''Brygmophyseter'', known as the biting sperm whale, is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species ...

in the

sperm whale family 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 ...

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 14–15 million years old. ''Brygmophyseter'' is thought to have been long, and it probably had 11 or 12 teeth in the upper and lower jaws. ''Brygmophyseter'' is part of a group of

macroraptorial sperm whale Macroraptorial sperm whales were highly predatory whales of the sperm whale superfamily (Physeteroidea) of the Miocene epoch (geology), epoch that hunted large marine mammals, including other whales, using their large teeth. They consist of five g ...

s (often shortened to "raptorial") which tended to be

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic le ...

s using their large teeth to catch struggling prey such as

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s. It had a

spermaceti organ The spermaceti organ is an organ present in the heads of toothed whales of the family Physeteroidea, in particular the sperm whale. This organ contains a waxy liquid called spermaceti and is involved in the generation of sound. Description In ...

which was probably used for

biosonar Echolocation, also called bio sonar, is a biological sonar used by several animal species. Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these ...

like in the modern

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus '' Physeter'' and one of three extant species in the sperm whale famil ...

. The whale has made an appearance on

The History Channel History (formerly The History Channel from January 1, 1995 to February 15, 2008, stylized as HISTORY) is an American pay television network and flagship channel owned by A&E Networks, a joint venture between Hearst Communications and the Dis ...

's TV series '' Jurassic Fight Club''.

History of discovery

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

specimen, SFM-0001, was excavated from the Bessho Formation in the

Nagano Prefecture is a landlocked prefecture of Japan located in the Chūbu region of Honshū. Nagano Prefecture has a population of 2,052,493 () and has a geographic area of . Nagano Prefecture borders Niigata Prefecture to the north, Gunma Prefecture to the n ...

in Japan in 1988 by the residents of Shiga-mura with assistance from the staff of the Shiga Fossil Museum. The specimen is nearly complete, and consists of a partial skull, the jawbone, the lingual bone in the neck, vertebrae, ribs, the

breastbone The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury ...

, and humeri and radii in the limbs. It was dated to the

Langhian The Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene Epoch/ Series. It spans the time between 15.97 ± 0.05 Ma and 13.65 ± 0.05 Ma (million years ago) during the Middle Miocene.GeoWhen (2007) The Langhian was ...

stage of the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

14–15 million

year A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the ...

s ago (mya), and the specimen is currently on display at the Gunma Museum of Natural History in Japan. The genus name is a combination of the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

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. The junior synonym ''Naganocetus'' derives from the Nagano Prefecture and the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

''cetus'' meaning "whale".

Description

Like other raptorials, ''Brygmophyseter'' had enamel-coated teeth in both jaws, unlike the modern

(''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 , 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 In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

features from

archaeocetes Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean radiation, they include the initial ...

, that is, it is an ancestral characteristic of the whale. The right

nasal passage The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal c ...

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

, and so the whale had

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. Brygmophyseter size

''Brygmophyseter'' is estimated to have been around long. The holotype had preserved zero neck vertebrae, ten

thoracic vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

, ten

lumbar vertebrae The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse ...

, and fifteen tail

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characterist ...

e. 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. The

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

of the humerus arm bone of ''Brygmophyseter'' was positioned perpendicular to the

shaft Shaft may refer to: Rotating machine elements * Shaft (mechanical engineering), a rotating machine element used to transmit power * Line shaft, a power transmission system * Drive shaft, a shaft for transferring torque * Axle, a shaft around whi ...

. The elbow joint on the humerus was not distinct from the

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

, 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

of the bone was smaller.

