What is ‘Pseudo’ in pseudotribosphenic teeth?

Abstract

The discovery of a ‘pseudotribosphenic’ lower tooth row in 1982, with a basin anterior to the trigonid rather than posterior, caused a large stir in mammalian palaeontology. This indicated that a tooth shape of equivalent complexity to the tribosphenic tooth form could evolve more than once. The upper tooth predicted to occlude with the pseudotribosphenic molar was reconstructed with a ‘pseudoprotocone’ to occlude with the pseudotalonid basin. Here I discuss the relative merits of naming the major upper lingual cusp of pseudotribosphenic molars as ‘protocone’ due to its likely similar developmental and functional relations as the protocone of tribosphenic molars. The use of a different name implies greater morphological distance between tribosphenic and pseudotribosphenic upper molars than is perhaps warranted, and likely exaggerates the perception of the difficulty in evolving both tribospheny and pseudotribospheny. The choice between the evolution of the alternative forms of tribospheny may in fact be related to the degree of anterior-posterior bias in lower molar development-tribospheny with a posterior bias, while pseudotribospheny with an anterior one.