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Tytuł:
Marine fishes (Elasmobranchii, Teleostei) from the Glendon Limestone Member of the Byram Formation (Oligocene, Rupelian) at site AWa-9, Washington County, Alabama, USA, including a new species of gobiid (Gobiiformes: Gobiidae)
Autorzy:
Ebersole, Jun A.
Cicimurri, David J.
Stringer, Gary L.
Powiązania:
https://bibliotekanauki.pl/articles/2024054.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chondrichthyes
Teleostei
otolith
Paleogene
Gulf Coastal Plain
Vicksburg Group
ryby chrzęstnoszkieletowe
otolity
paleogen
Opis:
The Oligocene (Rupelian) Byram Formation (Vicksburg Group) in Alabama, USA, is divided into three members, including (in ascending order) the Glendon Limestone, unnamed marl, and the Bucatunna Clay. The Oligocene marine units in Alabama have been historically under-investigated, but bulk samples recently obtained from Glendon Limestone Member exposures at site AWa-9 in Washington County yielded 20 unequivocal elasmobranch and teleost taxa. This surprisingly diverse paleofauna, based on isolated teeth, bones and otoliths, includes the new taxon, Gobiosoma? axsmithi sp. nov., as well as “Aetomylaeus” sp., Albula sp., Aplodinotus gemma Koken, 1888, Ariosoma nonsector Nolf and Stringer, 2003, Balistidae indet., Citharichthys sp., Myliobatoidei indet., Diretmus? sp., Hemipristis sp., Negaprion aff. N. gilmorei (Leriche, 1942), Pachyscyllium sp., Paralbula sp., Physogaleus sp., Preophidion meyeri (Koken, 1888), Sciaena pseudoradians (Dante and Frizzell in Frizzell and Dante, 1965), Sciaenops? sp., Sparus? elegantulus Koken, 1888, Sphyraena sp., and Syacium sp. Additional remains were recovered but could not be identified beyond undetermined Elasmobranchii or Teleostei. All these taxa represent first occurrences within the Glendon Limestone Member in Alabama, and the “Aetomylaeus” sp., Pachyscyllium sp., Paralbula sp., and Sciaenops? sp. specimens represent the first occurrences of each in the Oligocene of the Gulf Coastal Plain of the USA. We also report the first record of Oligocene Paralbula Blake, 1940 teeth, and the first occurrence of an Oligocene member of the Balistidae in the Western Hemisphere. This marine vertebrate assemblage indicates that the Glendon Limestone Member at site AWa-9 represented a subtropical to temperate, middle shelf paleoenvironment with a paleowater depth interpreted as 30–100 m.
Źródło:
Acta Geologica Polonica; 2021, 71, 4; 481--518
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Middle Palaeozoic chondrichthyans and the associated ichthyofauna from southern Poland : a review
Autorzy:
Ginter, Michał
Wilk, Olga
Powiązania:
https://bibliotekanauki.pl/articles/1835970.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Chondrichthyes
Osteichthyes
Devonian
Carboniferous
Polska
Opis:
During the last sixty years, large collections of ichthyofauna, mainly isolated, microscopic, skeletal remains (ichthyoliths), from the Middle–Upper Devonian and Lower Carboniferous rocks of southern Poland have accumulated in the hands of Polish palaeontologists and in palaeontological institutions. Some parts of these collections were described in unpublished dissertations and others were published in dispersed papers, dealing mostly with selected regions or taxa. This review summarises the available data from the following regions: the Holy Cross Mountains, the Cracow Upland, the Sudetes and the Lublin Coal Basin (in the latter two cases, single localities). Altogether, 29 chondrichthyan species were identified and a few more still require classification. Of the Sarcopterygii, three species of onychodontiforms and one of the actinistians were found, in addition to a collection of dipnoans that was described much earlier. A few morphological types were distinguished among actinopterygian scales; otherwise the actinopterygian fossils are not referred to any lower-level taxon, and the same applies to the acanthodians. There were several attempts in the past to apply Polish ichthyoliths in biostratigraphy and palaeoecology, but after all these years, it appears that such propositions have only limited significance.
