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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:
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:
A new species of the plagiaulacoid multituberculate mammal Eobaatar from the Early Cretaceous of southern Britain
Autorzy:
Sweetman, S C
Powiązania:
https://bibliotekanauki.pl/articles/23357.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new species
plagiaulacoid multituberculate
multituberculate
mammal
Eobaatar
Early Cretaceous
Cretaceous
paleontology
England
Mammalia
Multituberculata
Plagiaulacoidea
Wealden
Barremian
Opis:
Until recently, the only mammal remains to be obtained from the Early Cretaceous (Barremian, Wealden Group) Wessex Formation of the Isle of Wight, southern England were a poorly preserved left m2 and a well preserved left I2 crown representing one or possibly two plagiaulacoid multituberculate species. These were recovered in the early 1970s but despite subsequent efforts by a number of workers to recover additional Mesozoic mammal remains none were forthcoming until comprehensive bulk screening of the Wessex Formation was undertaken in a study commenced in 2002. This study resulted in the recovery of a number of new specimens representing an assemblage of at least six taxa. Among these are a well−preserved plagiaulacoid multituberculate left m1 and a similarly preserved left I3. The former permits diagnosis of a new species of eobaatarid, Eobaatar clemensisp. nov. The previously recovered left m2 is also tentatively assigned to the same taxon. In addition, another left m1, somewhat worn as a result of dietary attrition, was recently obtained by a private collector. This is of very similar morphology to the holotype of E. clemensi but slightly larger. It is undoubtedly referable to the same taxon and provides some insight into intraspecific size, and other minor morphological variations in the teeth of the new species. The I3 may also be referable to the new species, in which case it is the first well preserved I3 of a member of Eobaataridae to be fully described.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 373-384
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 symbiotic association of a boring polychaete and an echinoid from the Late Cretaceous of Germany
Autorzy:
Wisshak, M.
Neumann, C.
Powiązania:
https://bibliotekanauki.pl/articles/21643.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Germany
Cretaceous
Late Cretaceous
trace fossil
fossil
polychaete
Polychaeta
Spionidae
bioerosion
Maastrichtian
symbiotic association
echinoid
Caulostrepsis
Polydora
Echinocorys
Opis:
From the Early Maastrichtian white chalk of Rügen Island (N Germany), a specimen of the echinoid Echinocorys ovata featuring 27 boring traces of the ichnogenus Caulostrepsis is described. Individual traces are shallow to moderately deep U−shaped depressions and show distinct regeneration textures evidencing a syn−vivo infestation. All traces are located on the plastron between the peristome and periproct of the host echinoid, indicating an adaptation of the trace maker by choosing the most advantageous position of the specific host. The traces are attributed to the work of boring spionid polychaetes (Polydora complex), grounded on the close morphological resemblance with initial borings of Recent polydorids. This is the first evidence for a possible association of a boring polychaete not only with an echinoid but with an echinoderm in general. The symbiotic relationship was commensalistic in nature with the spionid probably taking advantage of organic matter resuspended by the echinoids locomotion and feeding activity and benefiting from effective shelter. For the host echinoid, the association was moderately harmful. The soft bottom environment of the chalk sea provided very limited hard substrate ecospace for settlers and bioeroders, available only in form of biogenic structures. Echinocorys was a dominant component of this benthic community and can be considered as a suitable host for symbiotic interactions because of its size and assumed longevity.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New cupedid beetles from the Lower Cretaceous of Spain and the palaeogeography of the family
Autorzy:
Soriano, C
Delclos, X.
