The Natural History of Dinosaurs (Eart 65)
UC Santa Cruz
Psittacosaurus is a genus of the psittacosaurid ceratopsian dinosaur from the Early Cretaceous Period, and represents one of the most primitive conditions of the ceratopsians (Fastovsky and Weishampel, 2009). Psittacosaur is Greek for ‘parrot lizard’, and receives such a name due to its skull being ‘parrot-beaked’, and is characterized by its short, deep snout and ventrolaterally projecting cheek horns (Sereno, 2010). It is a small bipedal dinosaur, with a very broad geographical distribution throughout Asia, and one species found in Russia. Psittacosaurs date back approximately 100 to 130 million years ago. They are recognized for being one of the most species-rich dinosaur genus, and today, is the most abundant and widely distributed ceratopsian in the Asian Lower Cretaceous. As many as 14 species of Psittacosaurus have been named, and have shown great signs of preservations, with many of their remains including complete skulls and skeletons (Lucas, 2006). In this research paper, the lifestyles and classification of Psittacosaurs will be examined, giving an insight into their prehistoric existence by displaying key aspects of the dinosaur, including their behavior, physiology, diet, predation tendencies, and parental care to create a complete scope of the life of a Psittacosaur in their prehistoric Asian environment. The first Psittacosaurus was discovered by Henry Fairfield Osborn, a paleontologist and president of the American Museum of Natural History (AMNH). On October 19, 1923, he published a paper on the dinosaur, naming the first of many psittacosaur species: Psittacosaurus mongoliensis. The remains of this dinosaur were first discovered the year before, on the third American Museum of Natural History expedition to the Gobi Desert of Mongolia (Osborn, 1923). Since this discovery, approximately 18 more species have been assigned to the ceratopsian genus Psittacosaurus, although only twelve to fourteen are considered valid (Zhao et al., 2007). This is the highest number of valid species currently assigned to any single dinosaur genus (not including birds). This fact makes psittacosaurus very unique, compared to other dinosaur genera, many of which are monospecific, containing only a single known species (Sereno, 2000). With such a large amount of psittacosaur remains discovered, the diversity of the dinosaur can be viewed in a more complete fashion compared to that of many other dinosaur genera, which would be the reason for so many species being recognized. Fossil remains of over 75 psittacosaur individuals have been recovered, including nearly 20 complete skeletons with skulls (Lucas, 2006). Although there are up to fourteen named species, some paleontologists such as Zhae et al. (2006) believe taxonomic revision of the psittacosaur genus is overdue and it is probable that the true number of diagnosable species is much lower; claiming the differential species classifications are mostly based on single specimens and are supposedly distinguished from each other by minor cranial features (Lucas 2006). However, this does not change the fact that a bountiful amount of psittacosaurs have been recovered; figure 1 displays the geographic distribution of said discoveries. Figure 1: Location Map(Lucas, 2006)
Psittacosaurus is a type genus that falls under the family of Psittacosauridae, which was also named by Osborn in 1923 (Osborn, 1923). The genus of Psittacosaurus is considered the archetypal ceratopsian, a genus which can be considered an almost stereotypical ceratopsian, and this is shown through its derived traits which are shared by most of the later ceratopsians. It holds many of the integral evolutionary qualities of the Ceratopsia, even though it has only the most rudimentary of frills (the posterior end of the skull roof just barely overhangs the back end of the skull) (Lucas,...
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