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Tytuł:
The last Cretaceous ammonites in Latin America
Autorzy:
Stinnesbeck, W.
Ifrim, C.
Salazar, C.
Powiązania:
https://bibliotekanauki.pl/articles/20513.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Cretaceous
ammonite
Latin America
Ammonoidea
Paleogene
Maastrichtian
Chile
Argentina
South America
Opis:
Sections yielding late Maastrichtian ammonite assemblages are rare in Latin America and precise biostratigraphic correlation with European type sections remains difficult. In all, the extinction pattern of ammonites appears to differ between sites in southern high latitudes and those in the tropics to subtropics. In austral sections of Chile, and possibly also in southern Argentina, diverse assemblages range throughout most of the substage and then show a gradual decline prior to the Cretaceous–Paleogene (K–Pg) boundary. Further north, in northeast Brazil, only two genera (Diplomoceras, Pachydiscus) range into the uppermost Maastrichtian, but disappear within the last 0.3 Ma of the Cretaceous. In tropical sections of Columbia and Mexico, the decline of ammonites started earlier and Sphenodiscus is the last ammonite known to occur in the late Maastrichtian. In all sections revised here the disappearance of ammonites was completed prior to the end of the Maastrichtian and was thus independent of the asteroid impact at, or near, the end of the Cretaceous.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A review of the endocerid cephalopod Protocyptendoceras from the Floian [Lower Ordovician] of the Eastern Cordillera, Argentina
Autorzy:
Cichowolski, M
Powiązania:
https://bibliotekanauki.pl/articles/20173.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cephalopoda
Floian
endocerid cephalopod
paleontology
cephalopod
Ordovician
Lower Ordovician
Proterocameroceratidae
Endocerida
Argentina
Opis:
Ordovician cephalopods from Western Gondwana are still poorly known and published data is in need of systematic and stratigraphical revision. In this work, the endocerid proterocameroceratid Protocyptendoceras from the Floian of the Eastern Cordillera of Argentina is revised using new material from La Ciénaga, 5 km upstream from Purmamarca. The species P. corvalani and P. teicherti are considered to be junior synonyms of P. fuenzalidae, which is redescribed in detail and reillustrated. Specimens preserve adapical parts of isolated siphuncles, related here to the presence of endocones in a posterior portion. Evidently P. fuenzalidae had a nektobenthic mode of life in a shallow water environment, oriented horizontally. Its palaeobiogeographical affinities are mainly with Floian proterocameroceratids from Eastern Gondwana, such as Anthoceras decorum and the related genera Lobendoceras, Ventroloboceras, and Notocycloceras.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 1; 99-109
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:
Climate and changes in mammal diversity during the late Pleistocene-Holocene in the Pampean Region [Argentina]
Autorzy:
Prado, J L
Alberdi, M T
Azanza, B
Sanchez, B
Powiązania:
https://bibliotekanauki.pl/articles/20763.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Argentina
Holocene
mammal diversity
mammal
diversity
change
extinction
Pleistocene
climate
paleontology
climate change
Opis:
The association of changes in mammal diversity with periods of global climatic change is suggestive of a causal relationship. Two important features in the testing of this climatic model are as follows: the timing and the pattern of the diversity changes, and the particular climatic variables examined, since different patterns of evolutionary interactions would be expected depending on different climatic variables. In order to analyse the relationship between climate change and faunal events, we need to establish a set of comparable data. To provide a finely resolved picture of both climatic and faunal events, the last 32,500-years were divided into 13 chronological units of 2,500-years each. The limit of 32,500-years was imposed by the availability of good localities with radioisotopic calibration. Climatic stability was measured in these analyses in terms of cycles per unit of time, the amount of variation in temperature per unit of time, and the magnitude of change between modal temperature of one interval less modal temperature from preceding interval. The data presented here suggest that the primary effect of climatic change is on: (1) levels of extinction (or migration) of large mammals; and (2) diversity and origination (or immigration) of small mammals.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systematic and biostratigraphic significance of a chinchillid rodent from the Pliocene of eastern Argentina
Autorzy:
Rasia, L.L.
