diff --git a/book/history/sourdough-history.tex b/book/history/sourdough-history.tex
index a7fbf4f..e348bdb 100644
--- a/book/history/sourdough-history.tex
+++ b/book/history/sourdough-history.tex
@@ -59,7 +59,7 @@ On October~4, bacteria first colonized land. By October~15, the
 first aquatic fungi appeared. They adapted and, by November~24, had colonized
 land.
 
-By December~3rd, yeasts emerged on land. This laid groundwork for bread-making.
+By December~3, yeasts emerged on land. This laid groundwork for bread-making.
 Jump 140~million years to December~14, and dinosaurs arose. Just a couple
 of days after their appearance on December~17 the super continent pangea
 started to rift apart, reshaping the continents into their current form.