Showing papers in "Palaeobiodiversity and Palaeoenvironments in 2009"
TL;DR: In this paper, the authors describe and interpret 27 assemblages of bivalves based on their taphonomic and ecological features and illustrate the mode of their formation and their palaeoecological and sequence stratigraphic significance.
Abstract: Bivalve concentrations are a conspicuous feature of the Upper Jurassic rock succession of the central Lusitanian Basin. In order to illustrate the mode of their formation and their palaeoecological and sequence stratigraphic significance, we describe and interpret in detail 27 assemblages of bivalves based on their taphonomic and ecological features. Bivalve concentrations are particularly widespread in marginally marine, salinity-controlled environments and less common in open shelf settings. Only the Eomiodon and Myophorella concentrations are dominated by a shallow infaunal bivalve; all other concentrations are composed mainly of epi- or endobyssate [Isognomon (Rostroperna), I. (Isognomon), Pteria, Alaperna, Juranomia] and cementing taxa (Praeexogyra, Actinostreon). Most of the concentrations are mono- to paucispecific, except for the highly diverse Alaperna polita–Pteria credneriana concentrations, which occur in nearshore shelf environments. Lack of sorting, a high percentage of articulated shells, and shells preserved in growth position are evidence that, with few exceptions, the concentrations are autochthonous. Main factors leading to their formation are, apart from a gregarious life habit, a high productivity and a reduced rate of sedimentation. Autogenic and allogenic successional stages can be recognized on the basis of their spatial separation. The time involved in the formation of the concentrations is generally in the order of 102–103 years. Due to the lack of compositional changes within concentrations, time-averaging played no or only a minor role, except in the Alaperna polita–Pteria credneriana concentrations. In sequence stratigraphic terms, most of the concentrations are the product of the maximum flooding zone, but in some cases they constitute the transgressive systems tract. Invariably, they are useful tools for defining depositional sequences. Several of the concentrations described here are not restricted to the Lusitanian Basin but also occur elsewhere in the epicontinental seas bordering the northern margin of the Neotethys.
30 citations
TL;DR: In this paper, 11 fossil Montastraea coral samples from Belize barrier and atoll reef cores were analyzed geochemically and the results indicated a higher climate variability in the early-mid-Holocene.
Abstract: Eleven fossil (Holocene) Montastraea coral samples from Belize barrier and atoll reef cores were analyzed geochemically. δ18O in fossil Montastraea cores suggest warmer and/or wetter conditions in the early–mid-Holocene and the modern age as compared to the mid–late-Holocene, ca. 5000–1,000 years before present (BP). Both δ18O and δ13C data in fossil coral cores exhibit the highest amplitudes from ca. 7,000–4,000 years BP, and indicate a higher climate variability in the early–mid-Holocene. Due to the maximum length of 20 years of individual samples, spectral analyses of fossil time series are beyond the methodological scope of this study. Oxygen and carbon isotope (δ18O and δ13C) time series from two modern (AD 1895–2005) Montastraea corals collected offshore of Belize are used for comparison. The δ18O and δ13C from these time series may be used as proxies for sea surface temperature (SST), precipitation, cloud cover, and the impact of anthropogenic production of CO2, respectively. δ18O variation indicates an increase in SST over the 20th century in the study area.
27 citations
TL;DR: In this paper, the correlation between echinoid species diversity and second-and third-order sequence stratigraphical cycles is investigated in the Lower Cretaceous carbonate platform sequences of central Texas.
Abstract: The correlation between echinoid species diversity and second- and third-order sequence stratigraphical cycles is investigated in the Lower Cretaceous carbonate platform sequences of central Texas. Echinoid faunas from the early Albian Glen Rose Formation have been collected and placed into a sequence stratigraphical framework for the region. There are three discrete communities, each characterising a different part of a second order transgression–regression cycle within the Coahuila Group. A peri-reefal community is found in the Transgressive Systems Tracts (TST) characterised by Pygopyrina, Balanocidaris, Hyposalenia and Pseudodiadema, an open shelf level-bottom community of spatangoids and saleniids is developed at the Maximum Fooding Surface, and a more coastal algal meadow community characterized by Loriolia is preserved in small flooding events in the Highstand Systems Tracts. Beds yielding echinoid faunas are restricted to early TST stages of small-scale cycles within the Glen Rose Formation. This, we argue, reflects changing preservation potential, with echinoid tests only entering the fossil record during periods when accommodation space on the carbonate platform temporarily increased, promoting sediment accumulation rates to rise. The following new taxa are recognized: Parorthopsis gen. nov., Goniopygus whitneyi sp. nov., Tetragramma tenerum sp. nov., Polydiadema travisensis sp. nov., Codiopsis (Hemicodiopsis) pulchella sp. nov. and Plagiochasma texanum sp. nov.
