Paramylodon
Encyclopedia
Paramylodon is an extinct genus of ground sloth
of the family Mylodontidae
endemic to North America
during the Pliocene
through Pleistocene
epochs, living from around ~4.9 Mya—11,000 years ago (approximately ).
as well as Mexico
and the United States and often mistaken as Glossotherium
. Currently there is just one recognized species, P. harlani, that is commonly referred to as Harlan's ground sloth in honor of American paleontologist Dr. Richard Harlan
who first discovered and described a lower jaw in 1835. Paramylodon exhibits the interesting characteristic of having had dermal ossicles, small bones embedded in the skin, presumably adding a degree of protection to the animal. This characteristic is also shared by the South American Mylodon
.
The genus was created by Barnum Brown
in 1903 with the species P. nebrascensis. The skull showed a number of characteristics similar to that of Mylodon harlani, which was also known from North America, but differed in the number of teeth present in the maxilla. Paramylodon had four teeth in the upper dentition, similar to that of Grypotherium darwini (=Mylodon darwini), but the then recognized genus of Mylodon
possessed five upper teeth. P. nebrascensis was later considered to be a junior synonym of M. harlani by Stock (1925) given the large number of specimens from the La Brea Tar Pits
that showed the presence of the upper caniniform to be variably lost in some specimens and retained in others. Thus the typical dental formula for the species of harlani is
. Work by Kraglievich (1928) sorted through the long standing historical confusion concerning the taxonomic validity of Mylodon
and Glossotherium
, and determined what the type species of each genus was. An additional result was to recognize Paramylodon as generically different from Mylodon of South America and P. harlani was used as the species name as it had seniority over P. nebrascensis.
Until recently, Paramylodon was also viewed as a subspecies of Glossotherium
and a number of institutions listed their specimens as Glossotherium harlani in part to work by Robertson (1976). Paramylodon is generically distinct from the South American genus of Glossotherium (see McAfee, 2007), although some question remains regarding the relationship of the late Blancan specimens that have been tentatively assigned as "Glossotherium
" chapadmalense due to their seeming similarity to the South American species of the same name.
jeffersoni. This is the first occurrence of Paramylodon in Iowa, and probably the first time these species have been found in close association. Since, these two species have been uncovered at the Fairmead Landfill Site and Irvington Site in California.
On December 3, 2009, the Press-Enterprise newspaper reports a specimen skull to have been recovered in San Timoteo Canyon (http://www.pe.com/localnews/inland/stories/PE_News_Local_S_sloth03.2dc60eb.html).
Ground sloth
Ground sloths are a diverse group of extinct sloths, in the mammalian superorder Xenarthra. Their most recent survivors lived in the Antilles, where it has been proposed they may have survived until 1550 CE; however, the youngest AMS radiocarbon date reported is 4190 BP, calibrated to c. 4700 BP...
of the family Mylodontidae
Mylodontidae
Mylodontidae is a family of extinct mammals within the order of Pilosa and suborder Folivora living from approximately 23 mya—11,000 years ago, existing for approximately . This family of ground sloths is related to the other families of extinct ground sloths, being the Megatheriidae, the...
endemic to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
during the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
through Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epochs, living from around ~4.9 Mya—11,000 years ago (approximately ).
Overview
Paramylodon is known from North America deposits as far south as GuatemalaGuatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
as well as Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and the United States and often mistaken as Glossotherium
Glossotherium
Glossotherium was a genus of ground sloth. It was a heavily built animal with a length of about snout to tail-tip, and could potentially assume a slight bipedal stance.Fossils of this animal have been found in South America...
. Currently there is just one recognized species, P. harlani, that is commonly referred to as Harlan's ground sloth in honor of American paleontologist Dr. Richard Harlan
Richard Harlan
Richard Harlan was an American naturalist, zoologist, physicist and paleontologist....
who first discovered and described a lower jaw in 1835. Paramylodon exhibits the interesting characteristic of having had dermal ossicles, small bones embedded in the skin, presumably adding a degree of protection to the animal. This characteristic is also shared by the South American Mylodon
Mylodon
Mylodon is an extinct genus of giant ground sloth that lived in the Patagonia area of South America until roughly 10,000 years ago.Mylodon weighed about and stood up to tall when raised up on its hind legs. Preserved dung has shown it was a herbivore. It had very thick hide and had osteoderms...
.
Taxonomic History
Barnum Brown
Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...
in 1903 with the species P. nebrascensis. The skull showed a number of characteristics similar to that of Mylodon harlani, which was also known from North America, but differed in the number of teeth present in the maxilla. Paramylodon had four teeth in the upper dentition, similar to that of Grypotherium darwini (=Mylodon darwini), but the then recognized genus of Mylodon
Mylodon
Mylodon is an extinct genus of giant ground sloth that lived in the Patagonia area of South America until roughly 10,000 years ago.Mylodon weighed about and stood up to tall when raised up on its hind legs. Preserved dung has shown it was a herbivore. It had very thick hide and had osteoderms...
