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Wyświetlanie 1-15 z 53
Tytuł:
Dinosaurs and scientific inquiry
Autorzy:
Barta, D.E.
Powiązania:
https://bibliotekanauki.pl/articles/2082339.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 436
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ultrastructure of some Ordovician graptoloid prosiculae
Autorzy:
Bates, D E B
Powiązania:
https://bibliotekanauki.pl/articles/22160.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
szkielet promienisty
ordowik
skamienialosci
graptolity
paleontologia
formacje skalne
rabdozomy
ultrastruktura
wapienie
Geniculograptus typicalis
prosicule
Opis:
The graptoloid prosicula (conus and cauda) forms the first part of the growing colony, and was probably secreted during a single continuous episode of growth. The wall is composed of a central unit of criss-cross fibrils (fusellar fabric), interlaced with parallel fibrils whose grouping appears as the spiral line (spiral line fabric). The conus is lined with a granular or felted sheet (sheet fabric). The diaphragm, at the apex of the conus, appears to be formed of fusellar fabric. The cauda is formed of fusellar and spiral fabrics with a central cavity apparently not open to the conus interior. An outer layer (diamond, mesh fabric) of fibrils forming a diamond mesh covers both conus and cauda, and is itself overlain by longitudinal rods. The apex of the cauda is formed of a second domed diaphragm of criss-cross fibrils, covered by a sheet fabric. The nema is extended distally as a series of finger-shaped increments, overlain by bandages. An outermost layer of clustered fibrils (stellate fabric) is occasionally present, lying on, or formed by a modification of, the diamond mesh fibrils of the conus.
Prosicula graptolitów jest najwcześniej tworzoną częscią rabdozomu i była najprawdopodobniej budowana przez pierwszego zooida tuż po jego metamorfozie ze swobodnie żyjącej larwy. Przedmiotem niniejszej pracy jest ultrastruktura prosicul z późnoordowickiego wapienia Viola Springs. Prosicule z tej formacji skalnej zapewne należą do dwuseryjnych grapiolitów, których najpospolitszym występującym tam gatunkiem jest Geniulograptus typicalis. Na przełamach ścianek prosiculi obserwowanych w skaningowym mikroskopie elektronowym ukazuje się ich trójwarstwowa budowa, z wysciółką wewnątrz o nieregularnie orientowanych włóknach, środkową ścianą z wplecionymi włóknami tworzącymi linię spiralną oraz zewnętrzną warstwą o włóknach krzyżujących się w rombowy splot. Środkowa warstwa ściany tworzona była zapewne w jednorazowym akcie sekrecji ale jej struktura nie różni się istotnie od fuzellarnych elementów rabdozomu. Nema powstawała jako seria palcowatych przyrostów okrytych przez bandaże; jej wnętrze jest lite, nie pozostawia miejsca na jakiekolwiek miękkie tkanki.
Źródło:
Acta Palaeontologica Polonica; 1996, 41, 1; 39-57
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Revisiting Sabaths "Larger Avian Eggs" from the Gobi Cretaceous
Autorzy:
Varricchio, D.J.
Barta, D.E.
Powiązania:
https://bibliotekanauki.pl/articles/945499.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Aves
Enantiornithes
ootype
bird
animal reproduction
egg
Cretaceous
Mongolia
Opis:
In 1991, Sabath described “larger avian eggs” from the Upper Cretaceous Barun Goyot and Djadokhta Formations of Mongolia. These were later included in the ootaxon Gobioolithus major. Here we recognize the larger avian eggs of Sabath as a distinct ootaxon, Styloolithus sabathi, oogen. et oosp. nov. These eggs differ from those of Gobioolithus in being larger (70 by 32 mm) and more elongate. Microscopically, the shell bears a third layer (possible external zone) thicker than the mammillary layer and nearly as thick as the second layer (possible squamatic zone); the continuous layer (including layers two and three) to mammillary layer thickness ratio is 3.1:1. Within the clutch, the tightly spaced eggs stand with their long axes steeply inclined. Adult remains are associated with two clutches, suggesting an incubation mode similar to that of troodontid maniraptorans, where adults sat atop largely buried eggs. S. sabathi provides evidence that relative egg size in Mesozoic non-ornithuromorph birds had increased markedly from the non-avian theropod condition in oviraptorids and troodontids, but had not yet reached the modern egg-adult proportions of Neornithes. Sediment-bound upright eggs appear common to Enantiornithes and more basal avians, suggesting that like non-avian theropods, these birds lacked chalazae, the chords of albumen allowing egg rotation in modern birds. Absence of this simple structure may have restricted these basal birds to ground nesting in areas with appropriate substrates and not permitted the type of nesting diversity found in Neornithes. Neornithes are the only Mesozoic clade of Dinosauria to nest completely free of sediment; this may have played a crucial role in their surviving the K-Pg mass extinction event.
