Brygmophyseter

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Brygmophyseter
Temporal range: Miocene (Langhian), 16–15  Ma
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Brygmophyseter skeleton (cropped).jpg
Restored skeleton
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Superfamily: Physeteroidea
Family: incertae sedis
Genus:† Brygmophyseter
Barnes, 2006
Species:
†B. shigensis
Binomial name
†Brygmophyseter shigensis
(Hirota and Barnes, 1995)
Synonyms
  • Scaldicetus shigensis
  • Naganocetus shigensis

Brygmophyseter, known as the biting sperm whale, is an extinct genus of toothed whale in the sperm whale family with one species, B. shigensis. When it was first described in 1994, the species was placed in the genus Scaldicetus based on tooth morphology, but this was later revised in 1995. In 2006, it was classified into the genus Naganocetus, which is considered to be a junior synonym. The only known specimen, a nearly complete skeleton, was dated to be around 16–15 million years old (middle Miocene). Brygmophyseter is thought to have been 6.5–7 meters (21–23 ft) long, and it probably had 11 or 12 teeth in the upper and lower jaws. Brygmophyseter is part of a group of macroraptorial sperm whales (often shortened to "raptorial") which tended to be apex predators using their large teeth to catch struggling prey such as whales. It had a spermaceti organ which was probably used for biosonar like in the modern sperm whale. The whale has made an appearance on The History Channel's TV series Jurassic Fight Club .

Contents

History of discovery

The holotype specimen, SFM-0001, was excavated from the Bessho Formation in the Nagano Prefecture in Japan in 1988 by the residents of Shiga-mura with assistance from the staff of the Shiga Fossil Museum. [1] The specimen is nearly complete, and consists of a partial skull, the jawbone, the lingual bone in the neck, vertebrae, ribs, the breastbone, and humeri and radii in the limbs. [1] [2] It was dated to the Langhian stage of the Miocene 14–15 million years ago (mya), and the specimen is currently on display at the Gunma Museum of Natural History in Japan. [1] [3]

The genus name is a combination of the Ancient Greek word brygmos, which means "biting" or "gnashing", combined with physeter, which is the generic name of the living sperm whale, and also means "blower" in Ancient Greek. [1] [4] The junior synonym Naganocetus derives from the Nagano Prefecture and the Latin cetus meaning "whale". [5]

Description

Restoration Brygmophyseter BW.jpg
Restoration

Like other raptorials, Brygmophyseter had enamel-coated teeth in both jaws, unlike the modern sperm whale (Physeter macrocephalus). It probably had 11 or 12 teeth in each jaw, though no upper teeth were preserved in the holotype. The skull of the holotype measured around 1.5 meters (4.9 ft), and it had an elongated snout. The brow ridge was broad and flat-topped, and the zygomatic process of the squamosal bone on the cheeks was large and robust. The temporal fossa on the sides of the skull were elongated, which may have been plesiomorphic features from archaeocetes, that is, it is an ancestral characteristic of the whale. [5] The right nasal passage was small and was asymmetrical with the left nasal passage, like in the modern sperm whale. Characteristic of sperm whales, it had a deep basin on the top of its skull, known as the supracranial basin. Like in the modern sperm whale, this basin probably held the spermaceti organ, and so the whale had biosonar capabilities. The nuchal crest which is the part of the whale skull which projects upwards on the back end of the skull, behind the supracranial basin, was low and broad. Similar to modern-day toothed whales, but unlike in the modern sperm whale, the shoulder blades were thicker than they were tall. [6] [1]

Brygmophyseter compared to a diver Brygmophyseter size.svg
Brygmophyseter compared to a diver

