Fossil climbing perch and associated plant megafossils indicate a warm and wet central Tibet during the late Oligocene

Feixiang Wu,Mee-Mann Chang,Gongle Shi,Desui Miao,Ning Wang

doi:10.1038/s41598-017-00928-9

Abstract

Understanding the Tibetan Plateau’s palaeogeography and palaeoenvironment is critical for reconstructing Asia’s climatic history; however, aspects of the plateau’s uplift history remain unclear. Here, we report a fossil biota that sheds new light on these issues. It comprises a fossil climbing perch (Anabantidae) and a diverse subtropical fossil flora from the Chattian (late Oligocene) of central Tibet. The fish, Eoanabas thibetana gen. et sp. nov., is inferred to be closely related to extant climbing perches from tropical lowlands in south Asia and sub-Saharan Africa. It has osteological correlates of a labyrinth organ, which in extant climbing perches gives them the ability to breathe air to survive warm, oxygen-poor stagnant waters or overland excursion under moist condition. This indicates that Eoanabas likewise lived in a warm and humid environment as suggested by the co-existing plant assemblage including palms and golden rain trees among others. As a palaeoaltimeter, this fossil biota suggests an elevation of ca. 1,000 m. These inferences conflict with conclusions of a high and dry Tibet claimed by some recent and influential palaeoaltimetry studies. Our discovery prompts critical re-evaluation of prevailing uplift models of the plateau and their temporal relationships with the Cenozoic climatic changes.

Highlights

The rise of the Tibetan Plateau is generally held responsible for the climatic cooling and monsoon intensification during the Cenozoic[1,2,3]
The climbing perches are closely related to kissing gouramies and fighting fishes[23,24,25] in the perciform suborder Anabantoidei[25]. They are common in freshwaters in tropical Asia and sub-Saharan Africa[23, 24]
A phylogenetic analysis based on morphological data resolves Eoanabas as the earliest diverging lineage within the family Anabantidae, with its African relatives being monophyletic and sister to the Asian single genus Anabas (Supplementary Fig. 6)

Summary

Introduction

The rise of the Tibetan Plateau is generally held responsible for the climatic cooling and monsoon intensification during the Cenozoic[1,2,3]. The other, Tchunglinius tchangii Wang et Wu, is a barbine carp, related to a lineage otherwise currently distributed in South Asia and Africa[21] Both of these fishes were probably inhabitants of comparatively low altitudes[16,17,18,19, 21]. Tibet (Supplementary Figs 1 and 2, and see Supplementary Information) is an important addition to the fossil record of the Tibetan Plateau These fossils represent a biota that comprises ideal environmental indicators of warm and humid environment at low elevations. The climbing perches (anabantid fishes) are closely related to kissing gouramies and fighting fishes[23,24,25] in the perciform suborder Anabantoidei (labyrinth fishes)[25] They are common in freshwaters in tropical Asia and sub-Saharan Africa[23, 24]. The capability of accessary air breathing allows some of anabantids to move onto land under moist conditions, or even reputedly climb trees, earning the common name “climbing perch”[23]

Methods

Results

Conclusion