492 research outputs found
<i>Caryosyntrips</i> : a radiodontan from the Cambrian of Spain, USA and Canada
No full textCaryosyntrips appendages have previously been reported from the Burgess Shale (Cambrian,
Stage 5), British Columbia, Canada. New specimens of the genus are here reported from the
Wheeler Formation (Cambrian, Drumian) and Langston Formation, Spence Shale Member
(Cambrian, Stage 5), Utah, USA. The original Burgess Shale specimens are re-examined
alongside the new specimens. Caryosyntrips is shown to have paired ventral spines on each
podomere. Three species of Caryosyntrips are recognised: C. serratus Daley and Budd, C.
camurus nov. sp. and C. durus nov. sp., differentiated by the overall shape of their
appendages and arrangement of dorsal and ventral spines. These differences have potential
implications for the feeding methods employed by different species of Caryosyntrips. A
specimen collected from the upper Valdemiedes Formation of Spain (Cambrian, Stage 4),
previously described as the lobopodian Mureropodia apae Gámez Vintaned et al., is
reinterpreted as a Caryosyntrips appendage. This identification is supported by the overall
shape of the fossil, and the presence, orientation, and height:width ratio, of ventral spines.
However the dorsal surface of the appendage is not well preserved, and the appendage and its
ventral spines are larger than other known Caryosyntrips. Therefore it is left in open
nomenclature as C. cf. camurus. These new finds increase the temporal range of
Caryosyntrips (Cambrian Series 2, Stage 4 to Series 3, Drumian) and the geographic range to
a new continent, Gondwana
Caryosyntrips: a radiodontan from the Cambrian of Spain, USA and Canada
No full textCaryosyntrips appendages have previously been reported from the Burgess Shale (Cambrian, Stage 5), British Columbia, Canada. New specimens of the genus are here reported from the Wheeler Formation (Cambrian, Drumian) and Langston Formation, Spence Shale Member (Cambrian, Stage 5), Utah, USA. The original Burgess Shale specimens are re-examined alongside the new specimens. Caryosyntrips is shown to have paired ventral spines on each podomere. Three species of Caryosyntrips are recognised: C. serratus Daley and Budd, C. camurus nov. sp. and C. durus nov. sp., differentiated by the overall shape of their appendages and arrangement of dorsal and ventral spines. These differences have potential implications for the feeding methods employed by different species of Caryosyntrips. A specimen collected from the upper Valdemiedes Formation of Spain (Cambrian, Stage 4), previously described as the lobopodian Mureropodia apae Gámez Vintaned et al., is reinterpreted as a Caryosyntrips appendage. This identification is supported by the overall shape of the fossil, and the presence, orientation, and height:width ratio, of ventral spines. However the dorsal surface of the appendage is not well preserved, and the appendage and its ventral spines are larger than other known Caryosyntrips. Therefore it is left in open nomenclature as C. cf. camurus. These new finds increase the temporal range of Caryosyntrips (Cambrian Series 2, Stage 4 to Series 3, Drumian) and the geographic range to a new continent, Gondwana
Caryosyntrips: a radiodontan from the Cambrian of Spain, USA and Canada
No full textCaryosyntrips appendages have previously been reported from the Burgess Shale (Cambrian, Stage 5), British Columbia, Canada. New specimens of the genus are here reported from the Wheeler Formation (Cambrian, Drumian) and Langston Formation, Spence Shale Member (Cambrian, Stage 5), Utah, USA. The original Burgess Shale specimens are re-examined alongside the new specimens. Caryosyntrips is shown to have paired ventral spines on each podomere. Three species of Caryosyntrips are recognised: C. serratus Daley and Budd, C. camurus nov. sp. and C. durus nov. sp., differentiated by the overall shape of their appendages and arrangement of dorsal and ventral spines. These differences have potential implications for the feeding methods employed by different species of Caryosyntrips. A specimen collected from the upper Valdemiedes Formation of Spain (Cambrian, Stage 4), previously described as the lobopodian Mureropodia apae Gámez Vintaned et al., is reinterpreted as a Caryosyntrips appendage. This identification is supported by the overall shape of the fossil, and the presence, orientation, and height:width ratio, of ventral spines. However the dorsal surface of the appendage is not well preserved, and the appendage and its ventral spines are larger than other known Caryosyntrips. Therefore it is left in open nomenclature as C. cf. camurus. These new finds increase the temporal range of Caryosyntrips (Cambrian Series 2, Stage 4 to Series 3, Drumian) and the geographic range to a new continent, Gondwana
Trilobitomorphs from the Fezouata Biota and the Ordovician Radiation
No full textLes trilobites sont un groupe éteint d'animaux proche des insectes, crustacés, araignées, scolopendres et mille-pattes, plus communément appelés arthropodes. Les trilobites sont apparus dans les océans il y a près des 530 millions d'années avant de s'éteindre après un règne de plus de 250 millions d'années. Au sein de ces anciens écosystèmes, les trilobites étaient l'un des groupes d'organismes les plus florissant, ayant colonisé tous les types d'environnements marins, et dont les fossiles peuvent être trouvés de nos jours dans les roches du monde entier. Par conséquent, les trilobites jouent un rôle important dans la recherche visant à mieux comprendre l'origine des animaux et l'établissement des écosystèmes marins actuels.
