Super-de Sitter and alternative super-Poincare symmetries

It is well-known that de Sitter Lie algebra $mathfrak{o}(1,4)$ contrary to anti-de Sitter one $mathfrak{o}(2,3)$ does not have a standard $mathbb{Z}_2$-graded superextension. We show here that the Lie algebra $mathfrak{o}(1,4)$ has a superextension based on the $mathbb{Z}_2timesmathbb{Z}_2$-grading. Using the standard contraction procedure for this superextension we obtain an {it alternative} super-Poincare algebra with the $mathbb{Z}_2timesmathbb{Z}_2$-grading.