Candela, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/22264.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
systematics
biostratigraphy
significance
chinchillid rodent
rodent
Mammalia
Rodentia
Caviomorpha
Chinchillidae
paleontology
Pliocene
Argentina
Opis:
Two species of chinchillid rodents, Lagostomus (Lagostomopsis) incisus and “Lagostomus (Lagostomopsis) spicatus”, have been recorded from the Monte Hermoso Formation (Montehermosan–Lower Chapadmalalan, Early Pliocene) of southern Buenos Aires Province, eastern Argentina. L. (L.) incisus is based on skull remains,while “L. (L.) spicatus” is based onmandible remains and fragmentary skulls. Detailed study of specimens recovered from the upper section of the Monte Hermoso Formation, from the Irene “Formation”, and the Chapadmalal Formation (late Early–early Late Pliocene, Buenos Aires Province), some of them represented by associated skull and mandible remains, indicates that L. (L.) incisus and “L. (L.) spicatus” are synonymous, with the valid name being L. (L.) incisus. The differences between both nominal species are here attributed to different ontogenetic states and sexual dimorphism. The stratigraphic provenance of the fossil material of L. (L.) incisus indicates a temporal distribution of this species restricted to theMontehermosan?–Chapadmalalan (Early–early Late Pliocene), instead of the Montehermosan (Early Pliocene).
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The bivalve Pholadomya gigantea in the Early Cretaceous of Argentina: taxonomy, taphonomy, and paleogeographic implications
Autorzy:
Lazo, D G
Powiązania:
https://bibliotekanauki.pl/articles/23388.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Argentina
Early Cretaceous
Pholadomya gigantea
Cretaceous
Bivalvia
Anomalodesmata
paleoecology
paleogeography
taxonomy
bivalve
paleontology
Opis:
Pholadomya gigantea is a widely distributed Early Cretaceous bivalve mollusc. It has been recorded in the North Temperate, Tethyan, and South Temperate Realms. Based on recent field work and newly collected material from the Neuquén Basin, the taxonomy, mode of occurrence and palaeobiogeography of this species is reviewed. In the Agrio Formation (Valanginian–Barremian) P. gigantea is neither abundant nor dominant, but occurs throughout the unit. It was facies−dependent being restricted to well−oxygenated waters and soft to firm, sandy and bioclastic substrates of shoreface to inner shelf environments. The life habit of P. gigantea was similar to that of Recent Pholadomya candida, deep burrowing and sedentary, but it has not a pedal gape and accessory muscle scars related to valve closure. Thus a suspension−feeding habit, not a pedal−feeding system, may be inferred as is commonly suggested in other Jurassic and Cretaceous Pholadomya species. Pholadomya agrioensis is a valid taxon that is recorded in the Berriasian–Valanginian of Neuquén. It is similar in outline to P. gigantea and had probably the same basic palaeoecology, even though it has a blunt anterior margin, deep umbonal−ventral sulcus and distinct anterior ornamentation. Once in life position this species was capable of further digging in the sediment. This species probably burrowed in muddy substrates in the offshore zone. Pholadomya sanctaecrucis from the Valanginian of Europe and also recorded in Argentina is ornamented only with commarginal lines and should be removed to the genus Homomya.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
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:
First ? cimolodontan multituberculate mammal from South America
Autorzy:
Kielan-Jaworowska, Z
Ortiz-Jaureguizar, E.
Vieytes, C.
Pascual, R.
Goin, F.J.
