20th century research and practice of science led to advancement in the fields of communication, engineering, travel, medicine, and war. 20th century The 20th (twentieth) century was a century that began on January 1, 1901 and ended on December 31, 2000. It was the tenth and final century of the 2nd millennium. It is distinct from the century known as the 1900s which began on January 1, 1900 and ended on December 31, 1999. The 20th century was dominated by a chain of events that heralded significant changes in world history as to redefine the era: flu pandemic, World War I and
20th century in ichnology excavation of fossil footprints in history. In the Lee Stokes reported unusual footprints he interpreted as the first known pterosaur tracks. This attribution would be controversial much of the rest of the century but has since been vindicated. The dinosaur footprints of Dinosaur Ridge in Colorado were also discovered and studied in the 20th century. The advent of the dinosaur renaissance and the publication by R. McNeil Alexander of a formula which could reconstruct their running speed based on data from fossil trackways brought renewed interest and prestige to ichnology during the late 20th century. This led to several symposia