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Wyświetlanie 1-15 z 27
Tytuł:
The revision of 'Cladodus' occidentalis, a Late Paleozoic ctenacanthiform shark
Autorzy:
Ginter, M
Ivanov, A.
Lebedev, O.
Powiązania:
https://bibliotekanauki.pl/articles/20599.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carboniferous
Cladodus mirabilis
Paleozoic
Late Paleozoic
Permian
tooth
Ctenacanthiformes
Glikmanius occidentalis
paleontology
Chondrichthyes
Opis:
The teeth of a well known late Palaeozoic cladodont chondrichthyan, “Cladodus” occidentalis from Russia, USA, and England are restudied and a new generic name, Glikmanius gen. nov., is proposed for this species. Yet another tooth−based species, formerly described as ?Symmorium myachkovensis, occurring on the Russian Platform and in Nebraska, is considered to belong to the newly erected genus. Although there is no direct evidence that Glikmanius possessed fin spines, the broad similarity between its teeth and those of Ctenacanthus compressus suggests it had a ctenacanthiform affinity. The possible relationships between Glikmanius, Cladodus sensu stricto, “Ctenacanthus” costellatus, and Heslerodus, are suggested. However, the proposition put forward by an earlier author that the teeth of Heslerodus might represent the lower jaw dentition of G. myachkovensis, is rejected. The overall resemblance of Glikmanius teeth and those of Cladoselache and Squatinactis is recognised as convergent.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spore-like bodies in some Early Paleozoic acritarchs: clues to chlorococcalean affinities
Autorzy:
Kazmierczak, J
Kremer, B.
Powiązania:
https://bibliotekanauki.pl/articles/20169.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
spore-like body
Early Paleozoic
Paleozoic
acritarch
microfossil
Chlorococcales
phytoplankton
evolution
polygonomorph
acanthomorph
sphaeromorph
herkomorph acritarch
Opis:
We present discoveries of internal bodies in problematic Silurian and Devonian organic−walled microfossils classified traditionally as polygonomorph, acanthomorph, sphaeromorph, and herkomorph acritarchs. These bodies are comparable with reproductive structures (autoand/or aplanospores) of modern unicellular green algae (Chlorococcales). Our findings suggest that many of these microfossils may represent asexually reproducing (sporulating) vegetative cells of chlorococcalean algae. The presence of spore−like bodies in the studied acritarchs supports earlier suggestions, based on ultrastructural and biomarker studies, that some acritarchs can be affined with green algae.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 541-551
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsuccessful predation on Middle Paleozoic plankton: Shell injury and anomalies in Devonian dacryoconarid tentaculites
Autorzy:
Berkyova, S
Fryda, J.
Lukes, P.
Powiązania:
https://bibliotekanauki.pl/articles/22057.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Tentaculitoidea
tentaculite
predation
Middle Paleozoic
Paleozoic
plankton
Devonian
shell repair
dacryoconarid tentaculite
paleontology
Opis:
Anomalous development of shell ornamentation and repaired shell injury in the Early Devonian dacryoconarid tentaculites are documented and interpreted as either a repaired injury of the shell (evidence of unsuccessful predation obscured by recrystallization), or as a result of an anomalous function of the mantle, caused by injury of the soft body. The manner of shell repair, which resembles the way that some modern marine animals, such as mollusks, repair their shells, is discussed. The issue of phylogenetic affinities of tentaculites has been also outlined. These findings represent the first documentation of unsuccessful predation on the Middle Paleozoic plankton.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Additional evidence for the drilling behavior of Paleozoic gastropods
Autorzy:
Gahn, F J
Fabian, A.
Baumiller, T.K.