Powiązania:
https://bibliotekanauki.pl/articles/23502.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Lower Cretaceous
Cretaceous
beetle
cupedid beetle
Coleoptera
paleobiogeography
Spain
paleontology
Cupedidae
Opis:
Thirteen new species of the family Cupedidae (Coleoptera: Archostemata) from Las Hoyas (Cuenca province) and El Montsec (Lleida province) fossil sites from the Barremian (Lower Cretaceous) of Spain are described. Ten of them belong to subfamily Ommatinae: Tetraphalerus ponomarenkoi, Tetraphalerus penalveri, Cionocoleus longicapitis, Brochocoleus indibili, Zygadenia viridis, Zygadenia oculata, Zygadenia martinclosas, Zygadenia longicoxa, and Zygadenia siniestri. Three of them are assigned to subfamily Cupedinae: Priacma sanzii, Anaglyphites zherikhini, and Anaglyphites pluricavus. Placement of genus Cionocoleus among subfamily Ommatinae is proposed. These new species extend the record of genera Zygadenia, Cionocoleus, Brochocoleus, Priacma, and Anaglyphites to the western part of Barremian European deposits. Nowadays the family Cupedidae is considered to be a relic group, restricted to few genera and species on Asia, Africa, Australia, and America, with limited geographical distribution, while during the Mesozoic the cupedids were distributed all over Laurasia. The Mesozoic cupedid−bearing localities are mostly interpreted as warm temperate to subtropical environments.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systematic palaeontology of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France), and its implications for biostratigraphy
Autorzy:
Frau, C.
Bulot, L. G.
Wimbledon, W. A. P.
Ifrim, C.
Powiązania:
https://bibliotekanauki.pl/articles/138820.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ammonites
Berriasian
Cretaceous
biostratigraphy
Le Chouet
France
amonity
berias
kreda
biostratygrafia
Francja
Opis:
This study describes ammonite taxa of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France). Emphasis is placed on new and poorly known Himalayitidae, Neocomitidae and Olcostephanidae from the lower part of the Jacobi Zone auctorum. Significant results relate the introduction of Lopeziceras gen. nov., grouping himalayitid-like forms with two rows of tubercles, and Praedalmasiceras gen. nov., grouping the early Berriasian Dalmasiceras taxa. Study of the ontogenetic sequences of both genera show that they were derived from late Tithonian Himalayitidae. This supports the distinction between the subfamilies Himalayitinae and Dalmasiceratidae subfam. nov. Content, variation, dimorphism and vertical range of the Neocomitidae Berriasella, Pseudoneocomites, Elenaella and Delphinella are discussed. A conservative use of the Olcostephanidae Proniceras is followed herein.
Źródło:
Acta Geologica Polonica; 2016, 66, 2; 175-204
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-destructive analysis of pathological belemnite rostra by micro-CT techniques
Autorzy:
Hoffmann, R.
Stevens, K.
Picollier, M.-C.
Mutterlose, J.
Klug, C.
Powiązania:
https://bibliotekanauki.pl/articles/2082134.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cephalopoda
Belemnitida
palaeopathology
rostra
micro computed-tomography
diagenesis
Jurassic
Cretaceous
Germany
Opis:
Previously, palaeopathological features of fossil hardparts were often difficult to interpret because it was impossible to decipher their internal structure without destroying the specimens. We applied high-resolution computedtomo graphy (CT) to document such internal structures. This enabled us to describe a variety of pathologies of Jurassic and Cretaceous belemnite rostra. The examined rostra have been assigned to the taxa ?Acrocoelites sp., Belemnello camax spp., Belemnitella sp., Duvalia emerici, Goniocamax sp., Gonioteuthis spp., Hibolithes jaculoides, Neoclavibelus subclavatus, and Pseudobelus sp. The studied pathologies comprise rostra with two apices, bulges, pearls, broken juvenile rostra, highly porous rostra with abnormal growth increments, blunt-rostra, rostra with callus- like structures, and bent- or knee-shaped rostra. In one rostrum the apex has been turned towards the anterior (alveolus) during ontogeny. Additionally, computed-tomography data were used to document diagenetic alterations of the rostra such as silification, sedimentary infill, pyrite formation. Specimens can also be tested for the presence or absence of internal elements (septa, siphuncle) and surface features. Palaeoecological studies clearly benefit from the application of computed-tomography to gain high resolution images of otherwise invisible internal features of extinct organisms, as demonstrated herein.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 1; 11-27
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new ornithomimid dinosaur with gregarious habits from the Late Cretaceous of China
Autorzy:
Kobayashi, Y
Lu, J.C.
