Echinoid Fauna Research Articles

Albian–Cenomanian echinoids from areas north of Bandar Abbas and south of Fars in the Zagros Mountains, Iran

Fossil echinoids have rarely been described from Iran. This study focuses on the echinoid fauna found in the Cretaceous strata (Kazhdumi Formation) of the Geno and Gerash sections in the Bandar Abbas and Fars areas of the Zagros Mountains, southern Iran. The age of the Kazhdumi Formation in both sections is determined to be Albian-Cenomanian based on the associated ammonites and microfauna, its stratigraphic position, and previous studies on this formation. Twenty-one echinoid species (twelve regular and nine irregular) belonging to seventeen genera were described in this study. Fourteen of these species are reported for the first time from Iran. In addition, a new diadematoid echinoid species, Arabicodidema jafariani sp. nov. is introduced. New age ranges are proposed for Pliotoxaster comanchei and Lambertiaster douvillei. The paleogeographic position of the Zagros Basin in the Tethyan realm is confirmed based on the distribution of the index species.

New sea urchins (Echinodermata: Echinoidea) from the Famennian of Velbert (W Germany): Evidence for echinoid faunal turnover in the Late Devonian

Despite the presumably lower diversity of Palaeozoic echinoids compared to their post-Palaeozoic relatives, a radiation during the Mississippian marked a first brief "golden age" of sea urchins. Carboniferous echinoid faunas feature distinct and specialised groups compared to those of the Devonian, suggesting important evolutionary changes during the Late Devonian, although the role of biotic crises like the Kellwasser and Hangenberg Events in these changes remains poorly known. This study describes an exceptionally well-preserved echinoid fauna from the middle to upper Famennian of Velbert near Düsseldorf, Germany. Description of six new species belonging to the lepidocentrid, hyattechinid, proterocidarid and archaeocidarid lineages along with a seventh species based on isolated remains greatly add to the knowledge of Late Devonian echinoids. The newly described genera Thielechinus gen. nov. and Velbertechinus gen. nov. represent the most derived proterocidarids and archaeocidarids known from the pre-Carboniferous. Moreover, the fossils offer new insights into phylogeny, ontogeny, and palaeobiology of several stem-group echinoid lineages. The fauna resembles Carboniferous echinoid faunas much more than earlier Devonian faunas, thus providing evidence that crucial developments had occurred from the Frasnian to the Famennian, possibly linked to global changes associated with the catastrophic Kellwasser Event. These developments include the appearance of several specialised lineages that would become important in the Late Palaeozoic as well as evolutionary innovations leading up to the establishment of the crown-group echinoid body plan.

Micropaleontological findings and absolute ages mark the termination of the Last Glacial Maximum in the Eastern Mediterranean Region: New electron spin resonance data from Gediz Delta (Western Turkey)

Sediments and fossil content of Gediz Delta (Eastern Aegean Sea-İzmir) were examined from the samples collected from three drilling cores from the west (seaward) to east (landward) of the delta. Each drilling core contains Quarternary marine deposits with a marine fauna of foraminifers, bivalves, gastropods, echinoids, and ostracods at the bottom and Quaternary continental delta deposits at the top. According to our Electron Spin Resonance (ESR) age model marine sediments of the Aegean Sea started to cover the western Gediz Delta area before 19.9 ka (thousand years). Following the Last Glacial Maximum (LGM), after the transgression due to deglaciation occurred 15.3 ka ago, the coastline progressed 15-20 km eastward and covered the entire delta area. At the end of the LGM, as a result of the overflow of Manisa Gediz Lake depending on the deglaciation in Western Anatolia, and its flow from the Emiralem Strait to the İzmir Bay, the continental deposits reaching the West Gediz Delta region are younger than 11.4 ka.