Powiązania:
https://bibliotekanauki.pl/articles/20969.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
drilling behaviour
gastropod
Paleozoic
paleontology
Opis:
Although the record of Paleozoic drillholes is long and extensive, evidence pertaining to the identity of the drillers is sparse. The most conclusive evidence, a driller “caught in the act”, has been documented only once (Baumiller 1990). In that example, a drillhole in the calyx of a crinoid was found directly beneath an attached platyceratid gastropod. Additional evidence for drilling by platyceratids has been circumstantial, i.e., based on the association of platyceratids with certain blastoids and crinoids, and the presence of drillholes in other crinoid and blastoid taxa. To a skeptic, the lack of congruence between drilled and platyceratidinfested crinoids and blastoids is not sufficient evidence that platyceratids were the drillers. More conclusive evidence requires examples of drillholes in taxa that are known to have been platyceratid−infested, preferably from localities where both infested specimens and drilled specimens co−occur.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of Paleozoic corals of the Verkhoyansk Mountains
Autorzy:
Khaiznikova, K.B.
Powiązania:
https://bibliotekanauki.pl/articles/20452.pdf
Data publikacji:
1980
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
The class Anthozoa is represented by Tabulata and Heliolitida in Paleozoic series of the Verkhoyansk Mountains (Verkhoyanie). Representatives of all the seven tabulate orders and of the heliolitid orders (Heliolitida, Proporida) moved into this area from the Siberian platform in the late Ordovician. At the end of the Ordovician and the beginning of the Silurian the orders Lichenariida, Sarcinulida, Tetradiida and Proporida died out in Verkhoyanie. The families Halysitidae, Favositidae, Pachyporidae experienced a burst of speciation in the early Silurian. The orders Halysitida and Heliolitida became extinct by the early Upper Silurian. With the Gedinnian-Siegenian transgression Favositidae, Pachyporidae, Alveolitidae, Coenitidae, Syringoporidae migrated from the Arctic basin into the Verkhoyansk sea. Known from the Givetian and Frasnian are only numerous representatives of Pachyporidae, Alveolitidae, Coenitidae and Syringoporidae. Corals Syringoporida and Auloporida disappeared by the beginning of Viséan time and those of the order Favositida in the Early Permian.
Źródło:
Acta Palaeontologica Polonica; 1980, 25, 3-4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An enigmatic chondrichthyan with Paleozoic affinities from the Lower Triassic of Western Canada
Autorzy:
Mutter, R J
Neuman, A.G.
Powiązania:
https://bibliotekanauki.pl/articles/19949.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
histology
fish
Triassic
Lower Triassic
Paleozoic
Canada
chondrichthyan
paleontology
Listracanthus pectenatus
Western Canada
Opis:
Listracanthus pectenatus sp. nov. represents the youngest record of the enigmatic chondrichthyan Listracanthus. This new species is the only Mesozoic record of this genus and highlights survival of a rare and enigmatic group of cartilaginous fishes across the Paleozoic–Mesozoic boundary. In the Vega−Phroso Siltstone Member of the Sulphur Mountain Formation (western Canada), two kinds of numerous dermal denticles identified as Listracanthus occur predominantly in strata probably of early Smithian age. The new species differs from all other known species of the genus in the structure of the anterior and posterior borders of the large denticles. The small denticles appear to be less diagnostic than the large ones and are readily distinguished from small denticles generally assigned to the genus Petrodus. Histology reveals that the largest denticles were originally hollow, probably secondarily ossified as acellular bone. The conclusion drawn by previous authors that Listracanthus may be a petalodontid shark, based on ambiguous non−skeletal associations with Deltoptychius, Petrodus, or Calopodusis not supported by this study. The large number of denticles, the size of both types of denticles and their arrangement suggest that Listracanthus pectenatus sp. nov. was a large chondrichthyan of aberrant body shape and yet uncertain systematic position.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stylophoran supertrees revisited
Autorzy:
Lefebvre, B
Powiązania:
https://bibliotekanauki.pl/articles/23222.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
supertree
Echinodermata
Mitrata
Paleozoic
Calcichordata
Stylophora
Ankyroida
Cornuta
paleontology
Opis:
Supertree analysis is a recent exploratory method that involves the simultaneous combination of two or more character−based source trees into a single consensus supertree. This method was recently applied by Ruta to a fossil group of enigmatic Palaeozoic forms, the stylophoran echinoderms. Ruta’s supertree suggested that mitrates are polyphyletic and originated from paraphyletic cornutes. Re−examination of Ruta’s data matrix strongly suggests that most source trees were based on dubious homologies resulting from theory−laden assumptions (calcichordate model) or superficial similarities (ankyroid scenario). A new supertree analysis was performed using a slightly corrected version of Ruta’s original combined matrix; the 70% majority−rule consensus of 24,168 most parsimonious supertrees suggests that mitrates are monophyletic and derived from paraphyletic cornutes. A second new supertree analysis was generated to test the influence of the pruning of three taxa in some calcichordate source trees; the 70% majority−rule consensus of 3,720 shortest supertrees indicates that both cornutes and mitrates are monophyletic and derived from a Ceratocystis−like ancestor. The two new supertree analyses demonstrate the dramatic influence of the relative contributions of each initial assumption of plate homologies (and underlying anatomical interpretations), in original source trees, on the final topology of supertrees.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Palaeozoic foliage from China displays affinities to Cycadales rather than to Bennettitales necessitating a re-evaluation of the Palaeozoic Pterophyllum species
Autorzy:
Pott, C.
McLoughlin, S.
Lindstrom, A.
Powiązania:
https://bibliotekanauki.pl/articles/23351.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Late Paleozoic
Paleozoic
China
Cycadales
Bennettitales
Pseudoctenis
Pterophyllum
cuticle analysis
epidermal anatomy
Carboniferous
Permian
paleontology
Opis:
The epidermal anatomy of Pseudoctenis samchokense is described revealing non−bennettitalean characters of these leaves from the Permo−Carboniferous of China (and Korea). The specimens were originally described as Pterophyllum samchokense suggesting a bennettitalean affinity. They can no longer be considered bennettitalean since their cuticles lack the distinctive brachyparacytic stomata of that clade. Pterophyllum was originally erected as a morphogenus for segmented leaves from the Mesozoic and has subsequently been clearly assigned to the Bennettitales. The segmented leaves from the Permo−Carboniferous of Shanxi and Hebei, China described herein require a new ordinal and generic assignment since the non−bennettitalean cuticular characters documented reinforce the uncertainties in attribution of any foliage older than Late Triassic to the Bennettitales. Based on leaf−architecture and epidermal anatomical characters, the specimens are at best assigned to the cycadalean genus Pseudoctenis. This genus was formerly known only from Mesozoic rocks. Consequently, the specimens are highly significant, as they are among the oldest known vegetative remains of cycads. Re−evaluation of the affinities of all specimens assigned to Pterophyllum from Palaeozoic rocks is thus essential. Based on a review of other Permian–Carboniferous fossil leaves assigned to Pterophyllum, we conclude that none yet reveals definitive bennettitalean characters.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new brittle star from the early Carboniferous of Poland and its implications on Paleozoic modern-type ophiuroid systematics
Autorzy:
Thuy, B.
Kutscher, M.
Plachno, B.J.
Powiązania:
https://bibliotekanauki.pl/articles/22083.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new record
fossil
paleontology
brittle star zob.ophiuroid
ophiuroid
Early Carboniferous
Carboniferous
Polska
Paleozoic
systematics
Echinodermata
Ophiuroidea
evolution
Tournaisian
Opis:
The fossil record of Paleozoic ophiuroids includes a number of forms which share striking similarities with modern relatives in terms of skeletal morphology. These so called modern-type Paleozoic ophiuroids yield an enormous potential for a better understanding of ophiuroid evolution, yet the scarcity of accurate and sufficiently detailed morphological descriptions available to date precludes any further-reaching assessments. Here, we describe an articulated ophiuroid specimen from the Late Tournaisian (early Carboniferous) of Czatkowice quarry, southern Poland, as a new species Aganaster jagiellonicus sp. nov. The good preservation of the specimen allowed for a morphological analysis at a level comparable to recent ophiuroid descriptions. It shows remarkable morphological similarities with extant former ophio-lepidids Ophiomusium and Ophiosphalma. The new find thus contributes to a solid basis for future investigations on the position of the modern-type Paleozoic ophiuroid in the phylogeny of the class.