Źródło:
Acta Palaeontologica Polonica; 2015, 60, 1; 11-25
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New albanerpetontid amphibians from the Early Cretaceous of Morocco and Middle Jurassic of England
Autorzy:
Gardner, J D
Evans, S.E.
Sigogneau-Russell, D.
Powiązania:
https://bibliotekanauki.pl/articles/21595.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Early Cretaceous
Middle Jurassic
Cretaceous
England
Albanerpetontidae
amphibian
albanerpetontid amphibian
Ramonellus
Morocco
Jurassic
paleontology
Lissamphibia
Opis:
A third albanerpetontid genus, Anoualerpeton gen. nov., is erected for two new species: An. unicussp. nov. (type species) from the Early Cretaceous (Berriasian) of Morocco and An. priscus sp. nov. from the Middle Jurassic (late Bathonian) of England. Anoualerpeton differs from the exclusively Laurasian albanerpetontid genera Albanerpeton (Early Cretaceous– Paleocene, North America; Miocene, Europe) and Celtedens (?Late Jurassic and Early Cretaceous, Europe) in a unique combination of primitive and derived character states of the jaws and azygous frontals. Monophyly of Anoualerpeton is supported by two synapomorphies of the maxilla and dentary (occlusal margin convex in labial outline and teeth strongly heterodont in size anteriorly) that are convergent with an unrelated, relatively derived Late Cretaceous species of Albanerpeton from North America. The two species of Anoualerpeton differ in character states of the premaxilla and azygous frontals. Cladistic analysis of 20 characters scored for ten albanerpetontid taxa postulates Anoualerpeton as the sister−taxon of Albanerpeton + Celtedens. The sister−pair of Albanerpeton + Celtedensis founded on one or, perhaps, two premaxillary synapomorphies. Anoualerpeton unicus documents the only known Gondwanan occurrence for the Albanerpetontidae and provides a minimum age of basal Cretaceous for the establishment of the clade in Africa. Characters of the mandible, vertebrae, and limbs support the interpretation that Ramonellus (Aptian; Israel) is a caudate, not an albanerpetontid.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics
Autorzy:
Snively, E.
Henderson, D.M.
Phillips, D.S.
Powiązania:
https://bibliotekanauki.pl/articles/21688.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carnosauria
computer tomography
Theropoda
Tyrannosauridae
biomechanics
computer modelling
dinosaur
feeding mechanism
paleontology
theropod dinosaur
tyrannosaurid dinosaur
cranial strength
Opis:
Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross−sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis. Cross−sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric exponents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exceptionally well-preserved Orsten-type phosphatocopid crustaceans from the Cambrian of Poland
Autorzy:
Olempska, E.
Maas, A.
Waloszek, D.
Eriksson, M.E.
Powiązania:
https://bibliotekanauki.pl/articles/20099.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Phosphatocopids are a group of small extinct marine crustaceans, which occur widespread in Cambrian dysoxic benthic lithofacies. Whereas the anatomy of the earliest ontogenetic stages of phosphatocopids, from the head larva with four pairs of appendages onward, is well documented, that of more advanced or adult growth stages has remained almost unknown (except for the external shields). Here we describe a three-dimensionally preserved specimen of a late growth stage of Cyclotron angelini from the Furongian strata (~490 Ma) of northern Poland, which possesses six pairs of appendages (2nd–7th pairs; antennula missing), much of setation, sternum with paragnath humps, and the trunk end with the putative anus. Based on comparisons with known phosphatocopids, the cephalic feeding system of this late larva comprises the antennae with their gnathobase-like median structures on their syncoxa and the mandible with a likewise strong but oblique gnathic coxal endite. Both appendages have a short, specialized endopod bearing a prominent, dentate, stout median spine on its proximal portion. The antennulae are missing but, as in other phosphatocopids, they are not expected to have contributed to the feeding and locomotory system like they do in crustacean stem-lineage representatives and the Eucrustacea, especially in the early larval phase. The lack of an antennal exopod and strong reduction in size of the mandibular exopod of C. angelini suggest that these appendages had lost their function as locomotory and sweeping devices, in contrast to other phosphatocopids (and eucrustaceans). Therefore, they may have served mainly for food gathering in the vicinity of the mouth, which may represent an autapomorphy of this phosphatocopid species. Furthermore, in this developmental stage of C. angelini the production of water currents and movement of food particles toward the median food path was likely achieved by the large, paddle-shaped setiferous exopods of the serially developed post-mandibular limbs. For comparisons, we studied additional phosphatocopid specimens from the Dębki 2 borehole belonging to other taxa and representing different ontogenetic stages. This is also the first report of exceptionally preserved cuticular apodemes in phosphatocopids, extending internally and still bearing partly preserved, putative muscle bundles. As known from extant eucrustaceans, these apodemes most likely served as attachment sites for appendage muscles.
