There is no taxon-free lunch

Over the last few decades, the term “taxon-free” has been widely used in paleoecological literature to highlight reasoning via ecomorphological or other functional traits of organisms as opposed to reasoning via taxonomic affiliations and phylogenetic conservatism. In practice, however, “taxon-free” inferences are very rarely free from using taxonomic information and occasionally they are even using phylogenetic conservatism to infer environmental or ecological conditions of taxa in the past. While some publications acknowledge the mismatch between the semantics of the term and the practice, others highlight the lack of reliance on taxonomic information as an advantage of the methodology, even in practice that reliance is present in a masked form. Here I present a structured survey on the use of the term “taxon-free” in paleoecological literature with an emphasis on mammalian community paleoecology. Based on the results I advocate dropping the use of the term “taxon-free” to minimize the potential for misinterpretations and use the term “trait-based” approaches instead, or alternatively, “phylogeny-free” if absence of reliance on phylogenetic niche conservatism is to be highlighted.