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Tytuł:
Devonian history of diversity of the rugosan Cyathaxonia fauna
Autorzy:
Wrzolek, T
Powiązania:
https://bibliotekanauki.pl/articles/21945.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
stratigraphy
fauna
history
Givetian-Frasnian crisis
Cyathaxonia
diversity
Devonian
paleontology
Opis:
Literature data indicate above average diversity of the Cyathaxonia fauna in the Devonian period,both in absolute numbers of (sub)families and genera per age and also with respect to taxonomic diversities as calculated per Ma (10⁶ years). The Emsian and Famennian faunas,although represented by most numerous (sub)families and genera,have less than average diversities,due to their more than average durations,whereas the shorter intervals of the Pragian and Givetian have the highest values for diversity per Ma,and Frasnian faunas the lowest diversities,for both (sub)families and genera. The post−Givetian crisis may have been responsible for the Frasnian minimum,although limited temporal resolution of the analysis does not allow for a more precise description of the Givetian/Frasnian transition. However,“silent taxa” are extremely numerous in the Frasnian,i.e.,taxa which are present both prior to and after the Frasnian,but missing from the Frasnian record itself indicating that the Famennian Cyathaxonia fauna contains significant numbers of Lazarus and/or Elvis taxa.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Climate and changes in mammal diversity during the late Pleistocene-Holocene in the Pampean Region [Argentina]
Autorzy:
Prado, J L
Alberdi, M T
Azanza, B
Sanchez, B
Powiązania:
https://bibliotekanauki.pl/articles/20763.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Argentina
Holocene
mammal diversity
mammal
diversity
change
extinction
Pleistocene
climate
paleontology
climate change
Opis:
The association of changes in mammal diversity with periods of global climatic change is suggestive of a causal relationship. Two important features in the testing of this climatic model are as follows: the timing and the pattern of the diversity changes, and the particular climatic variables examined, since different patterns of evolutionary interactions would be expected depending on different climatic variables. In order to analyse the relationship between climate change and faunal events, we need to establish a set of comparable data. To provide a finely resolved picture of both climatic and faunal events, the last 32,500-years were divided into 13 chronological units of 2,500-years each. The limit of 32,500-years was imposed by the availability of good localities with radioisotopic calibration. Climatic stability was measured in these analyses in terms of cycles per unit of time, the amount of variation in temperature per unit of time, and the magnitude of change between modal temperature of one interval less modal temperature from preceding interval. The data presented here suggest that the primary effect of climatic change is on: (1) levels of extinction (or migration) of large mammals; and (2) diversity and origination (or immigration) of small mammals.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The phanerozoic diversity of agglutinated foraminifera: Origination and extinction rates
Autorzy:
Kaminski, M A
Setoyama, E.
Cetean, C.G.
Powiązania:
https://bibliotekanauki.pl/articles/22888.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
phanerozoic diversity
Foraminifera
origination
extinction rate
biodiversity
fossil
paleontology
Opis:
New diversity curves for agglutinated foraminiferal genera are presented based on the stratigraphic ranges of 764 genera distributed over the 91 Phanerozoic chronostratigraphic subdivisions given in the ICS timescale. The data set for this analysis is based on the stratigraphic ranges of agglutinated genera published in Foraminiferal Genera and their Classification, 218 of which have been modified based upon subsequently published studies and new observations. Additionally, a total of 136 genera have been newly described or reinstated subsequent to the publication of Foraminiferal Genera and their Classification. The revision of stratigraphic ranges is part of the effort by the Grzybowski Foundation’s International Working Group on Foraminiferal Classification to compile a new Catalogue of Agglutinated Foraminiferal Genera. The mean standing diversity of agglutinated foraminiferal genera was compiled by counting the number of boundary crossers rather than the number of genera in each stage. This diversity curve displays a general upward trend throughout the Phanerozoic, punctuated by peaks and troughs of variable magnitude. The curve shows a period of initial radiation from the Early Cambrian to the Early Silurian, followed by a plateau to the Late Permian. The Permian/Triassic and the Triassic/Jurassic boundaries are characterised by small dips in the diversity record. The Jurassic begins with an exponential rise in mean standing diversity that continues to the Cenomanian. The Cenomanian to Holocene record of mean standing diversity is characterised by four peaks and troughs that are roughly in line with the cycles of global climate, with reductions in diversity in the end−Cenomanian, end−Cretaceous, and end−Miocene. Excluding modern values, the Phanerozoic maximum in the number of genera with a fossil record is observed in the Cenomanian, whereas the maximum Phanerozoic mean standing diversity is observed in the Langhian stage of the Miocene. The highest per−capita origination rates are observed in the Hettangian, Dapingian, Pleistocene, and Sheinwoodian (mid−Silurian). Linear regression analysis of the origination rates reveals a decrease towards the Holocene, in agreement with findings of Raup and Sepkoski. The highest per−capita extinction rates are observed in the Messinian, late Silurian (Gorstian), Hirnantian (latest Ordovician), and Maastrichtian. The background extinction rate shows an increasing trend towards the Recent, which is in disagreement with the findings of Raup and Sepkoski. We attribute this apparent discrepancy to the Late Cretaceous to Palaeogene extinctions of shallower−water larger agglutinates and the pull of the end−Miocene extinction event.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 529-539
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural diversity of the stylophyllid [Scleractinia] skeleton
Autorzy:
Stolarski, J
Russo, A.
