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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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New radiocarbon dates reveal pan-Holocene deposition of rodents at Trouing Jérémie #5, a sinkhole in the western Tiburon Peninsula, Haiti
We present eight new radiocarbon dates for endemic and invasive rodents from Trouing Jérémie #5, a paleontologically-rich sink hole on the Tiburon Peninsula, Haiti. This includes new dates for two species that have been previously directly dated ( Isolobodon portoricensis and Brotomys voratus) as well as three endemic rodents which have no previous direct radiometric dates ( Plagiodontia velozi, Hexolobodon phenax, and Rhizoplagiodontia lemkei). The radiocarbon date for P. velozi, the largest of these species, is from the very early Holocene (10,995 ± 190 calendar years before present; Cal BP). Specimens of medium-bodied species, H. phenax and R. lemkei date to the mid-Holocene, while specimens of smaller-bodied I. portoricencis and B. voratus have dates falling in the Late-Holocene. These dates confirm that several of the extinct rodent species coexisted with the first humans, who arrived on the island ca. 6000 years ago. In contrast, murid Rattus specimens date to the last few centuries. Rats arrived with Europeans in the late 15th or early 16th Century and a radiocarbon date of ca. 500 Cal BP for one individual suggests that they likely spread quickly across the island. Collectively, these dates establish that vertebrate accumulations at Trouing Jérémie #5 span the Holocene. Remains from this site may provide a useful time sequence for future work examining ecological change across the Holocene as well as regional extirpation patterns.
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- PAR ID:
- 10336169
- Date Published:
- Journal Name:
- The Holocene
- ISSN:
- 0959-6836
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1177/09596836221101279
