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Tytuł:
Gyrochorte “highways” and their environmental significance in shallow-marine sediments
Autorzy:
Wetzel, A.
Carmona, N.B.
Ponce, J.J.
Powiązania:
https://bibliotekanauki.pl/articles/2082149.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Polychaete
ichnology
behaviour
sequorichnia
Cretaceous
Argentina
Opis:
The reworking of a trace by a subsequently following organism represents a so-called sequorichnial behavior and leads to formation of a “burrowing highway”. Burrowing highways occur more frequently than assumed in the fossil record. Their ichnological and sedimentological meaning is elucidated by using the trace fossil Gyrochorte. Gyrochorte producers exploiting sandy event beds tend to use “burrowing highways” in the same direction. Evidently, the Gyrochorte producers are thigmotactically highly sensitive as they can recognize a burrow produced by the same species because of the less densely packed grains, a somewhat increased mud content, and supposedly mucus segregated within the burrow. These changes make the reworking of pre-existing burrows energetically advantageous. However, in shallow-marine settings mucus is degraded rapidly and loose sediment consolidates in a short while. Therefore, the time to recognize a pre-existing burrow appears to be limited and a rather high number of organisms is a prerequisite for reutilization of a previous trace. “Burrow highways” potentially represent an additional criterion to characterize an opportunistic population strategy.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 1; 209-218
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systematic revision of a Miocene sperm whale from Patagonia, Argentina, and the phylogenetic signal of tympano-periotic bones in Physeteroidea
Autorzy:
Paolucci, F.
Buono, M.R.
Fernandez, M.S.
Cuitino, J.
Powiązania:
https://bibliotekanauki.pl/articles/2082284.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Physeteroidea
Preaulophyseter gualichensis
Miocene
Patagonia
Argentina
Opis:
Sperm whales (Physeteroidea) include today only two genera of morphologically disparate odontocetes: the largest toothed whale known (Physeter macrocephalus) and small sized forms (Kogia spp.). In contrast, their fossil record indicates a high diversity for the group during the Miocene, with over 20 species recognized. Miocene marine sediments from Patagonia (Argentina) record this diversity, including at least five species. Among them, Preaulophyseter gualichensis, from the Miocene of Gran Bajo del Gualicho Formation, has been one of the most enigmatic. Despite the fragmentary nature of the type and referred materials (isolated teeth and periotics), which casts some doubts on its validity, this species has not been revised since its original description. In this contribution, we re-describe the materials referred to P. gualichensis, revise the taxonomic status of the species and evaluate the phylogenetic signal of ear bones among Physeteroidea. Our results indicate that the physeteroid tympano-periotic complex morphology is poorly diagnostic at the species level. Intraspecific variation (including ontogeny and sexual dimorphism) and/or taphonomic processes cannot be ruled out as the causes of the minor differences observed among specimens. We suggest that sperm whale tympano-periotics retain many plesiomorphic characters and are diagnostic only between kogiids and non-kogiid physeteroids. Based on the fragmentary and isolated state of the studied specimens, and the lack of diagnostic characters in both teeth and periotics, we consider P. gualichensis as nomen dubium and we re-assign the referred specimens as Physeteroidea indet. A conservative morphology of the tympano-periotic and, to a lesser extent, the nasal complex in sperm whales, might result from the morpho-functional constraints imposed by a highly specialized but successful echolocation system.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 1; 63-76
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The eoorthid brachiopod Apheoorthina in the Lower Ordovician of NW Argentina and the dispersal pathways along western Gondwana
Autorzy:
MUÑOZ, DIEGO F.
BENEDETTO, JUAN L.
