Timeline of ceratopsian research

The first scientifically documented ceratopsian fossils were described by Edward Drinker Cope starting in the 1870s; however, the remains were poorly preserved and their true nature was not recognized.

[4] Not long after, the Central Asiatic Expedition led by Roy Chapman Andrews of the American Museum of Natural History discovered the primitive ceratopsians Psittacosaurus and Protoceratops in Mongolia.

However, when later researchers like Sternberg and Osborn tried to mount the skeletons, they found that the forelimb bones apparently sprawled despite the hindlimbs standing straight up and down.

Early researchers like Richard Swann Lull thought that bony frills served as the attachment site for enlarged jaw muscles.

[8] 1872 1876 1878 1887 1888 1889 1890 1891 1896 1898 1901 1902 1904 1905 1907 1908 1910 1913 1914 1915 1917 1918 1922 1923 1924 1925 1928 1927 1929 1930 1931 1933 1935 1937 1940 1942 1946 1947 1949 1950 1951 1953 1955 1958 1959 1960 1961 1962 1964: 1966 1967 1969 1971 1972 1975 1976 1977 1978 1979 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 Sampson and others studied centrosaurine bonebeds and found that the individuals preserved therein could be categorized into three broad phases of developments; juveniles, subadults, and adults.

[36] They observed that the juveniles and subadults of different centrosaurine species are practically indistinguishable and can only be told apart upon reaching adulthood when their horns and frills were fully developed.

[12] Sampson and the other researchers interpreted the delay of ceratopsid horn and frill development to sexual maturity as further evidence for the hypothesis that these traits evolved primarily for competition over mates.

[12] 1998 1999 2000 2001 Centrosaurus apertus Triceratops horridus Zuniceratops christopheri Bagaceratops rozhdeventskyi Protoceratops andrewsi Microceratops gobiensis Udanoceratops tschzhovi Leptoceratops gracilis Asiaceratops salsopaludalis Archaeoceratops oshimai Psittacosaurus mongoliensis Chaoyangosaurus youngi Stegoceras validus Hypsilophodon foxi 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2022