Yet another article in PLoS One that uses stable isotopes to glean critical insights from fossils of long-dead animals. A mixed team including researchers from France, Thailand, Germany and Myanmar examined stable isotopes in the teeth of fossils of an extinct genus of horse called Hipparion found near the remains of a type of ape (a hominoid) to determine the nature of the environment when the creatures were alive. They found strong evidence of evergreen / green forests as indicated by the bias towards C3 plants in the stable isotope measurements. All of this may help scientists better understand the evolution of apes. Here's the abstract.

"For over a century, a Neogene fossil mammal fauna has been known in the Irrawaddy Formation in central Myanmar. Unfortunately, the lack of accurately located fossiliferous sites and the absence of hominoid fossils have impeded paleontological studies. Here we describe the first hominoid found in Myanmar together with a Hipparion (s.l.) associated mammal fauna from Irrawaddy Formation deposits dated between 10.4 and 8.8 Ma by biochronology and magnetostratigraphy. This hominoid documents a new species of Khoratpithecus, increasing thereby the Miocene diversity of southern Asian hominoids. The composition of the associated fauna as well as stable isotope data on Hipparion (s.l.) indicate that it inhabited an evergreen forest in a C3-plant environment. Our results enlighten that late Miocene hominoids were more regionally diversified than other large mammals, pointing towards regionally-bounded evolution of the representatives of this group in Southeast Asia. The Irrawaddy Formation, with its extensive outcrops and long temporal range, has a great potential for improving our knowledge of hominoid evolution in Asia."