scholarly journals Teasing Apart Impacts of Human Activity and Regional Drought on Madagascar’s Large Vertebrate Fauna: Insights From New Excavations at Tsimanampesotse and Antsirafaly

2021 ◽  
Vol 9 ◽  
Author(s):  
Laurie R. Godfrey ◽  
Brooke E. Crowley ◽  
Kathleen M. Muldoon ◽  
Stephen J. Burns ◽  
Nick Scroxton ◽  
...  
Keyword(s):  
Human Activity ◽  
Freshwater Ecosystem ◽  
Hypersaline Lake ◽  
Primary Role ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Terrestrial Vertebrates ◽  
Faunal Assemblages ◽  
Hydroclimate Variability ◽  
Freshwater Mollusks

Madagascar experienced a major faunal turnover near the end of the first millenium CE that particularly affected terrestrial, large-bodied vertebrate species. Teasing apart the relative impacts of people and climate on this event requires a focus on regional records with good chronological control. These records may document coeval changes in rainfall, faunal composition, and human activities. Here we present new paleontological and paleoclimatological data from southwestern Madagascar, the driest part of the island today. We collected over 1500 subfossil bones from deposits at a coastal site called Antsirafaly and from both flooded and dry cave deposits at Tsimanampesotse National Park. We built a chronology of Late Holocene changes in faunal assemblages based on 65 radiocarbon-dated specimens and subfossil associations. We collected stalagmites primarily within Tsimanampesotse but also at two additional locations in southern Madagascar. These provided information regarding hydroclimate variability over the past 120,000 years. Prior research has supported a primary role for drought (rather than humans) in triggering faunal turnover at Tsimanampesotse. This is based on evidence of: (1) a large freshwater ecosystem west of what is now the hypersaline Lake Tsimanampesotse, which supported freshwater mollusks and waterfowl (including animals that could not survive on resources offered by the hypersaline lake today); (2) abundant now-extinct terrestrial vertebrates; (3) regional decline or disappearance of certain tree species; and (4) scant local human presence. Our new data allow us to document the hydroclimate of the subarid southwest during the Holocene, as well as shifts in faunal composition (including local extirpations, large-vertebrate population collapse, and the appearance of introduced species). These records affirm that climate alone cannot have produced the observed vertebrate turnover in the southwest. Human activity, including the introduction of cattle, as well as associated changes in habitat exploitation, also played an important role.

Fauna assemblages in regrowth vegetation in tropical open forests of the Northern Territory, Australia

2009 ◽  
Vol 36 (8) ◽  
pp. 675 ◽  
Author(s):  
J. C. Z. Woinarski ◽  
B. Rankmore ◽  
B. Hill ◽  
A. D. Griffiths ◽  
A. Stewart ◽  
...  
Keyword(s):  
Fire Regime ◽  
Secondary Forest ◽  
Grazing Pressure ◽  
Northern Territory ◽  
Primary Forest ◽  
Faunal Composition ◽  
Faunal Assemblages ◽  
Terrestrial Vertebrate ◽  
Eucalypt Forests ◽  
Generalised Linear Modelling

Context. World-wide, primary forest is in decline. This places increasing importance on understanding the use by biodiversity of regrowth (secondary) forest, and on the management of such regrowth. Aims. This study aimed to compare the terrestrial vertebrate assemblages in tropical eucalypt forests, regrowth in these forests (following clearing for pastoral intensification) and cleared land without regrowth, to provide evidence for developing management guidelines for regrowth vegetation in a region (the Daly catchment of the Northern Territory) subject to increasing demands for land-use intensification. Methods. The terrestrial vertebrate fauna was surveyed consistently at 43 quadrats sampling forest, 38 sampling regrowth and 19 sampling cleared land (formerly forest), and the faunal composition was compared with ordination and analysis of variance. Further analysis used generalised linear modelling to include consideration of the relative importance of disturbance (condition) of quadrats. Key results. Faunal assemblages in regrowth vegetation were found to be intermediate between cleared land and intact forest, and converged towards the faunal assemblage typical of intact forest with increase in the canopy height of the regrowth. However, even the tallest regrowth quadrats that were sampled supported relatively few hollow-associated species. The management of fire, weeds and grazing pressure substantially affected the faunal assemblages of the set of regrowth and intact forest quadrats, in many cases being a more important determinant of faunal attributes than was whether or not the quadrat had been cleared. Conclusions. In this region, regrowth vegetation has value as habitat for fauna, with this value increasing as the regrowth structure increases. The convergence of the faunal composition of regrowth vegetation to that of intact forest may be substantially affected by post-clearing management factors (including fire regime and level of grazing pressure and weed infestation). Implications. Regrowth vegetation should be afforded appropriate regulatory protection, with the level of protection increasing as the regrowth increases in stature.