25 citations
TL;DR: Notable features of Pseudeumeces corroborate the previous assumption that this lacertid lizard was probably durophagous, and are known with certainty from the early Oligocene to the early Miocene.
Abstract: Pseudeumeces is a distinct lacertid lizard that is known from one species, P. cadurcensis (Filhol). Two species, Ligerosaurus pouiti and “Pseudeumeces” walbeckensis, previously referred to Pseudeumeces, do not belong to this genus. Pseudeumeces cadurcensis is characterized by a heterodont dentition, including large, posterior, crushing teeth on both the maxilla and dentary. Pseudeumeces differs from the Oligocene lacertid lizards Lacerta s.l. filholi and Mediolacerta that have non-expanded, bi- or tricuspid teeth. Dracaenosaurus, an Oligocene lacertid lizard, also possesses crushing, posterior teeth, but its teeth and jaw are much heavier than in those of Pseudeumeces. New specimens from Gannat document cranial elements previously unknown, i.e. frontal and parietal. Pseudeumeces is known with certainty from the early Oligocene (MP25) to the early Miocene (MN1). Notable features of Pseudeumeces (firm lateral contact between the coronoid and the dentary; strongly curved mandibule; tooth morphology and tooth number reduction) corroborate the previous assumption that this lacertid lizard was probably durophagous. Four Oligocene European lacertid lizards form a morphological and chronological series, but the common ancestry of these species has not been definitively proved.
20 citations
TL;DR: In an excavation campaign of the 30cm-thick Upper Permian Kupferschiefer Member (Werra Formation: Lower Zechstein, Lopingian) in the Huggel (Osnabrucker Bergland, NW Germany) as discussed by the authors, the authors mapped at six different planal levels on a 12m2 area.
Abstract: Plants, invertebrates and fish vertebrates were studied in an excavation campaign of the 30-cm-thick Upper Permian Kupferschiefer Member (Werra Formation: Lower Zechstein, Lopingian) in the Huggel (Osnabrucker Bergland, NW Germany). Taphonomy was mapped at six different planal levels on a 12 m2 area. Plant remains belong mainly to terrestrial conifers Ullmannia frumentaria (Schlotheim) and Pseudovoltzia liebeana (Geinitz), and rare Quadrocladus solmsii (Gothan and Nagelhard). Marine invertebrates consist mainly of the common nautilid Peripetoceras freieslebeni (Geinitz). Of importance is a rich fish fauna with rare skeletons of elasmobranchs Wodnika striatula Munster and Janassa bituminosa (Schlotheim) and numerous actinopterygians, dominated (83%) by Palaeoniscum freieslebeni Blainville as juvenile to adult individuals in different stages of disarticulation. Other, rarer, ray-finned species, including Pygopterus humboldti Agassiz, Platysomus striatus Agassiz, Eurysomus macrurus (Agassiz), Dorypterus hoffmanni Germar and Acentrophorus glaphyurus (Agassiz) are typical for the diverse European Late Permian Zechstein Sea fauna. Most important are concentrations of Coelacanthus granulatus Agassiz (3% of total), also represented by juvenile to adults. Fossil density variation within the Kupferschiefer reflects paleoenvironment in a shallowing-up sequence and bathymetrical change from deeper water to zones close to coastal patch reefs. The shallow-water submarine swell zone at Hasbergen can be related to uplift of the regional Huggel Horst. Charcoalified wood indicates forest fires, and palaeocurrent orientation of fossils correlates with the paleoclimatic of SW Passat wind-direction models based formerly on palaeodune analyses.
19 citations
TL;DR: The megafossil record of Chamaecyparis in the Northern Hemisphere, especially that in Europe, is reviewed with the aim of gaining a better understanding of the biogeographic history of this genus and providing an explanation of the causes of eastern Asian and western and eastern North American intercontinental disjunction of extant members as mentioned in this paper.
