Post by Infinity Blade on Feb 1, 2014 4:12:33 GMT 5
Andrewsarchus mongoliensis
Andrewsarchus mongoliensis (/?ændru??s?rk?s/ an-drew-sar-k?s; Andrews + Greek:
??, "ruler"), is an extinct mammal that lived during the Eocene epoch, roughly between 45 and 36 million years ago. It had a long snout with large, sharp teeth and flat cheek teeth that may have been used to crush bones. Because Andrewsarchus is only known from a single skull, whether it was an active predator or a large scavenger is open to debate, as is its exact time range. Andrewsarchus is named for the famous explorer and fossil hunter Roy Chapman Andrews. It was discovered in June 1923 by Kan Chuen Pao, a member of Andrews' expedition, at a site in the Gobi Desert in Mongolia known as Irdin Manha [variants: Erdeni-Mandal and Erdenemandal ('jeweled mandala')] on the third Asiatic expedition that was led by Andrews and sponsored by the American Museum of Natural History. The skull is now on display at the American Museum of Natural History in New York; the lower jaw was not found. It was classified in the clade Mesonychia due to the similarity in structure between its teeth and skull with those of other mesonychid species known from complete skeleton, however, much of this was based only on Osborn's original publication, and more recent studies have found it to have no special mesonychid affinities, instead grouping with various artiodactyl clades. Indeed one study (Spaulding et al.) has not only found them to be closer to entelodonts, but as kin to Whippomorpha in their Cetacodontamorpha. Andrewsarchus is known only from an enormous skull (32.8 in/83 cm long and 22 in/56 cm wide) and pieces of bone. If Andrewsarchus was proportioned in the same manner as Mesonyx obtusidens, it had a length from the snout to the back of the pelvis of about 11 feet (3.4 m) and a height from the ground to the shoulder or middle of the back of about 6 feet (1.8 m). Thus in round numbers it is possible that it may have been three times the size of Synoplotherium (Dromocyon) vorax or of Mesonyx obtusidens and possibly the largest land-dwelling carnivorous mammal known. Its chief rival for this title is the South American short-faced bear Arctotherium, which is estimated to have weighed up to 1,700 kg (3,700 lb). The cranium is about twice the length of that of a modern Alaskan brown bear (Ursus arctos middendorffi), but with a lower length-to-width ratio, and about triple the length of an American wolf's (Canis lupus occidentalis). With modern brown bears or polar bears weighing between 450 kg (~1,000 lb) and 675 kg (~1,500 lb) and only an extreme specimen of a wolf weighs up to 77 kg (170 lb), this plausibly puts Andrewsarchus in the 1,000 kg (2,200 lb) size range. This weight appears close to the practical size limit of carnivorous land mammals, possibly relating to available food as well as metabolic requirements. There is as yet no post-cranial material at all found. As it is not known if Andrewsarchus had a robust or gracile build, the weight of the average animal is in dispute. If the build was robust, some specimens of the animal might have weighed up to 4,000 pounds.
Sarkastodon mongoliensis
Sarkastodon is an extinct genus within the family Oxyaenidae that lived during the upper Eocene, approximately 35 million years ago. It was a large, carnivorous animal that lived in what is today Mongolia. Sarkastodon is known only from a skull and jawbones. Sarkastodon, like creodonts in general, was probably a hypercarnivore that preyed on large mammals in its range during the Late Eocene, such as brontotheres, chalicotheres, and rhinoceroses. The type specimens of S. mongoliensis are known from Eocene deposits from the Irdin Manha Formation of Mongolia. Additional material referred to Sarkastodon is known from the Ulan Shireb beds (100 miles away from the holotype locality) of Inner Mongolia. These specimens were discovered by Dr. Garber in 1930, on an expedition to the Gobi Desert. Sarkastodon was a hypercarnivore, with hyaena-like dentition specialised in bone-cracking. The sharp, slicing premolars (which form roughly rectilinear cutting blades) and crushing molars enabled Sarkastodon to eat both bone and flesh.