scholarly journals Preservational, paleoecological, and evolutionary patterns in the Wyoming-Montana Paleogene and Siwalik Neogene records

1992 ◽  
Vol 6 ◽  
pp. 13-13
Author(s):  
Catherine Badgley ◽  
Anna Kay Behrensmeyer ◽  
William S. Bartels ◽  
Thomas M. Bown
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
Fossil Record ◽  
Tectonic Setting ◽  
Sedimentary Environment ◽  
Depositional Environments ◽  
Taxonomic Resolution ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Historical Series

The Paleocene to early Eocene sequence of Wyoming-Montana and the Miocene to Pleistocene Siwalik record of Pakistan are exceptionally long, continental sequences, each containing a rich and well documented fossil record, especially of mammals. The two sequences are broadly similar in tectonic setting and sedimentary environment, in duration and facies changes, and in diversity of fossils. Each contains a paleoclimatic record in stable isotopes and, in the Paleogene, floras. Comparison of these two sequences has focused our attention on the interaction of tectonic, climatic, sedimentologic, and taphonomic factors that produce a particular fossil record and on the co-occurring ecological and evolutionary changes that result in a historical series of biotas, each the product of local and global events.In the Paleogene record, the geographic scope of the record encompasses much of the floodbasin, and the spatial distribution of paleoenvironments formed fairly straightforward gradients from channel to distal floodplain. The Siwalik record has a smaller window onto a larger, heterogeneous fluvial system often with multiple, contemporaneous river systems that differ in magnitude. The spatial distribution of paleoenvironments was a mosaic without long proximal to distal gradients. In both records, major facies changes are correlated with striking changes in fossil productivity.The overall pattern of fossil preservation by depositional environment differs substantially in the two areas. The Siwalik sequence has a greater variety of depositional environments that produce fossils throughout the section. The primary productive environment in the older part of the Paleocene record declined in productivity upsection, while a previously unproductive facies became the major source of fossils. Much of the record represents attritional accumulation in each area, but a significant portion is transported. The taphonomic processes that created fossil concentrations led to better taxonomic resolution for most Paleogene localities than in most Siwalik localities.In each record, both aquatic and terrestrial components of the vertebrate faunas are correlated with facies. Since facies varied in productivity over time, some changes in faunal composition may have resulted from change in the prevalence or productivity of particular facies. At least one faunal turnover coincided with major facies changes in each sequence.For mammals in each record, immigration rather than speciation in situ was the primary means of appearance of new species. Episodes of immigration were not closely followed by extinctions of resident species. Mean species longevity appears to have been more than twice as great in the Neogene than in the Paleogene record. Changes in faunal composition and species richness occurred during times of global climatic change; causal connections are still being explored. Changes in species richness did not track changes in relative abundance of taxa or changes in size within lineages or faunas. In terms of guild structure, the herbivore guild had high relative generic diversity through most of both sequences. The Paleogene record had a more even distribution of taxa in the five principal guilds, while the Siwalik record was heavily dominated by the herbivore guild. Size distributions differed substantially, reflecting the early and late windows into the mammalian radiation, rather than sampling bias.

scholarly journals The Late Capitanian Mass Extinction of Terrestrial Vertebrates in the Karoo Basin of South Africa

2021 ◽  
Vol 9 ◽  
Author(s):  
Michael O. Day ◽  
Bruce S. Rubidge
Keyword(s):  
South Africa ◽  
Mass Extinction ◽  
Large Igneous Province ◽  
Continuous Sampling ◽  
Faunal Turnover ◽  
Terrestrial Vertebrates ◽  
Karoo Basin ◽  
Extinction Rates ◽  
Permian Mass Extinction ◽  
Extinction Events

The Beaufort Group of the main Karoo Basin of South Africa records two major extinction events of terrestrial vertebrates in the late Palaeozoic. The oldest of these has been dated to the late Capitanian and is characterized by the extinction of dinocephalian therapsids and bradysaurian pareiasaurs near the top of Tapinocephalus Assemblage Zone. Faunal turnover associated with the extinction of dinocephalians is evident in vertebrate faunas from elsewhere in Pangaea but it can be best studied in the Karoo Basin, where exposures of the upper Abrahamskraal and lower Teekloof formations allow continuous sampling across the whole extinction interval. Here we present field data for several sections spanning the Capitanian extinction interval in the southwestern Karoo and discuss recent work to establish its timing, severity, and causes. A large collections database informed by fieldwork demonstrates an increase in extinction rates associated with ecological instability that approach that of the end-Permian mass extinction, and shows significant turnover followed by a period of low diversity. Extinctions and recovery appear phased and show similarities to diversity patterns reported for the end-Permian mass extinction higher in the Beaufort sequence. In the Karoo, the late Capitanian mass extinction coincides with volcanism in the Emeishan Large Igneous Province and may have been partly driven by short-term aridification, but clear causal mechanisms and robust links to global environmental phenomena remain elusive.

