Endocasts and Studies of Primate Brain Evolution

Endocasts can be made from fossil skulls either by cleaning out the braincase or making an artificial cast, or if the braincase is filled with a hard matrix, by removing part of the braincase to expose the natural fossil endocast. Endocasts include impressions of intracranial blood vessels, the stumps of cranial nerves, and often the pattern of braincase sutures. Since endocasts closely reproduce external brain morphology, they can be used to measure brain volume and thus provide data for studies of relative brain size. Two sources of information are available for studies of primate brain evolution. One source, comparative studies of brains of living forms, provides access to a wealth of anatomical detail. The second source of information for brain evolution studies is the actual fossil record of brains of extinct species. Anatomical features revealed by endocasts may be indicative of phylogenetic relationships between taxa and therefore of taxonomic significance.