''Kairuku'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of

penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

. It contains three species, ''K. grebneffi'', ''K. waitaki'' and ''K. waewaeroa''. This taxon is known from bones from 27

MYA Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

(late Oligocene), from the

Kokoamu Greensand The Kokoamu Greensand is a geological formation found in New Zealand. It is a fossil-bearing, late Oligocene, greensand rock unit of the eastern South Island, especially the Waitaki District of North Otago and the southern Canterbury region. The ...

Formation of New Zealand. It was historically referred to as '' Palaeeudyptes''.

Etymology

The name ''Kairuku'' comes from the Māori words ''kai'' (“food”) and ''ruku'' (“to dive”). From Māori waewae - "legs", roa - "long", referring to the elongated hind limbs. ''K. grebneffi'' was named after Andrew Grebneff, a paleontologist from the University of Otago who died in 2010.

Distribution

The fossils of ''Kairuku waewaeroa'' were found within the

Glen Massey Glen Massey is a former mining village, west of Ngāruawāhia, which was, until 1958, terminus of the Glen Massey Line. It then went into decline, but is now becoming a home for Hamilton commuters. Name There is no official name. Various n ...

formation (34.6–27.3 Ma) in the North Island of New Zealand.

Description

''Kairuku'' is one of the most completely known genus of

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

penguins. Described species are larger than modern

emperor penguin The emperor penguin (''Aptenodytes forsteri'') is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in length and weighing from . Feathers of th ...

which stood around a meter, ''K. grebneffi'' stood tall, and ''K. waewaeroa'' is even larger with height up to . Unnamed species called Glen Murray fossil penguin is estimated to have a height 2 to 20% taller than ''K. grebneffi''.

Kairuku grebneffi

''Kairuku grebneffi'' were nearly long and stood tall. Adult individuals weighed an estimated , 50% more than modern emperor penguins. ''K. grebneffi'' had the longest

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

bone of any penguin

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

or attested to in the fossil record. The bird had a longer bill and more slender body compared to living penguins. Relative to its body size, its flippers were longer and probably more flexible than those of extant species. The bird had short, thick legs, but overall, looked much like a modern penguin "from a distance." ''K. grebneffi'' is distinguished from its sister species ''K. waitaki'' primarily on the basis of vertebrae spacing and by having a straight tipped bill, compared to the curved tip of ''K. waitaki''. Additionally, all known specimens of ''K. grebneffi'' are larger, although small sample size prevents that from being a diagnostic characteristic. ''K. grebneffi'' likely used its slender beak to spear fish and squid. It likely was able to dive deeper and swim farther than living penguins. Predators of the bird likely included sharks and '' Squalodons''. ''K. grebneffi'' lived in what is now New Zealand late in the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

period, roughly 25-27 million years ago. At the time, most of the area was ocean, with a few isolated islands. It is believed that these rock outcrops provided safe breeding grounds and easy access to rich food resources in the surrounding seas. ''K. grebneffi'' lived alongside at least four other penguin species. It is likely that each species fed on different kinds of fish. ''K. grebneffi'' was among of the last of the giant penguins. The cause of ''K. grebneffis extinction is unknown, but was probably related to "the drastic change in paleoenvironment" according to Tatsuro Ando, one of the scientists who classified the penguin. Other possibilities include the arrival of new predators and increased food competition.

Kairuku waewaeroa

The skeleton of the holotype is one of the most complete skeletons of giant penguins that have ever been found. Phylogenetic analysis reveals a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

that unites New Zealand endemics ''Kairuku waewaeroa'', '' Kairuku waitaki'' and ''

Kairuku grebneffi ''Kairuku'' is an extinct genus of penguin. It contains three species, ''K. grebneffi'', ''K. waitaki'' and ''K. waewaeroa''. This taxon is known from bones from 27 MYA (late Oligocene), from the Kokoamu Greensand Formation of New Zealand. It ...

''. The probable height of ''K. waewaeroa'' is , and the length of the body from the fingertips to the tip of the beak is .

Discovery

The first ''Kairuku'' bones were discovered in 1977 by Ewan Fordyce, although they were not identified as such at the time. In February 2012, an international team of scientists led by Fordyce and Daniel Ksepka reconstructed a ''K. grebneffi'' skeleton using a few "key specimens" from the

of the North Otago and South Canterbury districts of New Zealand. The specimens used represent some of the most complete skeletons found of any extinct penguin, and thus provide valuable insight into the reconstruction of all extinct penguins. The king penguin was used as a guide during reconstruction. The holotype of ''K. grebneffi'' was collected in 1991 from a drainage area of the Waipati stream, a tributary of the

Maerewhenua River The Maerewhenua River, also known as the Marewhenua River, is a small river in the Otago region of New Zealand's South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, th ...

. Fossil remains of ''Kairuku waewaeroa'', or Kawhia giant penguin, fossil remains were found in Kawhia Harbour on the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

of New Zealand.

References

External links

First Full Look at Prehistoric New Zealand Penguin
Oligocene birds Bird genera Extinct birds of New Zealand Extinct penguins Fossil taxa described in 2012 {{NewZealand-stub