Powiązania:
https://bibliotekanauki.pl/articles/20688.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Argentina
mammal
Cretaceous
Argentodites coloniensis
new species
new genus
La Colonia Formation
South America
Multituberculata
paleontology
Cimolodonta
Opis:
We describe a Cretaceous ?cimolodontan multituberculate p4 from South America, for which we erect the new genus and species Argentodites coloniensis. This new taxon is represented by an isolated ?left p4 from the Upper Cretaceous (?Campanian or Maastrichtian) La Colonia Formation of Patagonia (Fig. 1). It has a strongly convex anterior margin and prismatic enamel, which attest to its cimolodontan nature, while the previously known p4 (MACN−RN 975) from the Late Cretaceous Los Alamitos Formation is roughly rectangular, suggesting “plagiaulacidan” affinity. The presence of normal prismatic enamel in Argentodites suggests similarities to Ptilodontoidea. However, it differs from the Late Cretaceous and Paleocene Laurasian cimolodontans (including Ptilodontoidea) in having a long, straight posterior margin, a nearly straight dorsal margin, characteristic of some “Plagiaulacida”, and in having the lingual side close to the mirror image of the labial side, the character that poses difficulties in establishing whether it is a right or left tooth. Because of these differences we assign Argentodites to ?Cimolodonta, tentatively only, superfamily and family incertae sedis.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Paleoecology of the large carnivore guild from the late Pleistocene of Argentina
Autorzy:
Prevosti, F.J.
Vizcaino, S.F.
Powiązania:
https://bibliotekanauki.pl/articles/23538.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carnivora
carnivore
Late Pleistocene
Pleistocene
South America
paleoecology
population density
Argentina
paleontology
fossil carnivore
locality
biomass
ecology
Opis:
The paleoecology of the South American fossil carnivores has not been as well studied as that of their northern relatives. One decade ago Fariña suggested that the fauna of Río Luján locality (Argentina, late Pleistocene–early Holocene) is not balanced because the metabolic requirements of the large carnivores are exceeded by the densities and biomass of the large herbivores. This conclusion is based on the calculation of densities using allometric functions between body mass and population abundance, and is a consequence of low carnivore richness versus high herbivore richness. In this paper we review the carnivore richness in the Lujanian of the Pampean Region, describe the paleoecology of these species including their probable prey choices, and review the available information on taphonomy, carnivore ecology, and macroecology to test the hypothesis of “imbalance” of the Río Luján fauna. The carnivore richness of the Río Luján fauna comprises five species: Smilodon populator, Panthera onca, Puma concolor, Arctotherium tarijense, and Dusicyon avus. Two other species are added when the whole Lujanian of the Buenos Aires province is included: Arctotherium bonariense and Canis nehringi. With the exception of D. avus and Arctotherium, these are hypercarnivores that could prey on large mammals (100–500 kg) and juveniles of megamammals (>1000 kg). S. populator could also hunt larger prey with body mass between 1000 and 2000 kg. The review of the “imbalance” hypothesis reveals contrary evidence and allows the proposal of alternative hypotheses. If high herbivore biomass occurred during the Lujanian, a higher density of carnivores could be supported than as inferred from the power function of body size and population density.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Miocene capybaras from Argentina: Skull anatomy, taxonomy, evolution, and biochronology
Autorzy:
Vucetich, M.G.
Deschamps, C.M.
Vieytes, E.C.
Montalvo, C.I.
