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Wyszukujesz frazę "skeleton" wg kryterium: Temat


Tytuł:
A partial skeleton of an enantiornithine bird from the Early Cretaceous of Northwestern China
Autorzy:
Lamanna, M.C.
You, H.-L.
Harris, J.D.
Chiappe, L.M.
Ji, S.-A.
Lu, J.-C.
Ji, Q.
Powiązania:
https://bibliotekanauki.pl/articles/20670.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
China
Cretaceous
Early Cretaceous
paleontology
skeleton
partial skeleton
bird
Aves
enantiornithine bird
Enantiornithes
Xiagou Formation
remains
Opis:
Although recent discoveries from Lower Cretaceous sediments in northeastern China have greatly improved our understanding of the initial stages of avian diversification in eastern Asia, the early evolution of Aves elsewhere on the continent remains poorly understood. In 2004, a collaborative field effort directed by personnel from the Chinese Academy of Geological Sciences and Carnegie Museum of Natural History recovered multiple partial to nearly complete avian skeletons from outcrops of the Lower Cretaceous Xiagou Formation exposed in the Changma Basin of northwestern Gansu Province, China. Here we describe a thrush−sized partial skeleton comprised of a fragmentary pelvic girdle and largely complete hind limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical characters places the specimen in Enantiornithes, and within that clade, in Euenantiornithes. When coupled with additional recent discoveries from the Changma Basin, the new skeleton improves our understanding of early avian evolution and diversification in central Asia.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Postcranial skeleton of a Cretaceous multituberculate mammal Catopsbaatar
Autorzy:
Hurum, J.H.
Kielan-Jaworowska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/20416.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
postcranial skeleton
skeleton
Cretaceous
paleontology
multituberculate
mammal
Catopsbaatar
mammalia
Multituberculata
Djadochtatheriidae
sprawling posture
Gobi Desert
Catopsbaatar catopsaloides
Opis:
We describe an incomplete postcranial skeleton of Catopsbaatar catopsaloides from the ?late Campanian red beds of Hermiin Tsav I, in the Gobi Desert, Mongolia. The skeleton is fragmentary and the preservation of bone surface does not permit reconstruction of the musculature. The studied skeleton contains some parts not preserved or incompletely known in other multituberculate genera, such as a long spinous process in a single lumbar vertebra, which together with long transverse processes preserved in Nemegtbaatar, might indicate that at least some multituberculates had jumping ability. The calcaneus of Catopsbaatar is unusual, differing from most other multituberculates (where known) and other mammals by having a short tuber calcanei, with a large proximal anvil−shaped process strongly bent laterally and ventrally, arranged obliquely with respect to the distal margin of the calcaneus, rather than arranged at 90° to it, as in other mammals. This suggests the presence of strong muscles that attached to the tuber calcanei, perhaps further attesting to jumping abilities in Catopsbaatar. We also describe an unfused pelvic girdle and the first extratarsal spur bone (os cornu calcaris) known in multituberculates.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New skeleton from the Early Oligocene of Germany indicates a stem-group position of diomedeoidid birds
Autorzy:
De Pietri, V.L.
Berger, J.-P.
Pirkenseer, C.
Scherler, L.
Mayr, G.
