许多二叠纪末大灭绝事件已被观察到增加四荚数而不是鱼，以鱼显然是由各种地理和自然灾害和漂移减少多样性，显示出一些非常小的下降，而不是沉思，大概6500万年前，小或没有在KT边境线表示（behrensmeyer和1990山）。KT灭绝事件很深，在结束了无数的四脚家庭从90到60的进化显著消退（麦斯威尔& Benton 1990）。
The Palaeozoic diversity record is totally crammed with ‘amphibians’ and known earliest tetrapods flip down in multiplicity radically within the amount of geological era, additionally last nonexistent within the Cretaceous. Late-Palaeozoic fossil records of amphibians depict the biological group Lissamphibia, additionally their diversity has raised bit by bit down from geological era stage of concerning ten families to concerning doubly that at the tip of the era. Note that the diversification pattern of ‘Amphibia’ focuses on a paraphyletic cluster within the Palaeozoic (that is, all tetrapods except amniotes) and a descendant biological group, the Lissamphibia has ended few diverse kind of organism which is double peaked in the same era was observed among ‘Amphibia’, as reported by Dodgson (1977). The outline or model is the entire whole thing of the traditional categorization of the cluster which is declined to be represented as uncommon breach within the fossil record.
Classification outlines and models for amphibian’s prototype for a reptile is uniformly unreasonable, nevertheless the teams are depicted during this prototype in order to point out few to point out the general perceptive of those terms. All the way through of the geological era, few successor clades, the birds and also mammals have been increased in numbers during the late Cretaceous. Reptilian diversity inflated slightly from beginning to end of the geological era with 20-30 families in the 50-60 late geological periods in the late Cretaceous stage, mainly dinosaurs. Existence of both birds and mammals are throughout found in the geographical era, on the other hand at small classifications, and every group of fishes have raised dramatically at very rapid in the same geographical era.
Many end-Permian mass extinction incident have been observed to increase the number of tetra pods but not fishes, in regard to the diversity of Fish which was clearly reduced by a variety of geographical and natural calamities and drift, showing some very small decline, yet not anything brooding, and supposedly 65 Million yr ago small or no at the KT border line was stated by (Behrensmeyer and Hill 1990). The KT mass extinction event was deep and was remarkable extinction in the evolution which brought an end to numerous tetra pod families from 90 to 60 (Maxwell & Benton 1990).