Brygmophyseter is estimated to have been around 6.5–7 meters (21–23 ft) long. [7] The holotype had preserved zero neck vertebrae, ten thoracic vertebrae, ten lumbar vertebrae, and fifteen tail vertebrae. In comparison, the modern sperm whale has eleven thoracic, eight lumbar, and twenty-two tail vertebrae, and the smaller tail in Brygmophyseter is probably a primitive characteristic. The vertebra segments increase in height until the seventh lumbar vertebra, then they begin to decrease. In the thoracic vertebrae, with the exception of the tenth one, the width of the segments is larger than the height. The lumbar and tail vertebrae are circular in shape. [6] [1]

The head of the humerus arm bone of Brygmophyseter was positioned perpendicular to the shaft. The elbow joint on the humerus was not distinct from the ulna, typical in cetaceans. The ulna was more primitive than that of the modern sperm whale, in that the shaft was longer and more slender, and the head of the bone was smaller. [1]

Taxonomy

Phylogeny

Reconstructed skeleton in side view Brygmophyseter shigensis.jpg
Reconstructed skeleton in side view

Brygmophyseter is a member of a fossil stem group of hyper-predatory macroraptorial sperm whales from the Miocene (often shortened to "raptorial"). The other members are Acrophyseter , Albicetus , Livyatan , and Zygophyseter , and these five whales have in common enamel-coated teeth in both the upper and lower jaws which were used in hunting large prey. [5] [8] These teeth are thought to have evolved in either a basilosaurid-like common ancestor, or multiple times independently in the group. Brygmophyseter is the oldest raptorial. [9] It has been proposed that these raptorials be placed into the extinct paraphyletic (hence, probably invalid) subfamily Hoplocetinae, alongside Scaldicetus , Diaphorocetus , Idiorophus , and Hoplocetus . [10]

The species was first described in 1994 by paleontologists Kiyoharu Hirota and Lawrence Barnes. Observing the teeth which were present in both jaws and coated in enamel, they had placed it into the genus Scaldicetus which was described in 1867 as having similar characteristics. [6] However, a 1995 study stated that since Scaldicetus is described only from tooth remains and is likely a wastebasket taxon, new species should not be assigned to the genus. Therefore, the study authored by paleontologists Kimura Toshiyuki, Hasegawa Yoshikazu, and Barnes Lawrence placed it into the newly erected genus Brygmophyseter. [1] A 2006 study by geologists Giovanni Bianucci and Walter Landini placed the whale into the genus Naganocetus which they had created, and concluded that it was most closely related to Zygophyseter , which they had for the first time described in the same study. This was justified by their similar body sizes, the basin containing the spermaceti organ (the supracranial basin) not extending forward (causing a convex snout), and the presence of long temporal fossae on the sides of the skull. [5] However, since Brygmophyseter was published first, Naganocetus is considered to be a junior synonym. [11]

Physeteroidea
Relationships between Brygmophyseter and other sperm whales, raptorials in bold [12] [9]

Paleoecology

Raptorial sperm whales like Brygmophyseter occupied a niche similar to the modern-day killer whale (Orcinus orca). Anim1102 - Flickr - NOAA Photo Library.jpg
Raptorial sperm whales like Brygmophyseter occupied a niche similar to the modern-day killer whale (Orcinus orca).

Since Brygmophyseter was a raptorial, and the group is characterized by their adaptations for subduing large prey, Brygmophyseter was likely a macropredator of marine mammals and other large marine vertebrates, occupying a niche similar to the killer whale. Though no stomach remains or bite marks have been found, it is thought to have preyed upon a variety of animals, including whales, seals, fish, and cephalopods. [7]

Brygmophyseter was discovered in the Middle Miocene deposits of the Bessho Formation of Japan, [1] which has also yielded some of the earliest oceanic dolphins and rorqual baleen whales, as well as beaked whale remains. [13] The formation also had fossil bivalves which indicate the presence of deep-sea hydrothermal vents, and there is also evidence of prehistoric cold vents in the area, which today host chemosynthetic specialist species; the formation was likely 1,000–2,000 meters (3,300–6,600 ft) deep in the Miocene. Also found were fossil plants, echinoderms, cephalopods, deep-sea teleost fish, and seabirds. [14] [15] The shark remains discovered in this formation belong to the sandbar shark (Carcharhinus plumbeus) and other unidentified Carcharhinus sharks, the seal shark (Dalatias licha), the extinct broad-toothed mako (Isurus hastalis), the extinct hook-tooth mako ( Isurus planus ), [16] the Japanese velvet dogfish (Scymnodon ichiharai), [17] and a species of Etmopterus lantern shark. [18]