Deux événements majeurs ont influencés l'évolution des premiers animaux, l'explosion cambrienne (approximativement de 540 à 510 millions d'années) et la radiation ordovicienne (approximativement de 485 à 440 millions d'années). Au cours de l'explosion cambrienne, la majorité des groupes d'animaux est apparus en un laps de temps relativement court d'un point de vue géologique (environ 30 millions d'années). L'étude de cet événement majeur a été possible grâce à la découverte de sites fossilifères montrant des préservations exceptionnelles, dont les organismes sont souvent très complets allant même jusqu'à préserver intacts les tissus mous (peu résistants à l'épreuve du temps) à l'instar des habituelles parties dures telles que les coquilles qui sont très résistantes au passage du temps. Durant la radiation ordovicienne, les animaux ont vécu l'une des plus importantes biodiversification de leur histoire. Cependant, de tels sites de préservation exceptionnelle, si utiles quant à la bonne compréhension de l'explosion cambrienne, sont rares durant !'Ordovicien. Par conséquent, notre connaissance vis-à-vis des changements au sein des anciens écosystèmes marins est incomplète. L'un des seuls sites permettant d'avoir une vue d'ensemble sur ces écosystèmes marins au cours de
!'Ordovicien Inférieur (~ 481 millions d'années) sont les Schistes de Fezouata, un site localisé au Maroc et caractérisé par une préservation exceptionnelle des fossiles. Les fossiles du biote de Fezouata sont dès lors fondamentaux quant à la compréhension des changements s'étant produits dans les débuts de l'histoire évolutive des animaux entre l'explosion cambrienne et la radiation ordovicienne.
Cette thèse se concentre sur l'étude des trilobites de !'Ordovicien et sur un de leur proche cousin arthropode afin d'identifier les étapes majeures de l'évolution des arthropodes au début de la radiation ordovicienne. De nouveaux fossiles du biote de Fezouata ont été décrits, comprenant une nouvelle espèce d'un petit arthropode proche des trilobites, Tarricoia tazagurtensis. La préservation partielle du système digestif a permis de faire des comparaisons avec l'anatomie du tube digestif d'autres arthropodes. De plus, les incroyables fossiles du biote de Fezouata ont révélé pour la première fois ce à quoi ressemblaient les pattes chez le trilobite Anacheirurus adserai. Bien que l'on soit dans l'Ordovicien, le tube digestif de Tarricoia tazagurtensis ainsi que les pattes deAnacheirurus adserai sont très similaires à ce qui est connu chez des espèces du Cambrien, témoignant que la radiation ordovicienne était un lent processus qui a mis quelques millions d'années à démarrer.
Cette thèse adopte ensuite une vision plus large de l'histoire évolutive des trilobites à l'Ordovicien afin de comprendre exactement comment, pourquoi et quand ces animaux se sont diversifiés durant la radiation ordovicienne. Dans cette optique, les relations entre différentes espèces de trilobites ont été étudiées afin de créer un arbre de la vie (connu comme arbre phylogénétique) pour un important sous-groupe de trilobites de l'Ordovicien. La reconstruction des relations entre différentes espèces de trilobites permet une compréhension plus en profondeur des étapes évolutives caractérisant leur histoire à l'Ordovicien. Finalement, cette thèse a jeté un œil à la distribution autour du globe des différentes espèces de trilobites de l'Ordovicien, révélant le rôle joué par la géographie et la position des anciens continents durant la diversification des trilobites.
Regardés simultanément, les résultats présentés lors de cette thèse suggèrent que ]'Ordovicien Inférieur était une période de grands changements dans l'histoire évolutive des trilobites comme en témoignent les différents changements de morphologies, de distribution globale et de diversités observés au sein de ce groupe. Tous ces changements représentent le prélude à l'ensemble des diversifications que connaitra ce groupe durant la radiation ordovicienne.
