Devonian Research Papers - Academia.edu (original) (raw)

This map folio should be referenced as: Scotese, C.R., 2013. Map Folio 70 Early Devonian (Emsian, 402.3 Ma), PALEOMAP PaleoAtlas for ArcGIS, volume 4, Late Paleozoic Paleogeographic, Paleoclimatic and Plate Tectonic Reconstructions,... more

Fossil occurrences across the world are endangered by development, construction, collecting, and vandalism, even though many outstanding examples have been protected by World Heritage Sites, national parks, monuments and reserves, state... more

Fossil occurrences across the world are endangered by development, construction, collecting, and vandalism, even though many outstanding examples have been protected by World Heritage Sites, national parks, monuments and reserves, state and provincial parks, and local government and non-profit organizations, as well as some private individuals. The International Palaeontological Association (IPA) established a PaleoParks Initiative to protect endangered sites and to catalog and make public established parks of any nature that protect fossils in the ground, a primary source of scientific data, educational opportunities and recreational activities, as well as key places protecting "living fossils". IPA has 15 aims and goals and a web site for documenting both established and proposed sites. IPA sponsored meetings and workshops at three international meetings over the past five years to discuss these problems, successful solutions, and its goals and aims. Ten examples of Pale...

Western Australia has one of the most diverse floras in the world. From the giant Karri and Tingle forests in the south, to the scattered tropical rainforests in the north; from the incredibly species-rich sand heath flora in the... more

Western Australia has one of the most diverse floras in the world. From the giant Karri and Tingle forests in the south, to the scattered tropical rainforests in the north; from the incredibly species-rich sand heath flora in the south-west, to the desert floras of the inland parts of the State, more than 12,000 species of vascular plants are estimated to exist. The changing pattern of the fossil floras in Western Australia is a legacy of both their evolutionary history and of the changing environments in which they grew. In this booklet we provide an illustrated overview of Western Australia’s fossil plant record, based on fossil collections of the Western Australian Museum, the Department of Geology and Geophysics in the University of Western Australia, and the Geological Survey of Western Australia. Although many fossil plants that have been collected over the last 30 years still remain to be described, sufficient is known to provide a broad overview of the ancestors of the state’s highly diverse modern flora.

The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the... more

The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian period (393-359 million years ago) 1. These taxa-known as elpistostegalians-include Panderichthys 2 , Elpistostege 3,4 and Tiktaalik 1,5 , none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian period of Canada, which represents-to our knowledge-the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates. The first tetrapods known from skeletal remains date back to the Late Devonian period (about 374 million years ago) 6,7 , while trackway fossils showing digitate impressions of limbs suggest an earlier origin for this clade 8. Over the past decade, fossils that provide information on the fish-to-tetrapod transition have been used to better understand anatomical transformations associated with locomotion 5,9-12 , breathing 13 , hearing 14 and feeding 11,15 , with regard to the change in habitat from water to land. Until now, the terrestrialization of vertebrates has primarily been a matter of comparing six relatively well-known Devonian taxa among stem-group tetrapods 16 : a true piscine sarcopterygian, Eusthe-nopteron foordi; a piscine elpistostegalian, Panderichthys rhombolepis; a near-tetrapod elpistostegalian, Tiktaalik roseae; and three true basal tetrapods, Acanthostega gunnari, Ventastega curonica and Ichthyostega sp. Here we adopt an apomorphy-based definition of tetrapods as 'all organisms derived from the first sarcopterygian to have possessed digits homologous with those in Homo sapiens' 17,18. However, these inferences regarding terrestrialization rely critically on the handful of specimens that have been referred to elpistostega-lians, none of which has been completely described. The postcranial anatomy of Panderichthys is primarily restricted to the morphology of the pectoral fins and girdle 2,19,20 , the vertebrae 2,21 , the scale patterning 22 and very little on the pelvic fin and girdle morphology 9. Although more than 60 specimens 1,10 of Tiktaalik have been found, most of the anatomy of this species has been described from a fairly complete individual for which the skull 1,15 , pectoral and pelvic fins and girdles 5,10,23 , scales 22 and the trunk region 1 anterior to the pelvic region are preserved.