Drilling predation on spatangoid echinoids from the Miocene of Sardinia: a taphonomic and paleoecological perspective

AbstractPredation is of great importance in understanding the diversification of spatangoid echinoids as well as their preservation in the fossil record. Herein, the spatangoid-dominated Miocene carbonate succession of Punta Foghe (Montiferru area, central-western Sardinia, Italy) is studied with the aim of reconstructing paleoenvironmental conditions and investigating abiotic and biotic factors, including predation, that influence the paleoecology and preservation potential of spatangoid echinoids.The echinoid fauna is dominated by the spatangoid Agassizia and, to a lesser extent, the clypeasteroid Clypeaster. The fauna also includes both regular (undetermined diadematoids and camarodonts) and irregular (Plagiobrissus, Echinocyamus, and Koehleraster) forms. Echinoids and associated fossil content, along with taphonomic and sedimentological signatures, indicate an inner sublittoral environment with moderate energy conditions affected by high-energy events. Agassizia remains, which consist mainly of complete and well-preserved tests, commonly bear subcircular drill holes that are interpreted as the result of cassid gastropod predation and investigated with respect to size selectivity and stereotypy of attack sites. Potential biases related to drilling predation and biostratinomy on the preservation potential of spatangoid tests are discussed.Agassizia lacks any morphological adaptation to minimize high predation risk, including defensive spines and the ability to burrow deeply into the sediment. An antipredator behavior possibly relied on a gregarious life-history strategy, reducing the frequency of attacks on specific individuals by cassid predators.

Benthic ecoregionalization based on echinoid fauna of the Southern Ocean supports current proposals of Antarctic Marine Protected Areas under IPCC scenarios of climate change.

The Southern Ocean (SO) is among the regions on Earth that are undergoing regionally the fastest environmental changes. The unique ecological features of its marine life make it particularly vulnerable to the multiple effects of climate change. A network of Marine Protected Areas (MPAs) has started to be implemented in the SO to protect marine ecosystems. However, considering future predictions of the Intergovernmental Panel on Climate Change (IPCC), the relevance of current, static, MPAs may be questioned under future scenarios. In this context, the ecoregionalization approach can prove promising in identifying well-delimited regions of common species composition and environmental settings. These so-called ecoregions are expected to show similar biotic responses to environmental changes and can be used to define priority areas for the designation of new MPAs and the update of their current delimitation. In the present work, a benthic ecoregionalization of the entire SO is proposed for the first time based on abiotic environmental parameters and the distribution of echinoid fauna, a diversified and common member of Antarctic benthic ecosystems. A novel two-step approach was developed combining species distribution modeling with Random Forest and Gaussian Mixture modeling from species probabilities to define current ecoregions and predict future ecoregions under IPCC scenarios RCP 4.5 and 8.5. The ecological representativity of current and proposed MPAs of the SO is discussed with regard to the modeled benthic ecoregions. In all, 12 benthic ecoregions were determined under present conditions, they are representative of major biogeographic patterns already described. Our results show that the most dramatic changes can be expected along the Antarctic Peninsula, in East Antarctica and the sub-Antarctic islands under both IPCC scenarios. Our results advocate for a dynamic definition of MPAs, they also argue for improving the representativity of Antarctic ecoregions in proposed MPAs and support current proposals of Conservation of Antarctic Marine Living Resources for the creation of Antarctic MPAs.

<strong>A project for analyzing the ecology and phylogeny of western Pacific echinoids</strong>

In 2017 we started a project to analyze the ecology and phylogeny of western Pacific echinoids. As the first step, we are establishing methods to infer their phylogenetic relationships using molecular data; we developed effective methods to obtain complete mitochondrial DNA sequences, and determined their effectiveness in phylogenetic analysis. We have also been gathering data concerning the ecology and systematics of Japanese extant echinoids, which arguably has among the highest genus-level diversities in the West Pacific or perhaps even in the world. We have collected 58 species from middle and southern Japan representing 48 genera. In the next year, we will collect sea urchins from northern Japan, and within 2 years we will finish collecting data on ecology and systematics of Japanese echinoids, and provide a set of standardized data that will be useful for many researchers studying western Pacific echinoids. At that time, we will start comparative analyses of echinoid faunas distributed in the western Pacific.

Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction.