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Les trilobites étaient l'un des groupes les plus diversifiés au sein des assemblages fossiles du Paléozoïque. Après leur première apparition au Cambrien inférieur, les trilobites sont rapidement devenus un constituant majeur des écosystèmes marins du Paléozoïque inférieur et le sont restés jusqu'à leur extinction à la fin du Permien. Leur importance au sein de ces premiers écosystèmes marins ainsi que leur abondance dans le registre fossile font des trilobites le parfait sujet d'étude concernant l'évolution basale des animaux ainsi que des écosystèmes qu'ils occupaient. Deux événements évolutifs majeurs définissent l'évolution basale des animaux : l'explosion cambrienne et la radiation ordovicienne. Au cours de l'explosion cambrienne, la majorité des embranchements des animaux est apparue, tandis que lors de la radiation ordovicienne, les embranchements apparus durant l'explosion cambrienne ont vécu une importante diversification au niveau taxonomique. Au cours de la transition entre le Cambrien et l'Ordovicien, les faunes typiques du Cambrien sont remplacées par les faunes typiques du Paléozoïque. Datés de l'Ordovicien Inférieur (Trémadocien, ~481 million d'années), les Schistes de Fezouata sont la localité idéale pour l'étude de cette transition entre l'explosion cambrienne et la radiation ordovicienne. Les Schistes de Fezouata, situés dans la région de l' Anti-Atlas au Maroc, est l'un des rares sites fossilifères de l'Ordovicien lnferieur montrant une préservation exceptionnelle. Le biote de Fezouata est constitué d'un mélange entre des faunes typiques du Cambrien et des faunes typiques du Paléozoïque.
Cette thèse se concentre sur l'étude de trilobites de l'Ordovicien ainsi que d'une forme apparentée, avec pour objectif l'identification des schémas évolutifs majeurs présents au sein de ce groupe durant la radiation ordovicienne. Le point de départ de cette étude consiste en un travail descriptif de fossiles du biote de Fezouata, comprenant la description d'une nouvelle espèce d'arthropode de l'ordre des nektaspides ainsi que des appendices du trilobite Anacheirurus adserai. La nouvelle espèce de nektaspide, Tarricoia tazagurtensis, partage des similarités avec l'espèce Tariccoia arrusensis identifiée dans !'Ordovicien Supérieur de Sardaigne (Italie). De plus, la description des restes du système digestif de T. tazagurtensis montre des similarités avec les systèmes digestifs des nektaspides du Cambrien. Les spécimens exceptionnellement bien préservés des Schistes de Fezouata d'A. adserai montrent en détails les appendices de cette espèce, révélant les morphologies des endopodites et des exopodites. Les exopodites d'A. adserai montrent des caractéristiques typiques de certaines espèces cambriennes et diffèrent considérablement de ce qui est connu chez les espèces post cambriennes.
La seconde partie de cette thèse se concentre sur l'identification des schémas évolutifs présents au sein des trilobites durant la radiation ordovicienne. A cet effet, le sous-ordre des Cheirurina a été sélectionné vu son importante diversité, avec plus de 840 espèces décrites. Afin de mieux comprendre l'évolution du groupe, des analyses phylogénétiques au sein du sous-ordre ont été réalisées. Les groupes majeurs des Cheirurinae et des Deiphoninae ont été analysés en utilisant des approches parcimonieuses et bayésiennes, dont les résultats indiquent que les deux sous familles sont monophylétiques, formant un clade majeur au sein des Cheirurina. De plus, les lignées principales au sein du clade Cheirurinae+Deiphoninae sont présentes dès le Floien et jusqu'au Dariwillien. Finalement, la paléobiogéographie ainsi que la diversité des Cheirurina ont été explorées grâce à l'établissement d'une base de données nouvellement établie regroupant les occurrences des fossiles de trilobites à l'Ordovicien. Des analyses de type "Hierachical clustering" et "non-metric multidimensional scaling" ont permis d'identifier quatre provinces majeures au sein des Cheirurina à l'Ordovicien : une province de haute latitude, une province Laurentia-Siberia de basse latitude, une province Gondwana de basse latitude et une province Baltica. Un haut niveau de provincialisme caractérise la diversification basale du groupe, suivi par une période d'expansion géographique au cours de l'Ordovicien Supérieur.