Andrewsarchus mongoliensis (/?ændru??s?rk?s/ an-drew-sar-k?s; Andrews + Greek:
??, "ruler"), is an extinct mammal that lived during the Eocene epoch, roughly between 45 and 36 million years ago. It had a long snout with large, sharp teeth and flat cheek teeth that may have been used to crush bones. Because Andrewsarchus is only known from a single skull, whether it was an active predator or a large scavenger is open to debate, as is its exact time range. Andrewsarchus is named for the famous explorer and fossil hunter Roy Chapman Andrews. It was discovered in June 1923 by Kan Chuen Pao, a member of Andrews' expedition, at a site in the Gobi Desert in Mongolia known as Irdin Manha [variants: Erdeni-Mandal and Erdenemandal ('jeweled mandala')] on the third Asiatic expedition that was led by Andrews and sponsored by the American Museum of Natural History. The skull is now on display at the American Museum of Natural History in New York; the lower jaw was not found. It was classified in the clade Mesonychia due to the similarity in structure between its teeth and skull with those of other mesonychid species known from complete skeleton, however, much of this was based only on Osborn's original publication, and more recent studies have found it to have no special mesonychid affinities, instead grouping with various artiodactyl clades. Indeed one study (Spaulding et al.) has not only found them to be closer to entelodonts, but as kin to Whippomorpha in their Cetacodontamorpha. Andrewsarchus is known only from an enormous skull (32.8 in/83 cm long and 22 in/56 cm wide) and pieces of bone. If Andrewsarchus was proportioned in the same manner as Mesonyx obtusidens, it had a length from the snout to the back of the pelvis of about 11 feet (3.4 m) and a height from the ground to the shoulder or middle of the back of about 6 feet (1.8 m). Thus in round numbers it is possible that it may have been three times the size of Synoplotherium (Dromocyon) vorax or of Mesonyx obtusidens and possibly the largest land-dwelling carnivorous mammal known. Its chief rival for this title is the South American short-faced bear Arctotherium, which is estimated to have weighed up to 1,700 kg (3,700 lb). The cranium is about twice the length of that of a modern Alaskan brown bear (Ursus arctos middendorffi), but with a lower length-to-width ratio, and about triple the length of an American wolf's (Canis lupus occidentalis). With modern brown bears or polar bears weighing between 450 kg (~1,000 lb) and 675 kg (~1,500 lb) and only an extreme specimen of a wolf weighs up to 77 kg (170 lb), this plausibly puts Andrewsarchus in the 1,000 kg (2,200 lb) size range. This weight appears close to the practical size limit of carnivorous land mammals, possibly relating to available food as well as metabolic requirements. There is as yet no post-cranial material at all found. As it is not known if Andrewsarchus had a robust or gracile build, the weight of the average animal is in dispute. If the build was robust, some specimens of the animal might have weighed up to 4,000 pounds.Sarkastodon mongoliensis
Sarkastodon is an extinct genus within the family Oxyaenidae that lived during the upper Eocene, approximately 35 million years ago. It was a large, carnivorous animal that lived in what is today Mongolia. Sarkastodon is known only from a skull and jawbones. Sarkastodon, like creodonts in general, was probably a hypercarnivore that preyed on large mammals in its range during the Late Eocene, such as brontotheres, chalicotheres, and rhinoceroses. The type specimens of S. mongoliensis are known from Eocene deposits from the Irdin Manha Formation of Mongolia. Additional material referred to Sarkastodon is known from the Ulan Shireb beds (100 miles away from the holotype locality) of Inner Mongolia. These specimens were discovered by Dr. Garber in 1930, on an expedition to the Gobi Desert. Sarkastodon was a hypercarnivore, with hyaena-like dentition specialised in bone-cracking. The sharp, slicing premolars (which form roughly rectilinear cutting blades) and crushing molars enabled Sarkastodon to eat both bone and flesh.