Źródło:
Annales Societatis Geologorum Poloniae; 2021, 91, 3; 253-286
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chondrichthyan spines from the Famennian (Upper Devonian) of Russia
Autorzy:
Lebedev, Oleg A.
Ivanov, Alexander O.
Linkevich, Valeriy V.
Powiązania:
https://bibliotekanauki.pl/articles/1835588.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chondrichthyes
Ctenacanthiformes
Euselachii
Fin spines
Famennian
Devonian
Russia
ryby chrzęstnoszkieletowe
famen
dewon
Rosja
Opis:
Very rare chondrichthyan spines from the Famennian (Upper Devonian) of European Russia are referred here to ctenacanthiforms, euselachians and a chondrichthyan group of uncertain systematic position. Ctenacanthus Agassiz, 1837 is recorded from the lower and middle Famennian of the central and north-western parts of the area. Sculptospina makhlaevi Lebedev gen. et sp. nov. originates from the lower Famennian of the Lipetsk Region. The holotype of ‘Ctenacanthus’ jaekeli Gross, 1933 and a new specimen from the upper Famennian of the South Urals are shown to belong to the same taxon, which is transferred to Acondylacanthus St. John and Worthen, 1875. New specimens of Tuberospina nataliae Lebedev, 1995 from the upper Famennian of Central Russia are described in detail. The newly presented material increases our knowledge of the composition of Famennian marine assemblages from the East European Platform. It is suggested that these assemblages may be classified as chondrichthyan-dominated and dipnoan-dominated. Hypothetically, after the end- Devonian Hangenberg extinction event, which affected numerous secondary consumers in vertebrate communities, some chondrichthyan groups could have encroached to take advantage of previously occupied ecological niches. Ctenacanthus, as well as Acondylacanthus and Amelacanthus survived the end-Devonian mass extinction to continue into the Carboniferous.
Źródło:
Acta Geologica Polonica; 2020, 70, 3; 339-362
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chondrichthyan spines from the Famennian (Upper Devonian) of Russia
Autorzy:
Lebedev, Oleg A.
Ivanov, Alexander O.
Linkevich, Valeriy V.
Powiązania:
https://bibliotekanauki.pl/articles/139186.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chondrichthyes
Ctenacanthiformes
Euselachii
Fin spines
Famennian
Devonian
Russia
ryby chrzęstnoszkieletowe
famen
dewon
Rosja
Opis:
Very rare chondrichthyan spines from the Famennian (Upper Devonian) of European Russia are referred here to ctenacanthiforms, euselachians and a chondrichthyan group of uncertain systematic position. Ctenacanthus Agassiz, 1837 is recorded from the lower and middle Famennian of the central and north-western parts of the area. Sculptospina makhlaevi Lebedev gen. et sp. nov. originates from the lower Famennian of the Lipetsk Region. The holotype of ‘Ctenacanthus’ jaekeli Gross, 1933 and a new specimen from the upper Famennian of the South Urals are shown to belong to the same taxon, which is transferred to Acondylacanthus St. John and Worthen, 1875. New specimens of Tuberospina nataliae Lebedev, 1995 from the upper Famennian of Central Russia are described in detail. The newly presented material increases our knowledge of the composition of Famennian marine assemblages from the East European Platform. It is suggested that these assemblages may be classified as chondrichthyan-dominated and dipnoan-dominated. Hypothetically, after the end- Devonian Hangenberg extinction event, which affected numerous secondary consumers in vertebrate communities, some chondrichthyan groups could have encroached to take advantage of previously occupied ecological niches. Ctenacanthus, as well as Acondylacanthus and Amelacanthus survived the end-Devonian mass extinction to continue into the Carboniferous.
Źródło:
Acta Geologica Polonica; 2020, 70, 3; 339-362
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diversity of vertebrate remains from the Lower Gogolin Beds (Anisian) of southern Poland
Autorzy:
Antczak, Mateusz
Ruciński, Maciej
Stachacz, Michał
Matysik, Michał
Król, Jan J.