Regardés simultanément, les résultats présentés suggèrent que l'Ordovicien Inférieur était une période de changements évolutifs au sein des communautés de trilobites, comme en témoignent l'écologie, la morphologie et la distribution géographique au sein de ce groupe. Ces changements ont mis en place les fondations permettant la diversification ultérieure qui s'est déroulée au sein de ce groupe durant le reste de !'Ordovicien.
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Trilobites were one of the most diverse groups of animals in fossil assemblages of the Palaeozoic. After their first appearance in the lower Cambrian, Trilobites rapidly became a major part of early Palaeozoic marine ecosystems and remained part of it until their extinction at the end of the Permian. Their importance in these early marine ecosystems and their abundance in the fossil record make trilobites the perfect model to study the early evolution of animals and the ecosystems they habited. Two major evolutionary events defined the early history of animals: The Cambrian Explosion and the Ordovician Radiation. During the Cambrian Explosion, most of the animal phyla originated, while during the Ordovician Radiation the phyla established during the Cambrian Explosion experienced a great diversification at lower taxonomic levels. During the Cambrian to Ordovician transition, the dominant Cambrian Evolutionary Fauna is replaced by the Palaeozoic Evolutionary Fauna. Dating from the Lower Ordovician (Tremadocian, 481 million years ago), the Fezouata Shale is the perfect locality for the study of this transition between the Cambrian Explosion and the Ordovician Radiation. The Fezouata Shale, located in the region of the Anti-Atlas in Morocco, is one of the few sites with exceptional fossil preservation. from the Lower Ordovician. The Fezouata Biota consists of a mixed fauna including typical members of the Cambrian Evolutionary Fauna and the Palaeozoic Evolutioriary Fauna.
The following thesis is focused on the study of Ordovician trilobites and a related form, in order to identify major patterns in the evolution of the group during the Ordovician Radiation. The starting point of the study is descriptive work on fossils from the Fezouata Biota, including the description of a new species of nektaspid arthropod and the appendages of the trilobite Anacheirurus adserai. The new nektaspid species, Tarricoia t zagurtensis, shares similarities with Tariccoia arrusensis from the Upper Ordovician of Sardinia (ltaly). In addition, remains from the digestive tract of T. tazagurtensis are described, showing similarities to the digestive tracts found in Cambrian nektaspids. Exceptionally preserved specimens of A. adserai from the Fezouata Shale show details of appendages, revealing the endopodite and exopodite morphologies. The exopodites of A. adserai show characters that are typical of some Cambrian species and differ considerably from that known from post-Cambrian taxa.
The second half of the thesis focuses on the identification of evolutionary patterns within trilobites during the Ordovician Radiation. For this purpose the sub-order Cheirurina has been selected as the group of study owing its great diversity, with more than 840 species formally described. In order to better understand the evolution of the group, phylogenetic analyses within the sub-order have been performed. The major groups Cheirurinae and Deiphoninae were analysed using parsimony and Bayesian approaches, and the results indicate that both subfamilies are monophyletic and form a major clade within Cheirurina. Additionally, the major lineages within the Cheirurinae + Deiphoninae clade are established between the Floian and the Darriwilian. Finally, the paleobiogeography and diversity of Cheirurina is explored through a newly built dataset of Ordovician trilobite fossil occurrences. Hierarchical clustering and non-metric multidimensional scaling analyses resolve four major Cheirurina Provinces in the Ordovician: a High latitude Province, Low latitude Laurentia-Siberia Province, Low latitude Gondwana Province and Baltica Province. High provincialism characterised the early diversification of the group, followed by a period of geographical expansion in the Upper Ordovician.
Taken together, the results presented here suggest that the early Ordovician is a period of evolutionary changè in the trilobite community, as reflected in the ecology, morphology and distribution of the group. These changes established the basis for the subsequent diversification experienced during the rest of the Ordovician
Comparative genomics of Shiga toxin encoding bacteriophages
No full textBackground
Stx bacteriophages are responsible for driving the dissemination of Stx toxin genes (stx) across their bacterial host range. Lysogens carrying Stx phages can cause severe, lifethreatening disease and Stx toxin is an integral virulence factor. The Stx-bacteriophage vB_EcoP-24B, commonly referred to as 24B, is capable of multiply infecting a single bacterial host cell at a high frequency, with secondary infection increasing the rate at which subsequent bacteriophage infections can occur. This is biologically unusual, therefore determining the genomic content and context of 24B compared to other lambdoid Stx phages is important to understanding the factors controlling this phenomenon and determining whether they occur in other Stx phages.
