Eudyptula wilsonae is the smallest extinct crown penguin yet known and is a possible ancestor of the kororā or New Zealand little penguin (Eudyptula minor minor), which is endemic to New Zealand and is the smallest living penguin species.
The Wilson’s little penguin (Eudyptula wilsonae). Image credit: Simone Giovanardi.
“Aotearoa New Zealand is home to three of the six living penguin genera, including the little penguins (genus Eudyptula),” said Dr. Daniel Thomas from Massey University and his colleagues from the Museum of New Zealand Te Papa Tongarewa and Bruce Museum.
“Little penguins occur across southern Australia and the New Zealand archipelago.”
“They are remarkable for being among the smallest obligate marine endotherms yet having breeding colonies distributed across the broadest range of mean annual sea-surface temperatures observed in penguins.”
“Their biogeographic origins and morphological evolution are therefore of great interest.”
The newly-described species is an extinct member of the little penguin lineage and is the smallest extinct crown penguin yet known.
Named Eudyptula wilsonae, or the Wilson’s little penguin, it lived during the Late Pliocene between 3.4 and 3 million years ago.
The two specimens — the nearly complete skulls of an adult and a fledged but immature individual — of the new species were found in the Tangahoe Formation, exposed in the southern Taranaki region of the North Island of New Zealand.
The fossils reveal that the physical characteristics of little penguins have remained largely unchanged across 3 million years, despite substantial environmental changes in the region across that time.
“Our work helps to illustrate ancient penguin origins and provides significant evolutionary links between living animals and their Zealandia ancestors,” Dr. Thomas said.
“These newly discovered fossils show little penguins like kororā have been part of coastal ecosystems of Zealandia for at least 3 million years.”
“This is important when thinking about the origins of these penguins, the evolution of the seabird diversity of Aotearoa and the dynamic environment in which they live.”
“For one thing, the climate has changed a lot over this time and this lineage has been robust to those changes.”
The study supports a Zealandian origin for the little penguins and confirms their presence during the Neogene period.
“Both skulls show more slender proportions than modern little penguins and precede genome-derived estimates for the divergence between Eudyptula minor minor and Eudyptula minor novaehollandiae,” the authors said.
“This raises the possibility that the fossil species represents a lineage directly ancestral to extant little penguins.”
“Our results support a Zealandian origin for little penguins, with subsequent Pleistocene dispersal to Australia and a more recent Holocene range expansion of Eudyptula minor novaehollandiae back into New Zealand.”
The study was published in the Journal of Paleontology.
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Daniel B. Thomas et al. Pliocene fossils support a New Zealand origin for the smallest extant penguins. Journal of Paleontology, published online June 21, 2023; doi: 10.1017/jpa.2023.30