Paleoecology

Since ''Brygmophyseter'' was a raptorial, and the group is characterized by their adaptations for subduing large prey, ''Brygmophyseter'' was likely a macropredator of

marine mammal Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as Pinniped, seals, Cetacea, whales, Sirenia, manatees, sea otters and polar bears. They are an informal group, ...

s and other large

marine vertebrate Marine vertebrates are vertebrates that live in marine environments. These are the marine fish and the marine tetrapods (primarily seabirds, marine reptiles, and marine mammals). Vertebrates are a subphylum of chordates that have a vertebral c ...

s, 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

cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, ...

s. ''Brygmophyseter'' was discovered in the Middle Miocene deposits of the Bessho Formation of Japan, which has also yielded some of the earliest

oceanic dolphin Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as th ...

s and

rorqual Rorquals () are the largest group of baleen whales, which comprise the family Balaenopteridae, containing ten extant species in three genera. They include the largest animal that has ever lived, the blue whale, which can reach , and the fin ...

baleen whale Baleen whales ( systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea ( whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in th ...

s, as well as

beaked whale Beaked whales ( systematic name Ziphiidae) are a family of cetaceans noted as being one of the least known groups of mammals because of their deep-sea habitat and apparent low abundance. Only three or four of the 24 species are reasonably well- ...

remains. The formation also had fossil

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

s 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 A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of env ...

; the formation was likely deep in the Miocene. Also found were fossil plants,

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

s, cephalopods, deep-sea

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

fish, and

seabird Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same envir ...

s. 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 ''Cosmopolitodus'' is an extinct genus of mackerel shark that lived between thirty to one million years ago during the late Oligocene to the Early Pleistocene epochs. Its type species is ''Cosmopolitodus hastalis'', the broad-tooth mako (other ...

(''Isurus hastalis''), the extinct hook-tooth mako ('' Isurus planus''), the Japanese velvet dogfish (''Scymnodon ichiharai''), and a species of ''

Etmopterus ''Etmopterus'' is a genus of lantern sharks in the squaliform family Etmopteridae. They are found in deep sea ecosystems of the Atlantic, Indian and Pacific Oceans. Ecology A number of species in this genus function as host to the specialized ...

lantern shark ''Etmopterus'' is a genus of lantern sharks in the squaliform family Etmopteridae. They are found in deep sea ecosystems of the Atlantic, Indian and Pacific Oceans. Ecology A number of species in this genus function as host to the specialized ...

Taxonomy

Phylogeny

''Brygmophyseter'' is a member of a fossil

stem group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...

of hyper-predatory

s from the

(often shortened to "raptorial"). The other members are ''

Acrophyseter ''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 ...

'', '' Albicetus'', ''

Livyatan ''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 ...

'', 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. 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. It has been proposed that these raptorials be placed into the extinct

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

(hence, probably invalid) subfamily Hoplocetinae, alongside '' Scaldicetus'', ''

Diaphorocetus ''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.Idiorophus'', and ''

Hoplocetus ''Hoplocetus'' is an extinct genus of raptorial cetacean of the sperm whale superfamily (biology), superfamily, Physeteroidea. Its remains have been found in the Miocene of Belgium, France, Germany and Malta, the Pliocene of Belgium and France, a ...

''. The species was first described in 1994 by

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

s 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. However, a 1995 study stated that since ''Scaldicetus'' is described only from tooth remains and is likely a

wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically define ...

, 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''. 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

(the supracranial basin) not extending forward (causing a convex

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is ...

), and the presence of long temporal fossae on the sides of the skull. However, since ''Brygmophyseter'' was published first, ''Naganocetus'' is considered to be a junior synonym.

In fiction

''Brygmophyseter'' was featured in the fifth episode of

'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 Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a me ...

, 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.

References

External links

Brygmophyseter Skeleton on display in a Japanese Museum

Brygmophyseter, ancient killer sperm whale

Age of Mammals – Specimen Spotlight – ''Aulophyseter morricei''
{{Taxonbar , from=Q923613 Miocene cetaceans Miocene mammals of Asia Prehistoric toothed whales Sperm whales Prehistoric monotypic mammal genera Prehistoric cetacean genera Fossil taxa described in 2006 Fossils of Japan