What is a survival period?
To be an heir and receive property under the intestacy statutes, you must outlive the deceased person. Most states, in their probate code, take this a step further and require an heir to outlive the deceased by a specified amount of time. For example, in most states a potential heir must outlive the deceased for 120 hours (five days) to be deemed an heir. If they outlive the deceased, but by less than this amount, they are treated as having died before the deceased.
For example, suppose that Bob had a son and a daughter. Bob and his daughter are both involved in an accident and while Bob dies on Monday, his daughter does not die until Thursday. As his daughter did not outlive him by more than 120 hours, she is treated as having died before Bob, which means that her children do not get her share of the estate (because she is not entitled to any share of the estate) and Bob’s son gets the entire estate. Had Bob’s daughter lived until the following Monday, longer than the survival period, then she would be entitled to her share, and her children could take her 50% in her place.