Livyatan melvillei

Livyatan melvillei
Temporal range: Serravallian, 13–12 Ma
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Reconstruction of Livyatan (left) and Cetotherium (right)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: Artiodactyla
Superfamily: Physeteroidea
Family: incertae sedis
Genus: †Livyatan
Lambert et al., 2010[1]
Species: †L. melvillei
Binomial name
Livyatan melvillei
(Lambert et al., 2010)[1]
Synonyms
  • Leviathan melvillei
    Lambert et al., 2010[1]

Livyatan melvillei is an extinct species of physeteroid whale, similar in size to the modern sperm whale. It lived during the Serravallian stage of the Miocene epoch, approximately 12 to 13 million years ago.[2][3]

Discovery

Lower jaw viewed from above

In November 2008, fossil remains of Livyatan melvillei were discovered in the coastal desert of Peru in the sediments of the Pisco formation at Cerro Colorado, 35 kilometres (22 mi) south-southwest of Ica.[1][3] The remains include a partially preserved skull with teeth and mandible.[1] Rotterdam Natural History Museum researcher Klaas Post stumbled across them on the final day of a field trip there in November 2008.[2] Post was part of an international team of palaeontologists.[4]

The fossils have been dated at 12–13 million years old and were prepared in Lima,[2] and are now part of the collection of the Natural History Museum there.[5]

Etymology and nomenclature

Researchers originally assigned the English name of the biblical monster, Leviathan, to this prehistoric whale as Leviathan melvillei, dedicating the discovery to Herman Melville, author of Moby-Dick—the researchers behind the excavation of L. melvillei were all fans of this novel.[4] However, the scientific name Leviathan was a junior homonym of Leviathan Koch, 1841 for a genus of mastodon (see Leviathan in Wikispecies). Junior homonyms need to be replaced with new names, except under certain special circumstances (ICZN 1999 Article 60). In August 2010, the authors rectified this situation by coining a new genus name for the whale, Livyatan, from the original Hebrew spelling.[6]

Description

Cast of skull with teeth and mandible

Livyatan melvillei was 13.5 to 17.5 metres (44–57 ft) long, about the same as a modern adult male sperm whale.[1] The skull of Livyatan melvillei is 3 metres (9.8 ft) long.[1] Unlike the modern sperm whale, Physeter macrocephalus, L. melvillei had functional teeth in both of its jaws.[1] The jaws of L. melvillei were robust and its temporal fossa was also considerably larger than in the modern-age sperm whale.[1] L. melvillei is one of the largest predators yet known, with whale experts using the phrase "the biggest tetrapod bite ever found" to explain their find.[1] The teeth of L. melvillei are up to 36 centimetres (1.18 ft) long and are thought to among be the largest of any animal yet known, with only a newly discovered relative from the Pliocene having teeth within the size range.[1] [7] Larger 'teeth' (tusks) are known, such as odobenocetops and narwhal tusks, but these are not used directly in eating.

Size

L. melvillei reached a length of about 13.5 to 17.5 metres (44–57 ft), nearly two times the length and more than three times the weight of a modern-day killer whale (Orcinus orca).

Two physeterids have been chosen by whale experts for comparison to estimate the size of L. melvillei.[1] The anatomy of Physeter macrocephalus yielded a total length (TL) of 13.5 m (= 44.3 feet) for L. melvillei,[1] and that of Zygophyseter varolai yielded a TL of 17.5 m (= 57.4 feet) for L. melvillei.[1]

In 2016, a large tooth of a whale was found on the coast of Australia. The tooth measured some 30 centimeters in length, making the owner of the tooth as large, if not larger than L.melvillei. The tooth also dates to around 5-6 million years ago. This means that the raptorial sperm whales survived for another 2 million years and were still doing well. The large tooth of the whale looks very much like Livyatan and may even be a species of Livyatan.[8]

Skull structure

Teeth

The fossil skull of L. melvillei has a curved basin which suggests it might have had a large spermaceti organ, a series of oil and wax reservoirs separated by connective tissue. This organ is thought to help modern sperm whales to dive deeply to feed. However, L. melvillei is likely to have hunted large prey near the surface, so it appears that this organ would have had other functions. Possible suggestions include echolocation, acoustic displays (with the spermaceti organ acting as a resonance chamber) or aggressive headbutting, possibly used against competing males in mating contests or to batter prey.[2]

Paleobiology

L. melvillei was a top predator along with the giant shark, C. megalodon,[1][9] which was contemporaneous with L. melvillei in the same region,[1] and the whale probably had a profound impact on the structuring of Miocene marine communities.[1] The appearance of gigantic raptorial sperm whales in the fossil record coincides with a phase of diversification and size-range increase of the baleen-bearing mysticetes in the Miocene.[1]

L. melvillei is likely to have preyed upon 7–10-metre (23–33 ft) sharks,[4] baleen whales,[1] seals,[4] dolphins[4] and other large marine vertebrates, which it captured with its long teeth.

As a matter of fact fossil remains of many marine vertebrates —including baleen whales, beaked whales, dolphins, porpoises, sharks, sea turtles, seals and sea birds—have been found at the same site where the remains of L. melvillei have been excavated.[1]

"Australian physeteroid"

In 2016, a gigantic physeteroid tooth was discovered among Pliocene-aged sediments in Beaumaris Bay, Australia. The tooth appears to belong to "an extinct species of sperm whale closely related to Livyatan melvillei from Peru".[10] The fossil has not received any official species designation yet.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle (1 July 2010). "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru". Nature 466 (7302): 105–108. doi:10.1038/nature09067. PMID 20596020. Retrieved 2 July 2010.
  2. 1 2 3 4 Fang, Janet (30 June 2010). "Call me Leviathan melvillei". nature news. Nature. doi:10.1038/news.2010.322.
  3. 1 2 Paleobiology Database
  4. 1 2 3 4 5 Ghosh, Pallab (30 June 2010). "'Sea monster' whale fossil unearthed". BBC News.
  5. ↑ Sample, Ian (30 June 2010). "Fossil sperm whale with huge teeth found in Peruvian desert". The Guardian.
  6. ↑ Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle (2010). "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru [Corrigendum]". Nature 466 (7310): 1134. doi:10.1038/nature09381.
  7. ↑ Smith, Bridie (21 April 2016). "Move Over Moby Dick: Meet Melbourne's Own Mega Whale". The Sydney Morning Herald.
  8. ↑ http://www.earthtouchnews.com/discoveries/fossils/giant-killer-sperm-whales-once-cruised-australias-waters-and-we-have-a-massive-tooth-to-prove-it
  9. ↑ "New Leviathan Whale Was Prehistoric "Jaws"?". Daily News. National Geographic. 30 June 2010.
  10. ↑ "Huge Tooth Reveals Prehistoric Moby Dick in Melbourne | Australasian Science Magazine". www.australasianscience.com.au. Retrieved 2016-04-24.

External links

Wikispecies has information related to: Livyatan melvillei

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