The end-Permian mass extinction (∼252 Ma) was responsible for high rates of extinction and evolutionary bottlenecks in a number of animal groups. Echinoids, or sea urchins, were no exception, and the Permian to Triassic represents one of the most significant intervals of time in their macroevolutionary history. The extinction event was responsible for significant turnover, with the Permian–Triassic representing the transition from stem group echinoid-dominated faunas in the Palaeozoic to Mesozoic faunas dominated by crown group echinoids. This turnover is well-known, however, the environmental and taxonomic distribution of echinoids during the latest Permian and Early Triassic is not. Here we report on an echinoid fauna from the Tesero Member, Werfen Formation (latest Permian to Early Triassic) of the Dolomites (northern Italy). The fauna is largely known from disarticulated ossicles, but consists of both stem group taxa, and a new species of crown group echinoid, Eotiaris teseroensis n. sp. That these stem group echinoids were present in the Tesero Member indicates that stem group echinoids did not go extinct in the Dolomites coincident with the onset of extinction, further supporting other recent work indicating that stem group echinoids survived the end-Permian extinction. Furthermore, the presence of Eotiaris across a number of differing palaeoenvironments in the Early Triassic may have had implications for the survival of cidaroid echinoids during the extinction event.

Miocene echinoids from Palenque, Chiapas, Mexico

Recent collecting in the Miocene Tulijá Formation near Palenque, Chiapas State of Mexico, has provided five species of echinoids: Stomopneustes pristinus, Echinolampas aldrichi, Clypeaster chiapasensis, Agassizia regia, and Schizaster dumblei; their reports are illustrated, measured and described. These new reports are a significant expansion of the known distribution of Stomopneustes pristinus and Agassizia regia, which were previously documented merely from their type localities; also, this is the first confirmed report of Schizaster dumblei in the Miocene. Neotype material is established for C. chiapasensis and discrepancies between previous descriptions have been resolved. The echinoid fauna of the Tulijá Formation shares species with the Meson and Tuxpan formations on the Gulf of Mexico and supports the description of the Tulijá Formation as a shallow marine paleoenvironment with high energy. With these revisions we start sketching an interesting system between the Caribbean and the Gulf of Mexico basin; due to the general quality of the fossil record and the scarce revisions on the paleofauna of the region, the present report help fill what has been a major gap in recognizing the distribution of echinoids.

Paleoecology of sublittoral Miocene echinoids from Sardinia: A case study for substrate controls of faunal distributions

AbstractA rich echinoid fauna within the middle Miocene carbonate sedimentary succession cropping out along the coast between Santa Caterina di Pittinuri and S'Archittu (central-western Sardinia) allows the comparison of faunal gradients and preservation potentials from both hard and soft substrata. Three echinoid assemblages are recognized. Faunal composition, as well as taphonomic and sedimentological features and functional morphological interpretation of the echinoid test indicate an outer sublittoral setting. Assemblage 1 represents a highly structured environment within the photic zone, with mobile substrata occupied by infaunal irregular echinoids, mainly spatangoids, and localized hard substrata, provided by rhodolith beds, with epibenthic regular echinoids represented by the co-occurrence of the diadematidDiademaGray, 1825 and the toxopneustidsTripneustesL. Agassiz, 1841 andSchizechinusPomel, 1869. Assemblage 2 shows a higher diversity of irregular echinoids, dominated by the clypeasteroidsEchinocyamusvan Phelsum, 1774 andClypeasterLamarck, 1801 and different spatangoids, with the minute trigonocidaridGenocidarisA. Agassiz, 1869 among regular echinoids. This assemblage points to a soft-bottom environment with moderate water-energy conditions, periodically affected by storms. A low-diversity echinoid fauna in Assemblage 3, dominated by the spatangoidsBrissopsisL. Agassiz, 1840 andOvaGray, 1825, documents a deeper, soft-bottom environment, possibly below storm-wave base. These results indicate that the diversity of echinoid faunas originating in sublittoral environments is related to: (1) the presence of both soft and hard substrata, (2) differential preservation potentials of the various echinoid taxa, (3) intense bioturbation, and (4) sediment deposition by sporadic storm events.

Four notable additions to the South African echinoid fauna (Echinodermata, Echinoidea).

Although a comprehensive guide to the South African echinoid fauna was published as recently as 2017, four notable additions to the fauna have emerged since that time and are reported on here. The first South African records for Histocidarispurpurata (Thomson, 1872), Echinothrixdiadema (Linnaeus, 1758), Microcyphusrousseaui L. Agassiz, in Agassiz and Desor 1846, and Pseudoboletiamaculata Troschel, 1869 are presented. All four species have previously been recorded from the Atlantic and/or Indian Oceans and their ranges are thus extended southwards here. These additions increase the total number of echinoid species known from South Africa to 74.