Powiązania:
https://bibliotekanauki.pl/articles/20983.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cretaceous
Late Cretaceous
Theropoda
Dinosauria
China
Ornithomimosauria
gragarious habit
dinosaur
Ornithomimidae
paleontology
ornithomimid dinosaur
Opis:
At least fourteen ornithomimid skeletons were recovered from the Upper Cretaceous Ulansuhai Formation in Nei Mongol (Inner Mongolia) Autonomous Region of China. They are assigned to a new genus and species, Sinornithomimus dongi. The anatomy of the species is described. Comparative and phylogenetic studies of ornithomimosaurs prove that these skeletons represent a new taxon that is more derived than Archaeornithomimus and more basal than the clade of [(Anserimimus + Gallimimus)+[Struthiomimus + (Dromiceiomimus + Ornithomimus)]]. The phylogenetic analysis suggests that the structure of the hand is similar to Archaeornithomimus and represents an intermediate condition between the primitive (Harpymimus) and the derived (Anserimimus, Gallimimus, Struthiomimus, Dromiceiomimus, and Ornithomimus) conditions. The monophyly of Ornithomimidae is supported by a single synapomorphy (arctometatarsalian condition) in this analysis, indicating that the family is not as strongly supported as previously suggested. The analysis also implies that the shape of the rhamphotheca in North American taxa may have been different from that in Asian taxa. Previous study suggests herbivorous habits of this dinosaur based on characteristics of the gastroliths. The skeletons of Sinornithomimus were collected from a single monospecific bonebed with a high ratio of juvenile individuals (11 of the 14), suggesting gregarious behavior for protection from predators. The abundance of juveniles indicates high mortality of juveniles or a catastrophic mass mortality of a population with a high proportion of juveniles. An increase in the relative ratio of the tibia to femur through the ontogeny of Sinornithomimus suggests higher cursoriality in adult individuals than in juveniles.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new glimpse on trophic interactions of 100-million-year old lacewing larvae
Autorzy:
Hornig, M.K.
Kiesmuller, C.
Muller, P.
Haug, C.
Haug, J.T.
Powiązania:
https://bibliotekanauki.pl/articles/2082238.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Neuroptera
Nymphidae
food-web reconstruction
Burmese amber
larvae
syninclusions
Cretaceous
Myanmar
Opis:
Larvae of lacewings (Neuroptera) are known to be fierce predators. According to the morphology of fossil forms this seems to have been the case already in the Early Cretaceous. While being predators, lacewing larvae are also food items for other organisms. Here we report two pieces of amber from Myanmar providing instances of such cases. In one amber piece several isolated stylets of lacewing larvae are preserved closely associated together. The most likely interpretation is that a predator preying on lacewing larvae has regurgitated or defecated these non-digestible pieces, yet the identity of the predator remains unclear. The other amber piece preserves a larva resembling modern day larvae of split-footed lacewings (Nymphidae). The larva has projections on its trunk, allowing it to wear a camouflaging cloak. In the head region, a mite (Acari) is attached to the larva; more precisely, the entire anterior body region of the mite is apparently inserted into the lacewing larva. The mite is smaller than the larva. It is known from the modern fauna that stage 1 larvae of Ascalaphidae can be attacked also by rather small predators, such as ants. The mite can therefore well be interpreted as a true predator instead of a parasite, especially considering the unusual mode of attachment. We briefly review interactions of lacewing larvae with other organisms represented in amber from Myanmar and add two new pieces to the puzzle of reconstructing the trophic interactions in the 100-million-year old amber forest.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 4; 777-786
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First North American occurrence of hairy cicadas discovered in the Cenomanian (Late Cretaceous) of Labrador, Canada
Autorzy:
Demers-Potvin, A.V.
Szwedo, J.
Paragnani, C.P.
Larsson, H.C.E.
