| Brygmophyseter Temporal range: Miocene |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Cetacea |
| Superfamily: | Physeteroidea |
| Family: | incertae sedis |
| Genus: | †Brygmophyseter Kimura et al. 2006 |
| Species: | †B. shigensis |
| Binomial name | |
| Brygmophyseter shigensis (Hirota and Barnes), 1995 |
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| Synonyms | |
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Brygmophyseter is an extinct genus of toothed whale in the sperm whale family with one species Brygmophyseter shigensis.[1] When first described, this species was placed in an extinct form genus Scaldicetus of toothed whale, as Scaldicetus shigensis).[1][2] In 2006, it was transferred to a new genus Naganocetus as ''Naganocetus shigensis'', however later in 2006, it was then moved to Brygmophyseter leaving Naganocetus as a nomen nudum name.[3]
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The genus name is a combination of the Greek word brygmos, which means "biting" or "gnashing", combined with suffix Physeter, which is the generic name of the living sperm whale, and which is also the Greek word for "blower".[1][4] This has led to the occasional vernacular term "biting sperm whale" being given to the species in popular culture.[5]
The holotype specimen (SFM-0001) was excavated from Bessho Formation in Nagano Prefecture in Japan in 1988 by the residents of Shiga-mura with assistance from staff of Shiga Fossil Museum.[1] The specimen is nearly complete,[1] and includes a 140 cm long skull.[2] This specimen came from 15-14 million years old sediments.[1] Unlike the extant giant sperm whale, Physeter macrocephalus, which has teeth in its lower jaw only; Brygmophyseter has 12 functional teeth on each side of the lower jaws and 12 functional teeth on each side of the upper jaws.[1] The holotype specimen is currently on display in Gunman Museum of Natural History in Japan.[1]
The holotype specimen is around 7 metres (23 ft) long.[6] However, in popular culture, Brygmophyseter have been depicted significantly larger in size — up to 12 metres (39 ft) long.[5]
Brygmophyseter was likely among the apex predators of its time.[5] It packed a formidable jaws armed with teeth up to 14 cm (5.5 inches) long.[4] It may have employed sonar to track and disorient a prey item in deep waters, like the modern age Sperm Whales.[5] It may also have used its large head to ram a potential opponent during conflict.[5] Brygmophyseter would also have lived in social groups called pods, and probably hunted in packs, like modern age Orcas.[5]
Brygmophyseter is assumed to have preyed upon a variety of animals including fish,[5] pinnipeds,[5] giant squid,[5] and other cetaceans.[5]
It shall be noted that remains of undetermined mysticeti whales have been found in the same region where the holotype specimen was found,[1] however a predator-prey relationship between Brygmophyseter and these whales have not been inferred in the scientific literature.[1]
The shark species C. megalodon was likely a primary predator of the sperm whales.[5][7] A large number of cetacean bones have been found with large bite marks (deep gashes) in them, which were caused by teeth that belong to C. megalodon.[5]
Brygmophyseter is featured in an episode of Jurassic Fight Club - as an adversary of the C. megalodon. The history of its finding and probable behavior have also been explored within the show.