Taxonomic guide and historical review of echinoids (Echinodermata: Echinoidea) from northeastern Brazil.

The class Echinoidea contains among the best-known echinoderms. The group has left the most complete fossil record of this phylum, and contains about 1000 living species, of which 51 are recorded along the Brazilian coast. Although the first record of echinoids in Brazil was made 369 years ago, the knowledge of this fauna remains quite unsatisfactory from a taxonomic and ecological point of view, particularly in the north and northeastern regions of the country. This study provides the first annotated list of echinoids from northeastern Brazil. The studied material largely belongs to collections of the Federal University of Paraíba (CIPY), Federal University of Sergipe (LABIMAR-UFS), Federal University of Bahia (MZUFBA), University of São Paulo (MZUSP), and National Museum of the Federal University of Rio de Janeiro (MNRJ). Thirty-two species from 29 genera, 18 families, and 10 orders were identified. Descriptions of species are provided. Highest diversities of Echinoidea were encountered for the states of Bahia (19 spp.), Alagoas (11 spp.), Paraíba (10 spp.), Ceará (7 spp.), Rio Grande do Norte (7 spp.), and Pernambuco (6 spp.). On the basis of the data analysed, Maranhão (2 spp.), Piauí (2 spp.), and Sergipe (3 spp.) have the lowest diversity. Sandy substrates and depths below 10 m were the least sampled areas over the continental shelf. Although the studied species are common, some taxonomic problems were encountered and discussed. We also provide ecological information and comments on status of the species from the studied region. As a result of this inventory, we were able to provide the first assessment of the echinoid fauna of northeastern Brazil.

Echinoid Fauna from the Coloso Basin, Lower Cretaceous, Northern Chile

The Lower Cretaceous echinoids from the carbonate rocks of the El Way Formation, deposited in the Coloso Basin, northern Chile, are described. Six species were identified: four of them not previously reported for the El Way Formation, Temnocidaris (Stereocidaris) malum (Gras), Tetragramma tenerum Smith and Rader, Leptosalenia prestensis (Desor) and Leptosalenia texana (Credner); an endemic species, Pliotoxaster andinum sp. nov.; and another species already mentioned in previous studies, Phymosoma mollense (Paulcke). In addition, other three different species are described and left in open nomenclature (Tetragramma sp., Phymosoma sp. and Saleniidae indet.) and the species Hemiaster wayensis (Larrain) is reassigned to the genus Pliotoxaster Fortau. The fossil echinoids collected in the Coloso Basin show different temporal distributions, all between the late Barremian and early Aptian.

A new evidence of cretaceous echinoids at the region Paleokastro of Stylis area (Fthiotida district)

The rich Fauna of Echinoids (114 individuals) coming from the region Paleokastro Fthiotida has been found for the first time in Greece. The most part of the Echinoids studied, belongs to the genus Echinocorys{12%), and in minor quantity to the genus Micraster(8%), Galeaster(l%) and Coraster(19%). 17 species has been indentidied which have been distributed 13 to the genus Echinocorys ( E. conoideus, E. gravesi, E. humilis, E. lamberti, E. marginatus, E. obliquus, E. ovatus, E. pyramidatus, E. rectus, E. sulcatus, E. turritus, E. vulgaris, E. zejszneri), 1 to the genus Micraster (M. coranguinum), 1 to the genus Galeaster (G. cf. bertrandi) and 2 to the genus Coraster (C. sphaericus, C. frechi). The accompagnied fauna is consisting of one Scleractinian (Caryophyllia sp.) and one Nautiloid (Eutrephoceras dekayi (MORTON)). The stratigraphical distributions of the studied fauna allow us to accept that the cretaceous layers with the Echinoid Fauna belong to the Upper Maestrichtian age. The studied fauna, with his monotonous character, is an ecological niche of the genus Echinocorys living in almost littoral waters.

