December 2023: publication Historical Biology
The Pleistocene grassland-dominated mammal fauna from Tham Kra Duk (Nakhon Si Thammarat, Peninsular Thailand)
Controversy exists as to whether the Pleistocene vegetation in northern Sundaland was dominated by lowland tropical grasslands or rainforests, due to limited palaeoecological evidence recorded from the region. We describe a new Pleistocene large mammal fauna from Tham Kra Duk, a cave in the Tham Phedan mountain, Nakhon Si Thammarat Province in Peninsular Thailand, with emphasis on its palaeoecological and palaeoenvironmental investigations using the stable isotope analysis of mammalian tooth enamel. The fossil site has yielded at least nine mammalian taxa almost comparable to late middle to latest Pleistocene faunas in the mainland, thus suggesting the same biogeographic mammal elements with a range extension south of the Kra Isthmus. The stable isotope results indicate that mixed woodland to grassland ecosystems were dominated by C4 vegetation in the area. This supports the assumption that the expansion of Pleistocene tropical savanna ecosystems might have held the key to facilitating the southward distribution range of grazing mammals such as gaurs and Himalayan gorals into the Thai-Malay Peninsula. The presence of the Tham Kra Duk fauna was probably linked to some major biogeographic events of Pleistocene hominin and mammal migration through the land-bridge peninsula into the islands of Southeast Asia during a period of glaciation.
Figure 3. Fossil teeth of large mammals from Tham Kra Duk. Hystrix sp. (A): CUF-TPD-20, an incisor fragment in labial view; Crocuta ultima (B – C): CUF-TPD-1, a right mandibular fragment with the P3 and P4 in occlusal (B) and medial (C) views; Rhinocerotidae indet. (D – E): CUF-TPD-19, a left incisor fragment in lingual (D) and labial (E) views; Sus scrofa (F – G): CUF-TPD-16, a left m1 in occlusal view (F) and CUF-TPD-17, a right m3 in occlusal view (G); Rusa unicolor (H – I): CUF-TPD-13, a right P3 fragment in occlusal view (H) and CUF-TPD-15, a left p4 in occlusal view (I); Bos javanicus (J – L): CUF-TPD-2, a left M3 in occlusal view (J), CUF-TPD-4, a right m2 in occlusal view (K) and CUF-TPD-5, a right m3 in occlusal view (L); Bos gaurus (M – O): CUF-TPD-3, a left p4 in occlusal (M) and lingual (N) views and CUF-TPD-6, a left m3 in occlusal view (O); Capricornis sumatraensis (P – Q): CUF-TPD-8, a right M3 in occlusal view (P) and CUF-TPD-9, a right m3 in occlusal view (Q); Naemorhedus goral (R – S): CUF-TPD-10, a right P4 in occlusal view (R) and CUF-TPD-11, a right M3 in lingual view (S).
References
Suraprasit k., Yamee C., Chaimanee Y., Jaeger J.-J., Bocherens H. 2023 – The Pleistocene grassland-dominated mammal fauna from Tham Kra Duk (Nakhon Si Thammarat, Peninsular Thailand) – Historical Biology – DOI: 10.1080/08912963.2023.2283936