possessed five upper teeth. P. nebrascensis was later considered to be a junior synonym of M. harlani by Stock (1925) given the large number of specimens from the La Brea Tar Pits
La Brea Tar Pits
The La Brea Tar Pits are a cluster of tar pits around which Hancock Park was formed, in the urban heart of Los Angeles. Asphaltum or tar has seeped up from the ground in this area for tens of thousands of years. The tar is often covered with water...
that showed the presence of the upper caniniform to be variably lost in some specimens and retained in others. Thus the typical dental formula for the species of harlani is
. Work by Kraglievich (1928) sorted through the long standing historical confusion concerning the taxonomic validity of MylodonMylodon
Mylodon is an extinct genus of giant ground sloth that lived in the Patagonia area of South America until roughly 10,000 years ago.Mylodon weighed about and stood up to tall when raised up on its hind legs. Preserved dung has shown it was a herbivore. It had very thick hide and had osteoderms...
and Glossotherium
Glossotherium
Glossotherium was a genus of ground sloth. It was a heavily built animal with a length of about snout to tail-tip, and could potentially assume a slight bipedal stance.Fossils of this animal have been found in South America...
, and determined what the type species of each genus was. An additional result was to recognize Paramylodon as generically different from Mylodon of South America and P. harlani was used as the species name as it had seniority over P. nebrascensis.
Until recently, Paramylodon was also viewed as a subspecies of Glossotherium
Glossotherium
Glossotherium was a genus of ground sloth. It was a heavily built animal with a length of about snout to tail-tip, and could potentially assume a slight bipedal stance.Fossils of this animal have been found in South America...
and a number of institutions listed their specimens as Glossotherium harlani in part to work by Robertson (1976). Paramylodon is generically distinct from the South American genus of Glossotherium (see McAfee, 2007), although some question remains regarding the relationship of the late Blancan specimens that have been tentatively assigned as "Glossotherium
Glossotherium
Glossotherium was a genus of ground sloth. It was a heavily built animal with a length of about snout to tail-tip, and could potentially assume a slight bipedal stance.Fossils of this animal have been found in South America...
" chapadmalense due to their seeming similarity to the South American species of the same name.
Fossil distribution
Sites and specimen ages (not complete):- El Golfo de Santa Clara Site, Sonora, Mexico ~4.9—1.8 Mya.
- Tri-Britton Site, Hendry County, FloridaHendry County, FloridaHendry County is a county located in the U.S. state of Florida. As of 2000, the population was 36,210. The U.S. Census Bureau 2007 estimate for the county is 39,611 . Its county seat is La Belle. The county comprises the Clewiston, Florida, Micropolitan Statistical Area.-History:Hendry County...
~2.1 Mya.—700,000 years ago. - Turin Pit Site (or Elliott Pit) Monona County, IowaMonona County, Iowa-2010 census:The 2010 census recorded a population of 9,243 in the county, with a population density of . There were 4,697 housing units, of which 4,050 were occupied.-2000 census:...
~1.8—300,00 years ago. - Port Kennedy Cave Site, Montgomery County, PennsylvaniaMontgomery County, PennsylvaniaMontgomery County is a county located in the U.S. state of Pennsylvania, in the United States. As of 2010, the population was 799,874, making it the third most populous county in Pennsylvania . The county seat is Norristown.The county was created on September 10, 1784, out of land originally part...
~1.8 Mya.—300,00 years ago. - Fairmead Landfill Site, Madera County, CaliforniaMadera County, CaliforniaMadera County is a county of the U.S. state of California, located in the Central Valley and the Sierra Nevada north of Fresno County. It comprises the Madera-Chowchilla, CA Metropolitan Statistical Area. As of the 2010 census the population was 150,865...
~1.8 Mya.—300,00 years ago. - Rio de la Pasion Site, PetenPeténPetén or Peten may refer to:*Petén , a department of Guatemala*Petén Basin, the geographical / archaeological region of Mesoamerica and a center of the Maya civilization*Lake Petén Itzá, a lake in the Petén Basin region...
, GuatemalaGuatemalaGuatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
~100,000—11,000 years ago. - TualatinTualatinTualatin may refer to:* Tualatin , a part of the Kalapuya Native American tribe in western Oregon in the United States* Tualatin Academy, a building and former school in Forest Grove, Oregon...
, OregonOregonOregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
-15,000 to 10,000 years ago. - Medicine Hat Unit V Site, Alberta, Canada ~1.8 Ma—11,00 years ago.
Notable discoveries
Recently a Paramylodon harlani specimen was identified from the Tarkio Valley site in Iowa association with MegalonyxMegalonyx
Megalonyx is an extinct genus of giant ground sloths of the family Megalonychidae endemic to North America from the Hemphillian of the Late Miocene through to the Rancholabrean of the Pleistocene, living from ~10.3 Mya—11,000 years ago, existing for approximately .-Taxonomy:The generic name...
jeffersoni. This is the first occurrence of Paramylodon in Iowa, and probably the first time these species have been found in close association. Since, these two species have been uncovered at the Fairmead Landfill Site and Irvington Site in California.
On December 3, 2009, the Press-Enterprise newspaper reports a specimen skull to have been recovered in San Timoteo Canyon (http://www.pe.com/localnews/inland/stories/PE_News_Local_S_sloth03.2dc60eb.html).