Lophocetus

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Lophocetus
Temporal range: Late Miocene, 11.6–7.2  Ma
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Lophocetus sp skull.jpg
Lophocetus sp skull
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family:† Kentriodontidae
Genus:† Lophocetus
Cope, 1867
Type species
†Delphinus calvertensis
Harlan, 1842
Other species
  • L. repenningiBarnes, 1978

Lophocetus ("crested whale") is an extinct genus of dolphin belonging to the clade Delphinida that is known from late Miocene (Tortonian) marine deposits in California and Maryland. Although usually placed in Kentriodontidae, recent studies have found it only distantly related to Kentriodon .

Contents

Discovery and taxonomy

Lophocetus was the first fossil odontocete to be described from North America. The type species, L. calvertensis, was originally described as Delphinus calvertensis by the American naturalist Richard Harlan in 1842 on the basis of USNM 16314, a skull from the St. Marys Formation of Maryland. [1] Edward Drinker Cope subsequently recognized it as distinct from extant oceanic dolphins and considered it congeneric with the franciscana (as Pontoporia calvertensis), before renaming it as a distinct genus, Lophocetus. [2] [3]

The phylogenetic analysis of Brujadelphis recovered Lophocetus as polyphyletic, with L. calvertensis and L. repenningi forming a clade with taxa assigned to Pithanodelphininae and Tagicetus , and L. pappus falling as the sister taxon of Lipotidae. [4] If "Lophocetus" pappus is a relative of the baiji, it would fill a gap in the early evolutionary history of the baiji because the oldest unambiguous extinct relative of the baiji, Parapontoporia , hails from younger marine deposits. However, a strict consensus phylogenetic analysis of the pontoporiid Scaldiporia recovers "Lophocetus" pappus outside the clade formed by Inioidea+Lipotidae and Delphinoidea, while recovering Lophocetus as a relative of beaked whales and Squaloziphius . [5]

Reassigned species

In 1955, Remington Kellogg described a new species of Lophocetus, L. pappus, on the basis of the skull USNM 15985 from the Langhian-age Plum Point Member of the Calvert Formation. [6] In 1978, however, Lawrence Barnes of the Los Angeles Museum of Natural History referred this species to the similarly Langhian-age genus Liolithax based on similarities in the earbone morphology, as Liolithax pappus. The new subfamily Lophocetinae was erected to accommodate Liolithax and Lophocetus, and Barnes also named Lophocetus repenningi on the basis of the skull USNM 23886 from the Tortonian-age Santa Margarita Formation of Santa Barbara, California. [7] The assignment of Lophocetus pappus to Liolithax by Barnes (1978) was followed by several authors, including Ichishima et al. (1995), Dawson (1996), and Uhen et al. (2008), although Whitmore and Kaltenbach (2008) did not. However, in a couple of abstracts published in 2000 and 2008, Barnes and colleagues recognized Lophocetus pappus as a new genus of lophocetine distinct from Liolithax after the discovery of a skull from Middle Miocene marine deposits in Baja California Sur showed that Liolithax was a kentriodontine rather than a lophocetine and different from L. pappus in its smaller tooth diameter, smaller size, and more elongated rostrum. [8] [9] Godfrey and Lambert (2023) confirmed the generic distinctness of "L." pappus from Liolithax and erected the new genus Miminiacetus for it. [10]

Related Research Articles

<span class="mw-page-title-main">Lipotidae</span> Family of river dolphins

Lipotidae is a family of river dolphins containing the possibly extinct baiji of China and the fossil genus Parapontoporia from the Late Miocene and Pliocene of the Pacific coast of North America. The genus Prolipotes, which is based on a mandible fragment from Neogene coastal deposits in Guangxi, China, has been classified as an extinct relative of the baiji, but is dubious.

<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.

Kentriodon is an extinct genus of toothed whale related to modern-day dolphins. Fossils have been found in North America, Europe and Japan. Several species have been described.

<span class="mw-page-title-main">Kentriodontidae</span> Extinct family of dolphins

Kentriodontidae is an extinct family of odontocete whales related to modern dolphins. The Kentriodontidae lived from the Oligocene to the Pliocene before going extinct.

<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. 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 mammals

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.

The St. Marys Formation is a geologic formation in Maryland and Virginia, United States. It preserves fossils dating back to the Miocene Epoch of the Neogene period. It is the youngest Miocene formation present in the Calvert Cliffs and is part of the Chesapeake Group.