In fiction

Brygmophyseter was featured in the fifth episode of The History Channel's Jurassic Fight Club , "Deep Sea Killers". In this episode, Brygmophyseter, which was referred to as the "biting sperm whale," was portrayed as being able to weaponize sonar in order to stun prey, and to have traveled in pods like the modern-day killer whale. The pod was attacked by a megalodon, which seemingly had a similar size to the whales. When the megalodon severely wounded one of the members of the pod, the rest of the whales teamed up to drive the megalodon off. Once the member of the pod died, however, the megalodon returned to feed on it. [19]

See also

Related Research Articles

<span class="mw-page-title-main">Physeteroidea</span> Superfamily of toothed whales

Physeteroidea is a superfamily that includes three extant species of whales: the sperm whale, in the genus Physeter, and the pygmy sperm whale and dwarf sperm whale, in the genus Kogia. In the past, these genera have sometimes been united in a single family, the Physeteridae, with the two Kogia species in the subfamily Kogiinae; however, recent practice is to allocate the genus Kogia to its own family, the Kogiidae, leaving the Physeteridae as a monotypic family, although additional fossil representatives of both families are known.

<span class="mw-page-title-main">Megalodon</span> Extinct giant shark species from 23 to 3.6 million years ago

Otodus megalodon, commonly known as megalodon, is an extinct species of giant mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. O. megalodon was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark, but has been reclassified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous.

<i>Squalodon</i> Extinct genus of mammals

Squalodon is an extinct genus of whales of the Oligocene and Miocene epochs, belonging to the family Squalodontidae. Named by Jean-Pierre Sylvestre de Grateloup in 1840, it was originally believed to be an iguanodontid dinosaur but has since been reclassified. The name Squalodon comes from Squalus, a genus of shark. As a result, its name means "shark tooth". Its closest modern relative is the South Asian river dolphin.

<i>Prosqualodon</i> Extinct genus of mammals

Prosqualodon is an extinct genus of Early to Middle Miocene cetacean from Argentina, Australia, New Zealand and Venezuela.

<i>Thalassocnus</i> Extinct, aquatic ground sloth from South America

Thalassocnus is an extinct genus of semiaquatic ground sloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within the subfamily Thalassocninae. The five species—T. antiquus, T. natans, T. littoralis, T. carolomartini, and T. yuacensis—represent a chronospecies, a population gradually adapting to marine life in one direct lineage. They are the only known aquatic sloths, but they may have also been adapted to a terrestrial lifestyle. They have been found in the Pisco Formation of Peru, the Tafna Formation of Argentina, and the Bahía Inglesa, Coquimbo, and Horcón formations of Chile. Thalassocninae has been placed in both the families Megatheriidae and Nothrotheriidae.

<i>Zygophyseter</i> Extinct genus of sperm whales

Zygophyseter varolai is an extinct sperm whale that lived during the Tortonian age of the Late Miocene 11.2 to 7.6 million years ago. It is known from a single specimen from the Pietra Leccese Formation in Italy. It was a member of a stem group of fossil macroraptorial sperm whales also including Brygmophyseter, Acrophyseter, and Livyatan. It probably grew to be around 6.5 to 7 meters in length and shared some characteristics with other raptorials, such as large teeth with tooth enamel that were functional in both the upper and lower jaws which the modern sperm whale lacks. It also had a beak, the ability to echolocate prey, and could have probably swum faster than the modern-day sperm whale which can reach 4 kilometers per hour (2.5 mph). These were probably used in the capture of large prey, such as large fish, seals, and whales. In fact, its common name, the killer sperm whale, refers to its feeding habits that would have had a resemblance to the modern-day killer whale.

