Artiocetus
Encyclopedia
Artiocetus clavis is an extinct genus
of early whales belonging to the family Protocedidae. Their name arises from a combination of Cetacean and Artiodactyl, as this fossil was the first to show that early whales possessed artiodactyl-like ankles.
Artiocetus belongs to the order Cetacea
, which includes whales, dolphins and porpoises. Cetus is Latin, its literal meaning being "large sea mammal" and is used in biological names to mean "whale". It comes from Ancient Greek κῆτος (kētos), meaning "whale" or "any huge fish or sea monster".
Artiodactyla refers to the mammal order of even-toed ungulates the group containing cattle
, deer
, camels, giraffes, antelope
, goats, sheep, pigs
and hippopotamuses. If the animal has more than two toes, the weight is borne equally by the third and fourth toe. The shape of the astragalus is another key feature which has a double-pulley structure in artiodactyls, giving the foot greater flexibility.
age (47 million years ago) and is one of the oldest known protocetid archaeocetes. Though the whale may have been primarily aquatic, the discovery of ankle bones lends to the idea that this fossil may have been a transition between sea-based and land-based mammals. While whales eventually returned to the sea, a cousin of the whales, the hippopotamus
is thought to have descended from an ancestor shared with the whale.
Though it likely spent the majority of its time in the water, the well-developed fore and hind limbs suggest that this species may have been a wader - capable of movement in more shallow water and possibly able to propel itself on land as well.
Protocetidae were the first group of whales to develop tail flukes, which suggests they were quick, agile predators. Though Protocetidae as a family possessed tail flukes, it has been suggested that Artiocetus did not. Thewissen et al. states that " Artiocetus had a long tail and thus probably lacked a tail fluke".
Province of Pakistan showed that Artiocetus had both an astragalus and cuboid bone in the ankle (a diagnostic traits of artiodactyls), suggesting that early whales had fore and hind limbs. The distribution of fossils in Indo-Pakistan, Africa, Europe, and North America suggests that this species preferred a warmer sea climate, preferably in the tropics.
There is no commonly agreed ancestry of the whale, but they are thought to have evolved from an early group of carnivorous artiodactyla (even-toed ungulates).
DNA studies have suggested that the hippopotamus is the closest land relative to the whale. Artiocetus fossils represent intermediate forms between land-living ungulates and whales, lending support to the theory that whales and hippopotomi descended from a common ancestor.
The discovery of this fossil is important as it helped solidify the theory that whales shared a common ancestor with Artiodactyl. In 2005, an international team of scientists suggested that whales and hippopotami share a common water and terrestrial dwelling ancestor, which lived 50 to 60 million years ago. Two groups emerged from this common ancestor: early cetaceans, which in time returned to the sea permanently, and a large group of pig-like land-based mammals called anthracotheres. The only surviving descendant of anthracotheres is the hippopotamus.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of early whales belonging to the family Protocedidae. Their name arises from a combination of Cetacean and Artiodactyl, as this fossil was the first to show that early whales possessed artiodactyl-like ankles.
Artiocetus belongs to the order Cetacea
Cetacea
The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...
, which includes whales, dolphins and porpoises. Cetus is Latin, its literal meaning being "large sea mammal" and is used in biological names to mean "whale". It comes from Ancient Greek κῆτος (kētos), meaning "whale" or "any huge fish or sea monster".
Artiodactyla refers to the mammal order of even-toed ungulates the group containing cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
, deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
, camels, giraffes, antelope
Antelope
Antelope is a term referring to many even-toed ungulate species indigenous to various regions in Africa and Eurasia. Antelopes comprise a miscellaneous group within the family Bovidae, encompassing those old-world species that are neither cattle, sheep, buffalo, bison, nor goats...
, goats, sheep, pigs
PIGS
PIGS is a four letter acronym that can stand for:* PIGS , Phosphatidylinositol glycan anchor biosynthesis, class S, a human gene* PIGS , the economies of Portugal, Italy , Greece and Spain...
and hippopotamuses. If the animal has more than two toes, the weight is borne equally by the third and fourth toe. The shape of the astragalus is another key feature which has a double-pulley structure in artiodactyls, giving the foot greater flexibility.
Description
Artiocetus clavis existed in the early LutetianLutetian
The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between and . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene subepoch...
age (47 million years ago) and is one of the oldest known protocetid archaeocetes. Though the whale may have been primarily aquatic, the discovery of ankle bones lends to the idea that this fossil may have been a transition between sea-based and land-based mammals. While whales eventually returned to the sea, a cousin of the whales, the hippopotamus
Hippopotamus
The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...
is thought to have descended from an ancestor shared with the whale.
Though it likely spent the majority of its time in the water, the well-developed fore and hind limbs suggest that this species may have been a wader - capable of movement in more shallow water and possibly able to propel itself on land as well.
Protocetidae were the first group of whales to develop tail flukes, which suggests they were quick, agile predators. Though Protocetidae as a family possessed tail flukes, it has been suggested that Artiocetus did not. Thewissen et al. states that " Artiocetus had a long tail and thus probably lacked a tail fluke".
Fossil finds
Fossils located in 2001 in the BalochistanBalochistan (Pakistan)
Balochistan is one of the four provinces or federating units of Pakistan. With an area of 134,051 mi2 or , it is the largest province of Pakistan, constituting approximately 44% of the total land mass of Pakistan. According to the 1998 population census, Balochistan had a population of...
Province of Pakistan showed that Artiocetus had both an astragalus and cuboid bone in the ankle (a diagnostic traits of artiodactyls), suggesting that early whales had fore and hind limbs. The distribution of fossils in Indo-Pakistan, Africa, Europe, and North America suggests that this species preferred a warmer sea climate, preferably in the tropics.
There is no commonly agreed ancestry of the whale, but they are thought to have evolved from an early group of carnivorous artiodactyla (even-toed ungulates).
DNA studies have suggested that the hippopotamus is the closest land relative to the whale. Artiocetus fossils represent intermediate forms between land-living ungulates and whales, lending support to the theory that whales and hippopotomi descended from a common ancestor.
The discovery of this fossil is important as it helped solidify the theory that whales shared a common ancestor with Artiodactyl. In 2005, an international team of scientists suggested that whales and hippopotami share a common water and terrestrial dwelling ancestor, which lived 50 to 60 million years ago. Two groups emerged from this common ancestor: early cetaceans, which in time returned to the sea permanently, and a large group of pig-like land-based mammals called anthracotheres. The only surviving descendant of anthracotheres is the hippopotamus.