.7% (n = 606) of participants needed assistance in negotiations with health insurers and 28.0% (n = 459) needed support for transportation to medical appointments. Conclusion: This study shows a significant impact of MG on family planning decisions, affecting both women and men, and often resulting in life-altering decisions such as voluntary childlessness due to MG. The significance of social support becomes evident as a vital factor, especially when navigating through the healthcare system. Tailored healthcare approaches, organized guidance and comprehensive support is needed to enable informed decision-making and offer assistance for MG patients. Clinical trial registration: https://clinicaltrials.gov/study/NCT03979521, Registered 7 June 2019 (retrospectively registered).

20.
Proc Biol Sci ; 279(1748): 4699-704, 2012 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-23055069

RESUMO

Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (sclerotization and jointing of the exoskeleton) evolved to facilitate swimming. Predatory and fully benthic habits evolved later in the euarthropod stem-lineage and are plesiomorphically retained in pycnogonids (sea spiders) and euchelicerates (horseshoe crabs and arachnids).


Assuntos
Artrópodes/anatomia & histologia , Evolução Biológica , Bivalves/anatomia & histologia , Fósseis , Abdome , Animais , Artrópodes/fisiologia , Bivalves/fisiologia , Paleontologia/métodos , Tórax
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