Kairuku

For the local-level government area in Papua New Guinea, see Kairuku Rural LLG.

Kairuku
Temporal range: late Oligocene
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Artist's impression of Kairuku
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Sphenisciformes
Genus: †Kairuku
Ksepka, Fordyce, Ando & Jones, 2012
Type species
Kairuku waitaki
Ksepka, Fordyce, Ando & Jones, 2012
Species

Kairuku is an extinct genus of penguin.[1] It contains three species, K. grebneffi, K. waitaki [2] and K. waewaeroa.[3] This taxon is known from bones from 27 MYA (late Oligocene), from the Kokoamu Greensand Formation of New Zealand.[1] It was historically referred to as Palaeeudyptes.[1]

Etymology

The genus name Kairuku comes from the Māori words kai (“food”) and ruku (“to dive”).[1]

The species name waewaeroa is from Māori waewae - "legs", and roa - "long", referring to the elongated hind limbs.[3]

K. grebneffi was named after Andrew Grebneff, a paleontologist from the University of Otago who died in 2010.[4]

Distribution

The fossils of Kairuku waewaeroa were found within the Glen Massey formation (34.6–27.3 Ma) in the North Island of New Zealand.[3]

Description

Size comparation of various species of Kairuku.

Kairuku is one of the most completely known genus of Paleogene penguins. Described species are larger than modern emperor penguin which stood around a meter,[1] K. grebneffi stood 1.28 metres (4.2 ft) tall,[1] and K. waewaeroa is even larger with height up to 1.38 metres (4.5 ft).[3] Unnamed species called Glen Murray fossil penguin is estimated to have a height 2 to 20% taller than K. grebneffi.[5]

Kairuku grebneffi

Kairuku grebneffi were nearly 1.5 metres (4.9 ft) long and stood 1.3 metres (4.3 ft) tall.[4] Adult individuals weighed an estimated 60 kilograms (130 lb), 50% more than modern emperor penguins.[6] K. grebneffi had the longest humerus bone of any penguin extant or attested to in the fossil record.[4] The bird had a longer bill and more slender body compared to living penguins.[7] Relative to its body size, its flippers were longer and probably more flexible than those of extant species.[7][8] The bird had short, thick legs, but overall, looked much like a modern penguin "from a distance."[7][8] 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.[4] Additionally, all known specimens of K. grebneffi are larger, although small sample size prevents that from being a diagnostic characteristic.[4]

K. grebneffi likely used its slender beak to spear fish and squid.[7] It likely was able to dive deeper and swim farther than living penguins.[6] Predators of the bird likely included sharks and Squalodons.[7]

K. grebneffi lived in what is now New Zealand late in the Oligocene period, roughly 25–27 million years ago.[6] At the time, most of the area was ocean, with a few isolated islands.[6] It is believed that these rock outcrops provided safe breeding grounds and easy access to rich food resources in the surrounding seas.[6] K. grebneffi lived alongside at least four other penguin species. It is likely that each species fed on different kinds of fish.[9]

K. grebneffi was among of the last of the giant penguins.[7] The cause of K. grebneffi's 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.[7] Other possibilities include the arrival of new predators and increased food competition.[6]

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 that unites[clarification needed] New Zealand endemics Kairuku waewaeroa, Kairuku waitaki and Kairuku grebneffi. The probable height of K. waewaeroa is 1.38 m (4.5 ft), and the length of the body from the fingertips to the tip of the beak is 1.6 m (5.2 ft).[3][10]

Discovery

The first Kairuku bones were discovered in 1977 by Ewan Fordyce, although they were not identified as such at the time.[6][11] 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 Kokoamu Greensand of the North Otago and South Canterbury districts of New Zealand.[4][6] 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.[4] The king penguin was used as a guide during reconstruction.[6]

The holotype of K. grebneffi was collected in 1991 from a drainage area of the Waipati stream, a tributary of the Maerewhenua River.[4]

Fossil remains of Kairuku waewaeroa, or Kawhia giant penguin, fossil remains were found in Kawhia Harbour on the North Island of New Zealand.[3][12]

References

  1. ^ a b c d e f Ksepka, Daniel T.; Fordyce, R. Ewan; Ando, Tatsuro; Jones, Craig M. (March 2012). "New fossil penguins (Aves, Sphenisciformes) from the Oligocene of New Zealand reveal the skeletal plan of stem penguins". Journal of Vertebrate Paleontology. 32 (2): 235–254. Bibcode:2012JVPal..32..235K. doi:10.1080/02724634.2012.652051. JSTOR 41515052. S2CID 85887012.
  2. ^ Giant Prehistoric Penguin was Bigger Than an Emperor | Observations, Scientific American Blog Network
  3. ^ a b c d e f Giovanardi, Simone; Ksepka, Daniel T.; Thomas, Daniel B. (16 September 2021). "A giant Oligocene fossil penguin from the North Island of New Zealand". Journal of Vertebrate Paleontology. 41 (3): e1953047. Bibcode:2021JVPal..41E3047G. doi:10.1080/02724634.2021.1953047.
  4. ^ a b c d e f g h Ksepka, Daniel T.; Fordyce, R. Ewan; Ando, Tatsuro; Jones, Craig M. (March 2012). "New fossil penguins (Aves, Sphenisciformes) from the Oligocene of New Zealand reveal the skeletal plan of stem penguins". Journal of Vertebrate Paleontology. 32 (2): 235–254. Bibcode:2012JVPal..32..235K. doi:10.1080/02724634.2012.652051. JSTOR 41515052. S2CID 85887012.
  5. ^ Thomas, DB; Ksepka, DT (1 October 2016). "The Glen Murray fossil penguin from the North Island of New Zealand extends the geographic range of Kairuku". Journal of the Royal Society of New Zealand. 46 (3–4): 200–213. Bibcode:2016JRSNZ..46..200T. doi:10.1080/03036758.2016.1211541. ISSN 0303-6758. S2CID 132811234.
  6. ^ a b c d e f g h i "Scientists reconstruct 'elegant' giant penguin that lived in New Zealand 26 million years ago". Dawn. Associated Press. 1 March 2012. Archived from the original on 6 July 2021. Retrieved 1 March 2012.
  7. ^ a b c d e f g Viegas, Jennifer (27 February 2012). "Ancient Penguin Weighed 130 Pounds". Discovery News. Discovery Channel. Archived from the original on 23 April 2012. Retrieved 1 March 2012.
  8. ^ a b "Fossils show huge penguin once roamed New Zealand". Bangkok Post. Agence France-Presse. 28 February 2012. Archived from the original on 12 October 2021. Retrieved 1 March 2012.
  9. ^ Dell'Amore, Christine (27 February 2012). "Giant Prehistoric Penguins Revealed: Big but Skinny". National Geographic News. Archived from the original on 22 March 2016. Retrieved 1 March 2012.
  10. ^ "A mega-penguin stood tall on prodigious limbs". Nature. 597 (7878): 597. 21 September 2021. Bibcode:2021Natur.597R.597.. doi:10.1038/d41586-021-02562-y. S2CID 237594320.
  11. ^ "Kairuku - a new "giant" Late Oligocene Penguin from New Zealand". University of Otago. 23 November 2015.
  12. ^ Wetzel, Corryn (17 September 2021). "New Zealand Kids Discovered This Fossil of New Giant Penguin Species on a Field Trip". Smithsonian Magazine. Archived from the original on 22 September 2021. Retrieved 19 September 2021.