Powiązania:
https://bibliotekanauki.pl/articles/1836253.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Chondrichthyes
Actinopterygii
Reptilia
fossil vertebrate
tempestite
coprolite
Middle Triassic
Opis:
Middle Triassic (Muschelkalk) limestones and dolostones of southern Poland contain vertebrate remains, which can be used for palaeoecological and palaeogeographical analyses. The results presented concern vertebrate remains uncovered at four localities in Upper Silesia and one on Opole Silesia, a region representing the south-eastern margin of the Germanic Basin in Middle Triassic times. The most abundant remains in this assemblage are fish remains, comprising mostly actinopterygian teeth and scales. Chondrichthyan and sauropsid remains are less common. Reptilian finds include vertebrae, teeth and fragments of long bones, belonging to aquatic or semi-aquatic reptiles, such as nothosaurids, pachypleusorosaurids, and ichthyosaurids. Also, coprolites of possibly durophagous and predacious reptiles occur. In the stratigraphic column of Mikołów, actinopterygian remains are the most numerous and no distinct changes of the taxonomic composition occur. Although this assemblage differs from those described at other localities (Ząbkowice with numerous chondrichthyans, Żyglin, and Płaza with common sauropsid fossils), sampling bias has to be considered.
Źródło:
Annales Societatis Geologorum Poloniae; 2020, 90, 4; 419-433
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New specimen of the rare requiem shark Eogaleus bolcensis from the Bolca Lagerstätte, Italy
Autorzy:
Conte, G.L.
Trevisani, E.
Guaschi, P.
Fanti, F.
Powiązania:
https://bibliotekanauki.pl/articles/2082229.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Chondrichthyes
Carcharhinidae
Triakidae
Eogaleus
Galeorhinus
Von Bertallanfy Growth Function
age classes
Eocene
Europe
Opis:
A rare carcharhinid specimen (slab and counter-slab, MSNPV 24625-24626) from the world-renowned Eocene Bolca locality was recently rediscovered during a restoration project started in 1989 by the Museo di Storia Naturale di Pavia. The individual, the largest Eogaleus bolcensis known from Bolca, is disarticulated and lies in a massive limestone matrix, suggesting its provenience from the Monte Postale site. While assessing its taxonomic status, multiple morphological affinities and ontogenetic trends within the Bolca Carcharhiniformes assemblage where documented. Eogaleus bolcensis is here distinguished from the school shark Galeorhinus cuvieri exclusively according to dermal denticle morphology, suggesting partial overlap of ecologic and trophic niches between the two species. Further, measurements and meristic counts taken on different traits of E. bolcensis (two individuals) and G. cuvieri (five individuals) specimens show high degree of similarities. The ratios “trunk length/total length” and “sum of vertebral centra (head region)/total length” of four complete individuals of the fossil assemblage were averaged and employed to estimates the total length of MSNPV 24625-24626. Here, the total length of MSNPV 24625-24626 is estimated in about 172.1±0.1 cm. The same approach is applied to MCSNV T.311 (E. bolcensis, holotype) and MNHN F.Bol.516 (G. cuvieri, holotype), two partially-preserved fossil individuals from Bolca locality. To support the ontogenetic variability among the Bolca shark assemblage, the age of the fossil individuals was estimated following the Von Bertalanffy Growth Function, using the modern chondrichthyans growth parameters as a reference. Data presented here suggest that all G. cuvieri specimens are juvenile individuals, whereas the E. bolcensis specimens were young-adult.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 3; 547-560
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A preliminary note of egg-case oviparity in a Devonian placoderm fish
Autorzy:
Carr, R. K.
Jackson, G.