Źródło:
Acta Palaeontologica Polonica; 2015, 60, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On microstructures of columnaIs of some Paleozoic crinoids
O mikrostrukturze członów łodyg liliowców z osadów paleozoicznych Polski
Autorzy:
Gluchowski, E.
Powiązania:
https://bibliotekanauki.pl/articles/21935.pdf
Data publikacji:
1982
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Scanning electron microscope was used to study columnals of crinoids of Pisocrinus (?) costatus (Shevchenko), Schyschcatocrinus sp., Cyclocaudiculus gracilis Głuchowski, Rhysocamax cristata Moore et Jeffords and Platycrinites minor Głuchowski from Silurian, Devonian and Carboniferous deposits of Poland. The presence of microstructures, interpreted as stereom α and stereom β have been confirmed and the occurrence of what is known as “large” microstructures on the lateral surface of the columnals of Schyschcatocrinus sp. have been stated. Three types within the “large” microstructures have been distinguished, the first of them marked by a close spacing of round, oval or elongated pores, the second — with round, less closely spaced pores and the third — having irregular, labyrinthic furrows and depressions.
Elementy szkieletowe liliowców paleozoicznych stosunkowo rzadko zachowują swoją pierwotną sieciową strukturą w postaci przestrzennego układu kalcytowych beleczek i pręcików (stereom). Gdy szczątki te zostaną pogrzebane w materiale gwarantującym ich bardzo dobry stan zachowania, można przy pomocy odpowiedniego preparowania struktury te obserwować wykorzystując skanningowy mikroskop elektronowy (SEM). Dla pięciu gatunków: Pisocrinus (?) costatus (Schevtschenko), Schyschcatocrinus sp., Cyclocaudiculus gracilis Głuchowski, Rhysocamax cristata Moore et Jeffords i Platycrinites minor Głuchowski z osadów syluru, dewonu i karbonu wykazano istnienie mikrostruktur interpretowanych jako stereom α i stereom β (pl. 27; pl. 28; tablica 1). Mikrostruktura ta była wcześniej obserwowana na materiale współczesnym i pochodzącym z mezozoiku i kenozoiku. Ponadto po raz pierwszy stwierdzono i opisano tzw. „duże” mikrostruktury na powierzchni bocznej Schyschcatocrinus sp. Podzielono je na trzy grupy różniące się między sobą budową (pl. 29). Typ pierwszy charakteryzuje się gęstym ułożeniem okrągłych, owalnych lub wydłużonych porów, typ drugi charakteryzuje się rzadszym rozmieszczeniem porów okrągłych, natomiast typ trzeci stanowią nieregularne, labiryntycznie biegnące bruzdy.
Źródło:
Acta Palaeontologica Polonica; 1982, 27, 1-4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conulariids from the Lower Ordovician of the southern Montagne Noire, France
Autorzy:
Van Iten, H.
Lefebvre, B.
