what happens to beneficiary's shar of a trust if his death preceeds that of the Trustor ?

Hello, my Dad died and 2 days later his brother, my Uncle, dies. Uncle is filthy rich and leaves several Trusts, a few of which name his brother and siblings as beneficiaries. My uncle was also kind enough to name his nieces and nephews, including myself, on another trust. My Aunt is 'closely' administering my Uncle's estate. What happens to my father's share of the trust he is named on... since he passed before his brother? Do his children or spouse have any claim to his portion of the trusts? I believe there may be no residual beneficiaries named in either my Uncles trusts or his Will . thank you.