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.
Pakicetus is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Pakistan during the Ypresian period, 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.
Himalayacetus is an extinct genus of carnivorous aquatic mammal of the family Ambulocetidae. The holotype was found in Himachal Pradesh, India, in what was the remnants of the ancient Tethys Ocean during the Early Eocene. This makes Himalayacetus the oldest archaeocete known, extending the fossil record of whales some 3.5 million years.
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.
Remingtonocetidae is a diverse family of early aquatic mammals of the order Cetacea. The family is named after paleocetologist Remington Kellogg.
Dalanistes is an extinct genus of remingtonocetid early whale known from the late early Eocene of Kutch, India and Punjab and Balochistan, Pakistan. Dalanistes is closely related to Remingtonocetus, but also shares several features with Ambulocetus, and, with its combination of terrestrial and amphibious adaptations, Dalanistes apparently is an intermediate form between these two groups. Isotopic evidence suggest that Dalanistes had a marine diet.
Takracetus was a primitive cetacean that lived approximately 45 million years ago. The type specimen is a partial skull though the literature mentions a second more complete specimen.
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.
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.
Qaisracetus is an extinct protocetid early whale known from the Eocene of Baluchistan, Pakistan.
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.
Indocetus is a protocetid early whale known from the late early Eocene Harudi Formation in Kutch, India.
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.
Sobrarbesiren is a genus of extinct sirenian that lived in the Eocene, about 47 million years ago. The type and only species is S. cardieli, known from a multitude of specimens from the Spanish Pyrenees. Sobrarbesiren was a medium-sized animal, 2.7 m long and still retaining both pairs of limbs. Although initially thought to be amphibious, later studies instead suggest that they would have been fully aquatic and been selective sea grass browsers. Unlike modern dugongs and manatees, they likely lacked a tail fluke, although it would have appeared horizontally flattened.
