Search

Se presenta el tercer ejemplar del trilobites asáfido Megistaspis (Ekeraspis) cf. hammondi con conservación excepcional de apéndices, procedente del Fossil-Lagerstätte ordovícico de tipo Burgess Shale más importante del mundo, localizado en Marruecos. Los trilobites con apéndices o partes blandas se detectan en niveles del Tremadociense superior dentro de la Formación de Fezouata, pero son fósiles muy raros. El ejemplar estudiado conserva la antena derecha y nueve apéndices situados bajo el exoesqueleto, localizados en la parte derecha del cuerpo. Se trata principalmente de endópodos, pero al menos en dos apéndices se reconocen partes de los exópodos porque conservan sus largas lamelas. El primer endópodo parece corresponder al extremo distal del tercer apéndice cefálico, y el resto son apéndices torácicos. Las antenas observadas en ejemplares comerciales de la misma especie suelen estar manipuladas por los preparadores y son poco fiables. Además del asáfido estudiado, la conservación de partes blandas y apéndices se conoce en otras cuatro especies coetáneas, totalizando medio centenar de ejemplares publicados. Pero es muy posible que existan muchos más casos en los que los apéndices de aquellos ejemplares que conserven las antenas permanezcan en realidad ocultos bajo el caparazón dorsal., A third specimen of Megistaspis (Ekeraspis) cf. hammondi is described from the most important Ordovician Burgess Shale-type Fossil-Lagerstätte in Morocco. The trilobite specimens with soft-part preservation are located in late Tremadocian levels within the Fezouata Formation, but are very rare. The studied specimen preserves the right antenna, and nine appendages under the right side of the exoskeleton, only evident when a break in the rock released part of the exoskeleton and revealed the underlying biramous appendages. These mostly consist of endopods, but also at least a couple of exopods, recognizable by their long lamellae. The first endopod seems to correspond to the distal tip of the third cephalic appendage, while the rest are thoracic appendages. The features of the preserved antenna indicate that most such appendages in other specimens from the same area are created or enhanced during preparation. Besides the studied asaphid, soft-part preservation of digestive tract and appendages are known from four coeval species, totalling about fifty published specimens. But it is quite possible that, like in the present specimen, biramous appendages may be preserved under the carapace of other specimens with antennae., Ministerio de Ciencia e Innovación, PICG (IUGS-UNESCO), Fundação para a Ciência e Tecnologia, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

[EN] A third specimen of Megistaspis (Ekeraspis) cf. hammondi is described from the most important Ordovician Burgess Shale-type Fossil-Lagerstätte in Morocco. The trilobite specimens with soft-part preservation are located in late Tremadocian levels within the Fezouata Formation, but are very rare. The studied specimen preserves the right antenna, and nine appendages under the right side of the exoskeleton, only evident when a break in the rock released part of the exoskeleton and revealed the underlying biramous appendages. These mostly consist of endopods, but also at least a couple of exopods, recognizable by their long lamellae. The first endopod seems to correspond to the distal tip of the third cephalic appendage, while the rest are thoracic appendages. The features of the preserved antenna indicate that most such appendages in other specimens from the same area are created or enhanced during preparation. Besides the studied asaphid, soft-part preservation of digestive tract and appendages are known from four coeval species, totalling about fifty published specimens. But it is quite possible that, like in the present specimen, biramous appendages may be preserved under the carapace of other specimens with antennae., [ES] Se presenta el tercer ejemplar del trilobites asáfido Megistaspis (Ekeraspis) cf. hammondi con Conservación excepcional de apéndices, procedente del Fossil-Lagerstätte ordovícico de tipo Burgess Shale más importante del mundo, localizado en Marruecos. Los trilobites con apéndices o partes blandas se detectan en niveles del Tremadociense superior dentro de la Formación de Fezouata, pero son fósiles muy raros. El ejemplar estudiado conserva la antena derecha y nueve apéndices situados bajo el exoesqueleto, localizados en la parte derecha del cuerpo. Se trata principalmente de endópodos, pero al menos en dos apéndices se reconocen partes de los exópodos porque conservan sus largas lamelas. El primer endópodo parece corresponder al extremo distal del tercer apéndice cefálico, y el resto son apéndices torácicos. Las antenas observadas en ejemplares comerciales de la misma especie suelen estar manipuladas por los preparadores y son poco fiables. Además del asáfido estudiado, la conservación de partes blandas y apéndices se conoce en otras cuatro especies coetáneas, totalizando medio centenar de ejemplares publicados. Pero es muy posible que existan muchos más casos en los que los apéndices de aquellos ejemplares que conserven las antenas permanezcan en realidad ocultos bajo el caparazón dorsal.

