Confusingly, and remarkably, there were actually two Sylvanus Griswold Morleys whose careers were contemporaneous. This second Sylvanus G. Morley was in fact the older maternal cousin to the first, born February 23, 1878, in Baldwinville, Worcester County, Massachusetts. This latter was originally baptised Sylvanus Griswold Small ("Sylvanus Griswold" being a family "heirloom" name), but changed his surname from Small to Morley in his early twenties when his father did likewise. As a result, many biographical references confuse details of the two, such as interchanging their birthplaces.