Powiązania:
https://bibliotekanauki.pl/articles/22260.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new skeleton
skeleton
Early Oligocene
Oligocene
Germany
stem-group position
diomedeoidid bird
bird
Aves
Diomedeoididae
phylogenesis
paleontology
Diomedeoides brodkorbi
Opis:
We report a new specimen of the extinct procellariiform species Diomedeoides brodkorbi (Aves, Diomedeoididae) from the early Oligocene (Rupelian) of Rheinweiler in southwestern Germany. The well−preserved partial skeleton allows the recognition and reassessment of new osteological details that bear on the phylogenetic affinities of diomedeoidids. The presence on the coracoid of a deeply excavated, cup−like facies articularis for the scapula suggests a stem group position of the Diomedeoididae within Procellariiformes, because this trait also occurs in stem−group representatives of several avian groups, as well as in Mesozoic non−neornithine birds, and is a plesiomorphic character. We hypothesize that the similarities of Diomedeoides to extant southern storm−petrels (Oceanitinae), such as the long mandibular symphysis, the small processus supracondylaris dorsalis and the long legs are plesiomorphic for Procellariiformes.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The appendicular skeleton of Neuquensaurus, a Late Cretaceous saltasaurine sauropod from Patagonia, Argentina
Autorzy:
Otero, A
Powiązania:
https://bibliotekanauki.pl/articles/22709.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
appendicular skeleton
skeleton
paleontology
Neuquensaurus
Late Cretaceous
saltasaurine sauropod
sauropod
Patagonia
Argentina
Sauropoda
Saltasaurinae
Neuquensaurus australis
Neuquensaurus robustus
anatomy
Cretaceous
sauropod evolution
Opis:
Neuquensaurus, from the Late Cretaceous of Argentina and one of the first dinosaurs described from Patagonia, is one of the most derived sauropod dinosaurs, and its proportions and size place it among the smallest sauropods ever known. In this context, Neuquensaurus is central to understanding late stages of sauropod evolution. This contribution offers a full description of the appendicular skeleton of Neuquensaurus. The anatomical analysis reveals that the appendicular skeleton of Neuquensaurus exhibits unique characteristics only shared with closely related saltasaurine titanosaurs; for example, the laterally directed preacetabular lobe of the ilium, the prominent fibular lateral tuberosity, and the presence of an intermuscular line on the femoral shaft, which is proposed here as a synapomorphy of Saltasaurinae. Neuquensaurus also displays many reversals to primitive character states, such as the presence of a prominent olecranon process of the ulna, a trochanteric shelf, a lesser trochanter and an ischial tuberosity. Additional characters that allow its evaluation in a phylogenetic context are here provided. Among them are the extremely deflected femoral shaft, the elliptical femoral cross−section, and the anterolaterally oriented cnemial crest.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 399-426
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First complete heterosoricine shrew: A new genus and species from the Miocene of China
Autorzy:
Storch, G
Qiu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/20579.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Miocene
shrew
China
Soricidae
skeleton
new species
adaptation
new genus
Heterosoricinae
paleontology
Opis:
Heterosoricinae are the oldest known soricids, their records dating back to the middle Eocene of North America and earliest Oligocene of Eurasia. They became extinct during the Miocene and were thus far only known from dental and cranial remains. For the first time, a virtually complete heterosoricine is described, coming from the early/middle Miocene locality of Shanwang, Shandong Province, which is famous for the diversity and excellent preservation of its fossils. Lusorex taishanensis gen. et sp. nov. is closely related to Wilsonosorex from the early Hemingfordian of North America. Both are unusual in sharing well−developed conules on the upper molars and reduced ectocingulids on the lowers, and most likely these sister taxa reflect faunal exchange between North America and NE Asia in early Miocene time. L. taishanensis was the size of a European common shrew, Sorex araneus. The heavy masticatory apparatus of the new heterosoricine contrasts with its slender postcranial skeleton. Adaptively, L. taishanensis appears to be similar to the North American Blarina brevicauda in its strong masticatory apparatus, very short tail, and slight limb specializations toward fossorial habits. It differs from other soricids as far as is known by unfused tibia and fibula.
Źródło:
Acta Palaeontologica Polonica; 2004, 49, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A sauropod foot from the Early Cretaceous of Western Siberia, Russia
Autorzy:
Averianov, A O
Voronkevich, A.V.
Maschenko, E.N.
Leshchinskiy, S.V.
Fayngertz, A.V.