Źródło:
Acta Palaeontologica Polonica; 2019, 64, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisodontherium from the Late Miocene of north-western Argentina
Autorzy:
Brandoni, D.
Powell, J.E.
Gonzales, O.E.
Powiązania:
https://bibliotekanauki.pl/articles/20115.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Anisodontherium
Late Miocene
Miocene
paleontology
Argentina
Xenarthra
Megatheriinae
ground sloth
diversity
Upper Miocene
Opis:
The fossil record of Megatheriinae (Tardigrada, Megatheriidae) in Argentina extends from the Colloncuran (Middle Miocene of Patagonia) to the Lujanian (Late Pleistocene–Early Holocene of the Pampean region). In the Late Miocene of north−western Argentina, Megatheriinae is represented by just three species belonging to a single genus, Pyramiodontherium. Here, we describe a partial mandible and the phalanges of a third digit of the manus recovered from the Saladillo Formation (Upper Miocene) of Tucumán Province, and assign them to Anisodontherium sp. Anisodontherium is primarily characterized by mesiodistally compressed molariforms, an anterior margin of the coronoid process located posterior to m4, and a posterior margin of the mandibular symphysis located anterior to m1. While these features can also be observed in A. halmyronomum from the Arroyo Chasicó Formation (Buenos Aires Province, Pampean region), Anisodontherium sp. is smaller and more slender than the former. The shape of each molariform of Anisodontherium affects the total length of the molariform tooth row, and thus the interpretation of some characters used in cladistic and paleobiological analyses. The material described here adds to the knowledge of the mandibular and dental anatomy of early megatheriines. In addition, the occurrence of Anisodotherium in Tucumán Province provides the first record of this genus outside the Pampean region, and increases the diversity of megatheriines during the Late Miocene–Pliocene of north−western Argentina.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New information on scavenging and selective feeding behaviour of tyrannosaurids
Autorzy:
Hone, D.W.E.
Watabe, M.
Powiązania:
https://bibliotekanauki.pl/articles/20999.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
new information
scavenging
feeding behaviour
tyrannosaurid
Dinosauria
Theropoda
Tarbosaurus
paleoecology
carnivore
predation
fossil record
Opis:
Feeding traces for carnivorous theropod dinosaurs are typically rare but can provide important evidence of prey choice and mode of feeding. Here we report a humerus of the hadrosaurine Saurolophus which was heavily damaged from feeding attributed to the giant tyrannosaurine Tarbosaurus. The bone shows multiple bites made in three distinctive styles termed “punctures”, “drag marks” and “bite−and−drag marks”. The distribution of these bites suggest that the animal was actively selecting which biting style to use based on which part of the bone was being engaged. The lack of damage to the rest of the otherwise complete and articulated hadrosaur strongly implies that this was a scavenging event, the first reported for a tyrannosaurid, and not feeding at a kill site.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ultrastructure, development, and systematic position of the graptolite genus Mastigograptus
Autorzy:
Bates, D E B
Urbanek, A.
Powiązania:
https://bibliotekanauki.pl/articles/21265.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Graptolithina
internal structure
graptolite
development
remains
Pterobranchia
taxonomy
systematic position
stratigraphy
Mastigograptus
Ordovician
ultrastructure
paleontology
Opis:
Fragments of rhabdosomes isolated by chemical treatment from an erratic boulder of Baltic origin and ?Middle Ordovician age, provisionally assigned to Mastigograptus aff. tenuiramosus (Wallcott, 1881) were studied with SEM. Although exceptionally well preserved, remains lack the thin−walled free portions of thecae. Rhabdosomes are provided with a strongly developed basal disc, short stem and many branched stipes. The latter consist of heavily corticalized chains of stolothecae with alternately disposed thecal bases. Stolothecae display a morphological gradient and increase in size and change in shape distalwards. The stolon system studied with SEM on naturally and artificially broken specimens, as well as traced through open thecal bases, reveals a regular triad budding but no stolon inside the stolothecal cavity. We tentatively suggest that crassal lining, recognized earlier by TEM studies, corresponds to an unusually inflated stolonal stolon, filling the entire thecal cavity and adhering tightly to stolothecal wall. The systematic position of Mastigograptus, a matter of long debate, seems to be defined by a number of structural features which imply a distinct difference between genus in question and all known orders of sessile graptolites. The order Mastigograptida nov. and the family Mastigograptidae nov. are proposed.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acanthodian fish trace fossils from the Early Devonian of Spitsbergen
Autorzy:
Wisshak, M
Volohonsky, E.