<i>Livyatan</i> Extinct genus of sperm whale from the Miocene epoch

Livyatan is an extinct genus of macroraptorial sperm whale containing one known species: L. melvillei. The genus name was inspired by the biblical sea monster Leviathan, and the species name by Herman Melville, the author of the famous novel Moby-Dick about a white bull sperm whale. Herman Melville often referred to whales as "Leviathans" in his book. It is mainly known from the Pisco Formation of Peru during the Tortonian stage of the Miocene epoch, about 9.9–8.9 million years ago (mya); however, finds of isolated teeth from other locations such as Chile, Argentina, United States (California), South Africa and Australia imply that either it or a close relative survived into the Pliocene, around 5 mya, and may have had a global presence. It was a member of a group of macroraptorial sperm whales and was probably an apex predator, preying on whales, seals and so forth. Characteristically of raptorial sperm whales, Livyatan had functional, enamel-coated teeth on the upper and lower jaws, as well as several features suitable for hunting large prey.

<i>Acrophyseter</i> Extinct genus of sperm whales

Acrophyseter is a genus of extinct sperm whales that lived in the Late Miocene off the coast of Peru comprising two species: A. deinodon and A. robustus. It is part of a group of macroraptorial sperm whales which all shared several features for the purpose of hunting large prey, such as deeply rooted and thick teeth. Acrophyseter measured 4–4.5 metres (13–15 ft), making it the smallest raptorial sperm whale. Because of its short pointed snout, and its strong curved front teeth, it probably fed on the large marine vertebrates of its time, such as seals and other whales.

<i>Orcinus citoniensis</i> Extinct species of killer whale

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<i>Diaphorocetus</i> Extinct genus of mammals

Diaphorocetus is an extinct genus of odontocete cetacean belonging to Physeteroidea. Its remains were found in the Monte León Formation of Argentina, dating to the Early Miocene.

<i>Scaldicetus</i> Extinct genus of mammals

Scaldicetus is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct physeterids with primitive dental morphology consisting of enameled teeth, Scaldicetus as generally recognized appears to be a wastebasket taxon filled with more-or-less unrelated primitive sperm whales.

<span class="mw-page-title-main">Pisco Formation</span> Geologic formation in Peru

The Pisco Formation is a geologic formation located in Peru, on the southern coastal desert of Ica and Arequipa. The approximately 640 metres (2,100 ft) thick formation was deposited in the Pisco Basin, spanning an age from the Middle Miocene up to the Early Pleistocene, roughly from 15 to 2 Ma. The tuffaceous sandstones, diatomaceous siltstones, conglomerates and dolomites were deposited in a lagoonal to near-shore environment, in bays similar to other Pacific South American formations as the Bahía Inglesa and Coquimbo Formations of Chile.

<i>Albicetus</i> Extinct genus of mammals

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<i>Kogia pusilla</i> Small fossil whale from Italy

Kogia pusilla is an extinct species of sperm whale from the Middle Pliocene of Italy related to the modern day dwarf sperm whale and pygmy sperm whale. It is known from a single skull discovered in 1877, and was considered a species of beaked whale until 1997. The skull shares many characteristics with other sperm whales, and is comparable in size to that of the dwarf sperm whale. Like the modern Kogia, it probably hunted squid in the twilight zone, and frequented continental slopes. The environment it inhabited was likely a calm, nearshore area with a combination sandy and hard-rock seafloor. K. pusilla likely died out due to the ice ages at the end of the Pliocene.

<i>Idiorophus</i> Extinct genus of mammals

Idiorophus is a genus of toothed whales in the family Physeteridae. Fossils have been found in the Colhuehuapian Gaiman Formation of Argentina and the Libano Sandstone in Italy.