Results
The genome of the Stx2 encoding phage, 24B was sequenced and annotated. The genomic organisation and general features are similar to other sequenced Stx bacteriophages induced from Enterohaemorrhagic Escherichia coli (EHEC), however 24B possesses significant regions of heterogeneity, with implications for phage biology and behaviour. The 24B genome was compared to other sequenced Stx phages and the archetypal lambdoid phage, lambda, using the Circos genome comparison tool and a PCR-based multi-loci comparison system.
Conclusions
The data support the hypothesis that Stx phages are mosaic, and recombination events between the host, phages and their remnants within the same infected bacterial cell will continue to drive the evolution of Stx phage variants and the subsequent dissemination of shigatoxigenic potentia
The morphology and evolutionary significance of the anomalocaridids
No full textApproximately 600 to 500 million years ago, a major evolutionary radiation called the “Cambrian Explosion” gave rise to nearly all of the major animal phyla known today. This radiation is recorded by various fossil lagerstätten, such as the Burgess Shale in Canada, where soft-bodied animals are preserved in exquisite detail. Many Cambrian fossils are enigmatic forms that are morphologically dissimilar to their modern descendants, but which still provide valuable information when interpreted as stem-group taxa because they record the actual progression of evolution and give insight into the order of character acquisitions and homologies between living taxa. One such group of fossils is the anomalocaridids, large presumed predators that have had a complicated history of description. Their body has a trunk with a series of lateral lobes and associated gills, and a cephalic region with a pair of large frontal appendages, a circular mouth apparatus, stalked eyes and a cephalic carapace. Originally, two taxa were described from the Burgess Shale, Anomalocaris and Laggania, however data presented herein suggests that the diversity of the anomalocaridids was much higher. Newly collected fossil material revealed that a third Burgess Shale anomalocaridid, Hurdia, is known from whole-body specimens and study of its morphology has helped to clarify the morphology and systematics of the whole group. Hurdia is distinguished by having mouthparts with extra rows of teeth, a unique frontal appendage, and a large frontal carapace. Two species, Hurdia victoria and Hurdia triangulata were distinguished based on morphometric shape analysis of the frontal carapace. A phylogenetic analysis placed the anomalocaridids in the stem lineage to the euarthropods, and examination of Hurdia’s well-preserved gills confirm the homology of this structure with the outer branches of limbs in upper stem-group arthropods. This homology supports the theory that the Cambrian biramous limb formed by the fusion of a uniramous walking limb with a lateral lobe structure bearing gill blades. In this context, new evidence is present on the closely allied taxon Opabinia, suggesting that it had lobopod walking limbs and a lateral lobe structure with attached Hurdia-like gills. The diversity of the anomalocaridids at the Burgess Shale is further increased by two additional taxa known from isolated frontal appendages. Amplectobelua stephenensis is the first occurrence of this genus outside of the Chengjiang fauna in China, but Caryosyntrips serratus is an appendage unique to the Burgess Shale. To gain a better understanding of global distribution, a possible anomalocaridid is also described from the Sirius Passet biota in North Greenland. Tamisiocaris borealis is known from a single appendage, which is similar to Anomalocaris but unsegmented, suggesting this taxon belongs to the arthropod stem-lineage, perhaps in the anomalocaridid clade. Thus, the anomalocaridids are a widely distributed and highly diverse group of large Cambrian presumed predators, which provide important information relevant to the evolution of the arthropods.Arkivexemplar i Uppsala universitets arkiv</p
Predation in the Cambrian
No full textAlthough predation has been suggested repeatedly as a force shaping the diversification of animals during the Cambrian period, studies of the evolutionary dynamics of predation are lacking from this time period. Radiodonta, the largest Cambrian nektonic animals, and repaired injuries on trilobites, a diverse and disparate group of prey animals, provide study systems to assess predation dynamics at this time. Radiodont fossils were first discovered over 100 years ago, but are now known worldwide from early Palaeozoic deposits which preserve soft-bodied material. Intense research on radiodonts from the Chengjiang biota (China) and Burgess Shale (Canada) since 2009 recently greatly improved our knowledge of the group, outdating previous interpretations of USA specimens, which are needed for large-scale analyses. Anecdotal reports of repaired injuries on trilobites are common in the literature, but quantitative studies on the role of morphology, behaviour, or geography have not been conducted.
