Evolution of the First Dinosaurs
Throughout history, the debate over the origin and the true characteristics of dinosaurs have been rife. They are believed to belong to a group of species known as archosaurs, which are have been described as among the most successful groups of animals to have graced the planet (Reynolds, 2017). It is argued that the dinosaurs dominated the face of the earth for over 160 million years and included small creatures and the largest animals ever to have explored the earth (Brusate et al., 2010). However, despite their long evolutionary history, the origin of the first dinosaurs remains a mystery. This has led to the ongoing debate over their origin, life history, and extinction among their other related questionable aspects. Nonetheless, various research studies have provided detailed synthesis about the dinosaurs, though with numerous challenges.
Defining and classifying dinosaurs have been among the challenges encountered by researchers of different centuries. According to Baron et al. (2017), the definition and classification of dinosaurs have been based on the configuration of their pelvis. Specifically, there have been 2 major groups of the dinosaurian order, namely the ornithischian and the Saurischia. Various sub-group under archosaurs highly experienced evolution during the Triassic period. During the Triassic period, new land vertebrates, as well as the first mammals, are known to have appeared. However, the dinosaurs were the latecomers into this era of radiation and evolution. The first true dinosaur might have appeared after 230 million years, in the late Triassic according to Brusate et al. (2010). They appeared to have evolved from the reptiles and the Plateosaurus, a plant-eating dinosaur was among the first to appear. Many of them were characteristically small animals who inhabited warm and seasonal places on Earth. However, the Plateosaurus dinosaur was large, approximately 9 meters in length. However, due to volcanic activities, about 200 million years later, the dinosaurs were cleared from the face of the Earth and the lineage of the archosaurs. Nonetheless, they persisted into the Jurassic period, which marked the beginning of their ecological dominance.
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