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Wyświetlanie 1-13 z 13
Tytuł:
Relationships between dimensionless models of ammonoid shell morphology
Autorzy:
Parent, H.
Bejas, M.
Greco, A.
Hammer, O.
Powiązania:
https://bibliotekanauki.pl/articles/22303.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
relationship
dimensionless model
ammonoid
shell morphology
ADA model
Opis:
In morphological studies the shape may be conveniently quantified by relative dimensions or dimensionless quantities. The analyses of shell morphology and morphospace occupation have been historically approached mainly by means of statistical analysis on classical dimensions (distance measurements: diameter, umbilical width, whorl width, whorl height and apertural whorl height), the Raup’s coiling and expansion rate parameters and, more recently, by means of the ADA−model which conjugates the classical variables in a single simple equation. Relationships between these studies should be possible based on mathematical equivalences between classical dimensions and those of coiling and expansion rates. These equivalences, which are presented in this paper, have been obtained on the basis of the ADA−model and a new general method for deriving dimensionless models of morphology based on exponential trajectories as a function of a rotational angle.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New evidence on brain-endocranial cavity relationships in ornithischian dinosaurs
Autorzy:
Evans, D C
Powiązania:
https://bibliotekanauki.pl/articles/23142.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
relationship
brain
endocranial cavity
Cretaceous
Dinosauria
ornithischian dinosaur
Hadrosauridae
dinosaur
Pachycephalosauridae
paleontology
Opis:
Discussions of brain morphology and relative brain size in nonavian dinosaurs have been complicated by uncertainty in the extent to which the brain filled the endocranial cavity. Recently reported vascular imprints (valleculae) on the endocranial surfaces of the braincase suggest that nonavian maniraptoriform theropods had brains that tightly fit the endocranium. Similar impressions of the intracranial vascular system are reported here in two ornithischian clades, Hadrosauridae and Pachycephalosauridae. These structures are more widespread in dinosaurs than previously thought, and suggest that the brain closely fit the endocranium in some regions of the forebrain through hindbrain in several distantly related dinosaur groups.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New data on the anatomy and relationships of the Paleocene crocodylian Akanthosuchus langstoni
Autorzy:
Hill, R.V.
Lucas, S.G.
Powiązania:
https://bibliotekanauki.pl/articles/20775.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Akanthosuchus langstoni
Alligatoroidea
Crocodylia
holotype
Paleocene
anatomy
dwarfism
paleontology
phylogenetic relationship
phylogenetic analysis
Opis:
The phylogenetic relationships of the Paleocene crocodylian Akanthosuchus langstoni are assessed using published data matrices and morphological data from the holotype and referred specimens. Cladistic analyses indicate that Akanthosuchus is unequivocally nested within Alligatoroidea. Weak support from a majority rule consensus tree indicates that Akanthosuchus may be more closely allied with alligatorines than with caimanines, but in the strict consensus tree these relationships remain ambiguous. There is no evidence from phylogenetic analyses to support the hypothesis that Akanthosuchus represents the postcrania of the Paleocene crocodylians Navajosuchus or Ceratosuchus. Growth marks observed in histological sections of osteoderms of the holotype of Akanthosuchus langstoni indicate that it was at least eight years old at the time of death. Although the individual may not have been fully mature at the time of death, lineage dwarfism cannot be ruled out as a possible reason for its relatively small size.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size-shape relationships in the Mesozoic planispiral ammonites
Autorzy:
Parent, H.
Greco, A.F.
Bejas, M.
Powiązania:
https://bibliotekanauki.pl/articles/19942.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
size-shape relationship
Mesozoic
planispiral ammonite
ammonite
Ammonoidea
shell
Cephalopoda
paleontology
marine fossil
Opis:
Ammonites are of outstanding importance in dating events of the Mesozoic and in the study of mechanisms, modes and timing of evolutionary processes. These applications rely on a detailed understanding of their morphology and the modes of variation. It has been known for a long time that their shape is composed of a number of highly correlated features. A new model, called the ADA−model, is introduced for the study of shell morphology (size and shape). The new model is based on classic dimensions which are stable parameters throughout ontogeny, giving very close agreement between pre− dictions and actual observations. It was applied in the exploration of the morphospace occupied by the planispirally coiled and the regularly uncoiled Mesozoic Ammonoidea, based on two new reduced morphospaces introduced for the analysis. Results obtained expose close relationships between size and shape, and general patterns in the ammonite shell morphol− ogy and morphogenesis. (i) The relative apertural height of the whorl section relative to the diameter of the shell (H₂/D) is involved in definition of size and shape. (ii) This same dimension shows a strong tendency to be H₂/D = 0.3. (iii) There are some geometrically possible shell shapes (or morphotypes) which seem to have not been developed since they are not known in the current record. Assuming the known ranges of protoconch size and whorl number as constraints, the ADA−model strongly suggests that these morphotypes have not been developed for the too large or too small sizes the shells would have attained, well outside of the actual size range of the planispirally coiled Ammonoidea. (iv) The law of covariation is shown to be a general pattern within the planispiral ammonites which describes structured variation of the shell shape. (v) A large fraction of the non−structured variation seems originate in the lack of correlation between the rela− tive umbilical diameter and width of the whorl section.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New elmisaurine specimens from North America and their relationship to the Mongolian Elmisaurus rarus
Autorzy:
Funston, G.F.