Powiązania:
https://bibliotekanauki.pl/articles/139073.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Devonian
Famennian
Cleveland Shale
Ohio
USA
Placodermi
Arthrodira
oviparity
egg case
Chondrichthyes
dewon
famen
ryby pancerne
tarczowce
plakodermy
zawiasowce
jajorodność
ryby chrzęstnoszkieletowe
ryby chrzęstne
chrzęstniki
Opis:
Six enigmatic fossils from the Famennian (Devonian) Cleveland Shale in Ohio, U.S.A., are interpreted here as arthrodiran (Placodermi) egg cases. Recognition as egg cases is confirmed based on the observation of layered collagen fibers. The presence of a tuberculated bone fragment preserved within one case confirms a vertebrate source. The nature of the tubercles and the unique morphology of the egg cases supports the interpretation of an arthrodiran source. Reports of Devonian egg cases are limited to either assumed chondrichthyan producers or a putative ‘egg sac’ with a morphology atypical for any vertebrate. The Cleveland Shale egg cases thus represent the first record for a non-chondrichthyan producer. Among placoderms, behaviors of a pelagic life style with obligate nesting sites, reef fishes with live birth, and estuarine and fluvial nurseries, along with eggcase oviparity testifies to the diversity of reproductive strategies. As with modern fishes these strategies may be ecologically driven and the derived and variable reproductive biology of extant chondrichthyans is actually a primitive condition among gnathostomes. One consequence of the diversity of reproductive strategies (dependent on the topology of relationships) is the independent origin of internal fertilization within placoderms, possibly suggesting external fertilization as the primitive gnathostome reproductive mode.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 381-389
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A revision of Campyloprion Eastman, 1902 (Chondrichthyes, Helicoprionidae), including new occurrences from the Upper Pennsylvanian of New Mexico and Texas, USA
Autorzy:
Itano, W. M.
Lucas, S. G.
Powiązania:
https://bibliotekanauki.pl/articles/139067.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carboniferous
permian
eugeneodontiformes
helicoprionidae
edestoidea
Chondrichthyes
geometric morphometrics
karbon
perm
ryby chrzęstnoszkieletowe
ryby chrzęstne
chrzęstniki
morfometria geometryczna
Opis:
Campyloprion Eastman, 1902 is a chondrichthyan having an arched symphyseal tooth whorl similar to that of Helicoprion Karpinsky, 1899, but less tightly coiled. The holotype of Campyloprion annectans Eastman, 1902, the type species of Campyloprion, is of unknown provenance, but is presumed to be from the Pennsylvanian of North America. Campyloprion ivanovi (Karpinsky, 1922) has been described from the Gzhelian of Russia. A partial symphyseal tooth whorl, designated as Campyloprion cf. C. ivanovi, is reported from the Missourian Tinajas Member of the Atrasado Formation of Socorro County, New Mexico, USA. Partial tooth whorls from the Virgilian Finis Shale and Jacksboro Limestone Members of the Graham Formation of northern Texas, USA, are designated as Campyloprion sp. Two partial tooth whorls from the Gzhelian of Russia that were previously referred to C. ivanovi are designated as Campyloprion cf. C. annectans. The age of Toxoprion lecontei (Dean, 1898), from Nevada, USA, is corrected from the Carboniferous to the early Permian. An alternative interpretation of the holotype of T. lecontei is presented, resulting in a reversal of its anterior-to-posterior orientation. The genera Helicoprion, Campyloprion, and Shaktauites Tchuvashov, 2001 can be distinguished by their different spiral angles.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 403-419
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First record of the deep-water shark Etmopterus spinax (Chondrichthyes: Etmopteridae) from the Southern Baltic Sea (Pomeranian Bay)
Autorzy:
Wiecaszek, B.
Sobecka, E.
Panicz, R.
Keszka, S.
Gorecka, K.
Linowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/48454.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Etmopterus spinax
deep-water shark
Anisakis simplex
Chondrichthyes
Etmopteridae
Pomeranian Bay
Baltic Sea
Źródło:
Oceanologia; 2018, 60, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Orthacanthus platypternus (Cope, 1883) (Chondrichthyes: Xenacanthiformes) teeth and other isolated vertebrate remains from a single horizon in the early Permian (Artinskian) Craddock Bonebed, lower Clear Fork Group, Baylor County, Texas, USA
Autorzy:
Johnson, G. D.