Powiązania:
https://bibliotekanauki.pl/articles/22102.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
stylophyllid
paleobiology
Scleractinia
skeleton
morphology
Jurassic
Stylophyllina
microstructure
Haimeicyclus haimei
ontogenesis
diversity
Stylophyllopsis
deposit
coral
solitary coral
paleontology
Opis:
Coralla of the three species of solitary corals described herein from the Sinemurian (Lower Jurassic) of Sicily, i.e., Haimeicyclus haimei (Chapuis and Dewalque, 1853), Stylophyllopsis sp. cf. S. rugosa (Duncan and Wright, 1867), and Stylophyllopsis sp. A., conform to the overall stylophyllid morphology. Their septa consist of spines that are increasingly covered with sclerenchyme and low in the calice form compact blades. The pattern of diagenetic alteration of septa is diverse but consistent within particular taxa. It suggests that the spectrum of the original microstructures is wider than traditionally suggested for stylophyllids. In H. haimei, the septa are covered with dense granulations and completely recrystallized. Granulations also cover septal faces of Stylophyllopsis cf. rugosa and have rod−like foundations. In Stylophyllopsis sp. A., vestiges of the narrow mid−septal zone (similar to that in minitrabecular corals) occur in the proximal part of larger septa, whereas septal spines which are similar to those in Stylophyllopsis cf. rugosa occur in their distal parts. Similar diversity of microstructures is reported also in Triassic stylophyllids that have aragonitic coralla. The presence of distinct septal spines along with wide−ranging microstructural diversity of traditional Triassic–Jurassic stylophyllids, casts light on their possible evolutionary relationships, and can be a useful criterion for further revision of the group. For example, Jurassic thecocyathids, considered ancestral to caryophylliinans, share similar spiny/lobate septa with stylophyllids. Also Recent deep−water anthemiphylliids with spiny/lobate septa are strikingly similar to stylophyllids. Although this may be another example of parallel evolution, the separation of anthemiphylliids from other scleractinian clades on a mitochondrial 16S RNA tree topology suggests their ancient roots and enable us to suggest a stylophyllid ancestry. The supposed cyclic pattern of protoseptal insertion in Early Jurassic H. haimei supports the hypothesis of scleractinian−like (and not rugosan) ancestory of the stylophyllid evolutionary lineage.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity of the adapisoriculid mammals from the early Palaeocene of Hainin, Belgium
Autorzy:
De Bast, E.
Sige, B.
Smith, T.
