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Dryad

Data from: Inferring the locomotor ecology of two of the oldest fossil squirrels: Influence of operationalisation, trait, body size, and machine learning method

Data files

Oct 03, 2024 version files 908.36 MB

Abstract

Correlations between morphology and lifestyle of extant taxa are useful for predicting lifestyles of extinct relatives. Here, we infer the locomotor behaviour of Palaeosciurus goti from the middle Oligocene and P. feignouxi from the lower Miocene of France using their femoral morphology and different machine learning methods. We used two ways to operationalise morphology, in the form of a geometric morphometric shape dataset and a multivariate dataset of eleven femoral traits. The predictive models were built and tested using more than half (180) of the extant species of squirrel relatives. The neural network model had the greatest predictive power, sometimes outperforming more traditional methods such as linear discriminant analysis. However, the predictive power also depended on the operationalisation and the femoral traits used to build the model. We also found that predictive power tended to slightly improve with increasing body size. Contrary to previous suggestions, the older species, P. goti, was most likely arboreal, whereas P. feignouxi was more likely terrestrial. This provides further evidence that arboreality was already the most common locomotor ecology among the earliest squirrels, while a predominantly terrestrial locomotor behaviour evolved shortly afterwards, before the vast establishment of grasslands in Europe.