Radiodonts are nektonic stem-group euarthropods that played various trophic roles in Paleozoic marine ecosystems, but information on their vision is limited. Optical details exist only in one species from the Cambrian Emu Bay Shale of Australia, here assigned to Anomalocaris aff. canadensis. We identify another type of radiodont compound eye from this deposit, belonging to ‘Anomalocaris’ briggsi. This ≤4-cm sessile eye has >13,000 lenses and a dorsally oriented acute zone. In both taxa, lenses were added marginally and increased in size and number throughout development, as in many crown-group euarthropods. Both species’ eyes conform to their inferred lifestyles: The macrophagous predator A. aff. canadensis has acute stalked eyes (>24,000 lenses each) adapted for hunting in well-lit waters, whereas the suspension-feeding ‘A.’ briggsi could detect plankton in dim down-welling light. Radiodont eyes further demonstrate the group’s anatomical and ecological diversity and reinforce the crucial role of vision in early animal ecosystems., Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited., NHM Repository

En este capítulo se tratan una serie de grupos que son típicamente bioconstructores o formadores de arrecifes. Aunque otros grupos de organismos de diversa afinidad biológica, tales como procariotas (bacterias, cianobac­terias), algas, braquiópodos, bivalvos, etc., pueden cons­truir o participar en la construcción de arrecifes, a lo lar­go de la historia geológica de la Tierra y en la actualidad, po­ríferos, cnidarios y afines han sido y son los más impor­tantes componentes de los depósitos arrecifales.

En este capítulo se tratan una serie de grupos que son típicamente bioconstructores o formadores de arrecifes. Aunque otros grupos de organismos de diversa afinidad biológica, tales como procariotas (bacterias, cianobac­terias), algas, braquiópodos, bivalvos, etc., pueden cons­truir o participar en la construcción de arrecifes, a lo lar­go de la historia geológica de la Tierra y en la actualidad, po­ríferos, cnidarios y afines han sido y son los más impor­tantes componentes de los depósitos arrecifales.

The Fezouata Shale has yielded remarkably diverse assemblages of non-biomineralizing and biomineralizing organisms of Early Ordovician age. Overall, some 160 genera have been documented, about a quarter of which are essentially soft-bodied. Exceptional preservation in the Fezouata Shale occurs in two main separated intervals, of late Tremadocian and mid-Floian age respectively. These intervals are best regarded as distinct Konservat-lagerstätten, since they contain different faunas and are separated in time by c. 9 Ma. Both assemblages are dominated by arthropods, including a diverse trilobite fauna (c. 25 genera). Here we report the discovery of fossilized appendages and guts in 31 trilobite specimens from the lower Fezouata Konservat-lagerstätte belonging to the genera Anacheirurus, Bavarilla, and Prionocheilus (Order Phacopida). The preservation of appendages is generally poor, especially for their proximal parts covered by the dorsal exoskeleton. However, when appendages project from below the dorsal carapace, they exhibit delicate structures, such as annuli boundaries and lateral spines of antennae, or podomere boundaries, clustered endites and terminal claws of endopods. Lamellate exopods are rarely preserved, and when they are, their morphologies are largely obscured by the dorsal carapace. Appendages are typically preserved as thin, yellowish films of iron oxides, interpreted as oxidized pyrite. Among preserved gut structures, Anacheirurus displays a parallel-sided, sediment-filled digestive tract, running under the entire trunk axis while the tract of Bavarilla (wide and sediment-filled) is associated with 10 pairs of digestive glands, which are atypically preserved as a sediment infill. The new examples of fossilized ‘soft’-parts of trilobites from the lower Fezouata Lagerstätte complement previous observations in Megistaspis and Symphysurus, two taxa also belonging to the pilekiid-bavarillid biofacies typical of lower shoreface settings. Despite notable d

