endemic to Madagascar. This suggests that ancestor of the dipterocarps originated in the southern supercontinent of Gondwana, and that the common ancestor of the Asian dipterocarps and the Sarcolaenaceae was found in the India-Madagascar-Seychelles land mass millions of years ago, and were carried northward by India, which later collided with Asia and allowed the dipterocarps to spread across Southeast Asia and Malaysia. The first dipterocarp pollen has been found in Myanmar (which at that time was part of the Indian plate) and it dates from the upper Oligocene. The sample appears to slowly increase in terms of diversity and abundance across the region into the mid-Miocene. Chemical traces of dipterocarp resins have been found dating back to the Eocene of India. The oldest fossil of the family are from the latest Cretaceous (Maastrichtian) aged Intertrappean Beds of India, assignable to the extant genus Dipterocarpus. Subfamily Pakaraimoideae formerly placed here and native to the Guaianan highlands of South America, is now found to be more closely related the Cistaceae and is placed there in the APG IV (2016). Fossilized arthropods Some 52-million-year-old amber found in the Gujarat province, India, containing a large amount of fossilized arthropods, was identified as sap from the family Dipterocarpaceae. Ecology Dipterocarpaceae species can be either evergreen or deciduous. Species occurring in Thailand grow from sea level to about 1300 m elevation. Environments in which the species of the family occur in Thailand include lowland dipterocarp forest 0–350 m, riparian fringe, limestone hills, and coastal hills. Conservation and climate change As the dominant tree in Southeast Asia, the Dipterocarp family has seen extensive study relating to its conservation status. They are a keystone species of the native forests of this region, and are essential to their function and structure. One study by Pang et al. examined the impacts of climate change and land cover on the distribution of this important tree family in the Philippines. They used species distribution models (SDMs) for 19 species that were projected onto both current and future climate scenarios, with current land cover incorporated as well. They found that the current land cover alone reduced the species distributions by 67%, and 37% in protected areas. On the other hand, climate change reduced species distributions by 16-27% in both protected and unprotected areas. There was also an upward shift in elevation of species distribution as a result of climate change, as habitats changed.