Middle Eocene echinoids from El Sheikh Fadl-Ras Gharib stretch, Eastern Desert, Egypt: systematics, stratigraphy, palaeobiogeography

Twenty-two echinoid species (5 regular and 17 irregular) belonging to 14 genera, 10 families, 5 orders, and 3 subclasses are identified from the Middle Eocene succession cropping out in El Sheikh Fadl-Ras Gharib stretch, Eastern Desert. The echinoid fauna studied herein came from four sections: Gebel ElMehasham, South Gebel ElMehasham, Gebel ElMereir, and Gebel Qarara sections. The studied succession consists of three formations, from base to top Muweilih, Midawara, and Sath ElHadid, spanning the Middle Eocene (Lutetian and Bartonian), Lower-Middle Mokattamian (levels MK3 to MK6). The highest species diversity is recorded in the Midawara Formation (21 species), while the Muweilih Formation is barren of echinoid species. Four species are recorded for the first time in the studied area: Echinolampas cf. bastai Elattaar and Strougo 2001; Schizaster isidis Stefanini Boll Soc Geol Ital 38:39–63, 1919; Gillechinus humei (Fourtau 1908); and Eupatagus lefebvrei (de Loriol Memoires de la Societe de Physique et d’Histoire Naturelle de Geneve 27:58–148, 1880). One species consider to be new, Schizaster sp. (n. sp). Thirteen species are endemic to Egypt, and nine are common elsewhere in the world, in some countries of Europe, Africa, and Asia. Predation and malformation in growth are observed in two species: Schizaster humei Fourtau Memoires de l’Institut Egyptien 6(2):93–175, 1909b and Eupatagus cossmanni (Lambert Mem Soc Geol Fr, Paleontol 9:1–57, 1902) as a shallow infaunal species. All the identified echinoid fauna herein has been examined and systematically described with the aim to know their stratigraphic and paleogeographic distribution.

Correction: Diversification rates indicate an early role of adaptive radiations at the origin of modern echinoid fauna.

[This corrects the article DOI: 10.1371/journal.pone.0194575.].

Diversification rates indicate an early role of adaptive radiations at the origin of modern echinoid fauna.

Evolutionary radiations are fascinating phenomena corresponding to a dramatic diversification of taxa and a burst of cladogenesis over short periods of time. Most evolutionary radiations have long been regarded as adaptive but this has seldom been demonstrated with large-scale comparative datasets including fossil data. Originating in the Early Jurassic, irregular echinoids are emblematic of the spectacular diversification of mobile marine faunas during the Mesozoic Marine Revolution. They diversified as they colonized various habitats, and now constitute the main component of echinoid fauna in modern seas. The evolutionary radiation of irregular echinoids has long been considered as adaptive but this hypothesis has never been tested. In the present work we analyze the evolution of echinoid species richness and morphological disparity over 37 million years based on an extensive fossil dataset. Our results demonstrate that morphological and functional diversifications in certain clades of irregular echinoids were exceptionally high compared to other clades and that they were associated with the evolution of new modes of life and so can be defined as adaptive radiations. The role played by ecological opportunities in the diversification of these clades was critical, with the evolution of the infaunal mode of life promoting the adaptive radiation of irregular echinoids.

Mid-Cretaceous echinoids from the Dhalqut Formation of Dhofar, southern Oman – Taxonomy and biostratigraphical implications

Several small echinoid faunules are recorded from the Umbaraaf and Khadrafi members of the Dhalqut Formation, the upper unit of the Albian–Turonian Qamar Group in the eastern part of the Jeza-Qamar Basin of Dhofar (southern Oman). In all, 11 species, in nine (sub)genera, are described: Arabicodiadema dhofarense (Roman), Arabicodiadema romani Smith and Jagt n. sp., Heterodiadema libycum (Desor, in Agassiz and Desor), Emiratia raskhaimahensis Ali, Orthopsis miliaris (d’Archiac), Pedinopsis (P.) sphaerica Smith, Simmons and Racey, Pedinopsis (Sinaiopsis) sinaica (Desor, in Agassiz and Desor), Goniopygus dhalqutensis Smith and Jagt n. sp., Coenholectypus excisus (Desor, in Agassiz and Desor), Coenholectypus larteti (Cotteau) and Pliotoxaster dieneri (de Loriol). These novel echinoid data suggest that the Umbaraaf Member extends into the Cenomanian, thus supplementing previous biostratigraphical dating based on foraminifera. The echinoid fauna also suggests correlation of the Umbaraaf and Khadrafi members with strata such as the Natih Formation in north-central Oman, the Mauddud Formation of the northeastern United Arab Emirates, the Galala Formation of the North-Eastern Desert of Egypt and the Wasia Formation of central Saudi Arabia.

