Talks by Emmanuel Martin
" The recent discovery of several Early Ordovician Konservat-Lagerstätten in the Central Anti-Atl... more " The recent discovery of several Early Ordovician Konservat-Lagerstätten in the Central Anti-Atlas of Morocco offers new insights into the initial animal biodiversifications during Early Palaeozoic times. Indeed, the new Moroccan Konservat-Lagerstätten are critical in unraveling the progressive settlement of primary marine ecosystems, after the Cambrian bioradiation events. Exceptionally preserved soft-bodied faunas are particu-
larly abundant in the Cambrian (e.g., Sirius Passet, Chengjiang, Emu Bay Shale, Burgess Shale, Orsten), but far less common and associated to restricted environmental conditions (e.g., anoxic sea floors, shallow brackish estuarine embayment) in the Or-
dovician. The Fezouata Biota, from the Outer Feijas Group (Lower Ordovician…) of Zagora area partly fills in this lacuna. Description of the new Moroccan Konservat-Lagerstätten is in progress, and will permit to assess precisely Early Ordovician marine biodiversity for the first time but also, to compare marine assemblages with comparable preservational modes from the early-mid Cambrian and the Early Ordovician.
In the Ternata plain, north of Zagora, the Lower Ordovician succession lies unconformably over the middle Cambrian sandstones of the Tabanite Group, and consists of an extremely thick series of more or less silty and micaceous argillites (ca. 700 m; Lower and Upper Fezouata Formations) overlain by the sandstones of the Zini Formation.
Since the early 2000s, several fossiliferous horizons within the Lower Fezouata Formation (Tremadocian) and the conformably overlying Upper Fezouata (Floian) have yielded extremely abundant and diverse remains of fully marine assemblages. Fossils comprise numerous exquisitely preserved remains of shelly taxa typical of post-Cambrian faunas: e.g., machaeridians, articulate brachiopods, bivalves, gastropods, nautiloid, cephalopods, trilobites, ostracods, graptolites, glyptocystitid rhombiferans, mitrate stylophorans, asterozoans, and crinoids. However, the Fezouata Biota also contains abundant and diverse remains of non-biomineralized organisms with several representatives of the Palaeozoic Evolutionary Fauna (most previously known only from younger de-posits): e.g., aglaspidid and cheloniellid arthropods, cirripedian crustaceans, xiphosu-
rans. The fauna also contains non-biomineralized taxa typical of early to middle Cambrian Konservat-Lagerstätten: e.g., anomalocaridids, halkieriids, marrellomorphs, na-
raoiids, palaeoscolecids. This clearly shows that some Cambrian key faunal elements stepped into the Ordovician. This important information challenges current evolutionary models favouring abrupt changes during the Cambrian–Ordovician transition.
However, the different Lower Ordovician fossiliferous horizons around Zagora needed to be placed in a spatio-temporal framework. Indeed, studies on the Fezouata biota have been focusing on faunal elements but lack accurate data on the age and environmental setting of the fossil localities. In the last two years, under the auspices of the ANR project RALI and two French-Moroccan CNRS-CNRST projects (SDU 05/09 & SDU 02/13), two field campaigns logged in detail the whole Lower Fezouata Formation and the lower half of the Upper Fezouata Formation. The precise stratigraphic position of all fossiliferous levels yielding exceptional preservation was also identified. The occurrence of mm- to cm-thick silty layers displaying storm-wave influence (wave ripples) points to relatively shallow offshore depositional settings. Principles of sequence stratigraphy applied to the logs also permitted to reconstruct sea-level fluctuations, which were compared with the changes in composition of some taxa (e.g., graptolites, echinoderms, trilobites) in association with the soft-bodied faunas. "
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"La découverte récente de sites à préservation exceptionnelle dans l’Ordovicien inférieur du Maro... more "La découverte récente de sites à préservation exceptionnelle dans l’Ordovicien inférieur du Maroc ouvre des perspectives nouvelles sur l’étude des premières diversifications animales. Elle permettrait en effet d’éclairer une période méconnue mais néanmoins primordiale, marquée par l’établissement d’écosystèmes marins nouveaux suite à l’apparition du monde animal dans la colonne d’eau. Toutefois, les seules informations disponibles sur cette époque sont uniquement fournies par de célèbres gisements de faunes à préservation exceptionnelle (Burgess, Chengjiang, Sirius Passet, Orsten) qui sont tous d’âge Cambrien. La découverte de sites similaires dans le Groupe des Feijas externes au Maroc permet non seulement d’évaluer pour la première fois avec précision la biodiversité marine du début de l’Ordovicien mais également, à qualité de préservation égale, de comparer la vie marine cambrienne et ordovicienne.