Powiązania:
https://bibliotekanauki.pl/articles/945694.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
brachiopoda
palaeobiogeography
ordovician
tremadocian
gondwana
perunica
argentina
Opis:
The eoorthid brachiopod Apheoorthina is reported for the first time from the Lower Ordovician of NW Argentina. It is represented by a species similar to A. ferrigena from the Tremadocian of the Prague Basin, increasing the faunal affinities between the Central Andean Basin and the South European microcontinents, in particular the Bohemian region (Perunica). Nine out of the fourteen brachiopod genera reported from the Tremadocian of the Central Andean Basin (~64%) are shared with the Mediterranean region, four of which (~28%) have been recorded in the Prague Basin, and two (Kvania and Apheoorthina) are restricted to the Central Andes and Perunica. Dispersal pathways around Gondwana are analyzed in the light of major factors affecting large-scale distribution of brachiopods (environment, larval capacity for dispersal, oceanic currents). The presence in Apheoorthina aff. ferrigena of a well-preserved larval protegulum measuring 420 μm in width and 210 μm in length strongly suggests that this species had planktotrophic larvae capable of long-distance dispersal. According to recent ocean-atmosphere general circulation models for the Ordovician Period, the Central Andean margin was dominated by the cold-water Antarctica Current. Despite the complex non-zonal pattern produced by current deflections around the peri-Gondwanan microcontinents, the general westward circulation sense favoured larval dispersal from the Andean region to North Africa, Avalonia, the Armorican Terrane Assemblage, and Perunica. On the other hand, the eastwards flowing Gondwana Current connected the North Gondwana waters with the South American epicontinental seas, which could explain the reversed migration of some brachiopods.
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 3; 633-644
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Osteology of the unenlagiid theropod Neuquenraptor argentinus from the Late Cretaceous of Patagonia
Autorzy:
BRISSÓN EGLI, FEDERICO
ARANCIAGA ROLANDO, ALEXIS M.
AGNOLÍN, FEDERICO L.
NOVAS, FERNANDO E.
Powiązania:
https://bibliotekanauki.pl/articles/945635.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
dinosauria
theropoda
unenlagiidae
neuquenraptor
cretaceous
argentina
patagonia
Opis:
Neuquenraptor argentinus was described as the first undoubted deinonychosaurian theropod from Gondwana. The only known specimen is represented by a fragmentary skeleton, including a nearly complete foot, coming from Late Cretaceous beds of Neuquén Province, Patagonia, Argentina. Neuquenraptor was later considered as belonging to the Southern Hemisphere paravian clade Unenlagiidae, and proposed as a junior synonym of Unenlagia comahuensis. The aim of the present paper is to include a detailed anatomical description of Neuquenraptor (up to the date only known by a preliminary description). Comparisons with other paravians, especially unenlagiids, resulted in the finding of characters that may be considered as diagnostic of Unenlagiidae (e.g., scar-like fourth trochanter of femur, metatarsal II with tongue-shaped process over the caudal surface of metatarsal III, well-developed convex longitudinal plantar crest of metatarsal IV). Furthermore, comparisons between Neuquenraptor and Unenlagia are carried out with the aim to evaluate the possible synonymy between these taxa. These comparisons indicate that at least two similar-sized unenlagiids were present on the Portezuelo Formation. However, in concordance with previous authors, we are not able to support nor dismiss the possible synonymy between Unenlagia and Neuquenraptor. Additional findings of unenlagiid fossils from the Portezulo Formation will help to clarify the taxonomic status of these taxa.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 3; 549-562
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Interatheriinae notoungulates from the middle Miocene Collon Cura Formation in Argentina
Autorzy:
VERA, BÁRBARA
REGUERO, MARCELO
GONZÁLEZ-RUIZ, LAUREANO
Powiązania:
https://bibliotekanauki.pl/articles/945958.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
notoungulata
interatheriidae
neogene
south america
patagonia
argentina
Opis:
he Interatheriinae (Notoungulata, Interatheriidae) from the Collón Curá Formation (Colloncuran South American Land Mammal Age, SALMA) are revised here, based on old and new collections from western Neuquén, Río Negro, and Chubut provinces where this geologic unit crops out. After a detailed study of the holotype of Icochilus endiadys, we conclude that its cranial and dental morphology are diagnostic of the genus Protypotherium, and as a result we include I. endiadys in this genus (P. endiadys comb. nov.). Deciduous dentition and postcranial remains are also ascribed to P. endiadys, which allows us to determine its pattern of dental eruption and describe part of its limbs, expanding its diagnosis. In addition, we describe a new species of Protypotherium, P. colloncurensis sp. nov., which differs from P. endiadys in having larger size, a more robust mandible, strongly imbricate upper molars, a well-developed parastyle on P1, a subcircular and non-overlapping p1, a much reduced p2, and a smaller talonid on p3–4. Based on the revision, we identified only one genus of Interatheriinae in the Collón Curá Formation (i.e., Protypotherium). Protypotherium endiadys extends its distribution from Neuquén to Chubut provinces, including Río Negro; the new species, in turn, was only recognized in Río Negro Province, appearing together with P. endiadys in Estancia El Criado, Comallo, and Chico River localities. Discriminant and cladistic analyses were performed including P. endiadys, the new taxon, and other middle Miocene interatheres, and yielded strong support for our systematic conclusions. A thorough phylogenetic analysis of Protypotherium is provided for the first time. Based on this analysis, Protypotherium and Miocochilius form a monophyletic group supported by four synapomorphies.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 4; 845-863
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The enamel microstructure of Manidens condorensis: New hypotheses on the ancestral state and evolution of enamel in Ornithischia
Autorzy:
Becerra, M.G.
Pol, D.
Powiązania:
https://bibliotekanauki.pl/articles/2082136.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Dinosauria
Ornithischia
Heterodontosauridae
Manidens
enamel microstructure
evolution
Jurassic
Argentina
Opis:
Previous studies on enamel microstructure in Ornithischia have focused on derived lineages of this clade based on species from the northern hemisphere. Here we describe the enamel microstructure of Manidens condorensis from the late Early Jurassic of Argentina that belongs to Heterodontosauridae (interpreted as the basal-most clade of Ornithischia). Enamel microstructure in the cheek teeth lacks a basal unit layer, presents incipient divergent crystallite as the dominant enamel type and parallel crystallite enamel type (with or without incrementing lines). Enamel of maxillary and dentary teeth differs from each other in enamel distribution (asymmetric vs. symmetric), structure (presence vs. absence of tubules, and less vs. more abundant parallel crystallite enamel with incrementing lines) and ordering (regular ordering of enamel types vs. in patches). The enamel microstructure of Manidens is the simplest of all known Ornithischia, and is more similar to that of the sauropodomorph Plateosaurus than to the one reported for the basal theropod Coelophysis. Similarities within Ornithischia are present with pachycephalosaurids and, to a lesser extent, with ankylosaurs. Phylogenetic optimization of enamel characters in Ornithischia allows the inference of new ancestral states for the internal nodes of the major lineages and to highlight evolutionary transformations: (i) absence of a basal unit layer and presence of parallel crystallite and incipient divergent columnar enamel as the ancestral state for Ornithischia; (ii) the shared presence of incipient divergent columnar units or poorly developed divergent columnar enamel in Pachycephalosauridae and Thyreophora represents a retention of the plesiomorphic ornithischian condition; (iii) the wavy enamel of Dryomorpha evolved from the ancestral incipient divergent columnar units present in Ornithopoda and; (iv) enamel thickness and asymmetry has independently evolved at least four times in Ornithischia.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 1; 59-70
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New postcranial remains of large toxodontian notoungulates from the late Oligocene of Mendoza, Argentina and their systematic implications
Autorzy:
DEL PINO, SANTIAGO HERNÁNDEZ
SEOANE, FEDERICO D.
