Cenogram analyses as habitat indicators for Paleogene–Neogene mammalian communities across the globe, with an emphasis on the early Eocene Cambay Shale mammalian community from India

Abstract

The present study is an attempt to utilize cenogram methodology (both qualitative and quantitative) to consider mammalian communities from five early to late Eocene localities across the globe (i.e., Polecat Bench, Bighorn Basin, North America; Abbey Wood, Blackheath Formation, UK; Cambay Shale, Cambay Basin, India; Wutu Formation, Wutu Basin, China; Pondaung Formation, Myanmar) so as to provide a comparative palaeohabitat framework. It is also a first attempt to examine the palaeohabitat of an extinct mammalian community (i.e., from Cambay Shale) in India utilizing the cenogram approach. In addition, seven extinct middle-Miocene communities (Laogou, Linxia Basin, China; Estacion Imperial, Spain; Paseo de las Acacias, Spain; Arroyo del Olivar-Puente de Vallecas, Spain; Somo-saguas, Spain; Paracuellos 5, Spain; Paracuellos 3, Spain) have also been considered, in order to provide a global perspective to the climatic inferences in a temporal context. The majority of statistical calculations for Paleogene communities expose forested and humid conditions, excluding the Cambay Shale mammalian community of India. A hidden diversity within the medium to large body-size category of mammals (disguising the mammal biodiversity expected in tropical forested habitats) from Cambay Shale (western India) is a plausible cause of digression in the results. This is reflected in the histograms showing relationships between proportions of mammal species in various body-mass categories. Furthermore, the results show that Neogene mammalian communities were sustained in comparatively open habitats. Differences between occidental European and Asian localities in the canopy and humidity of the Neogene environments are also reflected in our analyses.