This catalogue presents the Devonian vertebrates of China. The ages of some vertebrate fossils are corrected according to recent biostratigraphic correlations. The vertebrate bio-events in the Devonian of China are also investigated. ln... more

This catalogue presents the Devonian vertebrates of China. The ages of some vertebrate fossils are corrected according to recent biostratigraphic correlations. The vertebrate bio-events in the Devonian of China are also investigated. ln South China, the Early Emsian Event is characterized by a changeover from strong endemic fauna to cosmopoJitan fauna. The endemic Galeaspida become almost extinct after the Mid-Emsian Event. The Late Eifelian Event results in the disappearance of rnany placoderms. The Antiarcha have their last radiation in the late Famennian, and become extinct at Carboniferous - Devonian boundary.

Le gisement du Bois de la Hè constitue le troisième site d'extraction et de taille de meules va-et-vient connu pour la Protohistoire dans les niveaux lochkoviens du Massif des Ardennes, presque à mi-chemin entre les deux autres de... more

Le gisement du Bois de la Hè constitue le troisième site d'extraction et de taille de meules va-et-vient connu pour la Protohistoire dans les niveaux lochkoviens du Massif des Ardennes, presque à mi-chemin entre les deux autres de Macquenoise (une centaine de kilomètres à l'ouest) et de Salmchâteau (une soixantaine de kilomètres au nord-est). Ces meulières sont à mettre en relation avec les objets finis qui commencent à être identifiés sur les sites de consommation dès le Néolithique et au Bronze final dans le nord de la France, puis à l'Âge du Fer dans le nord de la France, en Belgique, aux Pays-Bas et au Grand-Duché de Luxembourg. Cette dernière observation ouvre donc de nouvelles perspectives sur l'exploitation et la distribution des ressources lithiques autour du massif ardennais.

The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching... more

The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (<0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (<0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. Calcimudstones and peloidal wackestones overwhelmingly dominate with significant proportions of intraclasts, aggregates, dasycladalean calcareous algae, crinoid ossicles and minor amounts of brachiopods, gastropods, ostracodes and sponge spicules; bioturbation was ubiquitous and multi- generational. The shallow seafloor was flat and virtually featureless, with widespread meadows of algae and crinoids plus a few areas of low-relief stromatoporoidal patch reefs. In this storm-dominated system, the sediment surface of varying stiffness was swept and scoured frequently, leaving pack- to grainstones composed of rounded intraclasts and sediment-filled burrows. The abundance of algae and dominantly micritized aspect of crinoid ossicles suggest that the platform was mesotrophic, receiving elevated nutrient supply from the Ellesmerian orogen on the northern side of the craton.
Although superficially uniform and ‘layer-cake’ in aspect, subtle compositional changes show that the platform exhibits four, hitherto unrecognized, long-term transgressive– regressive sequences, culminating in the demise of carbonate sedimentation and burial by nearly craton-wide black shales. Eustatic sea level and, more importantly, subsidence rate fluctuated during these sequences, with the third sequence characterized by subaerial exposure of the proximal region. Thicknesses calibrated to conodont biozones indicate that the marginal ramp had the greatest accumulation rate, although without any dramatic alteration of paleotopography. The ability of carbonate production to keep a balance with subsidence and eustasy over ~10 million years and hundreds of metres of strata yet not display in peritidal cycles is a characteristic shared by many other large platforms. It may reflect insufficient carbonate production rates, a higher energy regime, and off-platform sediment redeposition, coupled with stable mesotrophic conditions.

