| Togocetus Temporal range: Late Eocene, | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | † Protocetidae |
| Genus: | † Togocetus Gingerich & Cappetta 2014 |
| Species: | †T. traversei |
| Binomial name | |
| †Togocetus traversei | |
Togocetus (“Togo whale”) is a genus of extinct cetacean from the Lutetian (lower Eocene) of Togo, known from a fossilized skeleton discovered a few kilometers north-east of Lomé.
The skeleton was found in a phosphate mining area, Kpogamé-Hahotoé, which is located just north of Lake Togo. It was embedded in a phospharenite bone bed dating back to 46 – 44 million years ago, and overlying an older rock unit, the Tabligbo Group. [3] The remains were described in 2014 by Philip D. Gingerich and Henri Cappetta, who established for it the new monotypic genus Togocetus and the new species T. traversei, dedicated to Michel Traverse. [1]
According to the two authors, Togocetus was a semiaquatic animal which must have weighed around 300–400 kilograms (660–880 lb). It was a protocetid with rather primitive traits such as a still quite long neck, a digitigrade manus and a swim-specialized pes. [4] It shared many similarities with the protocetid genera Protocetus and Pappocetus , the main differences being a smaller mandibular canal, the loss of the fovea capitis femoris (hence of the ligament of head of femur) and some traits related to the molar trigonids. [5] Later analysis of ear structure evidence originally attributed to Togocetus raised some question regarding established understanding of protocetid evolution. [6] The original analysis revealed a contradiction in assumed relationship between ear ossicle structure and mandibular canal size; later research and additional evidence revealed multiple places where more modern, specialized traits were blended unexpectedly with archaic ones, causing some controversy. Despite the fragmentary nature of the fossil record and the subtleties differentiating protocetids, T. traversei has consistently been shown to have unique features defining it, including a completely novel entoglenoid shape and several fossae otherwise not seen in contemporary cetaceans. [7]
Rodhocetus is an extinct genus of protocetid early whale known from the Lutetian of Pakistan. The best-known protocetid, Rodhocetus is known from two partial skeletons that taken together give a complete image of an Eocene whale that had short limbs with long hands and feet that were probably webbed and a sacrum that was immobile with four partially fused sacral vertebrae. It is one of several extinct whale genera that possess land mammal characteristics, thus demonstrating the evolutionary transition from land to sea.
Pakicetidae is an extinct family of Archaeoceti that lived during the Early Eocene in Pakistan.
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya. Cetaceans are thought to have evolved during the Eocene, the second epoch of the present-extending Cenozoic Era. Molecular and morphological analyses suggest Cetacea share a relatively recent closest common ancestor with hippopotami and that they are sister groups. Being mammals, they surface to breathe air; they have 5 finger bones (even-toed) in their fins; they nurse their young; and, despite their fully aquatic life style, they retain many skeletal features from their terrestrial ancestors. Research conducted in the late 1970s in Pakistan revealed several stages in the transition of cetaceans from land to sea.
Pakicetus is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Pakistan during the Eocene, about 50 million years ago. It was a wolf-like animal, about 1 metre to 2 metres long, and lived in and around water where it ate fish and other small animals. The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. It belongs to the even-toed ungulates with the closest living non-cetacean relative being the hippopotamus.
Archaeoceti, 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 amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. This initial diversification occurred in the shallow waters that separated India and Asia 53 to 45 mya, resulting in some 30 species adapted to a fully oceanic life. Echolocation and filter-feeding evolved during a second radiation 36 to 35 mya.
Protocetus atavus is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago. The first discovered protocetid, Protocetus atavus was described by Fraas 1904 based on a cranium and a number of associated vertebrae and ribs found in middle Lutetian Tethyan marine limestone from Gebel Mokattam near Cairo, Egypt.
Ichthyolestes is an extinct genus of archaic cetacean that was endemic to Indo-Pakistan during the Lutetian stage. To date, this monotypic genus is only represented by Ichthyolestes pinfoldi.
