The Permo-Triassic Analysis

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New fossil evidence suggests that dinosaurs originated early in the Middle Triassic time period, during the recovery of life from the Permian-Triassic mass extinction (Benton et al. 2014). Transient episodes of unusually warm and wet conditions, interrupting long periods of cool and dry conditions, may have played a role in mass extinctions and long-term evolutionary trends (Retallack 2013). Although the Permo-Triassic mass extinction wiped out nearly 85% of species, the crises marked the beginning of the Mesozoic Era, a time period often associated with the Age of Reptiles (Benton et al. 2014). The Permo-Triassic extinction was likely a consequence of massive volcanic activity and consequent severe global warming, acid rain and ocean anoxia …show more content…
2014). Other key characteristic features that may have enabled dinosaurs to benefit from the ecological crises would include: high thermal inertia, exceptional growth rate, and efficient (avian-like) respiratory systems (Benton et al. 2014). Furthermore, the supposedly mammalian-like endothermy and their upright, bipedal posture are other potential examples of adaptive advantages (Benton et al. 2014). These factors enabled the dinosaurs to undergo adaptive radiation following the Permo-Triassic mass extinction.

The Cretaceous/ Tertiary (K/T) boundary is associated with the mass extinction of dinosaurs, a geological event that dates back approximately 65 million years (Brisman et al. 2001). The extinction of dinosaurs is commonly attributed to a large bolide impacting the Earth and a massive series of volcanic eruptions at the end of the Cretaceous period (Brisman et al. 2001). Either of these proposed hypotheses could account for the short-term (rapid) cooling, cessation of photosynthesis, acid rain and extensive wildfires that ultimately led
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For example, non-avian dinosaurs became extinct following the asteroid impact, yet birds survived (Kukuchi and Vanneste 2010). The impact of ground-level ozone with respect to varying survival rates among dinosaurs had hardly been considered since the K-T impact theory was reported. More recently, however, reverse trajectory models actually predicted an ozone concentration above the health-threatening level that persisted near the ground after the K-T impact (Kukuchi and Vanneste 2010). Due to potential respiratory ozone irritation, non-avian dinosaurs likely experienced significantly lower survival probability compared to avian dinosaurs (Kukuchi and Vanneste

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