THE FEATURES OF THE GEOLOGICAL STRUCTURE AND SEDIMENTATION OF THE EARLY CRETACEOUS SITE OF THE TERRESTRIAL VERTEBRATES OF SHESTAKOVO (KEMEROVO REGION, RUSSIA)

2018 ◽  
pp. 13-23
Author(s):  
A. V. Podlesnov ◽  
B. I. Morkovin ◽  
E. N. Maschenko
Keyword(s):  
Early Cretaceous ◽  
Western Siberia ◽  
Geological Structure ◽  
Point Of View ◽  
Faunal Composition ◽  
Terrestrial Vertebrates ◽  
Coastal Marine ◽  
Geological Section ◽  
The Given

A new data on the geological structure, conditions of formation and faunal composition of the Early Cretaceous site of the terrestrial vertebrates by Shestakovo village (Kemerovo Region, Western Siberia) has been presented.The consolidated geological section has been constructed along the line Shestakovo-1 — Shestakovo-4 — Shestakovo-3 in which five lithologic members have been identified. A distribution of the vertebrates fauna taxons has been carried out along the selected lithologic members composing the Shestakovo series of the Ilek formation. A new data obtained during fieldwork in 2017 has made it possible to distinguish two main bony levels (lithologic members 3 and 5), which contain whole skeletons of reptiles. Lithofacies analysis has shown that the formation of the sites occurred under the conditions of the fluviolacustrine plain, where the channel, delta and floodplain facies were replaced by lake and lake-marshy facies, forming a series of sedimentation cycles. The latter are the evidence of the increase in the aridization of the climate upwards along the section. The given data calls into question previously expressed point of view about the coastal-marine or lagoon genesis of the Shestakovo series.

scholarly journals Upper Triassic and Lower Jurassic stratigraphy from exploration well L134/5-1, offshore Inner Hebrides, west Scotland

2001 ◽  
Vol 20 (2) ◽  
pp. 155-168 ◽  
Author(s):  
Nigel R. Ainsworth ◽  
Ian Boomer
Keyword(s):  
Sea Level ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Sedimentary Sequence ◽  
Sea Level Changes ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Northwest Europe ◽  
Published Account ◽  
Exploration Well

Abstract. A thick (c.1368 m) Upper Triassic to Lower Jurassic sedimentary sequence from exploration well L134/5-1, offshore Inner Hebrides, has yielded a rich and diverse foraminiferal and ostracod microfauna. Many of the taxa have been previously described throughout northwest Europe. Poor preservation (often due to crushing and/or overgrowth) and low numbers preclude a complete taxonomic review of this material, although changes in the faunal composition, rates of faunal turnover and palaeoenvironmental analyses are discussed. This is the first published account of ostracod and foraminiferal assemblages from the Sea of Hebrides and they indicate that the sediments (argillaceous, arenaceous and carbonates) were deposited in a shelf-marine setting with environmental fluctuations that are possibly the result of local relative sea-level changes.

The Exploration of Submarine Canyons and their Benthic Faunal Assemblages.

1972 ◽  
Vol 73 ◽  
pp. 159-169 ◽  
Author(s):  
Gilbert T. Rowe
Keyword(s):  
Sedimentary Environment ◽  
Adaptive Strategy ◽  
Turbidity Currents ◽  
Geological Exploration ◽  
Submarine Canyons ◽  
Organic Detritus ◽  
Faunal Composition ◽  
Faunal Assemblages

SynopsisThe geological exploration of submarine canyons and valleys began late in the nineteenth century.Theories of canyon genesis are many, but the probable causes are turbidity currents or sediment slumps, or both. Recent biological investigations indicate that the faunal composition of canyons is quite different from adjacent depths without canyons. The predominance of motility in the fauna implies that canyons today are physically more dynamic than previously expected. Motility could be an adaptive strategy for survival in an unstable sedimentary environment, or the species may be trophic opportunists which are able to take advantage of the entrapment by canyons of large aggregates of organic detritus.