Powiązania:
https://bibliotekanauki.pl/articles/138953.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Orthacanthus platypternus
early Permian
Craddock Bonebed
Texas
ryby chrzęstnoszkieletowe
ryby chrzęstne
chrzęstniki
Chondrichthyes
wczesny perm
Teksas
Opis:
An unusual 6–8 cm layer of prismatic cartilage and matrix containing some 8,800 teeth, coprolites, incomplete occipital spines, and denticles of Orthacanthus platypternus (Cope, 1883) occurs in the lower Permian (Artinskian) Craddock Bonebed in Texas, USA. It is the only species of shark present in the Clear Fork Group except for three worn Xenacanthus Beyrich, 1848 occipital spine fragments and two teeth of ?Lissodus (Polyacrodus) zideki (Johnson, 1981) (Hybodontoidei), both being the first occurrences in this unit. Analysis of measurements of teeth with complete bases randomly selected from 3,050 initially available teeth failed to reveal the presence of sexual dimorphism or the discrete presence of juveniles as expected, based on an independent study which identified the presence of Orthacanthus juvenile occipital spines. A few highly symmetrical small teeth are present, which had not been previously observed in the Texas lower Permian. They may be symphyseals and restricted only to juveniles. Other unusual teeth include germinal teeth and deformed teeth, both of which occur in the Clear Fork and underlying Wichita groups. One tooth displays an apparent example of the equivalent of an “enamel pearl” on one of its cusps. The most unusual teeth are those that appear to have undergone various stages of resorption. Only the lingual margin of the base is affected in which the apical button is resorbed to varying degrees until only the labial margin with the basal tubercle and the three cusps are all that remain. If the teeth were undergoing resorption, then the perplexing problem is why the apical button is resorbed and not the superjacent basal tubercle. Other vertebrate remains include palaeoniscoid scales and teeth and unidentified tetrapod bone fragments, jaw fragments, and teeth. Rare fragments of bones (scales?) bear a “comb edge” which have not been previously observed in the Texas lower Permian.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 421-436
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A classic Late Frasnian (Devonian) chondrichthyan assemblage from southern Belgium
Autorzy:
Ginter, M.
Gouwy, S.
Goolaerts, S.
Powiązania:
https://bibliotekanauki.pl/articles/138985.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Late Devonian
Belgium
Dinant Synclinorium
chondrichthyes
microfossils
późny dewon
Belgia
ryby chrzęstnoszkieletowe
mikroskamieniałości
Opis:
Samples from the Upper Frasnian (Devonian) of Lompret Quarry and Nismes railway section in Dinant Synclinorium, southern Belgium, yielded several chondrichthyan teeth and scales. The teeth belong to three genera: Phoebodus, Cladodoides and Protacrodus. The comparison with selected Late Frasnian chondrichthyan assemblages from the seas between Laurussia and Gondwana revealed substantial local differences of taxonomic composition due to palaeoenvironmental conditions, such as depth, distance to submarine platforms, oxygenation of water, and possibly also temperature. The assemblage from Belgium, with its high frequency of phoebodonts, is the most similar to that from the Ryauzyak section, South Urals, Russia, and the Horse Spring section, Canning Basin, Australia.
Źródło:
Acta Geologica Polonica; 2017, 67, 3; 381-392
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new euselachian shark from the early Permian of the Middle Urals, Russia
Autorzy:
IVANOV, ALEXANDER O.
DUFFIN, CHRISTOPHER J.
NAUGOLNYKH, SERGE V.
Powiązania:
https://bibliotekanauki.pl/articles/945229.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
chondrichthyes
elasmobranchii
teeth
permian
russia
urals
Opis:
The isolated teeth of a new euselachian shark Artiodus prominens Ivanov and Duffin gen. et sp. nov. have been found in the Artinskian Stage (Early Permian) of Krasnoufimskie Klyuchiki quarry (Sverdlovsk Region, Middle Urals, Russia). The teeth of Artiodus possess a multicuspid orthodont crown with from four to nine triangular cusps; prominent labial projection terminating in a large round tubercle; distinct ornamentation from straight or recurved cristae; oval or semilunar, elongate, considerably vascularized base; dense vascular network formed of transverse horizontal, ascending, short secondary and semicircular canals. The teeth of the new taxon otherwise most closely resemble the teeth of some protacrodontid and sphenacanthid euselachians possessing a protacrodont-type crown, but differ from the teeth of all other known euselachians in the unique structure of the labial projection. The studied teeth vary in crown and base morphology, and three tooth morphotypes can be distinguished in the collection reflecting a moderate degree of linear gradient monognathic heterodonty. The range of morphologies otherwise displayed by the collection of teeth shows the greatest similarity to that described for the dentitions of relatively high-crowned hybodontids from the Mesozoic. The internal structure of the teeth, including their vascularization system is reconstructed using microtomography. The highest chondrichthyan taxonomic diversity is found in the Artinskian, especially from the localities of the Middle and South Urals.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 2; 290-298
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the Western Desert of Egypt
Autorzy:
VAN VLIET, HENDRIK JAN
SCHULP, ANNE S.
