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Africa's fossil record of late Cenozoic mammals documents considerable ecological and evolutionary changes through time. Here, we synthesize those changes in the context of the mechanisms proposed to account for them, including bottom-up (e.g., climate change) and top-down (e.g., hominin impacts) processes. In doing so, we (a) examine how the incompleteness of the fossil record and the varied spatiotemporal scales of the evidence complicate efforts to establish cause-effect relationships; (b) evaluate hypothesized drivers of long-term ecological and evolutionary change, highlighting key unknowns; and (c) synthesize major taxonomic and functional trends through time (e.g., downsizing of faunal communities) considering the proposed drivers. Throughout our review, we point to unresolved questions and highlight research avenues that have potential to inform on the processes that have shaped the history of what are today the most diverse remaining large mammal communities on Earth. The study of late Cenozoic African mammal communities is intertwined with questions about the context, causes, and consequences of hominin evolution. The fossil record documents major functional (e.g., loss of megaherbivores) and taxonomic (e.g., rise of the Bovidae) changes over the past ∼7 Myr. Complexities inherent to the fossil record have made it difficult to identify the processes that drove ecological and evolutionary changes. Unanswered questions about the drivers of faunal change and the functioning of past ecosystems represent promising future research directions. [ABSTRACT FROM AUTHOR]

Understanding how ecological communities are organized and how they change through time is critical to predicting the effects of climate change (1). Recent work documenting the co-occurrence structure of modern communities found that most significant species pairs co-occur less frequently than would be expected by chance (2,3). However, little is known about how co-occurrence structure changes through time. Here we evaluate changes in plant and animal community organization over geological time by quantifying the co-occurrence structure of 359,896 unique taxon pairs in 80 assemblages spanning the past 300 million years. Co-occurrences of most taxon pairs were statistically random, but a significant fraction were spatially aggregated or segregated. Aggregated pairs dominated from the Carboniferous period (307 million years ago) to the early Holocene epoch (11,700 years before present), when there was a pronounced shift to more segregated pairs, a trend that continues in modern assemblages. The shift began during the Holocene and coincided with increasing human population size (4,5) and the spread of agriculture in North America (6,7). Before the shift, an average of 64% of significant pairs were aggregated; after the shift, the average dropped to 37%. The organization of modern and late Holocene plant and animal assemblages differs fundamentally from that of assemblages over the past 300 million years that predate the large-scale impacts of humans. Our results suggest that the rules governing the assembly of communities have recently been changed by human activity., How are plant and animal communities organized, and does their structure change through time? This question has dominated many decades of research on community assembly rules and is critical to [...]

All modern humans use tools to overcome limitations of our anatomy and to make difficult tasks easier. However, if tool use is such an advantage, we may ask why it [...]

Author(s): S. Kathleen Lyons; Kathryn L. Amatangelo; Anna K. Behrensmeyer; Antoine Bercovici; Jessica L. Blois; Matt Davis; William A. DiMichele; Andrew Du; Jussi T. Eronen; J. Tyler Faith; Gary R. [...]

Author(s): S. Kathleen Lyons (corresponding author) [1]; Joshua H. Miller [2]; Kathryn L. Amatange [3]; Anna K. Behrensmeyer [4]; Antoine Bercovici [1]; Jessica L. Blois [4]; Matt Davis [5]; William [...]

The late Quaternary of North America was marked by prominent ecological changes, including the end‐Pleistocene megafaunal extinction, the spread of human settlements and the rise of agriculture. Here we examine the mechanistic reasons for temporal changes in mammal species association and body size during this time period. Building upon the co‐occurrence results from Lyons et al. (2016) – wherein each species pair was classified as spatially aggregated, segregated or random – we examined body mass differences (BMD) between each species pair for each association type and time period (Late Pleistocene: 40 000 14C–11 700 14C ybp, Holocene: 11 700 14C–50 ybp and Modern: 50–0 yr). In the Late Pleistocene and Holocene, the BMD of both aggregated and segregated species pairs was significantly smaller than the BMD of random pairs. These results are consistent with environmental filtering and competition as important drivers of community structure in both time periods. Modern assemblages showed a breakdown between BMD and co‐occurrence patterns: the average BMD of aggregated, segregated and random species pairs did not differ from each other. Collectively, these results indicate that the late Quaternary mammalian extinctions not only eliminated many large‐bodied species but were followed by a re‐organization of communities that altered patterns of species coexistence and associated differences in body size. [ABSTRACT FROM AUTHOR]