Néanmoins, dans un premier temps, il est indispensable de replacer les différents niveaux à préservation exceptionnelle de l'Ordovicien inférieur de la région de Zagora (Anti-Atlas central) dans leur contexte spatio-temporel. Pour y parvenir, deux approches ont été utilisées. La première, sédimentologique, a consisté à lever des coupes de référence couvrant une grand partie de la série (environ 600 mètres) et permettant de contraindre précisément les positions stratigraphiques des sites fossilifères. La seconde, paléontologique, est principalement axée sur les éléments de la faune les plus discriminants en terme de datation et/ou d’environnement (graptolites, trilobites et échinodermes) et que l'on retrouve associés aux faunes à préservation exceptionnelle (p.ex., aglaspidides, anomalocaridides, éponges, limules, marrellomorphes, vers). L’application des principes de stratigraphie séquentielle a également permis de mettre en évidence les variations du niveau marin relatif qui ont été comparées avec les changements de composition des assemblages fossilifères.
Suite à cette première phase exploratoire permettant de préciser les contextes biostratigraphique et paléoenvironnemental des différents niveaux fossilifères, l’étude des faunes ordoviciennes du Maroc va désormais pouvoir entrer dans une phase d’exploitation plus intensive, avec le lancement prochain d'un véritable chantier de fouilles niveau par niveau. Il permettra de mener des analyses paléoécologiques à haute résolution, comparables à celles réalisées sur les sites de Burgess (Canada) et de Chengjiang (Chine). En parallèle, le grand nombre de spécimens déjà récoltés nécessite un travail d’inventaire faunistique et de description systématique des nombreux taxons présents.
"
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Papers by Emmanuel Martin
Scientific Reports, 2020
An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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In the central Anti-Atlas (Morocco; Zagora region), the Fezouata Shale has yielded an extraordina... more In the central Anti-Atlas (Morocco; Zagora region), the Fezouata Shale has yielded an extraordinary fossil Lagerstätte documenting the initial stages of the Great Ordovician Biodiversification Event. This Lagerstätte contains abundant and exceptionally well-preserved fossils (EPF) exhibiting soft-bodied preservation as well as " hard " , mineralized parts of extinct organisms. While soft-bodied preservation in the Fezouata Shale is confined to a few stratigraphic intervals, other fossiliferous intervals contain only shelly fossils in sandstone lenses (SL). Placed in the context of a previously established depositional model, EPF are interpreted as autochthonous assemblages buried by storm deposits, close to storm wave-base. There, the current component of storms is reduced compared to proximal settings and weak oscillation is dominant resulting in the record of oscillation ripples. In contrast, bioclastic accumulations were generated upslope in shallower, more proximal lower shoreface environments. There, the current component of storms was significant, as suggested by the disarticu-lation of skeletal remains. Bioclastic materials are localized in SL, which are lenses a few tens of centimeters in thickness and a few meters in width and length. These lenses commonly display erosive bases and convex tops, resulting in a lobate or a channel-lobe morphology. A large amount of sediment was thus rapidly deposited, resulting in the rapid burial of allochthonous material across a strongly localized surface of the sea floor. Integrating both sedimentological and paleontological evidence, intervals yielding EPF are considered as Konservat-Lagerstätten (KsL), in contrast with bioclastic accumulations defined as Konzentrat-Lagerstätten (KzL). Thus, KsL assemblages are interpreted to approximate biocenoses, in which organisms experienced rapid burial by distal tempestites, while KzL assemblages more likely correspond to thanatocenoses, locally deposited by storm back-currents. Here, a genetic link between KsL and KzL is suggested within the Fezouata Shale. Both types of Lagerstätten were related to storm activity, but at different depths.
