Fossil Squamates of Pedernales Province, Dominican Republic: Novel Record of Human-Induced Extinction and Extirpation

Abstract

Hispaniola (Haiti & Dominican Republic (D.R.)), is the second largest island in the Caribbean and is a hotspot of squamate diversity (~184 species), yet little is known about their fossil record and how it relates to the present. Past studies on mammalian communities suggest that many rodent species go extinct after human arrival (~7,000 y.B.P.), most significantly after European colonization (~530 y.B.P.) corresponding to a rapid loss of 70-98% of original forest. Pedernales Province in the D.R., has much of its original forest cover, yet fossil squamates from this region have not been documented. Our study of Holocene dry cave fossil sites and a new archeological site located in Pedernales allows for evaluation of extinction in squamates in an area where deforestation is not a primary concern. Using dentigerous elements, several genera of squamates (Ameiva, Anolis, Celestus, Cyclura, Leiocephalus, and Geckos) were identified. We recorded their abundance at each depth, and found Anolis, Celestus, and Geckos to be the most common fossils. From this collection we discovered two new species of Celestus, a new species of Gecko, and revised the taxonomy of Leiocephalus. One of the newly identified large Celestus species, originally only known from fossils, was later discovered in a separate cave as a living specimen. These results suggest that deforestation is not the only driver of extinction in the D.R., and that even in well preserved areas, extinction of small taxa is happening. Additionally, some cryptic taxa may be unrecognized. The arrival of domesticated animals and associated pests (mice, rats, etc.), likely had a dramatic influence on these extinctions, as well as direct human predation, first reported here. Further radiocarbon and geochemical sampling of these herpetofaunal fossils will help assess why these species went extinct, and such trends can inform modern conservation efforts as to which taxa are most at risk.