Powiązania:
https://bibliotekanauki.pl/articles/2082146.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Insecta
Cicadoidea
Tettigarctidae
Cretaceous
Cenomanian
Redmond Formation
North America
Opis:
We report the discovery of Maculaferrum blaisi gen. et sp. nov, the first occurrence of the family Tettigarctidae, informally known as hairy cicadas, in North America. Maculaferrum blaisi is part of a new collection assembled during recent fieldwork in the Redmond Formation, Labrador, Canada, near Schefferville. It consists in a single isolated forewing whose venational characters allow a classification to Tettigarctinae at the subfamily level. Classification at a higher level remains uncertain since it displays a combination of characters supposedly unique to tribes Protabanini, Meunierini, and Tettigarctini. Thus, this discovery adds credence to suggestions of a revision of the definitions of these tribes since they seem to be based on many convergent or plesiomorphic characters. Remnants of a spotted pattern on the wing membrane and probable setae along some veins are also preserved. Observations of the holotype’s fine anatomical characters have been facilitated by the use of Reflectance Transformation Imaging (RTI), an emerging method for the visualization of compression and impression fossils. Considering that the estimated age of the Redmond Formation is the Cenomanian (Late Cretaceous), the discovery of M. blaisi contributes to a very recent expansion of the tettigarctid fossil record that fills a gap between Early Cretaceous and Cenozoic genera. It suggests that hairy cicadas maintained a global distribution and thrived in a variety of climate regimes well into the Late Cretaceous, and that their competitive exclusion by singing cicadas occurred definitely closer to the end of the Cretaceous, or even during the Cenozoic. This discovery is only the start of a thorough description of the recently expanded entomofauna in the Cretaceous of Labrador.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 1; 85-98
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cylindrichnus concentricus Toots in Howard, 1966 (trace fossil) in its type locality, Upper Cretaceous, Wyoming
Autorzy:
Ekdale, A. A.
Harding, S. C.
Powiązania:
https://bibliotekanauki.pl/articles/191694.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
bioturbation
Cretaceous
Cylindrichnus concentricus
type locality
Wyoming
Opis:
Cylindrichnus concentricus is a wide spread trace fossil in shallow marine sedimentary rocks of Mesozoic and Cenozoic age. This paper clarifies the ichnotaxonomy of C. concentricus by of fering an emended diagnosis of the ichnogenus and a new diagnosis of the ichnospecies. The broad, bow-shaped architecture of C. concentricus with two openings at the sediment surface suggests that the trace maker was either a filter-feeding animal that captured suspended food particles from the water column or else a surface deposit feeder that employed tentacles or an eversible pharynx to collect nutritious sediment from the surface around one or both of the burrow openings. Although C. concentricus has been reported in a variety of different sedimentary environments around the world, in its type locality in the Cretaceous of Wyoming the trace fossilis found in low-diversity or monoichnospecific beds that exhibit hummocky cross stratification. This occurrence suggests the burrower’s tolerance (or perhaps preference) for an episodic high-energy hydrodynamic environmentre lated to major storms.
Źródło:
Annales Societatis Geologorum Poloniae; 2015, 85, 3; 427-432
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calcite cements and the stratigraphical significance of the marine [delta^13]C carbonate reference curve for the Upper Cretaceous Chalk of England
Autorzy:
Jeans, C.
Hu, X.
Mortimore, R.
Powiązania:
https://bibliotekanauki.pl/articles/139078.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cement kalcytowy
chemostratygrafia
izotopy
korelacja
kreda
krzywa referencyjna
ograniczenia
calcite cement
chemostratigraphy
correlation
Cretaceous
[delta^13]C reference curve
isotope events
limitations
Opis:
The hypothesis of Jarvis et al. (2006) that a [delta^13]C (calcite) reference curve based upon bulk samples from the Upper Cretaceous Chalk of England can be used as a primary criterion for trans-continental correlation is reviewed in the light of new stable isotope data from the Upper Albian and Cenomanian chalks of eastern England and from the Cenomanian to Campanian chalks of southern England. Evidence demonstrates that in the coloured chalks of eastern England the cements invariably have positive [delta^13]C values (up to 3.5[per mil]) except where they have been affected by hardground development when the cements have negative [delta^13]C values down to -6.5[per mil]. in contrast, the White Chalk of southern England may have cements with [delta^13]C values as negative as -8[per mil]. Modelling indicates that the coloured chalks may preserve a truer record of the primary palaeo-oceanographic [delta^13]C signal than the white and grey chalks of southern England. it is suggested that (1) many of the 72 isotope events described from the [delta^13]C (calcite) reference curve and proposed for correlation may reflect the effects of variations in the type and extent of calcite cementation; and (2) until much more is known about the patterns of calcite cementation in the Upper Cretaceous Chalk the use of minor isotope events for trans-continental stratigraphic correlation can only be applied with the utmost caution.