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Keywords: Konservat-Lagerstätten Sedimentology Ordovician Gondwana Morocco Fezouata The Lower Ord... more Keywords: Konservat-Lagerstätten Sedimentology Ordovician Gondwana Morocco Fezouata The Lower Ordovician Fezouata Konservat-Lagerstätte from southern Morocco has been one of the major palaeontological discoveries of the last decade. It provides a unique insight into one of the most critical periods in the evolution of marine life: the Cambrian–Ordovician transition. However, its potential for deciphering key trends in animal diversification was hitherto largely limited by major uncertainties concerning its stratigraphic position, age and environmental setting. Based on extensive fieldwork, fossil evidence, and facies recognition, our study provides clarification on these three crucial issues. Exceptional preservation is limited to two intervals within the Fezouata Shale. Graptolites indicate a late Tremadocian age for the Fezouata Konservat-Lagerstätte as a whole, which is supported by biostratigraphical evidence provided by acritarchs. Sedimentological features and reconstructed patterns of relative sea-level changes indicate relatively shallow-water environmental conditions, under distal storm influence, in an offshore to lower shoreface siliciclastic ramp setting. The Fezouata Biota represents a unique and exceptional window into the palaeobiodiversity in open-marine conditions, thus contrasting with the other Ordovician Konservat-Lagerstätten presently known. In our analyses of this new set of data, we pave the way for accurate temporal, faunal and environmental comparisons with other Lower Palaeozoic Konservat-Lagerstätten, and unlock the full potential of the Fezouata Biota to better understand the processes and scenarios of early animal radiations.
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Palaeoscolecids are long cylindrical annulated vermiform ecdysozoans with an eversible proboscis ... more Palaeoscolecids are long cylindrical annulated vermiform ecdysozoans with an eversible proboscis comparable with that of priapulids. Their most conspicious external feature are aligned knob-like sclerites of assumed primary phosphatic origin associated to the annulations of their molting cuticle. Recent cladistic analyses indicate that palaeoscolecids probably belong to the stem lineage Priapulida. Their fossil record ranges from the early Cambrian to the late Silurian, but only isolated sclerites or small clusters of sclerites are usually found in sediments as SSF or SCF. By contrast, complete animals are relatively rare except in some Early Cambrian Lagerstätten such as in Chengjiang. Here are reported virtually complete specimens from several localities of Utah and Morocco which give important information on the anatomy, ecology and distribution of Palaeoscolecida through the Cambrian-Ordovician transition. Two specimens were recovered from the Issafen Formation (Cambrian Series ...
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Since the first discovery some 12 years ago of non-biomineralised fossils in the Tremadocian of t... more Since the first discovery some 12 years ago of non-biomineralised fossils in the Tremadocian of the Lower Fezouata Formation north of Zagora, south-eastern. Morocco, the Fezouata Biota has become one of the world's most important marine Konservat-Lagerstäitten, being the only exceptionally preserved fauna to document the critical Cambro-Ordovician faunal transition. It has revolutionized our understanding of Ordovician marine ecosystems, showing that Burgess Shale-type faunas, long thought to have disappeared after the middle Cambrian, continued to flourish well into the Ordovician while co-occurring with a host of remarkably derived, typical post-Cambrian organisms, many of which had been believed to have appeared much later. These findings indicate that the turnover between the Cambrian and Palaeozoic Evolutionary Faunas was more protracted than hitherto realized, while the presence of several surprisingly advanced forms in the biota suggests that at least in some non-biominer...