A cluster analysis interpretation of Middle Ordovician biofacies, southern Mackenzie Mountains

1980 ◽  
Vol 17 (10) ◽  
pp. 1377-1388 ◽  
Author(s):  
Brad J. R. Hayes
Keyword(s):  
Cluster Analysis ◽  
Continental Slope ◽  
Group Method ◽  
Areal Extent ◽  
Faunal Composition ◽  
Middle Ordovician ◽  
Faunal Assemblages ◽  
Pair Group ◽  
Mackenzie Mountains ◽  
Unweighted Pair Group Method

Collections of fossil trilobites, ostracods, bryozoans, and conodonts from Chazyan and Blackriveran strata of the southern Mackenzie Mountains are analyzed in an attempt to define biofacies, in terms of areal extent and faunal composition. Q-mode and R-mode cluster analyses, using Jaccard's coefficient and the unweighted pair-group method of clustering, are employed to delineate five biofacies. The interpretation of sedimentological features and composition of faunal assemblages shows that one nearshore biofacies, three progressively deeper shelf biofacies, and one continental slope biofacies are represented. A plot of biofacies succession through time in each measured section provides added support for the biofacies interpretations.

The Mesozoic Biogeographic History of Gondwanan Terrestrial Vertebrates: Insights from Madagascar's Fossil Record

2019 ◽  
Vol 47 (1) ◽  
pp. 519-553 ◽  
Author(s):  
David W. Krause ◽  
Joseph J.W. Sertich ◽  
Patrick M. O'Connor ◽  
Kristina Curry Rogers ◽  
Raymond R. Rogers
Keyword(s):  
Late Cretaceous ◽  
Fossil Record ◽  
Late Jurassic ◽  
Indian Subcontinent ◽  
Terrestrial Vertebrates ◽  
Faunal Assemblages ◽  
Theropod Dinosaurs ◽  
Biogeographic History ◽  
History Of ◽  
The Caribbean

The Mesozoic plate tectonic and paleogeographic history of Gondwana had a profound effect on the distribution of terrestrial vertebrates. As the supercontinent fragmented into a series of large landmasses (South America, Africa-Arabia, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particularly during the Late Jurassic and Cretaceous, its terrestrial vertebrates became progressively isolated, evolving into unique faunal assemblages. We focus on four clades that, during the Mesozoic, had relatively low ability for dispersal across oceanic barriers—crocodyliforms, sauropod dinosaurs, nonavian theropod dinosaurs, and mammals. Their distributions reveal patterns that are critically important in evaluating various biogeographic hypotheses, several of which have been informed by recent discoveries from the Late Cretaceous of Madagascar. We also examine the effects of lingering, intermittent connections, or reconnections, of Gondwanan landmasses with Laurasia (through the Caribbean, Mediterranean, and Himalayan regions) on the distributions of different clades. ▪ This article reviews the biogeographic history of terrestrial vertebrates from the Mesozoic of the southern supercontinent Gondwana. ▪ Relatively large, terrestrial animals—including crocodyliforms, sauropod and nonavian theropod dinosaurs, and mammals—are the focus of this review. ▪ Most patterns related to vicariance occurred during the Late Jurassic and Cretaceous, the intervals of most active Gondwanan fragmentation. ▪ Recent discoveries of vertebrates from the Late Cretaceous of Madagascar have played a key role in formulating and testing various biogeographic hypotheses.

A new cheilostome bryozoan from a dinosaur site in the Upper Cretaceous (Campanian) Judith River Formation of Montana

2021 ◽  
pp. 1-9
Author(s):  
Paul D. Taylor ◽  
Raymond R. Rogers
Keyword(s):  
Western Interior Seaway ◽  
North Central ◽  
Terrestrial Vertebrates ◽  
National Monument ◽  
Facies Associations ◽  
Recent Species ◽  
Central Montana ◽  
Judith River Formation ◽  
Depositional Setting ◽  
Freshwater Mollusks

Abstract Few bryozoans have been described from the Cretaceous Western Interior Seaway (WIS), which is consistent with the low diversity of other typically stenohaline groups in this large expanse of relatively shallow marine water. Here we describe a new cheilostome bryozoan, Conopeum flumineum n. sp., based on well-preserved material from the Campanian Judith River Formation of the Upper Missouri River Breaks National Monument in north-central Montana. The new species shows strong morphological similarities with Conopeum seurati, a Recent species that is often categorized as brackish, but which is euryhaline and can also be found in marine and stenohaline environments. The new Campanian bryozoan species was found in a locality also containing fragmentary remains of dinosaurs and other terrestrial vertebrates, as well freshwater mollusks and terrestrial plant debris. The sedimentology and facies associations of the fossil-bearing site suggest that the depositional setting was a swamp or tidally influenced fluvial backwater on the Judith River coastal plain. The proximity of the site to the western shoreline of the WIS presumably made it susceptible to occasional marine flooding during storms or extreme tides. Previous occurrences of Conopeum in the Cretaceous of the Western Interior have also been associated with dinosaur remains, corroborating the very nearshore and at times even ‘upstream’ distribution of this euryhaline genus. UUID: http://zoobank.org/bb1fdc8a-5017-44c5-9251-9e24ef3995e3.

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