Diverse and abundant trilobite faunas occur in several beds near the base of the section of the upper Emsian to Eifelian Timrhanrhart Formation exposed at Jbel Gara el Zguilma, south of Foum Zguid in Morocco. While trilobites occur... more

Diverse and abundant trilobite faunas occur in several beds near the base of the section of the upper Emsian to Eifelian Timrhanrhart Formation exposed at Jbel Gara el Zguilma, south of Foum Zguid in Morocco. While trilobites occur throughout much of this section, they are exquisitely preserved and most diverse in the lowest (upper Emsian) portion. Several of the trilobite species are commercially available, but their taxonomy has never been formalized, and their field occurrence has not previously been described. Near the base of the section, two nodular argillaceous limestone beds contain highly diverse trilobite faunas, with many spectacular spiny forms. These include examples deviating from bilateral symmetry that are apparently unique in the Trilobita. Alpha diversity is high, with as many as 23 trilobite species in one bed.
We suggest that these nodular beds represent thick, rapidly emplaced storm obrution deposits that underwent transport for a short distance before the trilobites came to rest in chaotic burial orientations. Calcareous nodule formation during early diagenesis protected the trilobites from compaction. Higher in the same section, in strata of Eifelian age, trilobite faunas are of lower diversity, and composed mainly of species of Phacops, Hollardops and Parahomalonotus, although one horizon has an alpha diversity of at least 9 species.
Twenty three new species-level taxa include: Acastoides zguilmensis, Acastoides haddadi, Coltraneia effelesa, Cyphaspis agayuara, C. eberhardiei, C. hamidi, Diademaproetus mohamedi, Gerastos tuberculatus marocensis, Hollardops hassainorum, Kayserops tamnrherta, Koneprusia dahmani, Leonaspis haddanei, L. spinicurva, Parahomalonotus calvus, Phacops granulops, P. lebesus, P. smoothops, Psychopyge hammerorum, Scabriscutellum hammadi, S. lahceni, Tropidocoryphe amuri, Walliserops hammii, and W. tridens. Cyphaspis new species A is known only from a single cephalon. “Sculptoproetus” new species A and “S.” new species B are being named in another work that will appear in print after this work.

New millipede specimens from the Paleozoic of Scotland are described, including Archidesmus macnicoli , from the Lower Devonian (Lochkovian) Tillywhandland Quarry SSSI and three new taxa—Albadesmus almondi, Pneumodesmus newmani, and... more

New millipede specimens from the Paleozoic of Scotland are described, including Archidesmus macnicoli , from the Lower Devonian (Lochkovian) Tillywhandland Quarry SSSI and three new taxa—Albadesmus almondi, Pneumodesmus newmani, and Cowiedesmus eroticopodus—from the mid Silurian (late Wenlock—early Ludlow) Cowie Formation at Cowie Harbour. Cowiedesmus eroticopodus new species is placed within the new Cowiedesmidae within the new order Cowiedesmida. Kampecaris tuberculata Brade-Birks from the Lower Devonian (Siegenian) of the Lanark Basin near Dunure is shown not to be a kampecarid myriapod, redescribed as Palaeodesmus tuberculata and placed order incertae sedis within Archipolypoda. Anthracodesmus macconochiei Peach is also redescribed and tentatively placed order incertae sedis within Archipolypoda. Archidesmus macnicoli, Albadesmus almondi, and Palaeodesmus tuberculata are each demonstrated to have broad sternites with laterally placed coxal sockets and paramedian pores containing paired valves. These pores are interpreted as having housed eversible vesicles. Some specimens of Archidesmus macnicoli and Cowiedesmus eroticopodus are male and have a pair of modified legs on trunk segment 8, identified as leg pairs 10 and 11, respectively. The presence of modified anterior legs restricted to segment 8 increases the range of variability known in modified appendage location in male millipedes and compounds existing uncertainty about using the presence of gonopods on trunk segment 7 as a synapomorphy of Helminthomorpha. An affinity between Archidesmida and Cowiedesmida is suggested based on possession of modified legs on segment 8 and Archidesmida + Cowiedesmida is placed along with Euphoberiida in Archipolypoda based on possession of free, broad sternites with bivalved paramedian pores and fused pleurotergites. The oldest known evidence of spiracles is demonstrated in Pneumodesmus newmani, proving that the oldest known millipedes were fully terrestrial.

Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the standard conodont zonation, between... more

Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the standard conodont zonation, between the Palmatolepis hassi and P. triangularis zones (Late Middle Frasnian to Early Famennian) in the Namur-Dinant Basin (Belgium) are described. The orders and suborders investigated include 32 species: 21 are described in open nomenclature, seven are previously known, four are new of which three are assigned to previously known genera: Aulacella aggeris n. sp., Dicamara plutonis n. sp., and Warrenella (Warrenella) aquaealbae n. sp. Th e fourth species belonging to a newly defined genus: Neptunathyris buxi n. gen., n. sp. A major brachiopod faunal change occurs at the top of the P. rhenana Zone in southern Belgium, with the disappearance of most existing species in parallel with the deterioration of the oxygenation conditions preceding the Upper Kelwasser Event. Only an impoverished fauna (Lingulida, Chonetidina, Rhynchonellida) has been collected in the P. linguiformis Zone. The recovery of the Famennian brachiopods after the end-Frasnian biotic crisis was rapid in the basal Famennian but, despite their great abundance, their diversity was relatively low. New cosmopolitan genera appeared at this time especially among the rhynchonellids, athyridids and spiriferids with new species of pre-existing orthid and orthotetid genera.

Traditionally, the evolutionary scenarios of Asteropyginae have been organized in two major clades involving four pygidial patterns. The first cladistic analysis performed on the subfamily maintained the organization in two clades, though... more

Traditionally, the evolutionary scenarios of Asteropyginae have been organized in two major clades involving four pygidial
patterns. The first cladistic analysis performed on the subfamily maintained the organization in two clades, though the
phylogenetic relationships between genera were unexpected compared to the traditional scenarios. Moreover, the previous
systematic scheme based on pygidial segmentation was rendered obsolete. In this study, we performed a new phylogenetic
analysis from well-known taxa and recent discoveries. Sixty species assigned to 36 genera have been analysed from a
dataset of 72 characters. Three more species are used as the outgroup. The 79 most parsimonious trees have a length of
492 steps and a retention index of 0.735. Our analysis confirms the monophyly of Asteropyginae excluding the genus
Protacanthina. The phylogenetic pattern is unconventional in that a largely pectinate topology is resolved, rather than two
clades corresponding to formerly delimited pygidial morphs. Nevertheless, most relationships between genera suggested in
the traditional evolutionary scenarios of the subfamily have been recovered, the main differences being the origin of the
group. Whereas Treveropyge was usually considered as the origin of the remaining Asteropyginae, the present results instead
identify Destombesina as the sister group to all remaining members of the subfamily. From the new phylogenetic pattern,
the diagnoses of genera are rewritten in a standard way and to delimit clades more accurately. This work implies modified
generic assignments for some species and the erection of four new genera: Minicryphaeus gen. nov., Gandlops gen. nov.,
Morzadecops gen. nov. and Pennarbedops gen. nov. The systematic position of Erbenochile is also discussed, the genus no
longer being assigned to Asteropyginae.

May, A. (1984a): Geologie Westfalens. Eine Einführung (Erdgeschichte, Fossilien, Mineralien). - In: Bergkamen gestern und heute, vol. 10 + 11: 1-74, 23 figs., 2 tabs.; Bergkamen (Heimatmuseum Stadt Bergkamen). A short overview on the... more

These denizens of the Paleozoic Era seas were surprisingly diverse

A consideration of pixy traditions of Devon and Cornwall reveals similarities and differences. Although people from both places described the supernatural beings in similar ways, examples of migratory legends diverge, particularly when... more

A consideration of pixy traditions of Devon and Cornwall reveals similarities and differences. Although people from both places described the supernatural beings in similar ways, examples of migratory legends diverge, particularly when comparing those from the far west of the peninsula with those from Devon. A method employing Reidar Christiansen’s index demonstrates that differences in these narratives reflect the isolation of far western Cornwall. This analysis indicates that nineteenth-century Cornish folklore should be seen as distinct from English traditions.

