Hoplocetus

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Hoplocetus
Temporal range: Middle Miocene-Early Pleistocene
~16.0–1.8  Ma
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: Hoplocetus
Gervais, 1852
Species
  • H. borgerhoutensisdu Bus, 1872
  • H. crassidensGervais, 1852(type)
  • H. curvidensGervais, 1852
  • H. obesusLeidy, 1868 [2]
  • H. ritziHampe, 2006 [3]

Hoplocetus is an extinct genus of raptorial cetacean of the sperm whale superfamily, Physeteroidea. [3] 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. [1]

Dentition

The teeth of Hoplocetus are massive (95–150 mm in length; 27–47 in maximum diameter), robust and have a short enamel cap on the crowns. [3] They are somewhat larger than those of modern orcas [4] but considerably smaller than those of macroraptorial sperm whales, such as Zygophyseter , as well as those of Scaldicetus caretti. [5] They display a large degree of abrasion, suggesting a highly predatory niche comparable to that of modern orcas. [3] The genus of the latter, Orcinus , first appears in the middle Pliocene and it may have eventually replaced Hoplocetus. [3]

These teeth features also characterize the other extinct toothed whale genera, Diaphorocetus , Idiorophus and Scaldicetus, sometimes placed with Hoplocetus in the subfamily Hoplocetinae. [6] However, some of these taxa are fragmentary and have been used as wastebasket taxa for non-diagnostic material of stem physeteroids.

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">Kogiidae</span> Family of mammals

Kogiidae is a family comprising at least two extant species of Cetacea, the pygmy and dwarf sperm whales. As their common names suggest, they somewhat resemble sperm whales, with squared heads and small lower jaws, but are much smaller in size, with much shorter skulls and more notable dorsal fins than sperm whales. Kogiids are also characterized by a "false gill slit" behind their eyes.

<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>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>Brygmophyseter</i> Extinct genus of toothed whale (fossil)

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. 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 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.

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

Australodelphis mirus is an extinct Pliocene dolphin. A. mirus is known from fossils found in the Sørsdal Formation, Mule Peninsula, Vestfold Hills, East Antarctica. The genus has been described as an example of convergent evolution with beaked whales.

<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, the 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 whale that lived in the Late Miocene off the coast of what is now Peru. The genus comprises two species: A. deinodon and A. robustus. It is part of a group of macroraptorial sperm whales that all share several features for hunting large prey, such as deeply rooted and thick teeth. Acrophyseter measured 4–4.5 metres (13–15 ft) in length, making it the smallest macroraptorial sperm whale currently known. Because of its short pointed snout and strongly 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

Orcinus citoniensis is an extinct species of orca identified in the Late Pliocene of Italy and the Early Pleistocene of England. It was smaller than the modern killer whale, 4 m (13 ft) versus 7 to 10 m, and had around 8 more teeth in its jaw. It may have resembled the modern killer whale in appearance, and could represent a transitional species between the modern killer whale and other dolphins. O. citoniensis could have hunted fish and squid in pods, and coexisted with other large predators of the time such as the orcinine Hemisyntrachelus and the extinct shark Otodus megalodon.

<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 Late Miocene up to the Early Pliocene, roughly from 9.6 to 4.5 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

Albicetus is a genus of stem-sperm whales that lived during the Miocene Epoch, around 15 million years ago, and was discovered in Santa Barbara, California in 1909. It was categorized for decades as belonging to a group of extinct walruses erroneously thought to be sperm whales. It was named Albicetus, meaning "white whale", is a reference to the leviathan in Herman Melville's classic 1851 novel Moby-Dick.

<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 extinct 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 grouping 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).

References

  1. 1 2 "Hoplocetus in the Paleobiology Database". Fossilworks . Archived from the original on 12 December 2021. Retrieved 17 December 2021.
  2. Leidy, J. (1868). "Notice of Some Extinct Cetaceans". Proceedings of the Academy of Natural Sciences of Philadelphia . 20: 196–197. Retrieved 2018-11-12.
  3. 1 2 3 4 5 Hampe, O. (2006). "Middle/late Miocene hoplocetine sperm whale remains (Odontoceti: Physeteridae) of North Germany with an emended classification of the Hoplocetinae". Fossil Record. 9 (1): 61–86. doi: 10.1002/mmng.200600002 .
  4. Bradford, A. (2014-11-20). "Orcas: Facts About Killer Whales". Live Science . Retrieved 2018-11-12.
  5. Reumer, J. W. F.; Mens, T. H.; Post, K. (2017). "New Finds of Giant Raptorial Sperm Whale Teeth (Cetacea, Physeteroidea) from the Westerschelde Estuary (Province of Zeeland, the Netherlands)" (PDF). Deinsea. 17: 32–38. Retrieved 2018-11-12.
  6. 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).