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The Weeks Formation preserves a diverse, yet largely undescribed, exceptionally preserved fauna o... more The Weeks Formation preserves a diverse, yet largely undescribed, exceptionally preserved fauna of late Guzhangian age (early late Cambrian). Recent investigations have shown that this fauna contains taxa previously regarded as typical of older or younger Konservat-Lagerstätten, which highlighted its transitional nature. Here we present two rare arthropods of uncertain affinities that further exemplify the uniqueness of the non-trilobite arthropod fauna of the Weeks Formation. Notchia weugi is characterized by a short cephalon, a trunk with 12 tergites and weakly differentiated into two morphological regions, and a spine-bearing rectangular telson. This taxon somewhat resembles other Cambrian arthropods, such as strabopids or Sidneyia, but detailed comparisons reveal many differences with them, arguing against close phylogenetic relationships. The affinities of Falcatamacaris bellua are even more problematic, for this large arthropod exhibits a mosaic of characters as-yet known in d...
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The Lower Ordovician Fezouata Lagerstätte from Morocco (central Anti-Atlas, Zagora area) has yiel... more The Lower Ordovician Fezouata Lagerstätte from Morocco (central Anti-Atlas, Zagora area) has yielded abundant and diverse soft-bodied fossils. Most described taxa were epibenthic or pelagic, so that little is known about the enbobenthic components of the fauna. Here we report the discovery of a locally abundant element of the biota, a palaeoscolecid worm, which may have played an important ecological role in the community. Palaeoscolecids had a long, annulated body with an eversible tooth-bearing pharynx. They probably represent stem priapulids, but unlike them, they were protected by biomineralized (phosphatic) microscopic plates covering most of the body. These sclerites are commonly found isolated within SSF assemblages, thus considerably extending the fossil record 24 of the group that ranges from the Cambrian Series 2 (Stage 3) to the upper Silurian. Like priapulids, palaeoscolecids might have been important bioturbators, contributing to the substrate colonization in the lower Palaeozoic. The discovery of abundant material (38 specimens) in the Fezouata Shale (Lower Ordovician, Morocco) allows us to reconsider their possible lifestyle, habitat and feeding habits. All the specimens belong to Palaeoscolex? tenensis, a species previously only known from a fragment of cuticle from the Floian of Bohemia (Czech Republic). Some exhibit remains of the gut and tail spines, all features that are highly informative with regard to the ecology of these extinct organisms, but rarely preserved. The phosphatic nature of the plates is demonstrated by compositional analyses and interpreted with regard to the diagenetic context of the Fezouata Shale as primary. We also hypothesize that (at least) some palaeoscolecids were makers of Tomaculum-type ichnofossils, which are elongate clusters of faecal pellets, and show that they ingested a notable amount of sediment during the normal course of feeding. The presence of Palaeoscolex? tenensis in the Lower Ordovician of Morocco further documents the great faunal similarities between Perunica and northern Gondwana at that time.
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STRATI 2013, 2014
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Talks by Emmanuel Martin
larly abundant in the Cambrian (e.g., Sirius Passet, Chengjiang, Emu Bay Shale, Burgess Shale, Orsten), but far less common and associated to restricted environmental conditions (e.g., anoxic sea floors, shallow brackish estuarine embayment) in the Or-
dovician. The Fezouata Biota, from the Outer Feijas Group (Lower Ordovician…) of Zagora area partly fills in this lacuna. Description of the new Moroccan Konservat-Lagerstätten is in progress, and will permit to assess precisely Early Ordovician marine biodiversity for the first time but also, to compare marine assemblages with comparable preservational modes from the early-mid Cambrian and the Early Ordovician.
In the Ternata plain, north of Zagora, the Lower Ordovician succession lies unconformably over the middle Cambrian sandstones of the Tabanite Group, and consists of an extremely thick series of more or less silty and micaceous argillites (ca. 700 m; Lower and Upper Fezouata Formations) overlain by the sandstones of the Zini Formation.
