Abstract Phacopid trilobites are well documented during the Paleozoic. Nevertheless, while 2D quantitative analyses have advanced our understanding of morphological relationships among trilobites, quantification their traits in 3D remains rarely documented. Based on two sets data (head and tail), versus shape approaches were used to explore allometries as how variations can be explained by phylogenetic phacopid trilobite species for first time. We demonstrate that (1) there similar patterns...

A detailed morphometric approach based on size and outline analyses has been used an exceptionally well-preserved assemblage of silicified trilobite exuvia, recovered from a Late Devonian limestone southeastern Morocco. The material comprises series late larval to postlarval growth stages belonging single phacopine species, Trimerocephalus lelievrei Cronier Feist, 1997. Plurimodality distribution allowed us discriminate instars. Distinct dimensional classes isolated parts are obtained using...

Abstract A diverse fauna of phacopid trilobites is described from the Late Devonian (middle Frasnian to early Famennian) northern Canning Basin, Western Australia. One new genus and four species in two genera are zones 11, 13a 13b middle late Frasnian: Trimerocephaloides sinevisus gen. nov. sp. nov., T. ? linguiformis Acuticryphops acuticeps (Kayser, 1889) A. klapperi phacopines either blind, as shown for first time , or show trends decreasing eye size up Frasnian–Famennian ‘Kellwasser’ mass...

Abstract Phacopid trilobites are relatively widespread in Devonian deposits of north Gondwana and some have been collected from several sections the Saoura Valley SW Algeria. New occurrences phacopids assigned to Trimerocephalus , Dianops Phacops sensu lato described this area comparisons made with closely allied species Morocco Europe. The trilobite assemblages ‘Argiles de Marhouma’ Formation considered be Frasnian–Famennian age. These new integrated into an analysis Upper phacopid...

Morphological disparity and taxonomic richness are two major aspects of evolution used to understand biodiversity changes. These metrics often decoupled in time, particularly during the early history clades. To assess pervasiveness this pattern post-acme a clade, both morphological diversity well-documented Devonian trilobites from North Africa were analysed. Morphospace occupancy body size estimated compared genus through time. This study highlights that, Early Devonian, pygidium cephalon...

Abstract Trilobites are widespread in Lower Devonian deposits of north Gondwana, and some have been collected from two known sections the Saoura Valley SW Algeria, ‘Chefar el Ahmar’ Formation. This formation is considered to be late Emsian Frasnian age, but only lower parts this yielded trilobites. Nevertheless, no detailed studies focused on their biodiversity morphological variability. New occurrences phacopids including Barrandeops chattertoni sp. nov., Geesops fabrei Austerops legrandi...

Abstract In trilobites as in many others extinct organisms, our understanding of the mechanisms evolution is based on morphological and ontogenetic features. Data from development are essential to provide an insight into origins evolutionary changes. phacopid trilobites, detailed studies series have been achieved using quantitative methods. A comparison trajectories closely related species has conducted understand how both disparity developmental patterning different stages were structured...

An assemblage of seven brachiopod species belonging to the orders Rhynchonellida, Atrypida and Spiriferida are studied from three localities (Ertych, Djravank Noravank) Central Armenia. The examined material is recovered shallow water nodular limestones provides insights into diversity Frasnian brachiopods on that part northern margin Gondwana preserved within South Armenian Block. revision Atrypa (Planatrypa) ertichensis, a biostratigraphically significant for Lesser Caucasus (Armenia...

Abstract Distributional patterns of eye lens variation in different morphs the phacopine trilobite Acuticryphops acuticeps (Kayser 1889) are investigated. The specimens were collected from latest Frasnian preceding Upper Kellwasser (UKW) global extinction event Frasnian– Famennian (Late Devonian) stratotype section at Coumiac, southern France. In six successive populations a gradual reduction mean number lenses occurs within short time span single conodont Zone. This morphological change...

Abstract Trilobite occurrences and biodiversity from Devonian sections of the Ardennes Massif are presented. Fluctuations in diversity reflect environmental changes event-stratigraphic turnovers throughout Devonian. Peak is attained during Eifelian (Middle Devonian) when carbonate system developed. Six trilobite associations have been delineated based on cluster analysis. Distribution these correlated with deposition environments age strata.