Powiązania:
https://bibliotekanauki.pl/articles/23133.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
diversity
adapisoriculid mammal
Early Paleocene
Paleocene
Hainin
Belgium
Mammalia
Adapisoriculidae
phylogenesis
paleontology
Opis:
Adapisoriculidae are an enigmatic group of small mammals known from the late Cretaceous of India, and from the early Palaeocene to early Eocene of Europe and Africa. Based on their primitive dental morphology, they have been classified as didelphids, nyctitheriids, leptictids, mixodectids, tupaiids, and palaeoryctids. While the latest hypothesis based on dental morphology suggests an affinity with Lipotyphla, postcranial remains indicate a close relationship with Euarchonta. Here, we present new adapisoriculid dental remains from the early Palaeocene locality of Hainin (Belgium). Adapisoriculidae are particularly abundant in Hainin, where they represent about one third of the mammalian fauna, offering new insights into both their specific and generic phylogenetic interrelationships. We describe three new species (Afrodon gheerbranti sp. nov., Bustylus folieae sp. nov. and Proremiculus lagnauxi gen. et sp. nov.) and document the previously unknown lower dentition of Bustylus marandati. The diversity of dental morphologies observed in the Hainin fauna suggests different interrelationships than previously suggested. In particular, the genus Proremiculus is considered morphologically intermediate between Afrodon and Remiculus, and the latter is no longer recognised as the sister group of Adapisoriculus. Although the highest diversity of adapisoriculids occurs in Europe, the oldest and most primitive members of the family were found in India and Africa, respectively. The geographic origin of the family could thus be located in any of these three continents, depending on the importance attributed to each of these factors. The coexistence of primitive and derived adapisoriculids at Hainin might indicate a very quick diversification in Europe, probably starting around the K−T boundary.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Populations, ecosystems and global diversity: the scientific work of Antoni Hoffman
Autorzy:
Reif, W.E.
Powiązania:
https://bibliotekanauki.pl/articles/23459.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
biography
evolutionary work
Hoffman A.bibliography
geology
global diversity
evolution
ecosystem
oceanic geochemistry
population
paleoecological work
Hoffman Antoni biography
Źródło:
Acta Palaeontologica Polonica; 1993, 38, 3-4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity dynamics of Early-Middle Jurassic brachiopods of Caucasus, and the Pliensbachian-Toarcian mass extinction
Autorzy:
Ruban, D A
Powiązania:
https://bibliotekanauki.pl/articles/21213.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
taxonomic diversity
brachiopod
Early-Middle Jurassic
Russia
mass extinction
Caucasus Mountains
Jurassic
Brachiopoda
paleontology
Opis:
Taxonomic diversity of NW Caucasus brachiopods changed cyclically in the Early–Middle Jurassic. Diversifications took place in the Late Sinemurian–Early Pliensbachian, Middle–Late Toarcian and Late Aalenian–Early Bajocian, while diversity decreases occured in Late Pliensbachian–Early Toarcian, Early Aalenian and Late Bajocian. Outstanding diversity decline in the Late Pliensbachian–Early Toarcian corresponds to a global mass extinction interval, whose peak has been documented in the Early Toarcian. Similar diversity changes of brachiopods are observed in other Tethyan regions, including the well−studied Bakony Mountains, although in NW Caucasus the recovery after demise have begun earlier. The causes of Pl−To mass extinction in the studied region are enigmatic. Probably, it could be linked to anoxia, but its correspondence to the beginning of transgression is not coincident with the global record, so eustatic causes seem to be doubtful for this region.
Źródło:
Acta Palaeontologica Polonica; 2004, 49, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aspects of diversity in early Antarctic penguins
Autorzy:
Jadwiszczak, P.
Mors, T.
Powiązania:
https://bibliotekanauki.pl/articles/21766.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
diversity
Antarctic
penguin
Aves
bird
Sphenisciformes
systematics
sexual dimorphism
body mass
Eocene
Antarctic Peninsula
paleontology
bone
La Meseta Formation
Seymour Island
animal species
Opis:
Penguin bones from the Eocene La Meseta Formation (Seymour Island, Antarctic Peninsula) constitute the only extensive fossil record of Antarctic Sphenisciformes. Here, we synonymize some of the recognized genera (Anthropornis with Orthopteryx, Delphinornis with Ichtyopteryx) and species (Anthropornis nordenskjoeldi with Orthopteryx gigas, Delphinornis gracilis with Ichtyopteryx gracilis). Moreover, we suggest that Antarctic species of Anthropornis and Palaeeudyptes, so−called giant penguins, may in fact comprise only one species each instead of two, based on evidence of well−marked sexual dimorphism. We also present new estimates of body mass based on femora testifying to the impressive scope of interspecific body−size variation in Eocene Antarctic penguins.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals
Autorzy:
Koenigswald, W.
Holbrook, L.
Rose, K.