Powiązania:
https://bibliotekanauki.pl/articles/2082222.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cnidaria
Scyphozoa
Conulariida
Paleozoic
Gondwana
Europe
Opis:
The Tremadocian–Floian (Lower Ordovician) Saint-Chinian, La Maurerie, and Landeyran formations of the southern Montagne Noire (France) collectively contain at least two species of conulariids, namely Archaeoconularia cf. insignis and Conularia azaisi, the latter herein designated as the type species of the new genus, Galliconularia. Archaeoconularia insignis may also occur in the Lower Ordovician Fezouata Shale of southern Morocco, and an indeterminate species of this genus probably occurs in the Lower Ordovician Tonggao Formation of South China. Galliconularia azaisi differs from all other conulariids in having a raised facial midline and very fine, trochoidal transverse ribs which cross the midline ridge without interruption or diminution. In specimens preserving the outermost peridermal lamellae, the transverse ribs bear sub-microscopic nodes, and the broad interspaces are crossed by very slender interspace ridges. Finally, even though the Montagne Noire was part of the western Gondwanan passive margin during Cambro-Ordovician times, G. azaisi remains unknown outside of France.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 3; 629-639
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Taxonomic notes on Phoebodus heslerorum and Symmorium reniforme [Chondrichthyes, Elasmobranchii]
Autorzy:
Ginter, M
Powiązania:
https://bibliotekanauki.pl/articles/23345.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carboniferous
Symmorium reniforme
Paleozoic
tooth
Elasmobranchii
Phoebodus heslerorum
taxonomy
paleontology
Chondrichthyes
Opis:
The revision of shark teeth from the Pennsylvanian black shales of central USA, ascribed to “Phoebodus heslerorum” Williams, 1985 and Symmorium reniforme Cope, 1893, shows that “Ph. heslerorum” is a junior synonym of “Cladodus” divergens Trautschold, 1879. This species belongs neither to Phoebodus nor to Cladodus, so a new genus Heslerodus is proposed. Very common, robust cladodont teeth with a deep labio−basal depression and two buttons, often referred to as S. reniforme, do not belong to the latter species, but to “Cladodus” occidentalis Leidy, 1859. The generic affinity of “C.” occidentalis is yet undetermined, but it is possible that it represents ctenacanthoids.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The oldest post-Paleozoic (Ladinian, Triassic) brachiopods from the Betic Range, SE Spain
Autorzy:
Baeza-Carratala, J.F.
Perez-Valera, F.
Perez-Valera, J.A.
Powiązania:
https://bibliotekanauki.pl/articles/22178.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Triassic brachiopods from the Betic Range were unknown hitherto. Herein we describe the first brachiopod occurrences in the early Ladinian of this domain referable to a new genus and species Misunithyris goyi derived from three localities of the south-Iberian Triassic outcrops. The analysis of internal and external characters of this brachiopod allowed to characterize systematically and biogeographically this fauna in a chronostratigraphic interval when the paucity of brachiopod records is attributable to the entire peri-Iberian epicontinental platform system established in the westernmost Tethyan margin. The new record is endemic to the Betic Range and represents a new faunal constituent of the multicostate zeillerids stock. This fauna inhabited the epicontinental seas of the Sephardic bioprovince since a closer affinity with the low-latitude Tethyan assemblages is revealed. The possible linkage of the Triassic stock with the Early–Middle Jurassic multicostate zeillerid representatives suggests feasible phylogenetic relationships between both groups.
Źródło:
Acta Palaeontologica Polonica; 2018, 63, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Graptolite-like fibril pattern in the fusellar tissue of Palaeozoic rhabdopleurid pterobranchs
Autorzy:
Mierzejewski, P
Kulicki, C.