Powiązania:
https://bibliotekanauki.pl/articles/20801.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Ilek Formation
Titanosauriformes
Cretaceous
Russia
Siberia
Sauropoda
sauropod foot
paleontology
postcranial skeleton
Opis:
We describe a reasonably complete sauropod foot from the Early Cretaceous (Aptian–Albian) Ilek Formation at the Shestakovo locality in Western Siberia, Russia.It shows some primitive characters, such as slender metatarsals, a relatively long second pedal ungual, and three claws.In the likely presence of the laterodistal process on the first metatarsal the Shestakovo sauropod is similar with diplodocoids, but its more elongated and gracile first metatarsal resembles brachiosaurids (Brachiosaurus, Pleurocoelus, and Cedarosaurus), titanosaurids (Laplatasaurus), and Euhelopus. Pleurocoelus−like isolated teeth from the Shestakovo assemblage may support the brachiosaurid affinities of the Shestakovo sauropod, but a strongly procoelous mid−caudal vertebra from another locality in the same formation establishes the presence of a titanosaurid in the fauna.The foot described is referred here to as Titanosauriformes gen.et sp.indet.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Body mass estimation in amphicyonid carnivoran mammals: A multiple regression approach from the skull and skeleton
Autorzy:
Figueirido, B.
Perez-Claros, J.A.
Hunt, R.M.Jr.
Palmqvist, P.
Powiązania:
https://bibliotekanauki.pl/articles/21366.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
body mass
estimation
amphicyonid
mammal
skull
skeleton
Mammalia
Carnivora
Amphicyonidae
multiple regression
paleontology
Opis:
The body masses of sixteen species of amphicyonids (Mammalia, Carnivora, Amphicyonidae) from the New and Old World were estimated on the basis of 86 osteological variables measured from the craniodental (N = 44) and postcranial (N = 42) skeleton of living species of Canidae and Ursidae. Given the absence of complete and well preserved skeletons of amphicyonids in the fossil record, multiple regression functions were derived separately from measurements taken from the mandible, the cranium and the major limb bones. The accuracy of the regression functions was evaluated using the percentage prediction error and the percentage standard error of the estimates. Mass values were calculated with these equations using measurements taken in adult individuals from a number of daphoenine and amphicyonine species. Results obtained show that three distinct size classes of amphicyonids emerged through the evolutionary history of the “beardog” family and that these size classes correlate with presumably different ecomorphs. Quantitative estimates of body size of amphicyonids are critical for deciphering the paleobiology of this poorly understood family of large fissiped carnivorans and can be used for placing it within a broader ecological context.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A review of Neusibatrachus wilferti, an Early Cretaceous frog from the Montsec Range, Northeastern Spain
Autorzy:
Baez, A M
Sanchiz, B.
Powiązania:
https://bibliotekanauki.pl/articles/21953.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cretaceous
Lleida Province
Amphibia
frog
anuran
Palaeobatrachidae
Anura
skeleton
Neusibatrachus wilferti
Spain
paleontology
Pipoidea
Opis:
Neusibatrachus wilferti is an anuran from the late Berriasian–early Valanginian fossiliferous lacustrine limestones that are exposed in the eastern part of the Montsec Range, province of Lleida, Spain. It was originally described by Seiffert in 1972 and its phylogenetic position has since been discussed. Neusibatrachus has been considered an undeterminable fossil, an abnormal individual, or a primitive palaeobatrachid. Here we redescribe the only available specimen, and clarify features, such as absence of palatines, nine presacrals, and procoelous vertebral centra, that have been the subject of previous debates. We consider the specimen to be a postmetamorphic individual and make developmental interpretations of some of its characters. In particular, we provide evidence of a living anuran (Rana iberica) that resembles Neusibatrachus in the development of intervertebral articulations. Neusibatrachus is considered a valid genus, which differs from other anurans, except for the pipoids, in the joint presence of an azygous frontoparietal and a parasphenoid lacking the subotic alae, although it differs from the pipoids in having nine presacral vertebrae. Morphological evidence indicates that Neusibatrachus is related to Xenoanura, the pipoid branch in the living Amphibia Tree of Life based on molecular data. Moreover, it might be a member of the pipoid clade proper, which presently includes the Pipidae, Rhinophrynidae, and several fossil taxa, including the Palaeobatrachidae, although the evidence is not conclusive.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-dimensional micro- and nanostructural characteristics of the scleractinian coral skeleton: A biocalcification proxy
Autorzy:
Stolarski, J
Powiązania:
https://bibliotekanauki.pl/articles/23012.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
scleractinian coral
biomineralization
Flabellum
Scleractinia
skeleton
Galaxea
microstructure
Desmophyllum
Platygyra
Stephanocyathus
coral
paleontology
fibre
Opis:
The contemporary “two−step model” of growth of the scleractinian skeleton is based mostly on transversely sectioned samples. According to this model, many skeletal elements e.g., septa are formed in two temporally distinct phases represented by (1) “centers of calcification” that are composed of homogenously distributed microcrystalline or/and organic components and serve as scaffolding for the further growth of (2) fibrous skeleton. Based on transverse and longitudinal sections and histochemical staining techniques, I demonstrate herein that in extant corals (i.e., Stephanocyathus, Flabellum, Desmophyllum, “Ceratotrochus”, Galaxea, Platygyra), the entire septal skeleton is composed of superimposed layers of mineral and organic−enriched phases. These may be interrupted in some directions of growth but in other directions there is continuity between “centers of calcification” and “fibers”, making any distinction between these two structures unclear. As an alternative to the “two−step model”, a “layered model” of skeletal growth is proposed, that explains the differences between “centers of calcification” and “fibers” in terms of differential growth dynamics between these regions. Instead of the traditional but inadequate “trabecular” and “centers of calcification” concepts, a distinction between deposits of the Rapid Accretion Front (dRAF; which in particular cases can be organized into Centers of Rapid Accretion (CRA), and Thickening Deposits (TD) is proposed. In the dRAF region, mineral components, ca. 50 nm in diameter, seem to match the size range of nodular structures recently interpreted as nascent CaCO₃ crystals. Remarkable regularity of the mineral/organic phase alternations (microbanding) in the TD skeleton of zooxanthellate corals and lack of such regular microbanding in azooxanthellate coralla is a promising criterion for distinguishing these two ecological coral groups on a skeletal basis, and one that could be applicable to fossils.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A dicynodont-theropod association in the latest Triassic of Poland
Autorzy:
Dzik, J.
Sulej, T.
Niedźwiedzki, G.
Powiązania:
https://bibliotekanauki.pl/articles/20095.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
dicynodont-theropod association
Triassic
Polska
dicynodont
theropod dinosaur
bone
paleontology
skeleton
fossil
Late Triassic
Opis:
It is generally accepted that during the Triassic the composition of tetrapod faunas underwent a series of fundamental transformations, mainly as a result of diversification of archosaurs and decline of therapsids (Benton 1994, 2004, 2006). The last herbivorous basal synapsids, dicynodonts, disappeared from the record in the early Norian of the Americas, about 220 Ma (Langer et al. 2007), being unknown from the Late Triassic of Europe. Here, we report a partially articulated skeleton and isolated bones of a giant rhino−size dicynodont in the Upper Triassic fluvial sediments at Lisowice (Lipie Śląskie clay−pit) in southern Poland. Paleobotanical data indicate an early Rhaetian age for the fauna (Dzik et al. 2008; Niedźwiedzki and Sulej 2008). The dicynodont bones are associated with bones of carnivorous dinosaurs, pterosaurs, as well as capitosaur and plagiosaur amphibians. Dicynodonts were represented in the Germanic Basin throughout the Late Triassic, as proven by findings of smaller dicynodonts in older deposits in the same area, associated there with temnospondyl amphibians. It appears, thus, that the fossil record of tetrapod succession in the Late Triassic was strongly controlled by ecological factors and biased by uneven representation of particular environments. The Lisowice assemblage proves that faunas dominated by dicynodonts did not entirely disappear at least until the end of the Triassic.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The digital Plateosaurus II: An assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount
Autorzy:
Mallison, H
Powiązania:
https://bibliotekanauki.pl/articles/20500.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
motion
limb
vertebral column
Prosauropoda
Plateosaurus
reconstruction
digital skeleton
3D model
accuracy
prosauropod
Plateosaurus engelhardti
Opis:
Scientific literature and museum exhibits are full of explicit and implicit claims about the possible postures and motion ranges of dinosaurs. For the example of the prosauropod Plateosaurus engelhardti I assessed the motion range of limbs and vertebral column in a CAD program using a 3D virtual skeletal mount. The range of motion of the forelimb is very limited, allowing the grasping of objects placed directly ventrally and ventrolaterally of the anterior torso. The manus is adapted for grasping. The powerful fore limb can barely reach in front of the shoulder, making a quadrupedal walking cycle impractical. Only a digitigrade pose of the pes with a steeply held metatarsus is feasible, and the morphology of the stylopodium and zeugopodium indicates a slightly flexed limb posture. Hind limb protraction and retraction are limited by the pelvic architecture. The neck has significant mobility both dorsoventrally and laterally, but blocks torsion. The dorsal vertebral column is flexible to a degree similar to the neck, mainly in the anterior half, but blocks torsion totally in the anterior and posterior thirds. The anterior dorsals are similar in shape to the posterior cervicals and significantly increase the motion range of the neck. The tail is highly flexible due to its large number of elements, showing more lateral than dorsoventral mobility. These results are compared to reconstruction drawings and museum skeletal mounts, highlighting a pattern of errors specific to certain widely used reconstruction methods.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 433-458
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Description of a new stromateoid fish from the Miocene of St. Eugene, Algeria
Autorzy:
Carnevale, G.