Blomeier, D.
Powiązania:
https://bibliotekanauki.pl/articles/21739.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
fish trail
trace fossil
Old Red Sandstone
fossil
Devonian
Acanthodii
Undichna
Spitsbergen
paleontology
Svalbard
Opis:
We describe and interpret Undichna septemsulcata isp. nov., from the fluvial Old Red Sandstone deposits of the Early Devonian Wood Bay Formation, of Northern Spitsbergen (Svalbard). Its delicate scratch pattern, comprising one unpaired median groove and three pairs of lateral grooves, all with a regular in−phase sinusoidal wave pattern of equal wavelength, allow the reconstruction of the number, position and relative spacing of the fins. The comparatively high−amplitude median groove is attributed to the main propelling action of the tail or caudal fin, the inner pair of the lateral grooves to the action of the pelvic fins, and the low−amplitude outer set of duplicate grooves to bifurcated pectoral fins, respectively. The in−phase geometric pattern is explained by a distance between the unpaired fin (caudal or anal fin) to the pectoral fins corresponding to one wavelength and a position of the pelvic fins half way in between. The direction of movement and the mode of locomotion of the trace maker (a carangiform to ostraciiform type) are deduced. This analysis is leading to an acanthodian (possibly Diplacanthus) as the most probable trace maker. By being Pragian or early Emsian (Early Devonian) in age, according to vertebrate and palynomorph biostratigraphy, these specimens are among the world’s oldest trace fossils made by a vertebrate.
Źródło:
Acta Palaeontologica Polonica; 2004, 49, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kirkigraptus, a new retiolitid graptolite from Poland
Autorzy:
Kozlowska, A
Bates, D.E.B.
Powiązania:
https://bibliotekanauki.pl/articles/21786.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
deposit
Polska
systematics
paleontology
Silurian
Kirkigraptus inexpectans
retiolitid skeleton
Retiolitidae
graptolite
Graptolithina
retiolitid graptolite
new species
new aspect
East European Platform
evolution
Opis:
The new retiolitid graptolite Kirkigraptus inexpectans gen. et sp. nov., from the Neodiversograptus nilssoni Biozone of the Bartoszyce borehole, Poland is described. It is unique among the retiolitids not having a preserved virgella or ancora. Instead the most proximal structures are two round proxi−lateral lists, joining the two genicular lists of the first thecae, connecting the two sides of the rhabdosome. The lists are interpreted as a possible homologue of the distal edge of the ancora umbrella in typical retiolitids. The size of rhabdosome with large proximal lateral orifices, and the ventral panels of thecae with mid−ventral lists, are similar to those of Plectograptus, whereas the two ancora sleeve panels consisting of spaced horizontal lists only, resemble those of Valentinagraptus. It is possible that the new retiolitid may represent a new pattern of development of the proximal end of the rhabdosome, different from that in all other retiolitids.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tapirs from the Pleistocene of Venezuela
Autorzy:
Holanda, E.C.
Rincon, A.D.
Powiązania:
https://bibliotekanauki.pl/articles/20061.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
tapir
Tapirus terrestris
Pleistocene
Venezuela
Mammalia
Perissodactyla
Tapirus
El Breal de Orocual
Zumbador Cave
locality
paleontology
remains
systematics
tooth
measurement
morphometric analysis
Opis:
The living tapir Tapirus terrestrisis widely distributed in Venezuela, occurring mainly south of the Orinoco, while being absent from arid, high Andean and insular areas. Here, we describe new material of fossil tapirs from two Pleistocene localities of Venezuela: Zumbador Cave and El Breal de Orocual. Based on its size and morphology, the material from Zumbador Cave (skull, mandible and postcrania) is assigned to the extant T. terrestris, and represents the most northwestern fossil record of this species in South America. By contrast, the remains from the tar seep of El Breal de Orocual are more gracile, and differ from T. terrestris and other fossil and living species from South America in the presence of a metastylid on the lower cheek teeth. We tentatively assign the latter remains to Tapirussp., based on juvenile and isolated dentary material. However, the possibility that these specimens may represent a new species or an immigrant from North America cannot be completely excluded.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The curvature-transition series: integral part of some simple-cone conodont apparratuses (Panderodontacea, Distacodontacea, Conodontata)
Szeregi przemian zagięcia jako integralne części pewnych pierwotnych aparatów konodontowych (Panderodontacea, Distacodontacea, Conodontata)
Autorzy:
Fahraeus, L.E.
