What is the purpose of preauricular sulcus in identification of a dead body?

Preauricular sulcus is present in pelvis, used for identification of sex in a skeleton. It is the attachment of anterior sacroiliac ligament. It is not frequent in males, if seen, it is narrow and shallow. It is more frequent in females and it is broad and deep. Ref: The Essentials of Forensic Medicine and Toxicology by Narayan Reddy, 27th edition, Page 56.