Powiązania:
https://bibliotekanauki.pl/articles/22681.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
rhabdopleurid
rhabdopleurid pterobranch
Paleozoic
graptolite
Permian
Ordovician
taxonomy
ultrastructure
pterobranch
Opis:
The fusellar tissue of Palaeozoic rhabdopleurid pterobranchs has been studied using the SEM techniques. The fibrillar material of Ordovician Kystodendron ex gr. longicarpus and Rhabdopleurites primaevus exhibits a distinct dimorphism, comprising: (1) thinner, wavy and anastomosing/branching fusellar fibrils proper, producing a tight three-dimensional meshwork; and (2) long, more or less straight and unbranched cortical fibrils, sometimes beaded, and arranged in parallel. These fibrils are similar to the fusellar and cortical fibrils of graptolites, respectively. Until now, dimorphic fibrils and their arrangement within fusellar tissue were regarded as unique characters of the Graptolithina. In general, the fibrillar material of these fossils is partially preserved in the form of flaky material (new term) composed of flakes (new term). Flakes are interpreted as flattened structures originating from the fusion of several neighbouring tightly packed fibrils. A Permian rhabdopleurid, referred to as Diplohydra sp., reveals a fabric and pattern of fusellar tissue similar to that of both Ordovician rhabdopleurids but devoid (?) of cortical fibrils. The results presented here question views that: (1) substantial differences in fabric and pattern of fusellar tissue exist between fossil pterobranchs and graptolites; and (2) the ultrastructure of pterobranch periderm has remained unchanged at least since the Ordovician. The Palaeozoic rhabdopleurids investigated are closer ultrastructurally to graptolites than to contemporary pterobranchs. The pterobranchs and the graptolites should be treated as members of one class - the Graptolithoidea.
Przeprowadzono badania ultrastrukturalne perydemy trzech paleozoicznych pióroskrzelnych (Pterobranchia) z rzędu Rhabdopleurida: ordowickich Kystodendron ex gr. longicarpus (Eisenack) i Rhabdopleurites primaevus Kozłowski, oraz permskiego Diplohydra sp. Wykazano, że tkanka fuzellarna form ordowickich składa się z tego samego tworzywa co u graptolitów oraz wykazuje typowy dla nich dymorfizm fibrylarny i układ przestrzenny: tworzą ją stosunkowo cienkie, rozgałęziające się, powyginane włókna fuzellarne oraz grube, często równolegle ułożone włókna kortykalne. Włókien kortykalnych nie stwierdzono u Diplohydra sp., która zachowała jednak typowo graptolitowy charakter włókien fuzellarnych. Między włóknami wszystkich zbadanych form występują struktury określone jako płatki (flakes), powstałe wskutek cementacji kilkunastu lub więcej sąsiadujących ze sobą włókien. Materiał perydermalny zbudowany z płatków (flaky material - nowy terrnin) obserwowany był uprzednio u graptolitów. Stwierdzony w badanym materiale dymorfizm fibrylarny był dotąd uważany za właściwy jedynie graptolitom, podczas gdy tkanka fuzellarna pióroskrzelnych, zarówno kopalnych jak i współczesnych miała być zbudowana wyłącznie z cienkich, nierozgałęziających się włókien. Uzyskane wyniki potwierdzają trafność koncepcji Beklemiszewa (1951) o traktowaniu współczesnych i kopalnych pióroskrzelnych jako przedstawicieli gromady Graptolithoidea.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new middle Cambrian trilobite with a specialized cephalon from Shandong Province, North China
Autorzy:
Sun, Z.
Zeng, H.
Zhao, F.
Powiązania:
https://bibliotekanauki.pl/articles/2082242.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Trilobita
Ptychopariida
ontogeny
specialization
Miaolingian
Paleozoic
Longgang
Asia
Opis:
Trilobites achieved their maximum generic diversity in the Cambrian, but the peak of morphological disparity of their cranidia occurred in the Middle to Late Ordovician. Early to middle Cambrian trilobites with a specialized cephalon are rare, especially among the ptychoparioids, a group of libristomates featuring the so-called “generalized” bauplan. Here we describe an unusual ptychopariid trilobite Phantaspis auritus gen. et sp. nov. from the middle Cambrian (Miaolingian, Wuliuan) Mantou Formation in the Shandong Province, North China. This new taxon is characterized by a cephalon with an extended anterior area of double-lobate shape resembling a pair of rabbit ears in later ontogenetic stages; a unique type of cephalic specialization that has not been reported from other trilobites. Such a peculiar cephalon as in Phantaspis provides new insights into the variations of cephalic morphology in middle Cambrian trilobites, and may represent a heuristic example of ecological specialization to predation or an improved discoidal enrollment.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 4; 709-718
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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