 The 1870s were the golden years of Cope 's career , marked by his most prominent discoveries and rapid flow of publications . Among his descriptions were the therapsid Lystrosaurus ( 1870 ) , the <unk> Champsosaurus ( 1876 ) , and the sauropod Amphicoelias ( 1878 ) , possibly the largest dinosaur ever discovered . In the period of one year , from 1879 to 1880 , Cope published 76 papers based on his travels through New Mexico and Colorado , and on the findings of his collectors in Texas , Kansas , Oregon , Colorado , Wyoming , and Utah . During the peak years , Cope published around 25 reports and preliminary observations each year . The hurried publications led to errors in interpretation and naming — many of his scientific names were later canceled or withdrawn . In comparison , Marsh wrote and published less frequently and more succinctly — his works appearance in the widespread American Journal of Science led to faster reception abroad , and subsequently Marsh 's reputation grew more rapidly than Cope 's . 