CERDEÑO, ESPERANZA
Powiązania:
https://bibliotekanauki.pl/articles/945282.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
toxodontidae
leontiniidae
homalodotheriidae
postcranium
deseadan age
argentina
mendoza
Opis:
During the last decade, the Deseadan (late Oligocene) Quebrada Fiera locality, Mendoza Province, Argentina, has provided a large amount of mammal remains. Taxonomic studies have shown the presence of faunal elements common with other Deseadan associations from Patagonia and lower latitudes (Salla, Bolivia), as well as endemic taxa of different groups of mammals (Notohippidae, Leontiniidae, Homalodotheriidae, Hegetotheriidae, and Metatheria) and even a gastropod. In this work, we present a taxonomic and phylogenetic analysis of a set of postcranial fossils of three families of the suborder Toxodontia (Notoungulata). The postcranial elements are assigned to taxa previously recognized at Quebrada Fiera, such as the leontiniid Gualta cuyana and the homalodotheriid Asmodeus petrasnerus, but also to the family Toxodontidae that is represented by Proadinotherium sp. and another larger toxodontid; a few dental remains of Proadinotherium are also included as this is the first time that toxodontids from Quebrada Fiera are described. In the case of A. petrasnerus, an almost complete calcaneum allows us to expand the diagnosis of this taxon. The bones assigned to G. cuyana enlarge the anatomical knowledge of this species. In turn, the presence of the genus Proadinotherium extends its geographic distribution in Argentina and adds to the extra-Patagonian record of P. saltoni from Salla, Bolivia. Phylogenetic results do not differ much from previous analyses using postcranial characters, and the obtained consensus trees show low node supports. The various phylogenetic analyses performed here provide a more robust framework to interpret the relationships of the studied taxa.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 1; 195-210
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New insights into the early diversification of the Ostracoda: Tremadocian ostracods from the Cordillera Oriental, Argentina
Autorzy:
Salas, M.J.
Vaccari, N.E.
Powiązania:
https://bibliotekanauki.pl/articles/22883.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
insight
early diversification
Ostracoda
Tremadocian
ostracod
Argentina
Andes Mountains
Opis:
New species of ostracods from the Tremadocian in the northwest region of Argentina are described. These are among the earliest well−documented records of ostracods, which shed new light onto the early diversification of the group. The described fauna consists of seven species, five of which are new: Saltite uchuy sp. nov., Saltite kuraq sp. nov., Conchoprimitia? iglesiasi sp. nov., Orechina violetae sp. nov., and Orechina catalinae sp. nov. The fauna consists primarily of soanellids, a non−dimorphic family of palaeocopids, and of binodicopids. One factor leading to diversification of the group in this region may have been the complex configuration of the northwest basin, which had a restricted pattern of circulation. The distribution of the first ostracods is largely restricted to Gondwana and peri−Gondwana regions. Accordingly, it is possible to envision that the origin or at least an important radiation of the group was centred in this region. Both the Soanellidae and the genus Orechina would have originated in Gondwana and would have become widespread later during the Middle Ordovician. The Tremadocian fauna located in Argentina show significant affinities with fauna located in the warm−water setting of the east Gondwana, mainly in Australia and China.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth dynamics and body size evolution of South American long-necked chelid turtles: A bone histology approach
Autorzy:
Pereyra, M.E.
Bona, P.
Cerda, I.A.
Jannello, J.M.
De La Fuente, M.S.
Desantolo, B.