A Brissus genus (Echinoidea) első előfordulása a magyarországi badeniből és a Brissus mihalyi n. sp. leírása

A budapesti Örs vezér téri üzletközpontok alapozása során nagy számban fordultak elő tengeri sünök is a badeni korú Lajtai Mészkő Formáció rétegeiben. Az Árkád 1 alapgödréből előkerült egy Magyarországról eddig nem ismert tengeri sün nemzetség, a Brissus. 
 A genust eddig a Paratethys térségéből csak burgenlandi és nyugat-ukrajnai lelőhelyekről írták le. A Budapesten megtalált mindkét Brissus egyed jó megtartású. Az egyik példányt a Brissus abeli (Reidl, 1941) fajba lehetett besorolni, ami csak a Paratethys késő-badeni korú üledékeiből ismert. Ezen felül előkerült egy az egész európai-mediterrán térségben eddig ismeretlen Brissus forma, amely morfológiai bélyegeit tekintve egyik európai vagy egyéb mediterrán formával sem egyezik meg. Emellett hordoz sajátságos morfológiai elemeket is, úgy, mint az erősen anterior helyzetű apicalis lemez, az anterior szirompár által bezárt szög mértéke, valamint a periproct elhelyezkedése. Mindezek alapján a forma új fajként való elkülönítése indokolt, melynek neve – Mihály Sándor tiszteletére – Brissus mihalyi nov. sp.
 Maga a Brissus genus ma széles földrajzi elterjedésű, de kis egyedszámú; a ma élő együtteseket részletesen nem vizsgálták. Az európai neogénben ritka, így a magyarországi megjelenés a forma eocéntől máig zajló evolúciójának megismeréséhez is fontos információt nyújt.

Illustrated guide to the echinoid (Echinodermata: Echinoidea) fauna of South Africa

The sea-urchins (class Echinoidea) of South Africa have received little taxonomic attention since the last comprehensive regional monographic guide, which was published in 1976 and is thus now severely outdated. That account was also poorly illustrated, making it difficult to use. Recent work by the authors has also added some 19 additional species to the known fauna, which now stands at 70 species. The aims of this study are thus to revise and update the South African echinoid fauna list, and to present a new, easy to use and fully-illustrated guide to all known regional species. The analysis is based mainly on examination of samples from the Iziko South African Museum collections, although additional records from other museum collections, the published literature, photographic images submitted to the EchinoMap Virtual Museum Database and any other reliable records are also included. A short account of each species is given, including relevant synonymy and literature, and brief notes on identification, size, and global distribution. Photographs that best represent the diagnostic features of each species and a map showing its known records within the region accompany each species account. A binary key to species is also provided.

Miocene echinoids from the Sadat area, south Gebel Ataqa, NW Gulf of Suez, Egypt: systematics, palaeobiogeography

The echinoid fauna from the Miocene sedimentary succession cropping out south Wadi Tweirig, and Wadi Hommath, south Gebel Ataqa, NW Gulf of Suez, has been examined with the aim to known their stratigraphic and paleogeographic distribution. The Miocene succession includes two formations: Sadat Formation, unconformably overlying the middle/upper Eocene rocks at the base and Hommath Formation at the top. Twenty-eight echinoid species (8 regular and 20 irregular) belonging to 18 genera, 13 families, and 7 orders have been identified, systematically described, and illustrated in this work. Eleven species are recorded for the first time from Egypt: ten of these came from the Hommath Formation (Schizechinus cf. serresii Desor (1856), Schizechinus pentagonus Kier 1972, Clypeaster cf. martini des Moulins 1837, Scutella checchiae occidentalis Desio 1934, Scutella melitensis Airaghi 1902, Echinodiscus desori Duncan and Sladen 1883, Echinolampas cf. zeitensis Fourtau 1920, Schizaster lovisatoi Cotteau 1895, Agassizia (Agassizia) powersi Kier 1972, and Hemipatagus ocellatus Defrance (1827)), and one from the Sadat Formation (Clypeaster campanulatus Schlotheim (1820)). The identified fauna shows a strong affinity with the Mediterranean bio-province.