Powiązania:
https://bibliotekanauki.pl/articles/23264.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Mammalia
Perissodactyla
tooth enamel microstructure
functional adaptation
phylogenesis
diversity
evolution
mammal
perissodactyl mammal
tooth
fossil
Hunter-Schreger Band
Opis:
Four different Hunter−Schreger Band (HSB) configurations were observed in the teeth of fossil and extant Perissodactyla. This variability exceeds that observed in Artiodactyla or Proboscidea. The four HSB configurations represent two different evolutionary pathways. Transverse HSB found in many mammalian taxa outside the Perissodactyla represents the most primitive HSB configuration. It occurs in several primitive perissodactyl families and is retained in Palaeotheriidae and extant Equidae. Curved HSB evolved from transverse HSB and occurs in Tapiridae, Helaletidae, and Lophiodontidae, as well as in Ancylopoda and Titanotheriomorpha. This likely indicates independent evolution of curved HSB in two or more lineages, but the number of instances of parallelism of this configuration is obscured by uncertainty in the relationships among these taxa and by a lack of data for some important basal taxa. A second evolutionary pathway leads from transverse HSB via compound HSB to vertical HSB. Compound HSB were detected in Hyrachyidae, Deperetellidae, and the early rhinocerotid Uintaceras. Vertical HSB configuration characterizes the molar dentition of other Rhinocerotidae, Hyracodontidae, Indricotheriidae, and Amynodontidae. Often, the incisors of rhinocerotids retain traces of compound HSB. Thus the HSB configuration reflects phylogenetic relationships to some degree. The selective value of the modified HSB configurations is interpreted functionally as a mechanism to reduce abrasion during mastication, assuming that the perpendicular intersection of prisms with the actual grinding surfaces resists wear better than prisms running parallel to the occlusal surface.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The European Early Cretaceous cryptodiran turtle Chitracephalus dumonii and the diversity of a poorly known lineage of turtles
Autorzy:
Perez-Garcia, A.
Powiązania:
https://bibliotekanauki.pl/articles/21609.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Europe
Lower Cretaceous
cryptodiran turtle
turtle
Chitracephalus dumonii
animal diversity
Testudines
Eucryptodira
Cryptodira
Cretaceous
Belgium
Spain
synonym
paleontology
phylogenetic analysis
systematics
holotype
Salasemys pulcherrima
Opis:
Chitracephalus dumonii was named based on some of the most complete turtle remains from the Lower Cretaceous of Europe, and yet the taxon has barely been mentioned since. Indeed, new specimens were erroneously attributed to a new taxon, “Salasemys pulcherrima”. The synonymy is recognized here, and this extends the geographical range of this turtle and provides examples of individuals at different stages of ontogenetic development. The peculiar structure of its shell, and its ontogenetic development, are unique to this taxon. The systematic position of C. dumonii was previously unclear, usually being referred to Testudinata incertae sedis. Here, it is placed in a cladistic analysis, which shows that C. dumonii, and the recently described Hoyasemys jimenezi form part of a Lower Cretaceous European clade of Cryptodira that includes “macrobaenid”, “sinemydid”, and panchelonioidean turtles.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity of diapsid fifth metatarsals from the Lower Triassic karst deposits of Czatkowice, southern Poland —functional and phylogenetic implications
Autorzy:
Borsuk-Bialynicka, M.
Powiązania:
https://bibliotekanauki.pl/articles/21653.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Three morphotypes of the fifth metatarsal (MttV), one of the most informative bones of the postcranium, have been described herein from the Early Triassic karst deposits of the Czatkowice locality (Southern Poland). Two of them have been assigned to a basal archosauriform Osmolskina czatkowicensis and a basal lepidosauromorph, Sophineta cracoviensis, respectively, while one is undetermined saurian. Two morphological categories of the hooked fifth metatarsals recognized from this assemblage account for two different solutions to the problem of improvement of locomotion. A strongly inflected (sensu Robinson 1975) MttV shaft consists of two parts, a distal one lying on the ground in a plantigrade manner and a proximal one bent at an angle to get align with the ventral surface of the crus and proximal tarsus. In contrast, a straight shaft of the hooked MttV, suggests its subvertical life position and thus a digitigrade foot stance. The hooking of the fifth metatarsal, that is currently accepted saurian synapomorphy, appeared in phylogeny in a primitive state referred to herein as a neckless type: with neither a neck-shaped articular protrusion for the fourth distal tarsal nor a directly medial orientation of the articular facet. A derived long-necked type with protruding arricular part and more directly medial orientation of the articular facet appeared, at various stages of further phylogeny. A strong plantar–dorsal inflexion of the fifth metatarsal associated with a protrusion of lateral plantar tubercle, dates from a directly pre-lepidosaurian stage of evolution.