The Bohemo-Iberian regional scale for South Gondwana, involving the ‘Mediter-ranean Province’, comprises five regional stages (Arenigian, Oretanian, Dobrotivian,Berounian and Kralodvorian) plus the global Tremadocian and Hirnantian. Thepredominance of shallow-water taxa in those high-latitude faunas imposes serious dif-ficulties for correlating the regional succession with the formal global chronostratigra-phy because of the almost total absence of the key graptolites and conodonts definingthe base of the standard series, stages and stage slices. Instead, the abundant benthicfaunas (trilobites, brachiopods, molluscs, echinoderms) of South Gondwanan originlargely dominated in the area from the middle Darriwilian to the late Katian. Thepoleward faunal migration of originally Avalonian, Baltic, Laurentian and even Asiatictaxa during the Boda Event of global warming progressively ends with the endemicityin the region, where the ensuing benthic assemblages were severely affected by the Hir-nantian glaciation. The regional scale significantly improves the precision of correla-tions between Ordovician strata from SW and central Europe, North Africa and alarge part of the Middle East. An updated record of palaeontological data from areaswhere Mediterranean faunas remain practically unknown, or are still poorly investi-gated, is also included. Palaeobiogeographical relationships based on the distributionof faunas across South Gondwana are suggested as an improvement for positioningmany territories in modern palaeogeographical reconstructions and offer a construc-tive approach to problems related to the pre-Variscan and pre-Alpine orogenic puz-zles.

Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana.

The Bohemo‐Iberian regional scale for South Gondwana, involving the ‘Mediterranean Province’, comprises five regional stages (Arenigian, Oretanian, Dobrotivian, Berounian and Kralodvorian) plus the global Tremadocian and Hirnantian. The predominance of shallow‐water taxa in those high‐latitude faunas imposes serious difficulties for correlating the regional succession with the formal global chronostratigraphy because of the almost total absence of the key graptolites and conodonts defining the base of the standard series, stages and stage slices. Instead, the abundant benthic faunas (trilobites, brachiopods, molluscs, echinoderms) of South Gondwanan origin largely dominated in the area from the middle Darriwilian to the late Katian. The poleward faunal migration of originally Avalonian, Baltic, Laurentian and even Asiatic taxa during the Boda Event of global warming progressively ends with the endemicity in the region, where the ensuing benthic assemblages were severely affected by the Hirnantian glaciation. The regional scale significantly improves the precision of correlations between Ordovician strata from SW and central Europe, North Africa and a large part of the Middle East. An updated record of palaeontological data from areas where Mediterranean faunas remain practically unknown, or are still poorly investigated, is also included. Palaeobiogeographical relationships based on the distribution of faunas across South Gondwana are suggested as an improvement for positioning many territories in modern palaeogeographical reconstructions and offer a constructive approach to problems related to the pre‐Variscan and pre‐Alpine orogenic puzzles.

Trilobites were one of the most successful groups of marine arthropods during the Palaeozoic era, yet their soft-part anatomy is only known from a few exceptionally-preserved specimens found in a handful of localities from the Cambrian to the Devonian. This is because, even if the sclerotized appendages were not destroyed during early taphonomic stages, they are often overprinted by the three-dimensional, mineralised exoskeleton. Inferences about the ventral anatomy and behavioural activities of trilobites can also be derived from the ichnological record, which suggests that most Cruziana and Rusophycus trace fossils were possibly produced by the actions of trilobites. Three specimens of the asaphid trilobite Megistaspis (Ekeraspis) hammondi, have been discovered in the Lower Ordovician Fezouata Konservat-Lagerstätte of southern Morocco, preserving appendages and digestive tract. The digestive structures include a crop with digestive caeca, while the appendages display exopodal setae and slight heteropody (cephalic endopods larger and more spinose than thoracic and pygidial ones). The combination of these digestive structures and the heteropody has never been described together among trilobites, and the latter could assist in the understanding of the production of certain comb-like traces of the Cruziana rugosa group, which are extraordinarily abundant on the shallow marine shelves around Gondwana.