Powiązania:
https://bibliotekanauki.pl/articles/945889.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Miocene
Late Miocene
capybara
mammalia
Rodentia
Cavioidea
Hydrochoerinae
Argentina
skull
anatomy
taxonomy
evolution
biochronology
morphometry
biostratigraphy
Opis:
Fossil capybaras are morphologically extremely varied, but previous studies have disagreed on whether this diversity reflects intraspecific variation or the existence of multiple species. Here, we review the capybaras from the classic Argentinian Late Miocene localities of Paraná River cliffs (“conglomerado osífero” of the Ituzaingó Formation, Entre Ríos), and Chillhué and Guatraché shallow lakes (Cerro Azul Formation, La Pampa), and perform a morphometric analysis of their upper cheek teeth and the posterior portion of the rostrum. Our results confirm that all of the specimens from the “conglomerado osífero” belong to the single species Cardiatherium paranense. In addition, we refer a specimen from Tupungato (Río de los Pozos Formation, Mendoza) to C. paranense, thus expanding its geographical range. The material from La Pampa represents a different taxon, and is here preliminary referred to Cardiatherium aff. orientalis. Our systematic interpretation of Late Miocene capybaras suggests that the early radiation of this group was not as explosive as previously thought, and was likely constrained by the early acquisition of large size, increasing complexity of the cheek teeth, and probably semi-aquatic habits.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 3; 517-535
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Body mass estimation and locomotion of the Miocene pelecaniform bird Macranhinga
Autorzy:
Noriega, J I
Powiązania:
https://bibliotekanauki.pl/articles/21168.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Miocene
Aves
paleobiology
Late Miocene
body mass
Macranhinga paranensis
Argentina
bird
fossil
Pelecaniformes
Macranhinga
paleontology
Anhingidae
locomotion
Opis:
The fossil darter Macranhinga paranensis (Aves: Pelecaniformes) from the late Miocene of Argentina is the largest of all known extinct or living Anhingidae. Its body mass is estimated at a mean value of 5.4 kg by using a scaling model derived from the logarithmic relationship between measurements of the least shaft circumference of the femur/tibiotarsus and body masses. Predictions of body mass, as well as the analysis of anatomical evidence, are used to infer that Macranhinga paranensis would have probably had a powered flapping flight and an aquatic locomotion similar to that of cormorants. The morphology of the pelvis and the hind-limb would have allowed Macranhinga paranensis to catch fishes by means of pursuit-diving rather than stalking them in an anhinga-like manner. As determined by adaptations mainly of tarsometatarsal morphology, the species had well developed perching and climbing abilities.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A glimpse at the ontogeny of the fossil neobatrachian frog Calyptocephalella canqueli from the Deseadan (Oligocene) of Patagonia, Argentina
Autorzy:
Muzzopappa, P.
Nicoli, L.
Powiązania:
https://bibliotekanauki.pl/articles/20186.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ontogenesis
paleontology
fossil
neobatrachian frog
frog
Calyptocephalella canqueli
Anura
Neobatrachia
Australobatrachia
Calyptocephalella
osteogenesis
Cenozoic
Deseadan
Oligocene
Patagonia
Argentina
Opis:
Two fossil tadpoles collected in the Deseadan levels (Oligocene) at the Scarritt Pocket locality of central Patagonia are studied herein. These specimens, which show different degrees of skeletal development, have been assigned to the neobatrachian Calyptocephalella canqueli based on the morphology of the frontoparietals and the presence of adult specimens of this fossil species at the same locality. The concurrent analysis of three developmental stages (Gosner Stages 35/36 and 38/39, and adult) has provided significant data about the ontogeny of this species, including the change of the pattern of exostosis of the frontoparietals, from a pitted to a tuberculated pattern, and the corroboration of the inclusion of two neural arches in the formation of the urostyle. This evidence will shed light on developmental mechanisms that might be involved in the evolution of the genus Callyptocephalella.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Capybaras, size, shape, and time: A model kit
Autorzy:
Vucetich, M G
Deschamps, C.M.
Olivares, A.I.
Dozo, M.T.