ABU EL-KHEIR, GEBELY A.M.M.
PAIJMANS, THEO M.
BOSSELAERS, MARK
UNDERWOOD, CHARLES J.
Powiązania:
https://bibliotekanauki.pl/articles/945646.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
palaeomastodontidae
hyracoidea
anthracotheriidae
chondrichthyes
oligocene
egypt
Opis:
A new fossil site at Minqar Tibaghbagh, east of Siwa, in the Egyptian Western Desert is described. This represents the first place in Egypt outside the Fayum Depression yielding Paleogene, terrestrial mammals. Initial studies indicate the presence of palaeomastodonts, hyracoids, and anthracotheres, presumably early Oligocene in age. As only surface prospecting has been performed, more taxa will almost certainly be discovered in future investigations here and probably also elsewhere in the surroundings. A comparison is made with the most important contemporaneous sites in Libya and Egypt that yield terrestrial mammal remains. The selachian fauna from a higher level in the section confirms the Paleogene age of the subjacent strata. It is compared with selachians faunas from the early Oligocene Eastern Tethys Ocean at other places (the Fayum Depression in Egypt, and sites in Oman and Pakistan), and differs from these sites in being fully marine. Contrary to earlier studies, the open marine mudstones of the Daba’a Formation at Minqar Tibaghbagh are overlain by Paleogene marine sediments of most probably early Oligocene age and not early Miocene marine sediments as previously reported. These strata represent not only a new site with great potential for future finds, but also allows for biostratigraphic correlation.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 3; 509-525
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphology and histology of dorsal spines of the xenacanthid shark Orthacanthus platypternus from the Lower Permian of Texas, USA: palaeobiological and palaeoenvironmental implications
Autorzy:
Beck, K.G.
Soler-Gijon, R.
Carlucci, J.R.
Willis, R.E.
Powiązania:
https://bibliotekanauki.pl/articles/21629.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
morphology
histology
dorsal spine
xenacanthid shark
shark
Orthacanthus platypterus
Chondrichthyes
Xenacanthiformes
Lower Permian
Texas
USA
paleobiology
paleoenvironment
Opis:
Detailed studies on Carboniferous species of the xenacanth Orthacanthus have shown that the xenacanth dorsal fin spine can be used for skeletochronological analyses and provides valuable information about development, growth and environmental life conditions of those extinct sharks. We report here for the first time the histology and skeletochronology of Permian specimens, dorsal spines of Orthacanthus platypternus from the Craddock Bone Bed (lower Clear Fork Formation; Early Permian, Leonardian age) of northern Baylor County (north-central Texas, USA). Twelve dorsal spines of O. platypternus preserve a highly vascularized wall mainly composed of centrifugally growing dentine in a succession of dentine layers, probably deposited with an annual periodicity. As expected, spines of individuals with 1–2 dentine layers, presumably juveniles, present the smallest sizes. However, spines of individuals showing at least 3–4 dentine layers and interpreted to be subadults/young adults, are distributed in two spine-size clusters corresponding to females (probably the largest spines) and males, in agreement with the hypothesis of sexual size dimorphism proposed in a previous biometric analysis. Our comparative study of O. platypternus and the Stephanian species O. meridionalis further suggests that spine denticulation can be useful for distinguishing between species of Orthacanthus and sexually dimorphic forms (juvenile to adults) in each species. Total body length estimations of O. platypternus from the Craddock Bone Bed point to relatively large juveniles and small subadults/young adults (less than 2 m in total length), living as opportunistic predators in the pond-channel coastal plain environments represented by the bone bed deposits. The comparative analyses of the ontogenetic stages of the recorded specimens of O. platypternus and their distribution along different facies and localities indicate that this species was euryhaline, diadromous with a catadromous life-cycle which was strongly regulated by the semi-arid, seasonally dry tropical climate affecting western Pangaea during the Early Permian.
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 35

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