Bannikov, A.F.
Powiązania:
https://bibliotekanauki.pl/articles/20914.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Algeria
Ariommatidae
Messinian
Miocene
Perciformes
sedimentary setting
Teleostei
Upper Miocene
axial skeleton
fish
fossil
paleontology
stromateoid fish
systematics
Opis:
A single specimen of the axial skeleton of an elongate fossil stromateoid fish, collected from the Upper Miocene (Messinian) St. Eugène locality of north−western Algeria, is identified as a new species Ariomma geslini sp. nov. of the family Ariommatidae. It is based on a unique combination of features, including morphology and arrangement of pleural ribs, structure and orientation of anterior portion of the anal fin, unique sequential arrangement of anal−fin pterygiophores in relation to the haemal spines, and presence of large cycloid scales and meristics. The morphology and orientation of the first anal−fin pterygiophore indicate that A. geslini sp. nov. is probably related to the amphi−Atlantic species A. bondi and A. melanum. The analysis of the fossil record of the Stromateoidei suggests that the ariommatids were already in existence at least as early as the Eocene.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ligamental scar in the costovertebral articulation of the tyrannosaurid dinosaurs
Autorzy:
Hirasawa, T
Powiązania:
https://bibliotekanauki.pl/articles/20611.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
thoracic rib
skeletal element
Theropoda
dinosaur
Tyrannosauridae
Dinosauria
paleontology
rib
articulated skeleton
tyrannosaurid dinosaur
soft tissue anatomy
ribcage
Opis:
The costovertebral articulation is integral to constrain the thoracic kinematics and to infer the breathing mechanism in the respect with costal aspiration. However, the structure of the costovertebral articulation in non−avian theropods has not been studied in great detail before. This study highlights the Tyrannosauridae, which is represented by numerous complete specimens. Costovertebral articulations of ten tyrannosaurid specimens, including two nearly in−situ articulated fossils, were investigated and compared with those in extant Archosauria. For extant archosaurs, dissections were conducted to rationalize the soft tissue anatomy in tyrannosaurids. This study shows that the rib articulates ventrally or posteroventrally with the distal end of the corresponding vertebral transverse process in the tyrannosaurid ribcage. A ligament (ligamentum costotransversarium) can be reconstructed to connect the rib tuberculum to the transverse process in each articulation. The scar for lig. costotransversarium is recognizable in many theropod skeletons, and this rugosity can be used to identify the rotational axis for the rib. This result provides a cornerstone for exploring the evolution of the ribcage and breathing mechanisms across the theropod lineage leading to birds.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 1; 49-59
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural diversity of the stylophyllid [Scleractinia] skeleton
Autorzy:
Stolarski, J
Russo, A.