Powiązania:
https://bibliotekanauki.pl/articles/2082231.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Testudines
Chelidae
growth rate
body size
paleohistology
ontogeny
Paleocene
Argentina
Opis:
Among turtles, cases of “gigantism” occur mostly in pleurodiran Pelomedusoides and cryptodirans, but are infrequent among pleurodiran chelids, which are mostly small-medium sized turtles. Yaminuechelys spp. are extinct South American long-necked chelids (from the Late Cretaceous–early Paleocene of Patagonia, Argentina) with caparaces almost three times larger than their extant sister taxon, Hydromedusa tectifera. Since evolutionary changes in size can be analyzed based on growth dynamics, we studied growth strategies from an osteohistological point of view. We sampled both extinct (Yaminuechelys maior) and extant (H. tectifera) species, in order to test hypotheses related to the mechanisms involved in the macroevolution of size within this clade. For this purpose, thin sections of long bone (humerus and femur) shafts of specimens of different ontogenetic stages for these species were prepared. The osteohistological study reveals a similar growth dynamic in both taxa, with a poorly vascularized cortex dominated by parallel- fibered bone and interrupted by lines of arrested growth (LAGs). The huge body size of Y. maior appears to be a consequence of the prolongation of the growth phase, suggesting that it had a longer lifespan than H. tectifera, allowing to reach greater sizes. In this way, and assuming that there is no displacement at the beginning of development (e.g., a delay in the earliest stages of growth) in H. tectifera, the acquisition of a large size in Yaminuechelys would be explained by hypomorphosis of the former or hypermorphosis of the latter, depending on the reconstruction of the ancestral condition of this clade.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 3; 535-545
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Osteology of the dorsal vertebrae of the giant titanosaurian sauropod dinosaur Dreadnoughtus schrani from the Late Cretaceous of Argentina
Autorzy:
VOEGELE, KRISTYN K.
LAMANNA, MATTHEW C.
LACOVARA, KENNETH J.
Powiązania:
https://bibliotekanauki.pl/articles/945927.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
sauropoda
titanosauria
dreadnoughtus
dorsal vertebrae
cretaceous
cerro fortaleza formation
argentina
Opis:
Many titanosaurian dinosaurs are known only from fragmentary remains, making comparisons between taxa difficult because they often lack overlapping skeletal elements. This problem is particularly pronounced for the exceptionally large-bodied members of this sauropod clade. Dreadnoughtus schrani is a well-preserved giant titanosaurian from the Upper Cretaceous (Campanian–Maastrichtian) Cerro Fortaleza Formation of southern Patagonia, Argentina. Numerous skeletal elements are known for Dreadnoughtus, including seven nearly complete dorsal vertebrae and a partial dorsal neural arch that collectively represent most of the dorsal sequence. Here we build on our previous preliminary description of these skeletal elements by providing a detailed assessment of their serial positional assignments, as well as comparisons of the dorsal vertebrae of Dreadnoughtus with those of other exceptionally large-bodied titanosaurians. Although the dorsal elements of Dreadnoughtus probably belong to two individuals, they exhibit substantial morphological variation that suggests that there is minimal, if any, positional overlap among them. Dreadnoughtus therefore preserves the second-most complete dorsal vertebral series known for a giant titanosaurian that has been described in detail, behind only that of Futalognkosaurus. The dorsal sequence of Dreadnoughtus provides valuable insight into serial variation along the vertebral column of these enormous sauropods. Such variation includes the variable presence of divided spinodiapophyseal laminae and associated spinodiapophyseal fossae. Given that dorsal vertebrae are the only elements that overlap between known remains of most giant titanosaurian taxa, the dorsal series of Dreadnoughtus provides a means to directly compare the morphologies of these sauropods. The dorsal vertebrae of Dreadnoughtus and Futalognkosaurus have dorsoventrally narrow transverse processes, unlike the condition in Puertasaurus. Further, Dreadnoughtus and Argentinosaurus have ventromedially inclined prezygapophyses, whereas Futalognkosaurus has almost horizontal prezygapophyses. The continued inclusion of new, well-represented skeletons of titanosaurians such as Dreadnoughtus in phylogenetic and functional morphological studies will aid in deciphering the interrelationships and paleobiology of Titanosauria.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 4; 667-681
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unusual shell anatomy and osteohistology in a new Late Cretaceous panchelid turtle from northwestern Patagonia, Argentina
Autorzy:
DE LA FUENTE, MARCELO S.