Źródło:
Acta Palaeontologica Polonica; 2018, 63, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frasnian-Famennian brachiopod extinction and recovery in Southern Poland
Autorzy:
Balinski, A
Powiązania:
https://bibliotekanauki.pl/articles/21294.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Famennian
fauna
Frasnian
diversity dynamics
Polska
brachiopod
extinction
paleontology
Brachiopoda
Opis:
The new trench Z−17 situated in the Dębnik anticline (Cracow Region, southern Poland) exposed strata representing the Frasnian–Famennian boundary interval. The latest Frasnian crisis interval is characterized by the fauna of Ryocarhynchus tumidus interval consisting of the nominal species, Barroisella campbelli, Biernatella polonica, and representives of Lingulipora, Athyris, ?Retichonetes, Longispina, Cyrtospirifer and Warrenella. The first brachiopods that appears immediately above the F–F boundary in the survival interval include the unidentified rhipidomellid, Praewaagenoconcha cf. speciosa, and Pampoecilorhynchus geniculatus sp. nov. The fauna in the succeeding layer is dominated by P. geniculatus and Cyrtospirifer minor. The earliest Famennian repopulation assemblage consists of representatives of Barroisella, ?Rhyssochonetes, Praewaagenoconcha, Nigerinoplica, Schizophoria, unidentified rhipidomellid, Pampoecilorhynchus geniculatus sp. nov., Chapinella striata sp. nov., Crinisarina angelicoides, and Cyrtospirifer minor. Low diversity and low frequency brachiopod assemblages consisting of stunted specimens characterize the succeeding brachiopod intervals spanning the remainder of the Palmatolepis triangularis Zone. Basinal dysoxia prevailed in the region for the duration of Pa. triangularis Zone. Resumption of aerobic bottom−water conditions is marked by the appearance of brachiopods of the Dmitria gibbosa interval (Pa. crepida Zone). Resumption of favorable environmental conditions during the recovery interval is marked by an increase in brachiopod diversity recording the beginning of a strong post−extinction rediversification of the fauna.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limits to randomness in paleobiologic models: the case of Phanerozoic species diversity
Autorzy:
Sepkoski, J J ,Jr
Powiązania:
https://bibliotekanauki.pl/articles/23116.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ewolucja
skamienialosci
kenozoik
gatunki
paleontologia
liczebnosc
Opis:
The question of how random, or unconstrained, paleobiologic models should be is examined with a case study: Signor’s (1982, 1985) inverse calculation of levels of marine species diversity through the Phanerozoic. His calculation involved an ingenious model that estimated species numbers and species abundances in the world oceans of the past by correcting known numbers of fossil species for variations in sedimentary rocks available for sampling and in effort paleontologists might devote to sampling. The model proves robust to changes in possible shapes of species-abundance distributions, but it is sensitive to alterations in the assumption that paleontologists collect fossils at random. If it is assumed that ease of collecting varies with age of sediment (with the Cenozoic offering easy sampling) or that paleontologists tend to seek out rarer fossils, results of the inverse calculation change. In particular, the magnitude of the calculated Cenozoic diversity increase always declines from the factor of about seven as originally reported to something considerably smaller. This leaves open the problem of the magnitude of Cenozoic increase in marine species diversity, awaiting better empirical data and, perhaps, more exacting models, random or otherwise.