Preservation of ontogenetic stages trilobites from the Cambrian Skryje-Týřovice Basin (Barrandian area) has been known several localities in upper part Buchava Formation.The most complete information on exoskeletal changes during ontogeny was based material assigned by Barrande (1852) to Sao hirsuta.Based quantitative methods and detailed study morphology exoskeleton, we recognize three protaspid two early meraspid instars hirsuta.We also describe indeterminate taxa Ptychopariida, one...

The new genus Aramazdospirifer n. gen. (Cyrtospiriferidae) is erected to include Spirifer orbelianus Abich, 1858 from the lower Famennian of Central Armenia as its type species and refute long-standing claims related affinities latter. micro-ornament internal structure this are investigated documented for first time, on basis recently collected material Ertych horizon three different sections. Additionally, a neotype selected Abich’s lost. (Abich, 1858) comb. biostratigraphically important...

The best insight into the development of Devonian phacopids has been obtained from Trimerocephalus lelievrei Crônier & Feist, 1997, a Famennian phacopine Morocco, where changes in size and shape have quantified. In this study, morphometric approach used: (1) to retrodeform then establish patterns morphological variation well preserved but tectonically deformed assemblage belonging another species Weyerites ensae (Richter Richter, 1926), Thuringia, (2) developmental evolutionary within two...

Exuviae comprising immature growth stages allow the tracing of morphological and morphogenetical features reduced-eyed phacopid species Plagiolaria poothaii Kobayashi Hamada, 1968, from Early Devonian Satun Province, southern Thailand. Biometric morphometric approaches have been used to characterize shape changes. This is fourth genus for which ontogenetic information known. Ontogenetic this are generally similar those Phacops Weyerites. However, ankylosis facial sutures occurs at end...

The recovery of well-preserved silicified immature exuviae allows the first description early ontogeny phacopid Nephranops incisus from lower Famennian Thuringia (central Germany). Evidence is presented that both planktonic and benthic protaspid larval stages were present in trilobites. Ontogenetic meraspid changes this species are similar to those Weyerites Phacops, supporting close phyletic relationships between these genera ontogenetic homogeneity Phacopidae.

Traditionally, the evolutionary scenarios of Asteropyginae have been organized in two major clades involving four pygidial patterns. The first cladistic analysis performed on subfamily maintained organization clades, though phylogenetic relationships between genera were unexpected compared to traditional scenarios. Moreover, previous systematic scheme based segmentation was rendered obsolete. In this study, we a new from well-known taxa and recent discoveries. Sixty species assigned 36...

Abstract The lower Famennian ‘ Cyrtospirifer ’ orbelianus brachiopod Zone established in Armenia by Abrahamyan (1957) (coeval to the crepida conodont Zone) contains an abundant and diverse fauna that still remains poorly studied. In effort revise update its systematic classification assess diversity this area after Kellwasser extinction event at end of Frasnian, our attention is here focused on rhynchonellides athyrides. Six rhynchonellide species are described belonging five genera as well...

Abstract Phacopidae were a successful family of the Silurian–Devonian period. Although their diversity trends are well identified, shape evolution is unknown; morphology often considered to be conservative. We have quantified these morphologies using geometric morphometrics (landmarks) and investigated morphological disparity indices. Results identified variations between genera, through time. Phacopids differ from each other by position facial suture linked size visual complex, genal angle...

Exceptionally rich and well-preserved silicified exuviae comprising numerous immature growth stages allow the tracing of detailed morphological morphogenetical features reduced-eyed phacopid species Cryphops ? ensae (Richter Richter, 1926) from latest Famennian Thuringia (Central Germany). Ontogenetic this are more similar to those Phacops than Trimerocephalus.

Decapod crustaceans are relatively widespread in Jurassic deposits of Europe and a small number have been collected from the north‐east France. A new fossil macrurous decapod assigned to Eryma burgundiaca sp. nov., an erymid lobster, is described this area comparisons made with closely allied species Europe. Probable pagurid anomurous decapods represented by Orhomalus magnificus Palaeopagurus acutus nov. neraudeaui No brachyurous presently known fauna. Based on associated ammonites, material...