Currie, P.J.
Burns, M.E.
Powiązania:
https://bibliotekanauki.pl/articles/22633.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new species
Elmisaurinae
Dinosauria
Oviraptorosauria
Caenagnathidae
Campanian
Maastrichtian
North America
relationship
Mongolia
Elmisaurus rarus
Opis:
New specimens from Canada confirm the presence of elmisaurines in North America and shed light on the relationship of Leptorhynchos elegans to Mongolian forms. These specimens have hindlimb elements previously unknown from elmisaurines in the Dinosaur Park Formation, including tibiae and pedal phalanges. Metatarsal anatomy is sufficiently different to merit a generic distinction from Elmisaurus rarus, and both can be distinguished from Caenagnathus collinsi and Chirostenotes pergracilis. Differences between these taxa include body size, degree of coossification of the tarsometatarsus, and development of cruciate ridges of the metatarsal III. Histological analysis confirms that these differences are not correlated with ontogenetic age of the specimens. The results support the informal separation of caenagnathids based on metatarsal structure, and allow comments on paleobiological differences between caenagnathids and oviraptorids.
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ostracods and facies of the Early and Middle Frasnian at Devils Gate in Nevada: Relationship to the Alamo Event
Autorzy:
Casier, J -G
Berra, I.
Olempska, E.
Sandberg, C.
Preat, A.
Powiązania:
https://bibliotekanauki.pl/articles/23394.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ostracod
Early Frasnian
Frasnian
Middle Frasnian
Nevada
relationship
Alamo Event
Ostracoda
conodont
sedimentology
paleoecology
Opis:
In order to document the Alamo Event and to investigate its influence on shallow−marine environments, we undertook a study of ostracods, conodonts, and analysis of the sedimentology of the lower member of the type Devils Gate Limestone. Six major carbonate microfacies (MF1–MF6) ranging from open−marine environments below storm wave base to pre−evaporitic supratidal lagoons were recognized. The sedimentological study detected no important sedimentological changes during the Alamo Event; only an influx of detrital material and lithoclasts indicate that an unusual event had occurred. Ostracods are generally rare or absent in the lower member of the Devils Gate Limestone, and only 2,000 carapaces, valves and fragments were extracted; from these some 26 taxa were identified. Two new species, Voronina? eureka and Serenida dorsoplicata are proposed. The ostracods belong to the Eifelian Mega−Assemblage and their distribution was influenced by strong salinity variations. Because of the rarity and low diversity of ostracods and conodonts in samples collected from the lower part of the lower member of the Devils Gate Limestone it is not adequate to demonstrate conclusively an extinction event close to the Alamo Event Bed. Nevertheless the greater abundance and diversity of ostracods above this bed seems to indicate that the Alamo Event did not result in significant extinction of ostracod taxa in this shallow water setting. The ostracod fauna present in the lower member of the Devils Gate Limestone suggests faunal exchanges between Nevada and the Russian Platform via the Western Canadian platform.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 4; 813-828
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relationships of the Malagasy fauna during the Late Cretaceous: Northern or Southern routes?
Autorzy:
Rage, J C
Powiązania:
https://bibliotekanauki.pl/articles/20436.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
vertebrate fauna
fauna
relationship
Cretaceous
Late Cretaceous
Madagascar
Africa
paleogeography
distribution
paleontology
South America
Opis:
Conjectures about the Cretaceous and post−Cretaceous vertebrate faunas of Madagascar are generally based on the fact that these faunas display similarities to those of South America, and that Africa lacks taxa that are common to Madagascar and South America. In order to account for this distribution, two ways of dispersal bypassing Africa have been proposed.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new capitosaur from the Middle Triassic of Spain and the relationships within the Capitosauria
Autorzy:
Fortuny, J.
Galobart, A.
de Santisteban, C.
