Gotowa bibliografia na temat „Riversleigh”

Riversleigh, Patrimoine Mondial de l’humanité, dans le nord-ouest du Queensland en Australie, contient plus de 200 localités fossilifères de l’Oligo-Miocène. L’étude présentée ici vise à trouver de nouvelles méthodes pour améliorer l'exactitude des études paléoécologique et biochronologique et décrire les paramètres paléoenvironnementaux et chronologique des localités de Riversleigh. L'une des méthodes développées dans cette thèse, le Minimum Sample Richness (MSR), détermine le nombre minimum d'espèces qui doivent être présents dans une faune pour permettre des comparaisons significatives avec les analyses multivariées. En utilisant le MSR, plusieurs localités de Riversleigh ont été choisies pour une étude paléoécologique utilisant la méthode des cénogrammes, permettant de déterminer les paléoenvironnements pendant l’Oligo-Miocène. Enfin, la méthode des âges numériques a été utilisée pour raffiner l’âge relatif des localités de Riversleigh et une réévaluation des Systems de Riversleigh est proposée<br>Riversleigh, World Heritage Property, located in North-western Queensland, Australia, contains over 200 fossil bearing localities from the Oligo-Miocene. The study presented here aims at finding new methods to improve the accuracy of palaeoecological and biochronological studies and describe the palaeoenvironmental and chronological settings of the Riversleigh fossil deposits. One of the methods developed in this thesis, Minimum Sample Richness (MSR), determines the minimum number of species that must be present in a fauna to allow meaningful comparisons using multivariate analyses. Using MSR, several Riversleigh localities were selected for a palaeoecological study using the cenogram method to determine the palaeoenvironment during the Oligo-Miocene. Finally, the Numerical ages method was used to refine the relative ages of the Riversleigh localities and a re-diagnosis of the Riversleigh Systems is proposed

The extinct diprotodontoids were large bodied, browsing herbivorous marsupials most closely related to, among living marsupials, wombats. Referred to two families, Diprotodontidae and Palorchestidae, diprotodontoids are geographically and temporally widespread vombatimorphian taxa in Australian and New Guinean Cenozoic deposits. The most diverse diprotodontoid fauna recorded from any single region in Australia comes from Oligo-Miocene limestone deposits of the Riversleigh World Heritage Area, northwestern Queensland. In this thesis a new diprotodontoid genus and five new species are described from Riversleigh, as well as additional material from Riversleigh for the palorchestids Propalorchestes novaculacephalus and Pr. ponticulus and diprotodontids Nimbadon lavarackorum, Neohelos tirarensis, Neohelos stirtoni and Ngapakaldia bonythoni. A new vombatomorphian family, Maradidae, known from a single species at Riversleigh, is recognised as the sister-group of a vombatid-diprotodontoid clade. New abundant, exceptionally well-preserved cranial material of the zygomaturine Nimbadon lavarackorum enables characterisation of intraspecific variation and ontogenetic development. The results of these analyses have been used to discriminate species boundaries throughout this work. Consequently: Nimbadon whitelawi is now considered a junior synonym of Ni. lavarackorum; Nimbadon scottorrorum is a junior synonym of Neohelos tirarensis; and Bematherium angulum is a synonym of Ngapakaldia bonythoni. The new Riversleigh diprotodontoids clarify phylogenetic relationships within and between diprotodontoid families. The monophyly of both Palorchestidae and Diprotodontidae is strongly supported as is their union in the superfamily Diprotodontoidea. Monophyly of the Zygomaturinae and Diprotodontinae is not supported, primarily due to the unstable position of Alkwertatherium webbi as well as the high degree of homoplasy in cranial morphology of the more derived members of each subfamily. Overall phylogenetic and distribution patterns for diprotodontoids is generally consistent with current interpretations of Riversleigh's stratigraphy. Five diprotodontoid species allow direct biocorrelation with other Australian Tertiary mammal faunas. Riversleigh's basal System A deposits correlate with late Oligocene deposits of the Etadunna Formation of South Australia. Riversleigh's low-mid System C deposits correlate with the middle Miocene Bullock Creek Local Fauna of the Northern Territory. Riversleigh's high System C Jaw Junction and Encore Local Faunas contain diprotodontoid taxa antecedent to diprotodontoids of the late Miocene Alcoota Local Fauna of the Northern Territory.

Riversleigh, World Heritage Property, located in North-western Queensland, Australia, contains over 200 fossil bearing localities from the Oligo-Miocene. The study presented here aims at finding new methods to improve the accuracy of palaeoecological and biochronological studies and describe the palaeoenvironmental and chronological settings of the Riversleigh fossil deposits. One of the methods developed in this thesis, Minimum Sample Richness (MSR), determines the minimum number of species that must be present in a fauna to allow meaningful comparisons using multivariate analyses. Using MSR, several Riversleigh localities were selected for a palaeoecological study using the cenogram method to determine the palaeoenvironment during the Oligo-Miocene. Finally, the Numerical ages method was used to refine the relative ages of the Riversleigh localities and a re-diagnosis of the Riversleigh Systems is proposed.