The pandemic brachiopod Hirnantia fauna characterizes the lower part of the Hirnantian (Hi1 Stage Slice of the uppermost Ordovician Global Stage). In the Moroccan Anti-Atlas, its occurrence in glacially-related successions allowed contrasting the onset of several Late Ordovician glacial events. In the Central Anti-Atlas, the Hirnantian is lithostratigraphically represented by the Second Bani Group, a sandstone-dominated succession. In the region immediately west of Tagounite (in the vicinity of Zagora), the group is subdivided into two formations, the basal Lower Second Bani Formation and the overlying Upper Second Bani Formation, separated by a major erosive (glaciogenic) unconformity. The Lower Second Bani Formation is composed of two members, the lower mostly made of clayey sandstones and the upper consisting of thick-bedded quartzitic sandstones (Fig. 1). Figure 1: Ait-Isioul section, west of Tagounite (Morocco). Upper Ordovician formations with the situation of the sampled levels in the Lower Second Bani Formation. We have revisited the stratotype of the Lower Formation of the Second Bani Group, west of Tagounite, and sampled brachiopods from its uppermost quartzitic horizons (from Destombes' horizon F upsection). In addition to those brachiopods listed by Destombes [1] from the region, we have found Plectothyrella sp. and Kinnella sp. Both genera are exclusive of the pandemic Hirnantia fauna, which allows confirmation of a Hirnantian age for the upper member of the Lower Second Bani Fm. By contrast, the lower member of the Lower Second Bani (concretely, Destombes' G bryozoan limestone horizon, rich in the echinoderms Maghrebocystis and Herpetocystis, and horizons slightly above it), has yielded Katian brachiopods and trilobites, such as Eostropheodonta intermedia, Destombesium sp., Hirnantia sp. (species different than H. sagittifera), Actinopeltis aff. insocialis, Mucronaspis termieri and Cekovia aff. loredensis. Thus, following the present-day lithostratigra

At a smaller scale than in the case of the peripatetic fossils from the Himalaya, known as the "Gupta affaire" [1], North African and South American paleontology of the late 20th Century and today continue to provide examples of misconduct in paleontological science. Most of these remain unknown outside the limited circles of specialists but could introduce confusion in the future, when contaminated, poorly constructed or unusable data may be used for regional geology or taken into account in global paleontological databases employed in paleogeography, correlations or any other Geological Science applications. As in the Gupta affaire, the "suspected" fossils came from places of difficult access -such as deserts, jungles or high mountains- with a great deficiency in valuable data. Apart from some "misplaced" fossils, the problem mainly falls upon the opportunistic individuals that use obscure journals to avoid a minimal scientific control of their published contents. In North Africa, the best example of this type of fraudulent behavior was carried out by the Egyptian micropaleontologist Mostapha M. Iman, who published dozens of "misplaced" and "recycled" fossils (mostly taken from papers from other authors), supposedly coming from Cretaceous to Miocene formations of Libya and Egypt, who was finally exposed by a Spanish journal [2][3]. Another example of unethical behavior in North African paleontology is denounced here: the activities of Joan Corbacho, a Spanish fossil collector and trader that, without a minimal scientific knowledge, published ca. 20 papers with several dozen new trilobite taxa coming from different Cambrian to Devonian formations in the Moroccan Anti-Atlas. A fraction of the original specimens were inadequately prepared or reconstructed by local dealers, and his descriptions of new taxa are very poor and lack of confident data about localities and stratigraphic position. Despite of this, papers were published by an old private museum connected to t, in value", were later offered for sale in Internet, and often with a "certificate of authenticity" signed by the Museum'director. In South America, Peruvian paleontology is living a critical period dominated by impostors with high penetration in the national and social media, like the electronic engineer Klaus Hönninger or the journalist Carlos A. Vildoso. Both of them have acted as highly reputed paleontologists for more than a decade, but never published any true scientific result. They founded private businesses under the aspect of a museum and a research institute, respectively. Mr Vildoso is the chairman of the IX Latin-American Paleontological Congress, to be held in Lima (September 20-24, 2016), while excluding from the organizing committee the most acknowledged Peruvian paleontologists

