This study surveys late Holocene vertebrate fossils from Isla Floreana, Galapagos Islands. 20,000 fossils from four lava tubes near Post Office Bay are loosely associated with four radiocarbon dates of 2400 years BP or younger. Most fossils originated as regurgitated pellets of barn owls (Tyto punctatissima). They include six species now extinct on Floreana: Geochelone elephantopus, Alsophis biserialis, Tyto puntatissima, Mimus trifasciatus, Geospiza nebulosa, and Geospiza magnirostris. These species are, respectively, 1st, 7th, 16th, 6th, 15th, and 2nd in abundance among those recorded as fossils, making up 57% of individuals in the fauna. Thus extinction probably has changed the composition of Floreana's fauna even more than suggested by the number of extinct species alone. The evidence is circumstantial, but I believe that all extinction on Floreana is related to human impact, such as predation, habitat alteration, and introduction of alien animals (rats, mice, cats, dogs, pigs, goats, cattle, and donkeys). Direct human predation was probably the main cause of extinction only for Geochelone elephantopus. Extinction of Tyto punctatissima was probably due to loss of preferred prey species. Extinction of Mimus trifasciatus and Geospiza magnirostris may have accompanied destruction of Opuntia cactus. Extinction of Geospiza nebulosa may be related to habitat changes in the highlands. All extinction on Floreana probably occurred in historic times; whether this is true elsewhere in the Galapagos awaits more research. The lack of fossils of Coccyzus melacoryphus and Dendroica pectechia is further evidence that these birds colonized the Galapagos very recently. Fossils enable us to reconstruct natural, pre-human faunas more completely than previously possible. Modern biogeographical studies usually do not consider how natural the faunas are; they would benefit by considering changes wrought by human impact.

Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / The Wahweap Formation is an ~400 m thick clastic sedimentary succession of fluvial and estuarine channel sandstones and floodbasin mudrocks that was deposited in western North America during the Late Cretaceous. It preserves important mammal, dinosaur, crocodile, turtle and invertebrate fossils that have been the subject of recent palaeontological investigations. The Wahweap Formation can be divided into lower, middle, upper, and capping sandstone members based on sand:mud ratios and degree of sandstone amalgamation. Facies analysis reveals the presence of ten facies associations grouped into channel and floodbasin deposits. Facies associations (FAs) from channels include: (1) single-story and (2) multistory lenticular sandstone bodies, (3) major tabular sandstone bodies, (4) gravel bedforms, (5) low-angle heterolithic cross-strata, and (10) lenticular mudrock, whereas floodbasin facies associations include: (6) minor tabular sandstone bodies, (7) lenticular interlaminated sandstone and mudrock, (8) inclined interbedded sandstone and mudrock, and (9) laterally extensive mudrock. The lower and middle members are dominated by floodbasin facies associations. The lower member consists dominantly of FA 8, interpreted as proximal floodbasin deposits including levees and pond margins, and is capped by a persistent horizon of FA 3, interpreted as amalgamated channel deposits. FAs 4 and 6 are also present in the lower member. The middle member consists dominantly of FA 9, interpreted as distal floodbasin deposits including swamp, oxbow-lake and waterlogged-soil horizons. FAs 1, 2, 5, 6, 7, 8, and 10 are present in the middle member as well, which together are interpreted as evidence of suspended-load channels. The upper member is sandstone-dominated and consists of FAs 1, 2, 3, 5, 7, and 8. FAs 5 and 7, which occur at the base of the upper member, are interpreted as tidally influenced channels and suggest a marine incursion during deposition of the upper member. The capping sandstone is characterized by FAs 3, 4, and 6, and is interpreted to represent a major change in depositional environment, from meandering river systems in the lower three members to a low-accommodation, braided river system. Combined results of facies and palaeosol analyses suggest that the overall climatic conditions in which the Wahweap Formation was deposited were generally wet but seasonally arid, and that iv conditions became increasingly moist from the time of lower member deposition up to the time of middle member deposition. Improved age constraints were obtained for the Wahweap Formation by radiometric dating of two devitrified ash beds (bentonites). This allowed for deposition to be bracketed between approximately 81 Ma and 76 Ma. This age bracket has two important implications: firstly, it shows that the Wahweap Formation is synchronous with fossiliferous deposits of the Judithian North American Land Mammal Age, despite subtle differences in faunal content. Secondly, it shows that the middle and upper members were deposited during the putatively eustatic Claggett transgression (T8 of Kauffman 1977) in the adjacent Western Interior Seaway. This is consistent with facies analysis which shows a marked increase in tidally-influenced sedimentary structures and trace fossils at the top of the middle and base of the upper members. Following recent alluvial sequence stratigraphic models, the middle member is interpreted as the isolated fluvial facies tract, while the upper member represents the tidally influenced and highstand facies tracts. Maximum transgression occurred during deposition of the lowest part of the upper member, synchronous with the Claggett highstand in other parts of the Western Interior Basin. The sequence boundary is placed at the base of the overlying capping sandstone member, diagnosed by a major shift in petrography and paleocurrent direction, as well as up to 4 m of fluvial incision into the underlying upper member. The capping sandstone member is interpreted as the amalgamated fluvial facies tract of an overlying sequence. Analysis of the western-most exposures of the Wahweap Formation on the Markagunt and Paunsaugunt plateaus shows facies variations in the proximal and distal parts of the central Western Interior Basin. The inconsistent thickness and variations in fluvial architecture, as well as the presence of unconformities and generally poor exposure in the west, hinder correlation attempts and also prevent the subdivision of the Wahweap Formation into members. Only the capping sandstone, which can be positively identified west of the Paunsaugunt fault, has a consistent thickness and fluvial architecture across the west-east extent of the Wahweap Formation. The capping sandstone also bears remarkable lithological similarity to the Tarantula Mesa Formation which is exposed to the east in the Henry Mountains Syncline, and it is suggested that these two units be equated under the name “Tarantula Mesa Formation”, which has precedence.

