Editing Penguin (section)

====Palaeeudyptines====
During the Late Eocene and the Early [[Oligocene]] (40–30 mya), some lineages of gigantic penguins existed. [[Nordenskjoeld's giant penguin]] was the tallest, growing nearly {{convert|1.80|m|ft|abbr=off|sp=us}} tall. The [[New Zealand giant penguin]] was probably the heaviest, weighing {{Convert|80|kg|lb}} or more. Both were found on New Zealand, the former also in the Antarctic farther eastwards.

Traditionally, most extinct species of penguins, giant or small, had been placed in the [[paraphyletic]] [[subfamily]] called [[Palaeeudyptinae]]. More recently, with new taxa being discovered and placed in the [[phylogeny]] if possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in [[Patagonia]], and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most [[Antarctic]] and [[Subantarctic]] coasts.

Size plasticity was significant at this initial stage of [[Adaptive radiation|radiation]]: on [[Seymour Island]], Antarctica, for example, around 10 known species of penguins ranging in size from medium to large apparently coexisted some 35 mya during the [[Priabonian]] (Late Eocene).<ref name="Jadwiszczak"/> It is not known whether the palaeeudyptines constitute a [[monophyletic]] lineage, or whether gigantism was evolved independently in a restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited (i.e., including ''[[Anthropornis nordenskjoeldi]]'').<ref name="Ksepka"/> The oldest well-described giant penguin, the {{convert|5|ft|m|adj=on}}-tall ''[[Icadyptes salasi]]'', existed as far north as northern [[Peru]] about 36 mya.

Gigantic penguins had disappeared by the end of the [[Paleogene]], around 25 mya. Their decline and disappearance coincided with the spread of the [[Squalodontidae]] and other primitive, fish-eating [[toothed whale]]s, which competed with them for food and were ultimately more successful.<ref name="Baker"/> A new lineage, the [[Paraptenodytes]], which includes smaller and stout-legged forms, had already arisen in southernmost South America by that time. The early [[Neogene]] saw the emergence of another morphotype in the same area, the similarly sized but more gracile [[Palaeospheniscinae]], as well as the radiation that gave rise to the current [[biodiversity]] of penguins.