We generalize the notion of a tame automorphism to the context of an affine quadric threefold and we prove that there exist non-tame automorphisms.
"The tame and the wild automorphisms of an affine quadric threefold." J. Math. Soc. Japan 65 (1) 299 - 320, January, 2013. https://doi.org/10.2969/jmsj/06510299