Abstract: The megafossil record of Chamaecyparis (Cupressaceae) in the Northern Hemisphere, especially that in Europe, is reviewed with the aim of gaining a better understanding of the biogeographic history of this genus and providing an explanation of the causes of eastern Asian and western and eastern North American intercontinental disjunction of extant members. The fossil data available favor the hypothesis that earlier members of Chamaecyparis were widely distributed in the mid to high latitudes of North America and Europe during the Paleogene and that they spread via the North Atlantic land bridges. During a period of successive global climatic coolings in the Neogene, the distribution of the genus was gradually restricted until Chamaecyparis ultimately disappeared from Europe in the Plio-Pleistocene. Eastern Asian Chamaecyparis most likely came from North America via Beringia during the Paleogene or migrated from Europe eastwards after the Oligocene, when the Turgai Strait retreated. Eastern North American Chamaecyparis appears to have originated either from northern high latitudes or western North America.
18 citations
TL;DR: Chen and Yao as discussed by the authors described the first major Paleozoic echinoderm faunas reported from China and performed a systematic and paleogeographic revision of these Middle and Late Devonian, Early Carboniferous, and Early Permian fauna collected from the Basoshan tectonic block of western Yunnan.
Abstract: In 1993, Chen and Yao described the first major Paleozoic echinoderm faunas reported from China. Restudy of these Middle and Late Devonian, Early Carboniferous, and Early Permian faunas collected from the Basoshan tectonic block of western Yunnan resulted in some systematic and paleogeographic revisions. The Baoshan block originated on the northern part of Gondwana at about 30°S latitude in the Devonian and Carboniferous, drifted away in the Early Permian, and docked with Cathaysia by the Late Triassic, becoming part of South China. Devonian and Early Carboniferous crinoids lived in a carbonate shelf environment, but Early Permian faunas lived in a colder water glaciogene environment. The Devonian and Mississippian faunas are more closely related to coeval European faunas than they are to North American faunas. The Yunnan Devonian and Mississippian faunas are camerate dominated, with few cladids, and lack flexible crinoids. As currently recognized, Middle Devonian endemic crinoids of western Yunnan are Shidianocrinus, Parascyphocrinites, Ovalocrinus, and Quasicydonocrinus. Early Carboniferous endemics of western Yunnan are Yunnanocrinus and Parabarycrinus. The crinoids in the Yudong Formation support a Tournaisian age for these crinoidal rich beds. The stratigraphic range of Stomiocrinus is extended downward into the Tournaisian. Shidianocrinus is reassigned to the Dimerocrinitidae and Parascyphocrinites is reassigned to the Melocrinitidae. Parabarycrinus is reassigned to the Gasterocomidae. New combinations are Ectocrinus anthodeus, Cantharocrinus sphaeroides, Rhodocrinites intermedius, Rhodocrinites excavatus, Rhodocrinites baoshanensis, Holcocrinus irregularis, and Separocrinus discoides. New taxa introduced are Amphoracrinus cheni n. sp., Synbathocrinus yaoi n. sp., and Platycrinites s.s. langbaensis n. sp.
15 citations
TL;DR: In this paper, six gymnosperm wood species from the Upper Permian Tacuary Formation from Eastern Paraguay are described, and an analysis of the anatomical characters shows evolutionary intermediate stages between the more primitive (araucarioid) Paleozoic and the more advanced (mixed to abietoid) Mesozoic wood taxa.
Abstract: Six gymnosperm woods from the Upper Permian Tacuary Formation from Eastern Paraguay are described. Protophyllocladoxylon dolianitii Mussa, has been recorded in the Lower Permian Rio Bonito Formation from Brazil and the Mount Glossopteris Formation of Antarctica; Podocarpoxylon paralatifolium Vozenin-Serra and Grant Mackie is similar to this species from the Lower Triassic Arawi Formation of New Zealand and the Upper Triassic Laguna Colorada Formation (El Tranquilo Group) from Santa Cruz province (Argentina); Austaloxylon teixeirae Marguerier has been recorded from the Raniganj Formation (India), the Karroo System (Mozambique), and the Yaguary Formation (Uruguay) all of Upper Permian age; Bageopitys herbstii Crisafulli, from the Yaguari Formation of Uruguay; and Prototaxoxylon brasilianum Krausel and Dolianiti, a wood assigned to the Taxales, has been recorded in the Upper Permian Estrada Nova Formation of Brazil. Wood with affinities to the order Ginkgoales is represented by Baieroxylon cicatricum Prasad and Lele recorded from the Triassic Tiki Formation from India and the Yaguari Formation of Uruguay. All the woods show well-marked growth rings which reflect favorable climatic conditions. An analysis of the anatomical characters shows evolutionary intermediate stages between the more primitive (araucarioid) Paleozoic and the more advanced (mixed to abietoid) Mesozoic wood taxa. Except for the numerous species of Podocarpoxylon, Protophyllocladoxylon, Prototaxoxylon and Baieroxylon which have more extended biochrons, Australoxylon and Bageopitys are exclusive Upper Paleozoic (Permian) taxa.
