Cope's rule is the Size Rule applied to biological objects. It was first observed in the fossile record [Error: Wrong macro arguments: "http://zotero.org/users/438144/items/DXH2C2PU" for macro 'ref' (maybe wrong macro tag syntax?)]
. Although named after Cope, he never actually stated that rule.
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Rational
Evolution favors larger in size individuals because those are better in competition and to resist predictors. This holds but for the most advanced species at any given time in evolution.
Examples
- It can be observed in marine animals [Error: Wrong macro arguments: "http://zotero.org/users/438144/items/Z94E73E6" for macro 'ref' (maybe wrong macro tag syntax?)]
.
- Among placental mammals body size increased independently [Error: Wrong macro arguments: "http://zotero.org/users/438144/items/XZWWHA4T" for macro 'ref' (maybe wrong macro tag syntax?)]
.
- Also observed among Dinosaurs at their time [Error: Wrong macro arguments: "http://zotero.org/users/438144/items/35I685IE" for macro 'ref' (maybe wrong macro tag syntax?)]
Discussion
Though this rule holds in many clades it is not true in all of them. For instance reptiles rather shrink in size since dinosaurs got extinct. This is perfectly explicable by Fauceir Evolution Theory. As mammals are the more advanced species they drive out the former dominating reptiles from their habitat. Reptiles have to retreat to smaller ecological vacancies where they are still compatible competitive. The remaining ecological refugia are small and therefore they have to shrink in size.
Conclusively Cope's Rule is valid only among the most advanced in evolution species.
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