Since the early 2000s, several fossiliferous horizons within the Lower Fezouata Formation (Tremadocian) and the conformably overlying Upper Fezouata (Floian) have yielded extremely abundant and diverse remains of fully marine assemblages. Fossils comprise numerous exquisitely preserved remains of shelly taxa typical of post-Cambrian faunas: e.g., machaeridians, articulate brachiopods, bivalves, gastropods, nautiloid, cephalopods, trilobites, ostracods, graptolites, glyptocystitid rhombiferans, mitrate stylophorans, asterozoans, and crinoids. However, the Fezouata Biota also contains abundant and diverse remains of non-biomineralized organisms with several representatives of the Palaeozoic Evolutionary Fauna (most previously known only from younger de-posits): e.g., aglaspidid and cheloniellid arthropods, cirripedian crustaceans, xiphosu-
rans. The fauna also contains non-biomineralized taxa typical of early to middle Cambrian Konservat-Lagerstätten: e.g., anomalocaridids, halkieriids, marrellomorphs, na-
raoiids, palaeoscolecids. This clearly shows that some Cambrian key faunal elements stepped into the Ordovician. This important information challenges current evolutionary models favouring abrupt changes during the Cambrian–Ordovician transition.
However, the different Lower Ordovician fossiliferous horizons around Zagora needed to be placed in a spatio-temporal framework. Indeed, studies on the Fezouata biota have been focusing on faunal elements but lack accurate data on the age and environmental setting of the fossil localities. In the last two years, under the auspices of the ANR project RALI and two French-Moroccan CNRS-CNRST projects (SDU 05/09 & SDU 02/13), two field campaigns logged in detail the whole Lower Fezouata Formation and the lower half of the Upper Fezouata Formation. The precise stratigraphic position of all fossiliferous levels yielding exceptional preservation was also identified. The occurrence of mm- to cm-thick silty layers displaying storm-wave influence (wave ripples) points to relatively shallow offshore depositional settings. Principles of sequence stratigraphy applied to the logs also permitted to reconstruct sea-level fluctuations, which were compared with the changes in composition of some taxa (e.g., graptolites, echinoderms, trilobites) in association with the soft-bodied faunas. "
Néanmoins, dans un premier temps, il est indispensable de replacer les différents niveaux à préservation exceptionnelle de l'Ordovicien inférieur de la région de Zagora (Anti-Atlas central) dans leur contexte spatio-temporel. Pour y parvenir, deux approches ont été utilisées. La première, sédimentologique, a consisté à lever des coupes de référence couvrant une grand partie de la série (environ 600 mètres) et permettant de contraindre précisément les positions stratigraphiques des sites fossilifères. La seconde, paléontologique, est principalement axée sur les éléments de la faune les plus discriminants en terme de datation et/ou d’environnement (graptolites, trilobites et échinodermes) et que l'on retrouve associés aux faunes à préservation exceptionnelle (p.ex., aglaspidides, anomalocaridides, éponges, limules, marrellomorphes, vers). L’application des principes de stratigraphie séquentielle a également permis de mettre en évidence les variations du niveau marin relatif qui ont été comparées avec les changements de composition des assemblages fossilifères.
Suite à cette première phase exploratoire permettant de préciser les contextes biostratigraphique et paléoenvironnemental des différents niveaux fossilifères, l’étude des faunes ordoviciennes du Maroc va désormais pouvoir entrer dans une phase d’exploitation plus intensive, avec le lancement prochain d'un véritable chantier de fouilles niveau par niveau. Il permettra de mener des analyses paléoécologiques à haute résolution, comparables à celles réalisées sur les sites de Burgess (Canada) et de Chengjiang (Chine). En parallèle, le grand nombre de spécimens déjà récoltés nécessite un travail d’inventaire faunistique et de description systématique des nombreux taxons présents.
"
Papers by Emmanuel Martin
larly abundant in the Cambrian (e.g., Sirius Passet, Chengjiang, Emu Bay Shale, Burgess Shale, Orsten), but far less common and associated to restricted environmental conditions (e.g., anoxic sea floors, shallow brackish estuarine embayment) in the Or-
dovician. The Fezouata Biota, from the Outer Feijas Group (Lower Ordovician…) of Zagora area partly fills in this lacuna. Description of the new Moroccan Konservat-Lagerstätten is in progress, and will permit to assess precisely Early Ordovician marine biodiversity for the first time but also, to compare marine assemblages with comparable preservational modes from the early-mid Cambrian and the Early Ordovician.