he IGCP 596–SDS Symposium is an international and multidisciplinary meeting aiming at a better understanding of the interactions existing between climate changes and biodiversity during the mid-Palaeozoic period (Devonian and... more

he IGCP 596–SDS Symposium is an international and multidisciplinary meeting aiming at a better understanding of the interactions existing between climate changes and biodiversity during the mid-Palaeozoic period (Devonian and Carboniferous). A time when terrestrial ecosystems experienced a biodiversity boom and oceanic ecosystems suffered from catastrophic extinctions of different magnitudes (e.g. Taghanic, Upper Kellwasser and Hangenberg events). This symposium brings together geochemists, geologists, palaeontologists and sedimentologists within the frame of the International Geoscience Programme (IGCP) Project 596 (climate change and biodiversity patterns in the mid-Palaeozoic) and the Subcommission on Devonian Stratigraphy (SDS) of the International Union of Geological Sciences.

During these last years, considerable attention has been given to unconventional oil and gas shale in northern Africa where the most productive Paleozoic basins are located (e.g. Berkine, Illizi, Kufra, Murzuk, Tindouf, Ahnet, Oued Mya,... more

During these last years, considerable attention has been given to unconventional oil and gas shale in northern Africa where the most productive Paleozoic basins are located (e.g. Berkine, Illizi, Kufra, Murzuk, Tindouf, Ahnet, Oued Mya, Mouydir, etc). In most petroleum systems, which characterize these basins, the Silurian played the main role in hydrocarbon generation with two main ‘hot’ shale levels distributed in different locations (basins) and their deposition was restricted to the Rhuddanian (Lllandovery: early Silurian) and the Ludlow-Pridoli (late Silurian). A third major hot shale level had been identified in the Frasnian (Upper Devonian). Southern Tunisia is characterized by three main Paleozoic sedimentary basins, which are from North to South, the southern Chotts, Jeffara and Berkine Basin. They are separated by a major roughly E-W trending lower Paleozoic structural high, which encompass the Mehrez-Oued Hamous uplift to the West (Algeria) and the Nefusa uplift to the East (Libya), passing by the Touggourt-Talemzane-PGA-Bou Namcha (TTPB) structure close to southern Tunisia. The forementioned major source rocks in southern Tunisia are defined by hot shales with elevated Gamma ray values often exceeding 1400 API (in Hayatt-1 well), deposited in deep water environments during short lived (c. 2 Ma) periods of anoxia. In the course of this review, thickness, distribution and maturity maps have been established for each hot shale level using data for more than 70 wells located in both Tunisia and Algeria. Mineralogical modeling was achievd using Spectral Gamma Ray data (U, Th, K), SopectroLith logs (to acquire data for Fe, Si and Ti) and Elemental capture Spectroscopy (ECS). The latter technique provided data for quartz, pyrite, carbonate, clay and Sulfur. In addition to this, the Gamma Ray (GR), Neutron Porosity (ΦN), deep Resistivity (Rt) and Bulk Density (ρb) logs were used to model bulk mineralogy and lithology. Biostratigraphic and complete geochemical review has been undertaken from published papers and unpublished internal reports to better assess these important source intervals.

The Palynology and Stratigraphy of Devonian and Carboniferous sedimentary rocks and metasediments outcropping along the Porto-Tomar shear zone are described and interpreted. The Palynology and Stratigraphy of the Santa Susana Basin and of... more