[ES] La nuevas divisiones de la escala global del Sistema Ordovícico, con excepción de los pisos Tremadociense e Hirnantiense, son difíciles de aplicar en la Península Ibérica, pues sus estratotipos de límite radican en facies y faunas de aguas profundas, desconocidas en las plataformas someras y de paleolatitud elevada del ámbito peri-gondwánico. Antes de ello, la escala regional británico-avalónica fue utilizada en Iberia durante todo el siglo XX, pero presenta serios inconvenientes de correlación vinculados con la propia evolución, conceptual y de criterio, registrada en las áreas tipo británicas durante los últimos 40 años. Sin embargo, la escala regional bohemo-ibérica es la que actualmente aporta una mayor precisión a las correlaciones, pues se basa en elementos bioestratigráficos y biocronológicos de distribución común a todo el margen peri-gondwánico europeo y norteafricano, y la que mantiene vínculos episódicos con otras escalas regionales, que permitirán resolver progresivamente las equivalencias con la escala global, [EN] The new divisions from the global scale for the Ordovician System, except for the Tremadocian and Hirnantian stages, are difficult to correlate in the Iberian Ordovician, because their GSSPs involve deep-water facies and faunas not recorded in the shallow, high-paleolatitudinal settings of the peri-Gondwanan area. Previously to the Global scale, the British-Avalonian regional scale had been widely adopted in the Iberian Ordovician during all the 20th Century, but there are serious correlation problems due to the former’s conceptual evolution and variable criteria used for the British type areas during the last 40 years. However, the use of the Bohemo-Iberian scale instead, provides better precision to Iberian correlations, because it is based in some local biostratigraphical and biochronological markers, widely recorded over an extensive area of the European and North African peri-Gondwanan margin. The Bohemo-Iberian scale shows episodic links with other regional scales, which will provide indirect correlations also with the global Ordovician scale.

Middle Ordovician shales from the Valongo and Moncorvo formations recorded temporary dysoxic environments, inhabited by opportunistic faunas that also include highly specialized deposit feeders. Resulting ichnofossils include Phycodes noa Mikuláš, a horizontally-ramified burrow complex, so far only known from older beds in the Prague Basin, as well as a large spiral grazing trace close to Rotundusichnium zumayensis Gómez de Llarena, which is widely distributed in Alpine flysch deposits. Phycodes noa from the Valongo Formation occurs as quite large, horizontally flabellate structure with up to 10 diverging passages. Specimens from the Canelas quarry (Arouca) are commonly infilled by pellets (Tomaculum), and are preserved flattened and tectonically expanded. Giant Rotundusichnium-like forms are exclusive from the Canelas quarry and consist of ?concentric to tightly spiral traces with a large elliptical outline (major axis up to 130 cm long), showing endichnial ribbons inclined to the centre of the structure. These are associated with imploded fragmocones of nautiloids preserved under them, and the trace maker harvested the microbial proliferation around them in tight centrifugal coils. The third remarkable trace corresponds to bite marks preserved in large trilobite carapaces. They have a consistent acute V-shaped outline and represent marginal breakage, usually placed in the right pygidial pleural border of asaphids, in diverse margins of calymenaceans or in semi-infaunal molluscs. These triangular bite marks are attributed to large nautiloid predators or scavengers, sometimes attacking freshly-molted giant trilobites.