Remingtonocetus is an extinct genus of early cetacean freshwater aquatic mammals of the family Remingtonocetidae endemic to the coastline of the ancient Tethys Ocean during the Eocene. It was named after naturalist Remington Kellogg.
Artiocetus is an extinct genus of early whales belonging to the family Protocetidae. It was a close relative to Rodhocetus and its tarsals indicate it resembled an artiodactyl.
Remingtonocetidae is a diverse family of early aquatic mammals of the order Cetacea. The family is named after paleocetologist Remington Kellogg.
Gaviacetus is an extinct archaeocete whale that lived approximately 45 million years ago. Gaviacetus was named for its characteristic narrow rostrum and the fast pursuit predation suggested by its unfused sacral vertebrae.
The Qasr el Sagha Formation is a geological formation located in Egypt. The formation is part of the Wadi El Hitan World Heritage Site. The Qasr el Sagha Formation overlies the Birket Qarun Formation and is overlain by the Gebel Qatrani Formation. The sandstones and shales of the formation were deposited in a deltaic to shallow marine environment. It dates to the Late Eocene.
Protocetidae, the protocetids, form a diverse and heterogeneous group of extinct cetaceans known from Asia, Europe, Africa, South America, and North America.
Aegyptocetus is an extinct genus of protocetid archaeocete whale known from Egypt.
Babiacetus is an extinct genus of early cetacean that lived during the late Lutetian middle Eocene of India . It was named after its type locality, the Harudi Formation in the Babia Hills, Kutch District, Gujarat, India.
Andrewsiphius is an extinct remingtonocetid early whale known from the Eocene of Gujarat and Kutch, India and Balochistan, Pakistan.
Carolinacetus is an extinct protocetid early whale found in the Bartonian Tupelo Bay Formation in Berkeley County, South Carolina.
Eocetus is an extinct protocetid early whale known from the early late Eocene Giushi Formation in Gebel Mokattam, outside Cairo, Egypt. The specimen was first named by Fraas as Mesocetus schweinfurthi. However, the name Mesocetus was previously used causing a change to the species name to Eocetus schweinfurthi. Since the genus was first described in the early 20th century, several other specimens, mostly isolated vertebrae, have been attributed to Eocetus, but the taxonomic status of these widely distributed specimens remain disputed.
Dagbatitherium is an extinct genus of proboscideans. So far a single molar from the phosphate basins of Togo in West Africa has been found. The fossil dates to the Middle Eocene, around 47 million years ago. A striking feature of the tooth are the three pairs of cusps oriented transversely to the longitudinal axis of the tooth. This feature is found in more derived proboscideans, which are grouped in the Elephantiformes. For its age, Dagbatitherium is the earliest member of Elephantiformes to date. Furthermore, it is characterized by a low tooth crown and a humped occlusal pattern. The genus was described in 2021.
Gingerich, P. D.; Cappetta, H. (2014). "A new archaeocete and other marine mammals (Cetacea and Sirenia) from lower middle Eocene phosphate deposits of Togo". Journal of Paleontology . 88 (1): 109–129. doi:10.1666/13-040. S2CID 85915213.
MKassegne, K. E (11 June 2021). "First partial cranium of Togocetus from Kpogamé (Togo) and the protocetid diversity in the Togolese phosphate basin". Annales de Paléontologie. 107 (2): 102488. doi:10.1016/j.annpal.2021.102488. S2CID 236757400 – via Elsevier Science Direct.
Mourlam, M.J.; Orliac, M.J. (2017). "Protocetid (cetacea, artiodactyla) bullae and petrosals from the Middle Eocene locality of KPOGAMÉ, Togo: New insights into the early history of cetacean hearing". Journal of Systematic Palaeontology. 16 (8): 621–644. doi:10.1080/14772019.2017.1328378. S2CID 89774296 – via EBSCO.
Archaeocete genera by family | |||||||
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| Pakicetidae | |||||||
| Ambulocetidae | |||||||
| Remingtonocetidae | |||||||
| Protocetidae |
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| Basilosauridae |
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