This paper examines the relationship between natural catastrophes and mass extinctions and their impact on vertebrate evolution. Natural catastrophes have a major influence on the likelihood of extinction. The largest mass extinctions are linked to these catastrophes and often reconstruct the biosphere. Therefore eliminate some species, while also allowing previously minor groups to survive and diversify. This involves extinction of certain groups based on certain parameters like body size and rate of life history.
Throughout Earth’s history, five major mass extinctions have been identified. These Big Five mass extinctions events include: the Cretaceous- Tertiary, the Triassic-Jurassic, the Permian-Triassic, the Late Devonian extinction, and the Ordovician-Silurian event. Each of these mass extinctions destroyed large numbers of species on Earth. Some species underwent radiation and diversified into the vertebrates found on Earth today. Such radiations can be understood by studying the fossil record.
The probability of extinction is thought to be greatly affected by particularly extreme bouts of environmental variation that severely decrease the size of wildlife populations over a relatively short time (Reed et al., 2003). Extinction of a species requires a physical or biological shock that does not usually occur during the life span of the species. The shock must occur rapidly as well as over a broad geographic area so that adaptation cannot occur (Raup, 1994). Extinction events provide opportunities such as new space and niche availability for later diversification by the survivors. Survivors are normally smaller organisms that adapted prior to the unanticipated stressful event (Reed et al., 2003). The frequency o...
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...rsification, and explosive Tertiary radiation. This radiation possibly occurred within a time frame as short as 5–10 million years, paralleling mammals (Feduccia, 2003).
Fossil evidence also supports the view that, like birds, mammals represent diverse lineages from either side of the K–T boundary. However, no truly modern orders of placentals are known before the Tertiary (Feduccia, 2003). Similar to birds, mammals underwent an explosive Tertiary evolution that produced diverse modern orders by the Paleocene–Eocene. The initial diversification of modern ornithurines might have taken place in the late Cretaceous but the explosive adaptive radiation followed the K–T extinction event. This explosive radiation following a major extinction event can be seen as a standard pattern of vertebrate evolution following any mass extinction event or catastrophe (Feduccia, 2003).