13 citations
TL;DR: The plesiomorphically narrow spatium intermetacarpale supports a position of Masillatrogon outside a clade including Primotrogon and crown group Trogoniformes, and the presence of successive sister taxa of extant Trogonidae in the Paleogene and early Neogene of Europe indicates an Old World origin of the crown group.
Abstract: A second skeleton of a trogon is reported from the middle Eocene of Messel in Germany, which represents the best preserved Eocene record of this group of birds known to date. The new specimen shows that the Messel trogon, which was originally described as ?Primotrogon pumilio, differs from Primotrogon in a narrower spatium intermetacarpale of the carpometacarpus and a proportionally longer hallux. The middle Eocene species is thus assigned to the new taxon Masillatrogon. The plesiomorphically narrow spatium intermetacarpale supports a position of Masillatrogon outside a clade including Primotrogon and crown group Trogoniformes, and the presence of successive sister taxa of extant Trogonidae in the Paleogene and early Neogene of Europe indicates an Old World origin of the crown group. Masillatrogon and Primotrogon further lack derived features of the wing skeleton of extant Trogonidae, and these early trogons thus probably employed a somewhat different flight and foraging technique.
8 citations
TL;DR: In this paper, the authors identified three late Frasnian conodont biozones (MN 11−12 and 13, as defined in the Montagne Noire, France) and several Famennian conodons (Early, Late, and Latest marginifera, and Late postera zones of the standard zonation) in the Palaeozoic record of the Stilo Unit (southern Calabria, southern Italy).
Abstract: The identification of three late Frasnian conodont biozones (MN 11–12 and 13, as defined in the Montagne Noire, France) and of several Famennian conodont biozones (Early, Late, and Latest marginifera, and Late postera zones of the standard zonation) in the Palaeozoic record of the Stilo Unit (southern Calabria, southern Italy) indicates the existence of a stratigraphic gap during the early Famennian (triangularis, crepida and rhomboidea zones). In the studied section, this gap occurs above a thin, black, pelitic horizon that appears just on top of the uppermost sample dated as late Frasnian. The conodonts obtained from the beds underlying this black horizon are all highly pyritized, unlike the few Famennian conodonts found in the limestone bed immediately overlying this horizon, which is richer in organic matter. Both stratigraphic features (the black pelitic horizon and the gap in the conodont record) are interpreted as being related to the Upper Kellwasser Anoxic Event. These new data indicate that this important biotic crisis was also evident in the pelagic environments of the Palaeozoic succession of the Stilo Unit at the very end of the Frasnian.
7 citations
TL;DR: In this article, several hundred samples from outcrops and drilling cores in the Eocene Messel Fossil Site were analyzed to study the geographic and stratigraphic distribution of spongillid spicules and spiculite layers.
Abstract: Several hundred samples from outcrops and drilling cores in the Eocene Messel Fossil Site (near Darmstadt, Germany) were analyzed to study the geographic and stratigraphic distribution of spongillid spicules and spiculite layers. We attempted to correlate the various spiculite occurrences and marker horizon M. The core of the scientific drilling project “FB 2001” is used as a reference, because it reaches the oldest limnic sediments of the fossil lake in a depth of about 140 m below the topographic surface. Only two spiculites are present in this core and they are restricted to the youngest lake sediments. Each spiculite is dominated by one of the two spongillid species known from Messel. In all older sediments, only a few scattered spicules of unknown origin occur. All other outcrops and drill cores show more or less similar distribution patterns. Abundance and distribution of fossil sponge species in Eocene Lake Messel and their value for the correlation of strata are discussed.