STL Science Center

STL Science Center

09 August 2013

Star Heads

©Mariana Ruiz Villareal
Technically it just means "five horned face" but most star shapes have five points, so calling Pentaceratops sternbergii a star headed animal is not too much of a stretch. The five horns mentioned are the three we typically think of on a ceratopsian skull plus two spikes lower on the skull referred to as "epijugal" spikes; these are the protrusions of bone below the orbits which extend laterally. Pentaceratops is one of the larger members of the Chasmosaurine ceratopsian.  Discovered initially in 1921 (by Charles H. Sternberg) and named in 1923 (by Harry Fairfield Osborn), Pentaceratops was initially recovered from the San Juan Basin in New Mexico. Many examples of this dinosaur have been extricated from the land since, including a rather large specimen that, at the moment, is generally considered a synonymous species but is known as Titanoceratops ouranos (more on this later). As with many other ceratopsians, Pentaceratops discoveries generally consist of only, or little more than, a skull. The holotype is a skull only find from Sternberg's 1922 expeditions to New Mexico. Sternberg did, in 1921, discover a nearly complete specimen (why the 1922 skull is the holotype and not the 1921 skeleton is something that will be explored later, potentially).

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