Quantitative analysis of morphology allows for identification of subtle evolutionary patterns or convergences in anatomy that can aid ecological reconstructions of extinct taxa. This study explores diversity and convergence in cranial morphology across living and fossil primates using geometric morphometrics. 33 3D landmarks were gathered from 34 genera of euprimates (382 specimens), including the Eocene adapiforms Adapis and Leptadapis and Quaternary lemurs Archaeolemur, Palaeopropithecus, and Megaladapis. Landmark data was treated with Procrustes superimposition to remove all nonshape differences and then subjected to principal components analysis and linear discriminant function analysis. Haplorhines and strepsirrhines were well separated in morphospace along the major components of variation, largely reflecting differences in relative skull length and width and facial depth. Most adapiforms fell within or close to strepsirrhine space, while Quaternary lemurs deviated from extant strepsirrhines, either exploring new regions of morphospace or converging on haplorhines. Fossil taxa significantly increased the area of morphospace occupied by strepsirrhines. However, recent haplorhines showed significantly greater cranial disparity than strepsirrhines, even with the inclusion of the unusual Quaternary lemurs, demonstrating that differences in primate cranial disparity are likely real and not simply an artefact of recent megafaunal extinctions. 1. Introduction Euprimates comprises two principal sister groups: Strepsirrhini, including Lemuriformes and Lorisiformes; and Haplorhini, including Tarsiiformes and Simiiformes (Anthropoidea). Strepsirrhines have a smaller geographic range, occupying parts of Southern Africa, Madagascar, and Southeast Asia, than do haplorhines, which, excluding humans, occupy every continent except Australia and Antarctica. In addition, haplorhine primates are far more speciose (~300 species) than strepsirrhines (~100 species) [1]. Tarsiiformes have previously been grouped with the strepsirrhines as “prosimians”, but most recent molecular and morphological analyses [2–4] have placed them firmly within Haplorhini (but see [5]). Estimates of the time of divergence of strepsirrhines and haplorhines are heavily debated. The earliest euprimate currently recognised is the late Paleocene Altiatlasius [6, 7]. However, molecular clock models and statistical models based on fossil occurrences place the origin of Euprimates between 70–103 mya (million years ago), well into the Cretaceous [8], despite the lack of any unambiguous placental
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