Źródło:
Acta Geologica Polonica; 2012, 62, 2; 173-196
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger
Autorzy:
Sereno, P C
Brusatte, S.L.
Powiązania:
https://bibliotekanauki.pl/articles/21335.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Allosauroidea
Cretaceous
Elrhaz Formation
paleontology
Eocarcharia
Africa
Lower Cretaceous
Theropoda
Kryptops
carcharodontosaurid theropod
Abelisauridae
theropod
Carcharodontosauridae
abelisaurid theropod
Niger
Opis:
We report the discovery of basal abelisaurid and carcharodontosaurid theropods from the mid Cretaceous (Aptian–Albian, ca. 112 Ma) Elrhaz Formation of the Niger Republic. The abelisaurid, Kryptops palaios gen. et sp. nov., is represented by a single individual preserving the maxilla, pelvic girdle, vertebrae and ribs. Several features, including a maxilla textured externally by impressed vascular grooves and a narrow antorbital fossa, clearly place Kryptops palaios within Abelisauridae as its oldest known member. The carcharodontosaurid, Eocarcharia dinops gen. et sp. nov., is represented by several cranial bones and isolated teeth. Phylogenetic analysis places it as a basal carcharodontosaurid, similar to Acrocanthosaurus and less derived than Carcharodontosaurus and Giganotosaurus. The discovery of these taxa suggests that large body size and many of the derived cranial features of abelisaurids and carcharodontosaurids had already evolved by the mid Cretaceous. The presence of a close relative of the North American genus Acrocanthosaurus on Africa suggests that carcharodontosaurids had already achieved a trans−Tethyan distribution by the mid Cretaceous.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stagodontid marsupials from the Late Cretaceous of Canada and their systematic and functional implications
Autorzy:
Fox, R C
Naylor, B.G.
Powiązania:
https://bibliotekanauki.pl/articles/23125.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Canada
Cretaceous
Late Cretaceous
Stagodontidae
Mammalia
stagodontid mursupial
Alberta
Marsupialia
paleontology
Opis:
Previously undescribed specimens of stagodontid marsupials from Late Cretaceous deposits in Alberta, Canada, reveal new information concerning the upper dentition of Eodelphisspp. and the lower dentition of Didelphodon coyi. Additionally, an incomplete upper dentition of D. coyi from the Scollard Formation extends the range of this species into the Lancian, co−eval with D. vorax and D. padanicus. Stagodontids are in accord with other North American Late Cretaceous marsupials for which the appropriate parts are known in lacking diastemata between the canines and the molars while possessing well−developed palatal vacuities, implying that these morphologies characterized ancestral marsupials. If so, the diastema between P1 and P2 in the Asian middle Early Cretaceous “metatherian” Sinodelphys szalayi is convergent on that in Cenozoic didelphids, and the absence of palatal vacuities in South American Paleogene and Neogene borhyaenids is derived, representing a paedomorphic truncation of development. Claims that the Asian Late Cretaceous “metatherian” Deltatheridium pretrituberculare had a marsupial−like dental replacement pattern are tautological, deduced from an a priori acceptance of a marsupial model of replacement to the exclusion of other, no less realistic, alternatives. The new specimens of Didelphodon coyi demonstrate that upper and lower premolars occluded broadly, implying that the inflated lingual lobes characteristic of Didelphodon premolars evolved primarily as a crushing mechanism, not for passive protection of the gums. Recent speculations that stagodontids were aquatic are not based on credible morphologic or taphonomic evidence and are dismissed, as is speculation that the Judithian species of Eodelphis are sexual morphs of a single species. Current knowledge of Didelphodon compels correction of numerous errors concerning its morphology as presented in recent analyses of marsupial relationships.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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