Portuguese naming practices

I've been reading a book titled OVER THE EDGE OF THE WORLD by Laurence Bergreen, it's the history of Ferdinand Magellan, the Portuguese Navigator or Fernao de Magalhaes who was said to have been born around 1480 in the Parish of Sabrosa in northwestern Portugal. His lineage can be traced through his father Rodrigo de Magalhaes who could trace his heritage back to the 11th century to a French crusader, De Magalhaes. Rodrigo qualified as minor Portuguese nobility.
As for Fernao's maternal heritage, his mother was Alda de Mesquita. The name Mesquita means mosque and this was a common name for Portuguese conversos who sought to disguise their Jewish heritage. One important detail is that the lineage was difficult to trace on the maternal side due to the unusual naming practices of the Portuguese. It was said that males assumed their father's last name but the females chose other surnames for themselves. They took on their father's name or their mother's, or even a saint's name and some children assumed their grandfather's name or still other family names. It says, " Ferdinad Magellan's brother Diogo took on the name de Sousa, from his paternal grandmother's family. "These irregularities make it difficult to determine even today exactly which branch of the Magalhaes family tree can rightfully claim the expolorer.

Just thought I'd share this with the group.

Alicia