A Late Pleistocene coastal ecosystem in French Guiana was hyperdiverse relative to today.

Warmer temperatures and higher sea level than today characterized the Last Interglacial interval [Pleistocene, 128 to 116 thousand years ago (ka)]. This period is a remarkable deep-time analog for temperature and sea-level conditions as projected for 2100 AD, yet there has been no evidence of fossil assemblages in the equatorial Atlantic. Here, we report foraminifer, metazoan (mollusks, bony fish, bryozoans, decapods, and sharks among others), and plant communities of coastal tropical marine and mangrove affinities, dating precisely from a ca. 130 to 115 ka time interval near the Equator, at Kourou, in French Guiana. These communities include ca. 230 recent species, some being endangered today and/or first recorded as fossils. The hyperdiverse Kourou mollusk assemblage suggests stronger affinities between Guianese and Caribbean coastal waters by the Last Interglacial than today, questioning the structuring role of the Amazon Plume on tropical Western Atlantic communities at the time. Grassland-dominated pollen, phytoliths, and charcoals from younger deposits in the same sections attest to a marine retreat and dryer conditions during the onset of the last glacial (ca. 110 to 50 ka), with a savanna-dominated landscape and episodes of fire. Charcoals from the last millennia suggest human presence in a mosaic of modern-like continental habitats. Our results provide key information about the ecology and biogeography of pristine Pleistocene tropical coastal ecosystems, especially relevant regarding the-widely anthropogenic-ongoing global warming.

Human impacts reduce morphological diversity in an insular species of lizard.

Fossil remains provide useful insights into the long-term impact of anthropogenic phenomena on faunas and are often used to reveal the local (extirpations) or global (extinctions) losses of populations or species. However, other phenomena such as minor morphological changes can remain inconspicuous in the fossil record depending on the methodology used. In this study, we used the anole of Marie-Galante Island (Anolis ferreus) in Guadeloupe (French, West Indies) as a model to demonstrate how the morphological evolution of an insular lizard can be tracked through the Pleistocene/Holocene climatic transition and the recent anthropization of the island. We used a fossil assemblage of nearly 30 000 remains and a combination of anatomical description, traditional morphometry and geometric morphometrics. These fossils are attributed to a single taxon, most likely to be A. ferreus on the basis of morphological and morphometric arguments. Our results show the disappearance of a distinct (sub)population of large specimens that were about 25% larger than the modern representatives of A. ferreus We also demonstrate an apparent size stability of the main fossil population of this species since the Late Pleistocene but with the possible occurrence of a reduction in morphological diversity during the Late Holocene. These results highlight the impact of anthropic disturbances on a lizard whose morphology otherwise remained stable since the Late Pleistocene.

Large-scale reptile extinctions following European colonization of the Guadeloupe Islands.

Large-scale extinction is one of the defining challenges of our time, as human processes fundamentally and irreversibly reshape global ecosystems. While the extinction of large animals with popular appeal garners widespread public and research interest, the importance of smaller, less "charismatic" species to ecosystem health is increasingly recognized. Benefitting from systematically collected fossil and archaeological archives, we examined snake and lizard extinctions in the Guadeloupe Islands of the Caribbean. Study of 43,000 bone remains across six islands revealed a massive extinction of 50 to 70% of Guadeloupe's snakes and lizards following European colonization. In contrast, earlier Indigenous populations coexisted with snakes and lizards for thousands of years without affecting their diversity. Study of archaeological remains provides insights into the causes of snake and lizard extinctions and shows that failure to consider fossil-derived data probably contributes to substantial underestimation of human impacts to global biodiversity.

A fossil Diploglossus (Squamata, Anguidae) lizard from Basse-Terre and Grande-Terre Islands (Guadeloupe, French West Indies).

Today, Diploglossine lizards (Anguidae) are common on the Greater Antillean Islands (West Indies), where they are represented by many endemic species. However these lizards are very rare on the Lesser Antillean Islands, where they are only represented by a single species, the Montserrat galliwasp (Diploglossus montisserrati). Here, we show that diploglossine lizards were present in the past on other Lesser Antillean islands, by reporting the discovery of Anguidae fossil remains in two Amerindian archaeological deposits and in a modern deposit. These remains are compared to skeletons of extant diploglossine lizards, including D. montisserrati, using X-ray microtomography of the type specimen of this critically endangered lizard. We also conducted a histological study of the osteoderms in order to estimate the putative age of the specimen. Our results show that the fossil specimens correspond to a member of the Diploglossus genus presenting strong similarities, but also minor morphological differences with D. montisserrati, although we postulate that these differences are not sufficient to warrant the description of a new species. These specimens, identified as Diploglossus sp., provide a new comparison point for the study of fossil diploglossine lizards and reflect the historical 17(th) century mentions of anguid lizards, which had not been observed since.