Eudelphis is an extinct genus of sperm whale belonging to Physeteroidea that lived in the ancient North Sea basin about 16-11 million years ago, during the middle Miocene (Langhian).

<span class="mw-page-title-main">Macroraptorial sperm whale</span> Predatory family of extinct whales

Macroraptorial sperm whales were highly predatory whales of the sperm whale superfamily (Physeteroidea) of the Miocene epoch that hunted large marine mammals, including other whales, using their large teeth. They consist of five genera: Acrophyseter, Albicetus, Brygmophyseter, Livyatan, and Zygophyseter. All species are known by at least a skull, and are informally grouped without a family designation. They were all likely the apex predator of their habitats, comparable to the modern day killer whale, and achieved great lengths, with one species–Livyatan–measuring about 13.5–17.5 m (44–57 ft).

Hoplocetus is an extinct genus of raptorial cetacean of the sperm whale superfamily, Physeteroidea. Its remains have been found in the Miocene of Belgium, France, Germany and Malta, the Pliocene of Belgium and France, and the Pleistocene of the United Kingdom and South Carolina.

<i>Ankylorhiza</i> Extinct genus of toothed whales from the Oligocene epoch

Ankylorhiza is an extinct genus of toothed whale that lived in what is now the United States during the Oligocene epoch, between 29 and 23.5 million years ago. The type and only known species is A. tiedemani, though two fossil skeletons may represent an additional, second species within the genus. Ankylorhiza was about 4.8 meters (16 ft) long, with a long, robust skull bearing conical teeth that were angled forwards at the tip of the snout.