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

Atocetus is an extinct genus of pontoporiid dolphin found in Miocene-age marine deposits in Peru and California.

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

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Macrokentriodon is an extinct genus of giant dolphin once assigned to the paraphyletic/polyphyletic family Kentriodontidae. Remains have been found in the late Miocene (Serravallian) Choptank Formation of United States.

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Hadrodelphis is an extinct genus of dolphin once assigned to the paraphyletic/polyphyletic family Kentriodontidae. Remains have been found in the middle Miocene (Langhian) Calvert Formation of United States.

Brujadelphis is an extinct genus of river dolphin-like cetaceans of uncertain family placement from the Late Miocene epoch (Serravallian) of present-day Peru. The type species is Brujadelphis ankylorostris, recovered from the Pisco Formation.

Tagicetus is an extinct genus of dolphin belonging to the polyphyletic family Kentriodontidae.

<span class="mw-page-title-main">Delphinida</span> Clade of mammals

Delphinida is a clade of cetaceans in the parvorder Odontoceti, the toothed whales. It includes all modern oceanic dolphins, porpoises, and their relatives, such as Lipotidae and Iniidae.

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).

Stenasodelphis is an extinct genus of pontoporiid dolphin from the mid-late Miocene epoch. Its name roughly translates to "the narrow-nosed dolphin." The genus is currently monotypic, containing only the species S. russellae. The specific epithet honors Mrs. Jean Hopper, who discovered the holotype. It was found in material derived from zone 22-23 of St. Marys Formation, which dates to the early Tortonian.

References

  1. ↑ R. Harlan. 1842. Description of a new extinct species of dolphin from Maryland. Bulletin of the Proceedings of the National Institution for the Promotion of Science 2:195-196.
  2. ↑ E. D. Cope. 1866. Third contribution to the history of the Balaenidae and Delphinidae. Proceedings of the Academy of Natural Sciences of Philadelphia 1866:293-300.
  3. ↑ E. D. Cope. 1867. An addition to the vertebrate fauna of the Miocene period, with a synopsis of the extinct Cetacea of the United States. Proceedings of the Academy of Natural Sciences of Philadelphia 19(4):138-157.
  4. ↑ Olivier Lambert, Giovanni Bianucci, Mario Urbina, Jonathan H. Geisler; A new inioid (Cetacea, Odontoceti, Delphinida) from the Miocene of Peru and the origin of modern dolphin and porpoise families. Zool J Linn Soc 2017; 179 (4): 919-946. doi: 10.1111/zoj.12479. https://academic.oup.com/zoolinnean/article/179/4/919/3076080/A-new-inioid-Cetacea-Odontoceti-Delphinida-from?guestAccessKey=3b956b95-d215-488a-8d90-1cff59554290#63703008
  5. ↑ Post K, Louwye S, Lambert O. (2017) Scaldiporia vandokkumi, a new pontoporiid (Mammalia, Cetacea, Odontoceti) from the Late Miocene to earliest Pliocene of the Westerschelde estuary (The Netherlands) PeerJ 5:e3991 https://doi.org/10.7717/peerj.3991
  6. ↑ R. Kellogg. 1955. Three Miocene porpoises from the Calvert Cliffs, Maryland. Proceedings of the United States National Museum 105(3354):101-154.
  7. ↑ L. G. Barnes. 1978. A review of Lophocetus and Liolithax and their relationships to the delphinoid family Kentriodontidae (Cetacea: Odontoceti). Bulletin of the Natural History Museum of Los Angeles County 28:1-35
  8. ↑ Flores-Trujillo, J.G., Aranda-Manteca, F.J., & Barnes, L.G. 2000. Identificación del delfín fósil del Mioceno Medio, Liolithax kernensis Kellogg 1931. [The identity of the fossil Middle Miocene dolphin, Liolithax kernensis Kellogg 1931.] Programa y Resúmenes, XXV Reunión Internacional para el Estudio de los Mamíferos Marinos, Sociedad Mexicana de Mastozoología Marina, La Paz, Baja California Sur, México, 7–11 May 2000, p. 4.
  9. ↑ http://svpca.org/years/2008_dublin/abstracts.pdf [ bare URL PDF ]
  10. ↑ Godfrey, S. J., and Lambert, O., 2023. Miocene Toothed Whales (Odontoceti) from Calvert Cliffs, Atlantic Coastal Plain, USA. Smithsonian Contributions to Paleobiology 107: 49–186. doi:10.5479/si.23847438.
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