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1. Mammoth featured heavily in Western Clovis diet

   https://doi.org/10.1126/sciadv.adr3814  

   Chatters, James C; Potter, Ben A; Fiedel, Stuart J; Morrow, Juliet E; Jass, Christopher N; Wooller, Matthew J (December 2024, Science Advances)

   Ancient Native American ancestors (Clovis) have been interpreted as either specialized megafauna hunters or generalist foragers. Supporting data are typically indirect (toolkits, associated fauna) or speculative (models, actualistic experiments). Here, we present stable isotope analyses of the only known Clovis individual, the 18-month-old Anzick child, to directly infer maternal protein diet. Using comparative fauna from this region and period, we find that mammoth was the largest contributor to Clovis diet, followed by elk and bison/camel, while the contribution of small mammals was negligible, broadly consistent with the Clovis zooarchaeological record. When compared with second-order consumers, the Anzick-1 maternal diet is closest to that of scimitar cat, a mammoth specialist. Our findings are consistent with the Clovis megafaunal specialist model, using sophisticated technology and high residential mobility to subsist on the highest ranked prey, an adaptation allowing them to rapidly expand across the Americas south of the Pleistocene ice sheets. 

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2. Late Holocene spread of pastoralism coincides with endemic megafaunal extinction on Madagascar

   https://doi.org/https://doi.org/10.1098/rspb.2021.1204  

   Hixon, S.; Douglass, K.; Crowley, B.; Rakotozafy, L.; Clark, G.; Anderson, A.; Haberle, S.; Ranaivoarisoa, J.; Buckley, M.; Fidiarisoa, S.; et al (July 2021, Proceedings of the Royal Society of London)

   Recently expanded estimates for when humans arrived on Madagascar (up to approximately 10 000 years ago) highlight questions about the causes of the island's relatively late megafaunal extinctions (approximately 2000–500 years ago). Introduced domesticated animals could have contributed to extinctions, but the arrival times and past diets of exotic animals are poorly known. To conduct the first explicit test of the potential for competition between introduced livestock and extinct endemic megafauna in southern and western Madagascar, we generated new radiocarbon and stable carbon and nitrogen isotope data from the bone collagen of introduced ungulates (zebu cattle, ovicaprids and bushpigs, n = 66) and endemic megafauna (pygmy hippopotamuses, giant tortoises and elephant birds, n = 68), and combined these data with existing data from endemic megafauna (n = 282, including giant lemurs). Radiocarbon dates confirm that introduced and endemic herbivores briefly overlapped chronologically in this region between 1000 and 800 calibrated years before present (cal BP). Moreover, stable isotope data suggest that goats, tortoises and hippos had broadly similar diets or exploited similar habitats. These data support the potential for both direct and indirect forms of competition between introduced and endemic herbivores. We argue that competition with introduced herbivores, mediated by opportunistic hunting by humans and exacerbated by environmental change, contributed to the late extinction of endemic megafauna on Madagascar. 

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3. Foraging adaptation of birds and humans during the Medieval Climatic Anomaly: stable isotope analysis of avian species from CA-ALA-554

   Su, Yiran; Eubanks, Jill S; Eerkens, Jelmer W; Garibay, Ramona (December 2023, Proceedings of the Society for California Archaeology)

   Stable isotope analysis has been widely used to investigate dietary and geographical information of organisms, but few studies have applied it to archaeological avian remains. Through carbon and nitrogen stable isotope analyses of bone collagen, this study examines the diet sources of several wild bird species in an attempt to discover their foraging patterns and associated human hunting behavior. These avian remains are from CA- ALA-554 in the East San Francisco Bay Area and represent a time span of 900 years, partly overlapping with the Medieval Climatic Anomaly (MCA). We compare the isotopic signatures of samples from different windows of time represented at the site to investigate the influence of droughts during the MCA and the responses of birds and humans. Our findings show that during the MCA, geese had a larger variance in δ13C and δ15N and avian fauna included a greater range of species. This suggests that birds might have migrated farther and widened their diets and ancient humans might have expanded their hunting range and diversified their prey, possibly in response to more challenging environmental conditions. 

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4. Dietary plasticity of North American herbivores: a synthesis of stable isotope data over the past 7 million years.

   https://doi.org/https://doi.org/10.1098/rspb.2021.0121  

   Pardi, Melissa I; DeSantis, R.G. Larisa. (April 2021, Proceedings)

   null (Ed.)

   Palaeoecological interpretations are based on our understanding of dietary and habitat preferences of fossil taxa. While morphology provides approximations of diets, stable isotope proxies provide insights into the realized diets of animals. We present a synthesis of the isotopic ecologies (δ13C from tooth enamel) of North American mammalian herbivores since approximately 7 Ma. We ask: (i) do morphological interpretations of dietary behaviour agree with stable isotope proxy data? (ii) are grazing taxa specialists, or is grazing a means to broaden the dietary niche? and (iii) how is dietary niche breadth attained in taxa at the local level? We demonstrate that while brachydont taxa are specialized as browsers, hypsodont taxa often have broader diets that included more browse consumption than previously anticipated. It has long been accepted that morphology imposes limits on the diet; this synthesis supports prior work that herbivores with ‘grazing’ adaptions, such as hypsodont teeth, have the ability to consume grass but are also able to eat other foods. Notably, localized dietary breadth of even generalist taxa can be narrow (approx. 30 to 60% of a taxon's overall breadth). This synthesis demonstrates that ‘grazing-adapted’ taxa are varied in their diets across space and time, and this flexibility may reduce competition among ancient herbivores. 

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5. Ecological Consequences of a Millennium of Introduced Dogs on Madagascar

   https://doi.org/10.3389/fevo.2021.689559  

   Hixon, Sean W.; Douglass, Kristina G.; Godfrey, Laurie R.; Eccles, Laurie; Crowley, Brooke E.; Rakotozafy, Lucien Marie; Clark, Geoffrey; Haberle, Simon; Anderson, Atholl; Wright, Henry T.; et al (June 2021, Frontiers in Ecology and Evolution)

   Introduced predators currently threaten endemic animals on Madagascar through predation, facilitation of human-led hunts, competition, and disease transmission, but the antiquity and past consequences of these introductions are poorly known. We use directly radiocarbon dated bones of introduced dogs ( Canis familiaris ) to test whether dogs could have aided human-led hunts of the island’s extinct megafauna. We compare carbon and nitrogen isotope data from the bone collagen of dogs and endemic “fosa” ( Cryptoprocta spp.) in central and southwestern Madagascar to test for competition between introduced and endemic predators. The distinct isotopic niches of dogs and fosa suggest that any past antagonistic relationship between these predators did not follow from predation or competition for shared prey. Radiocarbon dates confirm that dogs have been present on Madagascar for over a millennium and suggest that they at least briefly co-occurred with the island’s extinct megafauna, which included giant lemurs, elephant birds, and pygmy hippopotamuses. Today, dogs share a mutualism with pastoralists who also occasionally hunt endemic vertebrates, and similar behavior is reflected in deposits at several Malagasy paleontological sites that contain dog and livestock bones along with butchered bones of extinct megafauna and extant lemurs. Dogs on Madagascar have had a wide range of diets during the past millennium, but relatively high stable carbon isotope values suggest few individuals relied primarily on forest bushmeat. Our newly generated data suggest that dogs were part of a suite of animal introductions beginning over a millennium ago that coincided with widespread landscape transformation and megafaunal extinction. 

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