Powiązania:
https://bibliotekanauki.pl/articles/22975.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Miocene
allometry
Puerto Madryn Formation
Rodentia
Cardiatherium patagonicum
size
Argentina
tooth development
capybara
time
shape
Hydrochoeridae
Cardiatherium
paleontology
Opis:
The capybaras (Hydrochoeridae) are outstanding rodents for their large size and euhypsodont and multilaminated cheek teeth. Although today they are represented by a single species, it was generally thought that their past diversity was much higher, especially during the late Miocene–early Pliocene. Such diversity is here analyzed taking into account the ontogenetic variation of the p4–m3 in different populations. Numerous isolated teeth of different size found in the upper levels of the Puerto Madryn Formation (late Miocene, Peninsula Valdés, Argentina) were interpreted as members of an ontogenetic series of a new species here described, Cardiatherium patagonicum. They provided clues to evaluate ontogenetic variation and a new framework to analyze the family diversity. In this context, it is proposed that multiple species described from the Ituzaingó Formation (late Miocene, Entre Ríos, Argentina) based on lower teeth, may actually represent specimens of different stages of the ontogenetic trajectory of a single species. Likewise, we found that several nominal taxa from other localities were based on juvenile specimens. According to these results, the diversity of the Hydrochoeridae during the late Miocene and early Pliocene was drastically reduced. The validity of the subfamily Cardiatheriinae is debated. Finally, it is suggested that the whole family should be revised taking into account the ontogenetic variation.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The teeth of the unenlagiine theropod Buitreraptor from the Cretaceous of Patagonia, Argentina, and the unusual dentition of the Gondwanan dromaeosaurids
Autorzy:
Gianechini, F.A.
Makovicky, P.J.
Apesteguia, S.
Powiązania:
https://bibliotekanauki.pl/articles/20408.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
tooth
unenlagiine theropod
theropod
Buitreraptor
Cretaceous
Patagonia
Argentina
dentition
Gondwanan dromaeosaurid
dromaeosaurid
Theropoda
Dromaeosauridae
Unenlagiinae
Dinosauria
paleontology
dinisaur tooth
Opis:
The Unenlagiinae is a clade of Gondwanan dromaeosaurid theropods mainly known from incomplete skeletal material. The group includes two recently discovered theropods, Buitreraptor and Austroraptor, from which cranial remains are available with in situ maxillary and dentary teeth, thus allowing the study of tooth morphology. Among the derived traits that diagnose the dentition of unenlagiines are: (i) high tooth count, (ii) small size of individual teeth when compared with skull height, (iii) absence of denticles and carinae, and (iv) presence of longitudinal grooves on the tooth crown. This suite of dental characteristics, shared between Buitreraptor and Austroraptor, can be considered as diagnostic of the Unenlagiinae or, at least, a more exclusive clade within the group. The teeth of Buitreraptor exhibit a remarkable labiolingual compression, whereas Austroraptor possesses more conical teeth, probably respective autapomorphic features. On one hand, these dental morphologies differ from those observed in most Laurasian dromaeosaurids and, for instance, could be considered as further proof of the purported vicariant evolution of the lineage on the southern continents. On the other hand, the morphological similarities (e.g., absence of denticles) between the teeth of unenlagiines and other theropod lineages, including Mesozoic birds and ornithomimosaurs, can be considered as the result of parallel trends related to dental reduction.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The cervical vertebrae of the Late Cretaceous abelisaurid dinosaur Carnotaurus sastrei
Autorzy:
Mendez, A.H.
Powiązania:
https://bibliotekanauki.pl/articles/945887.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
cervical vertebra
vertebra
paleontology
Late Cretaceous
Cretaceous
abelisaurid dinosaur
dinosaur
Carnotaurus sastrei
Dinosauria
Abelisauridae
Majungasaurus
morphology
neck
Argentina
Madagascar
Opis:
The cervical vertebral series of Carnotaurus sastrei from Argentina is described in detail, and compared with Majungasaurus crenatissimus from Madagascar, both Late Cretaceous (Maastrichtian) in age. Notable differences in the morphology of the cervical vertebrae, especially in the shape and development of the epipophysis and the neural spines, are observed between these two genera. These differences show a neck much more robust in Carnotaurus than in Majungasaurus, may be linked to the evolution of the clade in relation to the divergence time since the two genera shared a common ancestor, and functionally may relate to the feeding function associated to the extreme reduction of the forelimbs.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 3; 569-579
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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