[2] He was a saltationist who opposed the theory of gradual evolution, and in the 1930s suggested that major evolutionary transformations must have occurred in large leaps between species.
He was known for presenting an alternative interpretation of the fossil record, combining orthogenesis, mutationism and extraterrestrial impacts, as opposed to Darwin's gradualism.
[3] His theory became known as typostrophism and stated that evolution occurs due to a periodic cyclic model of evolutionary processes which are predestined to go through a life cycle dictated by factors internal to the organism.
His theory also proposed that mass extinctions, especially the ones at the end of the Permian period 252 million years ago, were the result of cosmic radiation caused by supernova explosions.
[8][5] His book Basic Questions in Paleontology was published in German in 1950 and was translated into English in 1993 with a foreword written by Stephen Jay Gould.