Powiązania:
https://bibliotekanauki.pl/articles/22102.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
stylophyllid
paleobiology
Scleractinia
skeleton
morphology
Jurassic
Stylophyllina
microstructure
Haimeicyclus haimei
ontogenesis
diversity
Stylophyllopsis
deposit
coral
solitary coral
paleontology
Opis:
Coralla of the three species of solitary corals described herein from the Sinemurian (Lower Jurassic) of Sicily, i.e., Haimeicyclus haimei (Chapuis and Dewalque, 1853), Stylophyllopsis sp. cf. S. rugosa (Duncan and Wright, 1867), and Stylophyllopsis sp. A., conform to the overall stylophyllid morphology. Their septa consist of spines that are increasingly covered with sclerenchyme and low in the calice form compact blades. The pattern of diagenetic alteration of septa is diverse but consistent within particular taxa. It suggests that the spectrum of the original microstructures is wider than traditionally suggested for stylophyllids. In H. haimei, the septa are covered with dense granulations and completely recrystallized. Granulations also cover septal faces of Stylophyllopsis cf. rugosa and have rod−like foundations. In Stylophyllopsis sp. A., vestiges of the narrow mid−septal zone (similar to that in minitrabecular corals) occur in the proximal part of larger septa, whereas septal spines which are similar to those in Stylophyllopsis cf. rugosa occur in their distal parts. Similar diversity of microstructures is reported also in Triassic stylophyllids that have aragonitic coralla. The presence of distinct septal spines along with wide−ranging microstructural diversity of traditional Triassic–Jurassic stylophyllids, casts light on their possible evolutionary relationships, and can be a useful criterion for further revision of the group. For example, Jurassic thecocyathids, considered ancestral to caryophylliinans, share similar spiny/lobate septa with stylophyllids. Also Recent deep−water anthemiphylliids with spiny/lobate septa are strikingly similar to stylophyllids. Although this may be another example of parallel evolution, the separation of anthemiphylliids from other scleractinian clades on a mitochondrial 16S RNA tree topology suggests their ancient roots and enable us to suggest a stylophyllid ancestry. The supposed cyclic pattern of protoseptal insertion in Early Jurassic H. haimei supports the hypothesis of scleractinian−like (and not rugosan) ancestory of the stylophyllid evolutionary lineage.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limb posture in early mammals: Sprawling or parasagittal
Autorzy:
Kielan-Jaworowska, Z.
Hurum, J.H.
Powiązania:
https://bibliotekanauki.pl/articles/21484.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Mesozoic
Monotremata
Multituberculata
fossil mammal
mammal
multituberculate
os calcaris
paleontology
posture
reconstruction
sprawling posture
venomous mammal
spur
skeleton
Opis:
The limb posture in early mammals is a matter of controversy. Kielan−Jaworowska and Gambaryan presented arguments for a sprawling posture in multituberculates, based mainly on three characters of the hind limbs (deep pelvis, mediolateral diameter of the tibia larger than the craniocaudal, and position of MtV, which fits the peroneal groove on the calcaneus and is not aligned with the axis of tuber calcanei). Here we present two more arguments for sprawling hind limbs in early mammals. One is the presence of an os calcaris, supporting the probably venomous spur in hind legs of docodontans, multituberculates, eutriconodontans, and “symmetrodontans”, similar to those of extant monotremes. We argue that early mammals (except for boreosphenidans) had sprawling limb posture and venomous spur; acquisition of the parasagittal stance was apparently characteristic only of boreosphenidans, in which the spur has not been found. The second argument is based on taphonomic evidence from lacustrine conditions (e.g., Early Cretaceous Jehol Biota), in which the mammalian skeletons, except for boreosphenidans (Sinodelphys and Eomaia), have been preserved compressed dorso−ventrally, suggesting sprawling stance. In similar conditions of the Eocene Messel Biota the skeletons of boreosphenidan mammals (except for bats and pangolins) are preserved lying on flanks, suggesting parasagittal stance. Sereno argued that forelimbs in multituberculates were parasagittal, based on the stated presence of a ventrally facing glenoid, a mobile shoulder joint, and an elbow joint with enhanced flexion−extension capability. However, these characters are not unequivocally indicative of parasagittalism. We demonstrate that the structure of the distal end of the multituberculate humerus is condylar, with no tendency for developing a trochlea. We reconstruct multituberculates and other early mammals with sprawling stance in resting position as plantigrade.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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