The marsupial family Pseudocheiridae is currently known from seventeen species of six genera in Australia and New Guinea. These small to medium-sized arboreal animals are nocturnal and folivorous. Extinct pseudocheirids are recognised from several mid to late Cenozoic fossil localities across Australia and New Guinea. The single largest collection of pseudocheirid fossils has been recovered from the Oligo-Miocene freshwater carbonates of the Riversleigh World Heritage Area in northwest Queensland. This collection, which includes the first pseudocheirid cranial fossils, forms the basis of this investigation. Three new extinct pseudocheirid genera together containing four species are identified and described. Six new species of Paljara, Marlu and Pildra are also described from Riversleigh. Two of the new Marlu species are reported from South Australia??s Leaf Locality. From Riversleigh, Marlu kutjamarpensis is identified and additional material of Paljara tirarensae and P. nancyhawardae documented. New species attributed to Marlu and Pildra necessitate revision of those genera. Cranial material is identified for three of the new species. The rostrum of archaic pseudocheirids is shorter than in extant forms but cranial morphology is similar overall. Phylogenetic relationships of all extinct pseudocheirids are analysed. They include all new and previously described species, most of which have never been examined in a parsimony-based analysis. Two hypotheses of pseudocheirid evolution are presented: a paired lineage hypothesis and a single lineage hypothesis. Both hypotheses demonstrate that species of Paljara are not the most plesiomorphic pseudocheirids, Marlu praecursor does not cluster with other species of Marlu, the new genus Gawinga is most closely related to Paljara and there are no representatives of the extant genus Pseudochirops in any pre-Pliocene locality. All extant pseudocheirids cluster to form a crown clade sister to a stem lineage of Pseudokoala and Marlu species. Pseudocheirids are found in all Oligo-Miocene faunal zones of Riversleigh. Species of Paljara and Marlu are most frequently recovered from Faunal Zone B and C deposits respectively. Four pseudocheirid species biostratigraphically correlate the Kutjamarpu local fauna of the Leaf Locality with Faunal Zones B and C of Riversleigh, suggesting an early to middle Miocene age for both deposits. Modern pseudocheirids first evolved no later than the late Miocene from a descendant of the Marlu + Pseudokoala lineage when all other Oligo-Miocene pseudocheirids became extinct. At least three pseudocheirid lineages dispersed to New Guinea approximately five million years ago, but ecological barriers probably prevented subsequent migrations between the two landmasses.

Wombats (Vombatidae, Marsupialia) are fossorial marsupials that are most closely related to koalas amongst living marsupials. The cheek teeth of wombats are unique amongst Australian marsupials in being hypselodont (the condition where the teeth continue to grow throughout life and the formation of roots is suppressed). Hypselodonty is an adaptation to high degrees of tooth wear. The fossil record of vombatids is largely restricted to Pliocene to recent deposits and is largely represented by isolated teeth. Six genera are currently recognised from these deposits, all of which have hypselodont teeth. To date, a single isolated vombatid tooth has been described from pre-Pliocene deposits of South Australia and is the only example of a vombatid cheek tooth that possesses roots. Seventy specimens, representing five species of vombatid, have been recovered from Oligo-Miocene deposits in the Riversleigh World Heritage Site in northwestern Queensland and are described here. Among these are four new species and one new genus. A new species of Warendja from Riversleigh is described. It represents the oldest known hypselodont vombatid. This species is compared with additional specimens of the Pleistocene species of Warendja (W wakefieldi). Three species of Rhizophascolonus and a new monotypic genus are also described. Phylogenetic analysis of these taxa indicates that Rhizophascolonus may represent a sister taxon to the other vombatids. These specimens comprise almost all known examples of Oligo-Miocene vombatids. Most of the specimens are isolated teeth and are highly variable in size and morphology. Cusp detail is clearly preserved on many, allowing for omparison with the cusp morphology on juvenile cheek teeth of the common wombat (Vombatus ursinus). All of the taxa found in the deposits at Riversleigh share a number of characters such as marked differences in enamel thickness and height around the cheek teeth. It is argued here that these shared characters are indicative of high amounts of tooth wear and/or occlusal stresses acting on the trailing edge enamel. Combined with evidence of scratch-digging adaptations of the forelimbs it is suggestive of a rhizophagous niche for at least some of these early vombatids.

The fossil record of marsupial lions (family Thylacoleonidae) from Australian Oligo Miocene deposits is generally poor. Study of new material of this family collected from Oligo-Miocene limestone sediments of the Riversleigh World Heritage Area, northwestern Queensland adds significant new information about previously described species and also indicates a greater diversity of thylacoleonids during this period of geological time. Two new genera and five new species are described. Reassessment of the holotype of the type species of Priscileo, P. pitikantensis,indicates it shows stronger affinities to species of the genus Wakaleo than it does to Priscileo roskellyae. Priscileo is regarded here to be a junior synonym of Wakaleo. The cranium and lower dentition of Priscileo roskellyae show significant morphological differences from species of Wakaleo, and this species is referred to a new genus, Lekaneleo. Distinctive morphological differences are identified in the M3s of Wakaleo oldfieldi and W. vanderleueri, species previously distinguished only by relative size differences in their dentitions. Functional morphological assessment of postcranial remains of species of Wakaleo suggests that they were probably scansorial or arboreal, but does not support a previous hypothesis of a fossorial habit. Cladistic analyses of the interrelationships of marsupial lions support the referral of Priscileo pitikantensis to the genus Wakaleo. The monotypic genus Microleo is the sister-group to all remaining thylacoleonid taxa. Species of Lekaneleo are the sistergroup to a Wakaleo/Thylacoleo clade. Intraordinal relationships of thylacoleonids were also investigated. Phylogenetic analyses of the interrelationships of Diprotodontia that included representatives of all extinct vombatiform families as well as extant taxa were conducted employing cranial and dental morphological characters. These analyses provide support for the hypothesis that Thylacoleonidae are members of the suborder Vombatiformes. Two species of Wakaleo (W. oldfieldi and W. vanderleueri) present in Riversleigh deposits are also found at other localities - respectively, the Leaf Locality of central Australia (Kutjamarpu LF) and the Small Hills Locality of northern Australia (Bullock Creek LF) - and suggest age estimations of the relevant Riversleigh sites of early Miocene and late Miocene. The phyletic evolution of Wakaleo suggests that some Riversleigh deposits are probably late Oligocene in age.