I restudied radiodonts from the USA, placed them into an up to date taxonomic and taphonomic context, and revealed that these deposits hold a much higher diversity and disparity than previously reported. Findings include the first and last appearances of a number of families worldwide, and eight taxa not known from any other deposit. I used this new data to undertake the most comprehensive phylogenetic analysis and the first diversity and disparity analyses of Radiodonta, which showed two phases of evolution in the group, and that the ancestral radiodont was likely not a raptorial predator. I also performed the first quantitative measurements of predation pressure on trilobites, showing that morphology, geography, and behaviour, effect on the location and frequency of repaired injuries. These results suggest that predation pressure was a complex and changeable ecological influencing the early evolution of animals.</p
Molecular timetrees reveal a Cambrian colonization of land and a new scenario for ecdysozoan evolution.
No full textEcdysozoans have been key components of ecosystems since the early Cambrian, when trilobites and soft-bodied Burgess Shale-type ecdysozoans dominated marine animal communities. Even today, the most abundant animals on Earth are either nematode worms or plankton-forming crustaceans, whereas the most diverse are the insects. Throughout geological time, several ecdysozoan lineages independently colonized land, shaping both marine and terrestrial ecosystems and providing an adequate environment for successive animal terrestrialization. The timing of these events is largely uncertain and has been investigated only partially using molecular data. Here we present a timescale of ecdysozoan evolution based on multiple molecular data sets, the most complete set of fossil calibrations to date, and a thorough series of validation analyses. Results converge on an Ediacaran origin of all major ecdysozoan lineages (∼587-543 million years ago [mya]), followed by a fast Cambrian radiation of the pancrustaceans (∼539-511 mya), a Cambro-Ordovician colonization of land of different arthropod lineages (∼510-471 mya), and a relatively recent radiation of extant nematodes, onychophorans, and tardigrades (∼442 mya). Arthropods colonized land nearly synchronously with land plants. Further diversification within flying insects, nematodes and onychophorans might be related to the evolution of vascular plants and forests
A systematic revision of the Afrotropical members of the dung beetle genus Catharsius Hope, 1837 (Coleoptera: Scarabaeidae)
No full textThe Afrotropical members of the dung beetle genus Catharsius Hope, 1837 (Coleoptera: Scarabaeidae) are investigated and systematically revised. Morphological phylogenetic analyses of 138 taxa and molecular phylogenetic analyses of a subset of 15 taxa are conducted. The results indicate the paraphyly of the genus with regard the monotypic genus Copridaspidus Boucomont, 1920 and Catharsius is split into five species-groups. Biogeographical ancestral state reconstruction indicates that the woodlands to the south of the Congo Basin are the location of origin of the genus, with several independent colonisations of Asia. Dispersal-vicariance analysis shows that many dispersal events rather than vicariance events are responsible for the current geographical distribution of this genus. A new tribe, Catharsiini, is erected to include the genera Catharsius and Metacatharsius. Two genera, Copridaspidus and Catharsiocopris Balthasar, 1967, are synonymised with Catharsius. In total, 128 African species are recognised, of which 39 species are new to science. Name-bearing type specimens of 98 of 106 described taxa were studied with four neotypes and 48 lectotypes designated. Six taxa are raised from synonymy, eleven new synonymies are established and one species is placed as incertae sedis. The C. molossus species group of 29 species is fully revised with the re-description of 25 species and description of four new species. For each species of the C. molossus species group, images of both sexes and of the male genitalia are figured, along with distribution maps. A key to the five species-groups as well as a key to species of the C. molossus group are provided and a gazetteer of all African localities of Catharsius is compiled.</p
Comment on “Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris” by Stephen Pates, Allison C. Daley, and Javier Ortega-Hernández
No full textPates et al. (2017) and Pates and Daley (2017) reinterpreted a number of presumable xenusians (lobopodians) and described some new fossils from various Cambrian Lagerstätten as radiodontan (anomalocaridid) frontal appendages. The authors suggested that some features including overall length of a specimen, a number of tentative podomeres, a number of ventral blades (spines) and dorsal spines, their morphology, and an angle between the dorsal and ventral surfaces (θ) of a specimen provide enough information for a fairly good morphological description and a relevant systematic interpretation of stem group ecdysozoans. The case of xenusian Mureropodia apae from the lower Cambrian Valdemiedes Formation of Murero, northeastern Spain (Gámez Vintaned et al. 2011), which Pates and Daley (2017) identified as radiodontan Caryosyntrips cf. camurus, does not verify a plausibility of such a reductive approach
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