MANIEL, IGNACIO
JANNELLO, JUAN MARCOS
STERLI, JULIANA
GARRIDO, ALBERTO C.
GARCIA, RODOLFO A.
SALGADO, LEONARDO
CANUDO, JOSÉ I.
BOLATTI, RAÚL
Powiązania:
https://bibliotekanauki.pl/articles/945623.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
testudines
pleurodira
post-cranial morphology
paleohistology
cretaceous
argentina
río negro
Opis:
Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2–11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 3; 585-601
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lamellorthoceratid cephalopods in the cold waters of southwestern Gondwana: Evidences from the Lower Devonian of Argentina
Autorzy:
Cichowolski, M.
Rustan, J.J.
Powiązania:
https://bibliotekanauki.pl/articles/2082150.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cephalopoda
Lamellorthoceratidae
Arthrophyllum
Palaeozoic
Talacasto Formation
Malvinokaffric
Realm
Precordillera Basin
Argentina
Opis:
Based on three specimens assigned to Arthrophyllum sp., the family Lamellorthoceratidae is reported from the Lower Devonian Talacasto Formation in the Precordillera Basin, central western Argentina. These Devonian cephalopods have been known only from low to mid palaeolatitudes and its presence in the cold water settings of southwestern Gondwana is notable. A nektonic mode of life, not strictly demersal but eventually pelagic, with a horizontal orientation of the conch is proposed for adults lamellorthoceratids, whereas a planktonic habit is suggested for juvenile individuals. These features would had allow their arrival to this southern basin, explaining their unusual presence in the Malvinokaffric Realm, and reinforcing the need of re-evaluate the distribution pattern of several groups of cephalopods.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 2; 305-312
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz Formation of Patagonia, Argentina
Autorzy:
Toledo, N.
Cassini, G.H.
Vizcaino, S.F.
Bargo, M.S.
Powiązania:
https://bibliotekanauki.pl/articles/946022.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
xenarthra
folivora
santacrucian sloths
body mass
substrate preference
paleobiology
miocene
argentina
Opis:
Miocene deposits of the Santa Cruz Formation, Patagonia, comprise a diverse and excellently preserved vertebrate fauna, allowing detailed paleobiological and paleoecological studies based on three ecological parameters: body mass, diet, and substrate preference. In contrast to the small and arboreal extant sloths, Bradypus and Choloepus, Santacrucian sloths were much more diverse and larger, and comprised 11 genera previously characterized as arboreal or climbing forms. Here, we focus on body mass estimation based on measurements of postcranial elements. We present a morphometric database comprising 64 linear, base-ten logged variables applied to Santacrucian sloths and a wide sample of extant mammals, as well as the body mass of the extant taxa as reported in the literature. To detect any potential phylogenetical bias, we performed a variance decomposition test on our sample of extant mammals. Based on four orthogram statistics, logged body mass was found not to be dependent on phylogenetic tree topology. Predictive equations for the body mass of extant mammals were generated through multiple regression analysis, using weighting procedures to avoid taxonomic biases and stepwise analysis to discard redundant variables. Using this procedure, we derived separate equations for the scapula, humerus, radius, ulna, pelvis, femur, tibia plus fibula, astragalus, and calcaneum. These equations were then applied to estimate the body mass of our sample of Santacrucian sloths. We obtained an average body mass of about 70 kg for the megalonychid Eucholoeops. Among stem megatherioids, Hapalops ranged between 30 and 80 kg, Analcimorphus was estimated at 67 kg, and Schismotherium at 44 kg. Larger genera included the megatheriid Prepotherium (~123 kg), and the mylodontids Analcitherium (~88 kg) and Nematherium (~89 kg). The medium to large body size of Santacrucian sloths imposed constraints on their climbing abilities. Megalonychids and stem megatherioids were likely unable to access the finest branches, while megatheriids and mylodonts were more terrestrial forms.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 2; 267-280
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
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