References

  1. 1 2 3 4 5 6 7 8 9 Kimura, T.; Hasegawa, Y.; Barnese, L. G. (2006). "Fossil sperm whales (Cetacea, Physeteridae) from Gunma and Ibaraki prefectures, Japan; with observations on the Miocene fossil sperm whale Scaldicetus shigensis Hirota and Barnes, 1995". Bulletin of the Gunma Museum of Natural History. 103: 1–23.
  2. ↑ "Shigamakkoukujira (Scaldicetus shigensis)". Archived from the original on 1 February 2009.
  3. ↑ "Brygmophyseter Shignesis in Shiga Fossil Museum, Japan". Archived from the original on 9 February 2009.
  4. ↑ "Research & Collection News" (PDF). Paleontology. Natural History Museum of Los Angeles County. May 2006. Archived from the original (PDF) on 30 September 2007. Retrieved 29 April 2010.
  5. 1 2 3 4 Bianucci, G.; Landini, W. (2006). "Killer Sperm Whale: a New Basal Physeteroid (Mammalia, Cetacea) from the Late Miocene of Italy". Zoological Journal of the Linnean Society. 148: 103–131. doi: 10.1111/j.1096-3642.2006.00228.x .
  6. 1 2 3 Hirota, K.; Barnes, L. G. (1994). "A new species of Middle Miocene sperm whale of the genus Scaldicetus (Cetacea; Physeteridae) from Shiga-mura, Japan". Island Arc. 3 (4): 453–472. doi:10.1111/j.1440-1738.1994.tb00125.x.
  7. 1 2 3 Lambert, O.; Bianucci, G.; Beaty, B. (2014). "Bony Outgrowths on the Jaws of an Extinct Sperm Whale Support Macroraptorial Feeding in Several Stem Physeteroids". Naturwissenschaften. 101 (6): 517–521. Bibcode:2014NW....101..517L. doi:10.1007/s00114-014-1182-2. PMID   24821119. S2CID   14542690.
  8. ↑ Peri, E.; Falkingham, P.L.; Collareta, A.; Bianucci, G. (2021). "Biting in the Miocene seas: estimation of the bite force of the macroraptorial sperm whale Zygophyseter varolai using finite element analysis". Historical Biology. 34 (10): 1916–1927. doi: 10.1080/08912963.2021.1986814 . hdl: 11568/1117056 . S2CID   239510338.
  9. 1 2 Lambert, O.; Bianucci, G.; de Muizon, C. (2017). "Macroraptorial Sperm Whales (Cetacea, Odontoceti, Physeteroidea) from the Miocene of Peru". Zoological Journal of the Linnean Society. 179: 404–474. doi:10.1111/zoj.12456. hdl: 11568/814760 .
  10. ↑ Toscano, A.; Abad, M.; Ruiz, F.; Muñiz, F.; Álvarez, G.; García, E.; Caro, J. A. (2013). "Nuevos Restos de Scaldicetus (Cetacea, Odontoceti, Physeteridae) del Mioceno Superior, Sector Occidental de la Cuenca del Guadalquivir (Sur de España)" [New Remains of Scaldicetus (Cetacea, Odontoceti, Physeteridae) from the Upper Miocene, Western Sector of the Guadalquivir Basin]. Revista Mexicana de Ciencias Geológicas (in Spanish). 30 (2).
  11. ↑ Lambert, Olivier; Bianucci, Giovanni; Demuizon, Christian (2008). "A New Stem-Sperm Whale (Cetacea, Odontoceti, Physeteroidea) from the Latest Miocene of Peru". Comptes Rendus Palevol. 7 (6): 361–369. doi:10.1016/j.crpv.2008.06.002. S2CID   85723286.
  12. ↑ Berta, A. (2017). The Rise of Marine Mammals: 50 Million Years of Evolution. Baltimore, Maryland: Johns Hopkins University Press. pp. 112–113. ISBN   978-1-4214-2326-5.
  13. ↑ Marx, F. G.; Lambert, O.; Uhen, M. D. (2016). Cetacean Paleobiology. John Wiley and Sons. p. 125. ISBN   978-1-118-56155-3.
  14. ↑ Nazarkin, M. V.; Yabumoto, Y. (2015). "New fossils of Neogene pricklebacks (Actinopterygii: Stichaeidae) from East Asia" (PDF). Zoosystematica Rossica. 24 (1): 128–137. doi:10.31610/zsr/2015.24.1.128.
  15. ↑ Amano, K.; Jenkins, R. G.; Aikawa, M.; Nobuhara, T. (2010). "A Miocene chemosynthetic community from the Ogaya Formation in Joetsu: Evidence for depth-related ecologic control among fossil seep communities in the Japan Sea back-arc basin". Palaeogeography, Palaeoclimatology, Palaeoecology. 286 (3–4): 164–170. Bibcode:2010PPP...286..164A. doi:10.1016/j.palaeo.2009.12.013.
  16. ↑ Takakuwa, Y.; Koike, H.; Narita, K. (2009). "Outline of fossil elasmobranchs from the Middle Miocene Bessho and Aoki Formations, Nagano Prefecture, Japan". Research Report of the Shinshushinmachi Fossil Museum (in Japanese). 13: 7–18.
  17. ↑ Koike, H.; Ohe, F.; Narita, K. (2008). "A fossil dermal denticle, Scymnodon ichiharai (Elasmobranchii; Somniosidae) from Miocene Bessho Formation in Azumino City, Nagano Prefecture, Japan". Research Report of the Shinshushinmachi Fossil Museum (in Japanese). 11: 1–13.
  18. ↑ Koike, H.; Ohe, F.; Narita, K. (2008). "A fossil dermal denticle, Etmopterus sp. (Elasmobranchii; Etmopteridae) from the Middle Miocene Bessho Formation in Azumino City, Nagano Prefecture, Japan". Research Report of the Shinshushinmachi Fossil Museum (in Japanese). 11: 15–18.
  19. ↑ "Deep Sea Killers". Jurassic Fight Club . Episode 5. 26 August 2008. The History Channel . Retrieved 26 November 2017.
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