Powiązania:
https://bibliotekanauki.pl/articles/21637.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
capitosaur
Middle Triassic
Triassic
Spain
relationship
Capitosauria
paleontology
Temnospondyli
Mastodonsauroidea
phylogenesis
computer tomographic scanning
Anisian
Opis:
Capitosaurs were the largest and homogeneous group of Triassic temnospondyl amphibians with cosmopolitan distribution. However, their interrelationships are debated. The first capitosaur cranial remains found in the Iberian Peninsula were assigned to Parotosuchus; herein, a re−description of this material, together with information on other remains recovered from the same site, enables us to classify them as a new genus: Calmasuchus acri gen. et sp. nov. (Amphibia: Temnospondyli) from the early−to−middle Anisian (early Middle Triassic). This capitosaur had a combination of plesiomorphic and non−plesiomorphic characters, such as posterolaterally directed tabular horns, paired anterior palatal vacuities, and unique morphology of the lower jaw. By cladistic analysis, we propose a new phylogeny for the monophyletic capitosaurs. In the analysis, Capitosauria is supported by seven synapomorphies. Wetlugasaurus is the most basal member of the clade. The score of the Russian taxon Vladlenosaurus alexeyevi resulted in a clade including Odenwaldia and the latter taxa. The Madagascarian Edingerella is the sister taxon of Watsonisuchus. Finally, Calmasuchus acri, the new taxon described here, appears as a more derived form than Parotosuchus. The new genus is the sister taxon of the Cyclotosaurus–Tatrasuchus and Eryosuchus–Mastodonsaurus clades.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New information on the pterosaur Tupandactylus imperator, with comments on the relationships of Tapejaridae
Autorzy:
Pinheiro, F.L.
Fortier, D.C.
Schultz, C.L.
Andrade,de, J.A.F.G.
Bantim, R.A.M.
Powiązania:
https://bibliotekanauki.pl/articles/22426.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new information
pterosaur
Tupandactylus imperator
relationship
Tapejaridae
Pterosauria
phylogenesis
Crato Formation
Brazil
paleontology
Tapejarinae
Thalassodrominae
Opis:
A new specimen of Tupandactylus imperator, comprising an incomplete skull with associated lower jaw, is described. The material is the best preserved specimen of this species known so far and provides new information on the anatomy of this pterodactyloid pterosaur, especially with respect to the morphology of the lower jaw, the first one formally described for the species. Also, the new specimen shows an extensive preservation of soft tissues such as the soft−tissue component of the headcrest, ramphoteca associated with the premaxillae and lower jaw, as well as probable pycnofibres. A phylogenetic analysis was performed in order to test the relationships of the taxon within Tapejaridae. The results of the analysis support Tapejaridae, as well as monophyly of Tapejarinae and Thalassodrominae.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new Miocene penguin from Patagonia and its phylogenetic relationships
Autorzy:
Acosta, Hospitaleche C
Tambussi, C.
Donato, M.
Cozzuol, M.
Powiązania:
https://bibliotekanauki.pl/articles/23119.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
phylogenetic relationship
penguin
Argentina
Miocene
Aves
Spheniscidae
Puerto Madryn Formation
Chubut Province
Madrynornis mirandus
paleontology
Opis:
We describe a new medium−sized penguin, Madrynornis mirandus gen. et sp. nov., from the early late Miocene Puerto Madryn Formation, Chubut Province, Argentina. Although it is evident that extant and fossil penguins form a remarkably homogeneous family of birds, Spheniscidae, their within−group phylogenetic relationships are less obvious. In order to identify the phylogenetic position of the new taxon, we conducted a phylogenetic analysis using 44 osteological characters sampled from 14 representative species of all living genera and five fossil species of Spheniscidae. The family is clearly monophyletic and Madrynornis mirandus is closely related to living taxa. Our phylogenetic interpretation is congruent with biostratigraphic data, with Paraptenodytes from the early Miocene (about 20 Ma) located at the base of the Spheniscidae. Classically, two basic tarsometatarsal types were recognized (one for pre−Miocene and the other for the post−Miocene penguins) based on the pattern of the proximal foramina and the hypotarsus. Madrynornis mirandus exhibits an arrangement of the proximal foramina and a degree of metatarsals fusion similar to that in the living forms, although its elongation index (total length/proximal width) is reminiscent of the extinct Paraptenodytes(a penguin historically recognized as a pre−Miocene form, coming from the early Miocene of Argentina). Madrynornis reveals that the two basic tarsometatarsal types co−existed among Miocene penguins.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new species of mesonychian mammal from the lower Eocene of Mongolia and its phylogenetic relationships
Autorzy:
Geisler, J H
McKenna, M.C.
