[2] He was the head of Paleoanthropology and Quaternary at Naturmuseum Senckenberg in Frankfurt and participated in fossil excavation in Germany.
[1] From 1973 to 1984, Franzen protested with other members of the scientific community against a landfill near the Messel pit in Darmstadt.
He retired September 2000 and volunteered at the Senckenberg Research Institute as well as the Geosciences Department of the Natural History Museum in Basel.
[1] In 1998 he won the Friedrich von Alberti Prize for his studies in human history as well as his research and conservation of the UNESCO World Heritage Site of the Messel pit.
[4] Franzen dealt with paleogenic equidae, the primates from Messel, as well as the Eocene mammals from Eckfeld during the late Miocene.