Rzeczywista liczba gatunków współwystępujących w poszczególnych horyzontach czasowych przeszłości może być oszacowana w oparciu o znajomość liczby zidentyfikowanych gatunków kopalnych i liczby skamieniałości znalezionych w poszczególnych jednostkach czasu geologicznego. Liczba zebranych skamieniałości jest proporcjonalna do stopnia rozpoznania oraz powierzchni zajmowanej przez osady jednostek geologicznych. Rozumowanie umożliwiające takie szacunki oparte jest na założeniu lognormalnego rozkładu częstości gatunków w stosunku do liczebności ich osobników i losowego charakteru opróbowania paleontologicznego. Zaburzenie lognormalności rozkladu nie wpływa istotnie na wiarygodność szacunków. Nie jest również istotnym czynnikiem zaburzającym zróżnicowane trwanie gatunków rzutujące na wyliczenia w oparciu o różnej wielkości jednostki geologiczne. Istotnym problemem jest natomiast zdecydowanie nielosowy charakter opróbowania paleontologicznego, na przykład zmniejszający się udział czynników diagenetycznych w zachowaniu do dziś skamieniałości kenozoicznych tudzież skłonność badaczy do skupiania uwagi na rzadkich i niezwykłych skamieniałościach.
Źródło:
Acta Palaeontologica Polonica; 1993, 38, 3-4; 175-198
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Silurian palynomorphs from the Precordillera of San Juan, Argentina: Diversity, palaeoenvironmental and palaeogeographic significance
Autorzy:
Muro, V.J.G.
Rubinstein, C.V.
Steemans, P.
Powiązania:
https://bibliotekanauki.pl/articles/20221.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
The palynological content from the Cerro La Chilca and Quebrada Ancha sections of the Wenlock? to Přídolí Los Espejos Formation, in the Argentinean Precordillera is studied. The marine palynomorphs exhibit higher relative abundance and diversity in almost all the productive samples, except for the uppermost ones from both sections, in coincidence with the shift towards more proximal facies in this part. The Los Espejos Formation yielded a total of 114 species of marine organic walled-phytoplankton, 52 species of miospores and two non-marine phytoplankton species. The lower part of the Los Espejos Formation, dated as Ludfordian, displays the highest phytoplankton diversity and the better-preserved palynomorphs of the studied samples in both sections. Diversity tends to diminish towards the upper part of the Los Espejos Formation, dated as late Ludfordian–Přídolí, in coincidence with the transition to storm-dominated shelf and shoreface environments and subaerial exposures that probably hinder the preservation of palynomorphs. Comparisons with coeval phytoplankton assemblages from Gondwana and other palaeoplates such as Laurentia, Baltica, and Avalonia result in strong similarities, which suggest a cosmopolitan distribution pattern during the Ludlow and the Přídolí. Conversely, the trilete spores display more similarities with those from Gondwana and thus suggest a lesser dispersive potential in comparison to phytoplankton. A new trilete spore species Emphanisporites? tenuis is described.
Źródło:
Acta Palaeontologica Polonica; 2018, 63, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity of tissues in acanthodians with Nostolepis-type histological structure
Autorzy:
Valiukevicius, J
Burrow, C.J.
Powiązania:
https://bibliotekanauki.pl/articles/22517.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
histology
acanthodian
dentine
Devonian
Acanthodii
Silurian
bone
Nostolepis
tissue
paleontology
mesodentine
Opis:
Acanthodian scales with Nostolepis−type histological structure are separated into five groups based on the presence/absence and extent of stranggewebe, odontocytic and syncitial mesodentine networks, cellular unipolar mesodentine, bone−like mesodentine and durodentine in scale crowns. Two new families of acanthodians are erected, based primarily on histological structure of scales: the Vesperaliidae (stranggewebe extending throughout the scale crown) and the Acritolepidae (bone−like mesodentine in the scale crown). The latter family includes species erected for articulated fish. The families Tchunacanthidae and Lenacanthidae are united in the single family Tchunacanthidae, characterized by having scale crowns with mesodentine formed mainly by unipolar cells. A sixth group, which we exclude from the Nostolepis−type, has scale crowns composed of dentine without lacunae, plus durodentine, and bases with only rare osteocyte cavities. The new groups promote the revision and reassignment of many “nostolepid” taxa, in particular removing many species from the genus Nostolepis. Four new genera are erected: Pechoralepis (including part of Nostolepis), assigned to Acritolepidae nov.; and three genera assigned to an indeterminate family, which scales are composed of only odontocytic mesodentine without stranggewebe: Nostovicina (including part of Nostolepis), Nobilesquama (including part of Nostolepis), and Peregrinosquama (including part of Watsonacanthus). Histological structures are considered the primary characters of taxonomical value when based on isolated scales. Unfortunately, scale histology is unknown for most articulated acanthodians.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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