In the Ternata plain, north of Zagora, the Lower Ordovician succession lies unconformably over the middle Cambrian sandstones of the Tabanite Group, and consists of an extremely thick series of more or less silty and micaceous argillites (ca. 700 m; Lower and Upper Fezouata Formations) overlain by the sandstones of the Zini Formation.
Since the early 2000s, several fossiliferous horizons within the Lower Fezouata Formation (Tremadocian) and the conformably overlying Upper Fezouata (Floian) have yielded extremely abundant and diverse remains of fully marine assemblages. Fossils comprise numerous exquisitely preserved remains of shelly taxa typical of post-Cambrian faunas: e.g., machaeridians, articulate brachiopods, bivalves, gastropods, nautiloid, cephalopods, trilobites, ostracods, graptolites, glyptocystitid rhombiferans, mitrate stylophorans, asterozoans, and crinoids. However, the Fezouata Biota also contains abundant and diverse remains of non-biomineralized organisms with several representatives of the Palaeozoic Evolutionary Fauna (most previously known only from younger de-posits): e.g., aglaspidid and cheloniellid arthropods, cirripedian crustaceans, xiphosu-
rans. The fauna also contains non-biomineralized taxa typical of early to middle Cambrian Konservat-Lagerstätten: e.g., anomalocaridids, halkieriids, marrellomorphs, na-
raoiids, palaeoscolecids. This clearly shows that some Cambrian key faunal elements stepped into the Ordovician. This important information challenges current evolutionary models favouring abrupt changes during the Cambrian–Ordovician transition.
However, the different Lower Ordovician fossiliferous horizons around Zagora needed to be placed in a spatio-temporal framework. Indeed, studies on the Fezouata biota have been focusing on faunal elements but lack accurate data on the age and environmental setting of the fossil localities. In the last two years, under the auspices of the ANR project RALI and two French-Moroccan CNRS-CNRST projects (SDU 05/09 & SDU 02/13), two field campaigns logged in detail the whole Lower Fezouata Formation and the lower half of the Upper Fezouata Formation. The precise stratigraphic position of all fossiliferous levels yielding exceptional preservation was also identified. The occurrence of mm- to cm-thick silty layers displaying storm-wave influence (wave ripples) points to relatively shallow offshore depositional settings. Principles of sequence stratigraphy applied to the logs also permitted to reconstruct sea-level fluctuations, which were compared with the changes in composition of some taxa (e.g., graptolites, echinoderms, trilobites) in association with the soft-bodied faunas. "
Néanmoins, dans un premier temps, il est indispensable de replacer les différents niveaux à préservation exceptionnelle de l'Ordovicien inférieur de la région de Zagora (Anti-Atlas central) dans leur contexte spatio-temporel. Pour y parvenir, deux approches ont été utilisées. La première, sédimentologique, a consisté à lever des coupes de référence couvrant une grand partie de la série (environ 600 mètres) et permettant de contraindre précisément les positions stratigraphiques des sites fossilifères. La seconde, paléontologique, est principalement axée sur les éléments de la faune les plus discriminants en terme de datation et/ou d’environnement (graptolites, trilobites et échinodermes) et que l'on retrouve associés aux faunes à préservation exceptionnelle (p.ex., aglaspidides, anomalocaridides, éponges, limules, marrellomorphes, vers). L’application des principes de stratigraphie séquentielle a également permis de mettre en évidence les variations du niveau marin relatif qui ont été comparées avec les changements de composition des assemblages fossilifères.
Suite à cette première phase exploratoire permettant de préciser les contextes biostratigraphique et paléoenvironnemental des différents niveaux fossilifères, l’étude des faunes ordoviciennes du Maroc va désormais pouvoir entrer dans une phase d’exploitation plus intensive, avec le lancement prochain d'un véritable chantier de fouilles niveau par niveau. Il permettra de mener des analyses paléoécologiques à haute résolution, comparables à celles réalisées sur les sites de Burgess (Canada) et de Chengjiang (Chine). En parallèle, le grand nombre de spécimens déjà récoltés nécessite un travail d’inventaire faunistique et de description systématique des nombreux taxons présents.
"