Powiązania:
https://bibliotekanauki.pl/articles/20347.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
phylogenetic relationship
Dissacus zanabazari
Eocene
Mesonychia
Mammalia
Mongolia
new species
Lower Eocene
paleontology
mesonychian mammal
Mesonychidae
Opis:
We describe Dissacus zanabazari new species from a partial skeleton collected from the early Eocene Bumban Member of the Naran Bulak Formation at Tsagaan Khushuu (Omnogov Province, Mongolia). The holotype includes most of the skull with basicranium, mandibles, well preserved upper and lower dentitions, partially articulated left manus and right tarsus, and most of the long bones in the limbs. The presence of a rudimentary 1st metatarsal is confirmed in mesonychids, and the relatively unworn lower incisors display an unexpected trilobed morphology. Autapomorphies of this new species are short face, absence of diastemata between the lower premolars (except between p1 and p2), m3 metaconid subequal to protoconid, and foramen for superior ramus of stapedial artery entirely within the petrosal. A phylogenetic analysis of 89 characters scored for 14 mesonychians and 5 outgroups resulted in 8 most parsimonious trees. Dissacus zanabazari is in a clade with D. navajovius, but this genus is otherwise paraphyletic. The strict consensus of the eight trees has a monophyletic Mesonychia, Hapalodectidae, and Mesonychidae; Dissacus and Ankalagon as the most basal mesonychid genera; and paraphyly of Pachyaena.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany
Autorzy:
Frobisch, J.
Schoch, R.
Muller, J.
Schindler, T.
Schweiss, D.
Powiązania:
https://bibliotekanauki.pl/articles/22246.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carboniferous
Cryptovenator hirschbergeri
Germany
Late Carboniferous
phylogenetic relationship
Saar−Nahe Basin
Sphenacodontidae
Synapsida
geological setting
new species
paleontology
sediment
sphenacodontid synapsid
systematics
taxonomy
Opis:
A new basal sphenacodontid synapsid, represented by an anterior portion of a mandible, demonstrates for the first time the presence of amniotes in the largest European Permo−Carboniferous basin, the Saar−Nahe Basin. The new taxon, Cryptovenator hirschbergeri gen. et sp. nov., is autapomorphic in the extreme shortness and robustness of the lower jaw, with moderate heterodonty, including the absence of a greatly reduced first tooth and only a slight caniniform development of the second and third teeth. Cryptovenatorshares with Dimetrodon, Sphenacodon, and Ctenospondylus, but notably not with Secodontosaurus, enlarged canines and a characteristic teardrop outline of the marginal teeth in lateral view, possession of a deep symphyseal region, and a strongly concave dorsal margin of the dentary. The new find shows that sphenacodontids were present in the Saar−Nahe Basin by the latest Carboniferous, predating the record of sphenacodontid tracks from slightly younger sediments in this region.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Osteology and relationships of Olorotitan arharensis, a hollow−crested hadrosaurid dinosaur from the latest Cretaceous of Far Eastern Russia
Autorzy:
Godefroit, P.
Bolotsky, Y.L.
Bolotsky, I.Y.
Powiązania:
https://bibliotekanauki.pl/articles/20406.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
osteology
relationship
Olorotitan arharensis
dinosaur
hadrosaurid dinosaur
Cretaceous
Russia
Dinosauria
Ornithischia
Hadrosauridae
Lambeosaurinae
phylogenesis
Late Cretaceous
Maastrichtian Udurchukan Formation
Corythosaurus casuarius Hypacrosaurus stebingeri
Hypacrosaurus altispinus
Opis:
The holotype of Olorotitan arharensis from the Maastrichtian Udurchukan Formation in Kundur, Far Eastern Russia, is the most complete dinosaur discovered in Russia and one of the best preserved lambeosaurines outside western North America. This taxon is diagnosed by following autapomorphies: large helmet−like hollow crest higher than the rest of the skull and extending caudally well beyond the level of the occiput; very high postorbital process of jugal (ratio height of postorbital process/length of jugal = 1); rostral portion of the jugal shorter than in other lambeosaurines, with a perfectly straight rostral margin; very asymmetrical maxilla in lateral view, with ventral margin distinctly downturned; very elongated neck composed of 18 cervical vertebrae; tibia as high as the femur; shorter cnemial crest, about one fifth of tibia length. A phylogenetic analysis, based on 118 cranial, dental, and postcranial characters, indicates that Olorotitan is a member of the Corythosaurini clade, and is the sister taxon of Corythosaurus casuarius, Hypacrosaurus stebingeri, and Hypacrosaurus altispinus. The high diversity and mosaic distribution of Maastrichtian hadrosaurid faunas in the Amur−Heilongjiang region are the result of a complex palaeogeographical history and imply that many independent hadrosaurid lineages dispersed readily between western America and eastern Asia at the end of the Cretaceous.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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