RT @RonBaalke: Today is Walter Alvarez’s 76th birthday (1940). With his father, 1st to propose dinosaurs became extinct from an as… twitter.com/i/web/status/7…
RT @RonBaalke: Today is Walter Alvarez’s 76th birthday (1940). With his father, 1st to propose dinosaurs became extinct from an as… twitter.com/i/web/status/7…