The Palynology and Stratigraphy of Devonian and Carboniferous sedimentary rocks and metasediments outcropping along the Porto-Tomar shear zone are described and interpreted. The Palynology and Stratigraphy of the Santa Susana Basin and of the Odivelas Limestone are also described and interpreted.
There is a discontinuous sedimentary record possibly associated with the Porto-Tomar shear zone extending from the Late Devonian to the Pennsylvanian. From the Late Devonian to the Mississippian, the sedimentation was marine, essentially turbiditic, with a general shallowing trend. The thermal maturation of these rocks (Albergaria-a-Velha Unit) is high, and the unit is considered to be post-mature in terms of hydrocarbon generation potential. The incipient metamorphism is accompanied by intense deformation.
The Buçaco basin is entirely terrestrial and its age is restricted to the Gzhelian (upper Pennsylvanian). The sedimentation is clearly controlled by the Porto- Tomar shear zone. Its thermal maturity is relatively low (within catagenesis range) and the deformation milder, contrasting with the Albergaria-a-Velha Unit.
The contact between the two is tectonic. The field evidences and the thermal maturity data of the basin and surrounding units point to an important regional thermal and deformation event that took place between the Serpukovian and the Gzhelian and another, essentially tectonic, between the Gzhelian and the Carnian (Upper Triassic).
The Santa Susana basin has similarities with the Buçaco basin as it is also within an important shear zone, in this case separating the Ossa-Morena and South Portuguese Zones. Its age is kasimovian, and possibly moscovian (middle Pennsylvanian). The thermal evolution of the basin and the structural relations with the surrounding units point to a regional scale thermal and tectonic event occurring between the Viséan and the (?)Moscovian- Kasimovian.
The detailed study of several occurrences of the Odivelas Limestone allow an insight to the regional palaeogeography of the Western Ossa-Morena Zone during the latest Emsian – Givetian interval (latest lower Devonian – middle Devonian): marine (and possibly sub-aerial) volcanic activity forming volcanic buildings on top of which reef communities developed (and possibly on structural highs). The reef biota persisted, in terms of diversity, during all or most of this time interval. The basal Choteč event is recorded in one of these occurrences.

Two new specimens of the xiphosuran Kasibelinurus yueya Lamsdell, Xue & Selden, 2013 are described, from the same horizon and locality as the type. The new specimens are conspecific with the type, but show ventral morphology, which... more

Two new specimens of the xiphosuran Kasibelinurus yueya Lamsdell, Xue & Selden, 2013 are described, from the same horizon and locality as the type. The new specimens are conspecific with the type, but show ventral morphology, which considerably alters interpretation of the species. It can no longer be referred to Kasibelinurus Pickett, 1993, and a new genus, Houia n. gen., is erected. Houia shows a unique combination of xiphosurid and chasmataspidid/eurypterid characteristics such as lack of opisthosomal pleura and possession of a large, ventral metastomal plate. Phylogenetic analysis of all the major chelicerate orders suggests that Houia branched from the main euchelicerate lineage prior to the divergence of the three constituent clades of the Dekatriata Lamsdell, 2013 (Eurypterida, Arachnida, Chasmataspidida). Together with bunodids and pseudoniscids, Houia provides evidence for basal dekatriatans persisting into the middle Palaeozoic alongside eurypterids and arachnids and that the morphological diversity of these basal forms was greater than previously thought.

Two sections were sampled and measured at Mdâour-El-Kbîr (Dra Valley, western Anti-Atlas) and at eastern Ouidane Chebbi (Tafilalt, eastern Anti-Atlas). In situ elements of two partially limonitized and one carbonatic fauna were found in... more

Two sections were sampled and measured at Mdâour-El-Kbîr (Dra Valley, western Anti-Atlas) and at eastern Ouidane
Chebbi (Tafilalt, eastern Anti-Atlas). In situ elements of two partially limonitized and one carbonatic fauna were found
in both sections. We report this fauna from the upper Merzâ-Akhsaï Formation and the lower Mdâour-el-Kbîr Formation
at Mdâour-el-Kbîr for the first time. Based on these faunas, we recorded a correlation of the early Emsian (Zlíchovian)
strata in the Tafilalt and the Dra Valley regions, which are about 350 km apart. Additionally, new ammonoid finds
(Teicherticeras cf. senior, Lenzites gesinae, Weyeroceras angustus) are figured and described including the stratigraphic
context. The diagnoses of Lenzites gesinae and Weyeroceras angustus are emended. Tabulate corals (Michelinia
mdaourensis sp. nov., Petridictyum sp.) found in both the Tafilalt and Dra Valley are figured and described for the first
time. • Key words: early Emsian, Ammonoidea, Tabulata, Micheliniidae, biostratigraphy, Anti-Atlas, Morocco.