Hunter, D.R.
Powiązania:
https://bibliotekanauki.pl/articles/20595.pdf
Data publikacji:
1985
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Elements of species of Drepanoistodus Lindström, Panderodus Ethington, and Protopanderodus Lindström systematically vary from symmetrical to pronouncedly asymmetrical (symmetry-transition series) within each species, and a group of elements with systematic increase in curvature of the cusp can be recognized for each element type; each such group is named a curvature-transition series. Panderodus and Protopanderodus, both of the Panderodontacea, have essentially identical apparatuses with regard to symmetry and curvature-transition series whereas Drepanoistodus, of the Distacodontacea, differs in type of symmetry-transition series and number of curvature-transition series. The curvature-transition series is considered to represent a taxonomically distinct character at the suprageneric level.
W zespołach elementów każdego z gatunków konodontów z rodzajów Drepanoistodus Lindström, Panderodus Ethington i Protopanderodus Lindström objawia się zmienność stopnia asymetrii elementów i stopnia zagięcia ich zębów. W obrębie szeregów przemian symetrii (symmetry-transition series) identyfikuje się odrębne typy elementów, symetryczne i asymetryczne — o rosnącym stopniu asymetrii. Proponujemy wprowadzenie nowego pojęcia szeregów przemian zagięcia (curvature-transition series) obejmujących formy elementów o wzrastającym stopniu zagięcia zęba w obrębie każdego z członów szeregu przemian symetrii. Spośród rozpatrywanych rodzajów, rodzaje Panderodus i Protopanderodus (obydwa z nadrodziny Panderodontacea) obejmują aparaty o zasadniczo podobnych szeregach przemian symetrii i zagięcia, podczas kiedy Drepanoistodus (Distacodontacea) ma odmienny typ szeregu przemian symetrii i inną liczbę szeregów przemian zagięcia. Uważamy szeregi przemian zagięcia za odrębny rodzaj charakterystyki taksonomicznej jednostek rangi ponadrodzajowej.
Źródło:
Acta Palaeontologica Polonica; 1985, 30, 3-4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silurian synziphosurine horseshoe crab Pasternakevia revisited
Autorzy:
Krzeminski, W.
Krzeminska, E.
Wojciechowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/20993.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Silurian
horseshoe crab
arthropod
Pasternakevia
paleontology
Arthropoda
Xiphosura
Bunodidae
phylogenesis
Ukraine
stratigraphy
Opis:
The synziphosurine horseshoe crab Pasternakevia was until now known only from a single specimen. Herein we describe three new specimens from the outcrop close to the type locality of monotypic P. podolica that show several features that were unknown or only assumed in this genus. These characters include: a smooth surface of the carapace; an opisthosoma composed of ten segments, the first one being a microtergite (strongly reduced first opisthosomal segment usually hidden under the carapace), two or three last segments fused into a metasoma, and the telson. Pasternakevia is included in Bunodidae due to a hypertrophied tergite 2, but it is linked to the Pseudoniscidae by the shape of the opisthosoma.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The extent of the pterosaur flight membrane
Autorzy:
Elgin, R.
Hone, D.
Frey, E.
Powiązania:
https://bibliotekanauki.pl/articles/23515.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Reptilia
Pterosauria
flight
wing
Mesozoic
pterosaur
wing membrane
fossil
Opis:
The shape and extent of the membranous brachioptagium in pterosaurs remains a controversial topic for those attempting to determine the aerodynamic performance of the first vertebrate fliers. Various arguments in favour of the trailing edge terminating against either the torso or hip, the femur, the ankle, or different locations for various taxa, has resulted in several published reconstructions. Uncertainty over the correct model is detrimental to both aerodynamic and palaeoecological studies that are forced to simultaneously consider multiple and highly variable configurations for individual taxa. A review of relevant pterosaur specimens with preserved soft tissues or impressions of the wing membrane, however, strongly suggests that the trailing edge of the wing extended down to the lower leg or ankle in all specimens where the brachiopatagium is completely preserved. This configuration is seen across a phylogenetically broad range of pterosaurs and is thus likely to have been universally present throughout the Pterosauria. Support for opposing hypotheses where the trailing edge terminates against the body, hip, or knee are based on several specimens where the wing membrane is either incomplete or has undergone post−mortem contraction. An ankle attachment does not rule out a high aspect ratio wing as the curvature of the trailing edge and the ratio of the fore to hind limbs also play a major role in determining the final shape of the membrane.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 53

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