For approximately 160 million years, the terrestrial environment was dominated by dinosaurs. Dinosaurs arose from fully bipedal ancestors, who is believed to have been a carnivore or omnivore (Langer, Ezcurra, Bittencourt & Novas, 2010). These agile terrestrial archosaurs lived during the Late Permian and Early Triassic and had already developed key changes in the hips and ankles that set the stage for the increase in body size that is seen in dinosaurs (Pough, Janis & Heiser, 2013). This included an alteration in the hip that allowed the hind limbs to be held beneath the body, instead of on the sides, creating an erect stance. As well a simplified ankle structure, referred to as a mesotarsal ankle joint, which allowed the hind feet to
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Unlike the Saurischians, which included herbivores as well as carnivores, all Ornithischians were herbivores. Another difference is seen in the skull, which had small reduced openings between the eye sockets and nostrils. Ornithischians are also united by a three pronged pelvic bone and a unique jaw and dental evolution. This included the presence of a predentary bone in the jaw forming a chin like structure in all Ornithischian dinosaurs. The pelvic structure resembles that of a bird, and has a downward backwards facing pubis bone which running parallel to the ischium. There’s been evidence of complex social behaviors such as herding, parental care, and combat. The function of the elaborate structures that are seen on the heads of many Ornithischians has often been linked to both combat and species recognition. Fossils and nests found at Egg Mountain gave proof of colonies and nesting practices never before seen in dinosaurs. Unfortunately, due to a lack of evidence and fossils there are still many unsolved mysteries revolving Ornithischians. The functions of many of their structures and behavioral traits are still unknown; therefore, more fossils must be found and studied in order to advance future theories and
Unlike the Saurischians, which included herbivores as well as carnivores, all Ornithischians were herbivores. Another difference is seen in the skull, which had small reduced openings between the eye sockets and nostrils. Ornithischians are also united by a three pronged pelvic bone and a unique jaw and dental evolution. This included the presence of a predentary bone in the jaw forming a chin like structure in all Ornithischian dinosaurs. The pelvic structure resembles that of a bird, and has a downward backwards facing pubis bone which running parallel to the ischium. There’s been evidence of complex social behaviors such as herding, parental care, and combat. The function of the elaborate structures that are seen on the heads of many Ornithischians has often been linked to both combat and species recognition. Fossils and nests found at Egg Mountain gave proof of colonies and nesting practices never before seen in dinosaurs. Unfortunately, due to a lack of evidence and fossils there are still many unsolved mysteries revolving Ornithischians. The functions of many of their structures and behavioral traits are still unknown; therefore, more fossils must be found and studied in order to advance future theories and