Twenty-eight samples were collected from the stratigraphic section exposed one kilometer east of Buff Bay, Jamaica. This exposure includes the upper part of the Montpelier Formation and the type locality of the Buff Bay Formation. Planktic foraminifers were identified in each sample and age determinations made. The age of the section studied is interpreted as ranging from upper N 13 (Globorotalia mayeri Zone) to N 16 (Globorotalia acostaensis Zone). The uppermost portion of the Buff Bay Formation, exposed in 'Dead Goat Gully,' is reported by other authors to contain N 17 fauna, but was not collected in this study Three-hundred specimens of benthic foraminifers were picked from each sample. From this population sampling, 431 species and subspecies were identified, described and photographed. The percentage of the total benthic fauna of each taxon was calculated for each sample A comprehensive paleobathymetric analysis was made of the Buff Bay Formation, using planktic/benthic ratios, generic dominance, faunal diversity, and comparative modern species distributions The depositional environment of the upper Montpelier Formation and the Buff Bay Formation is interpreted as middle to lower bathyal water depths / acase@tulane.edu

Bulk samples collected from the Upper Cambrian (Sunwaptan) Hellnmaria Member of the Notch Peak Formation in Utah and the Upper Cambrian--Ordovician (Sunwaptan--Skullrockian) Wilberns and Tanyard Formations in Texas have yielded faunas of linguliform brachiopods that include many new taxa. Two new genera and eight new species are described. A new genus is proposed for species originally assigned to Angulotreta Palmer, 1954. In Utah, the stratigraphic ranges of several previously described species are extended. The two collections allow biostratigraphic correlation within Laurentia as well as globally. New zonation based on linguliform brachiopods is proposed for the Sunwaptan and lower Skullrockian stages of North America The Hellnmaria Member was deposited in a deep subtidal environment with possible access to the open ocean. The Utah fauna has affinities to coeval faunas in Kazakhstan and includes Zhanatella rotunda Koneva, 1986. This species was described previously from Kazakhstan as well as the Montagne Noire region of France and has potential for global biostratigraphy In Texas, collections from the Taenicephalus and lower Idahoia trilobite zones yielded a fauna with little affinity to brachiopods at a similar stratigraphic position in Utah but with strong affinity to a fauna from the same interval in Wyoming. Upper Sunwaptan and lowest Skullrockian strata yielded a fauna with close affinities to the Utah fauna. There is complete turnover of linguliform fauna in coincidence with two trilobite extinction events A lingulate specimen from the Hellnmaria Member exhibits a repair scar on its larval shell. Because lingulate brachiopod larvae are planktotrophic, the individual is interpreted to have been part of the pelagic realm at injury. The injury consists of a visible break and several areas of damage to the exterior of the shell, all consistent with damage done deliberately by a predator. This implies that durophagous predation was a part of the planktic realm during the Cambrian, and that the planktic realm was more modern in its structure than previously realized. This suggests that brachiopods may have been under predation pressure as larvae as well as adults, and this pressure may have played a role in their evolution and extinction / acase@tulane.edu

The palaeoecology of selected fossil sites from the Riversleigh World Heritage Area, northwestern Queensland, Australia, was studied with the aim of describing the palaeohabitats of the sites through the use of characteristics of mammalian community structure. Taphonomic analyses were carried out to determine whether the study sites represent allochthonous or autochthonous assemblages. Subsequently, ecological attributes of the mammalian fossil assemblages were inferred from functional morphology. Trophic and locomotor behaviours were used to describe the adaptive structure of communities and a method was established for inferring the locomotor behaviour of fossil taxa from morphometrics of their calcanea. Such ecological attributes of the assemblages can be used in reconstructing habitats. This is possible because modern mammalian community structure (as represented by ecological diversity/attribute characteristics) has been found to correlate with habitat structure and thus has predictive value, directly applicable in palaeoecology. Modern mammalian faunas from a variety of habitats around the world were used as possible analogues for the Riversleigh fossil faunas. Multivariate statistical techniques were explored for identifying potential similarities between the community structure of the fossil faunas and that of the modern faunas. Annual rainfall was then estimated for the fossil sites through regression analysis allowing climatic inference from the faunal palaeocommunities. On the basis of similarities in community structure, general habitat or vegetation structure was proposed for the fossil assemblages. The results of the analyses undertaken indicate that Riversleigh early-middle Miocene habitats were densely forested. The late Oligocene Quantum Leap Site local fauna and the late Miocene Encore Site local fauna suggest mixed vegetation, or more open environments. The trend of decreasing annual rainfall through the Miocene and the palaeohabitats of the Miocene sites proposed here fit the general pattern of vegetation and climate change during this period for the Australian continent as a whole.