Urocyon progressus
Encyclopedia
Urocyon progressus, also known as the Progressive Gray Fox, is an extinct
carnivorous
mammal
of the genus Urocyon
, and was most common in North America
during the Blancan Stage
on the geologic timescale. Fossil samples have been found in both Kansas and Texas. It may have been the ancestor of the modern Gray Fox
.
of the species was found by Claude W. Hibbard
during the summer of 1959. It was a complete left parietal bone
, with two paratype
s, being; an upper left molar
and an incomplete left tibia
. All of these were found in the Upper Pliocene Rexroad Formation in Meade County, Kansas
. These became the oldest remains of the genus Urocyon
discovered. Additional examples were also found in the Love Formation, in Hudspeth County, Texas
. Margaret Skeele Stevens described the species in the Journal of Mammalogy
in May, 1965.
differ from those of Vulpes
by possessing larger molars, the wider separation of a series of ridges along the top of the skull and the shape of its jaw. The collected material of progressus shows that it was slightly larger in size, although had a smaller skull than the modern Gray fox
, of which it is presumed to be an ancestor.
period in North America. This stage is usually considered to start in the early-mid Pliocene
epoch and end by the early Pleistocene
. It is thought to have inhabited terrain similar to that of the modern Gray Fox, including a mixture of forest, woodland and brushland.
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
carnivorous
Carnivora
The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...
mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
of the genus Urocyon
Urocyon
The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae, the Gray Fox and the closely related Island Fox which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus.Urocyon and the...
, and was most common in 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 Blancan Stage
Blancan
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...
on the geologic timescale. Fossil samples have been found in both Kansas and Texas. It may have been the ancestor of the modern Gray Fox
Gray Fox
The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...
.
Taxonomy
The holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of the species was found by Claude W. Hibbard
Claude W. Hibbard
Claude W. Hibbard, popularly known as Hibbie , was an American paleontologist....
during the summer of 1959. It was a complete left parietal bone
Parietal bone
The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....
, with two paratype
Paratype
Paratype is a technical term used in the scientific naming of species and other taxa of organisms. The exact meaning of the term paratype when it is used in zoology is not the same as the meaning when it is used in botany...
s, being; an upper left molar
Molar
Molar may refer to:*Molar , the fourth kind of tooth in mammals*Molar , another name for the Spanish wine grape Listan Negro*Molar concentration, a unit of concentration, or molarity, of solutions equal to 1 mole per litre*Molar volume...
and an incomplete left tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
. All of these were found in the Upper Pliocene Rexroad Formation in Meade County, Kansas
Meade County, Kansas
Meade County is a county located in the U.S. state of Kansas. It is named in honor of General George G. Meade. As of the 2010 census, the county population was 4,575...
. These became the oldest remains of the genus Urocyon
Urocyon
The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae, the Gray Fox and the closely related Island Fox which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus.Urocyon and the...
discovered. Additional examples were also found in the Love Formation, in Hudspeth County, Texas
Hudspeth County, Texas
Hudspeth County is a county located in the U.S. state of Texas. It is one of the nine counties that comprise the Trans-Pecos region of West Texas. As of 2000, the population was 3,344. By 2010, the population had increased to 3,476. Its county seat is Sierra Blanca. The largest city is Fort Hancock...
. Margaret Skeele Stevens described the species in the Journal of Mammalogy
Journal of Mammalogy
The Journal of Mammalogy is the flagship publication of the American Society of Mammalogists. Both the society and the journal were founded in 1919. The peer-reviewed journal publishes papers about mammals throughout the world and their conservation...
in May, 1965.
Description
Foxes of the genus UrocyonUrocyon
The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae, the Gray Fox and the closely related Island Fox which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus.Urocyon and the...
differ from those of Vulpes
Vulpes
Vulpes is a genus of the Canidae family. Its members are referred to as 'true foxes', although there are species in other genera whose common names include the word 'fox'....
by possessing larger molars, the wider separation of a series of ridges along the top of the skull and the shape of its jaw. The collected material of progressus shows that it was slightly larger in size, although had a smaller skull than the modern Gray fox
Gray Fox
The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...
, of which it is presumed to be an ancestor.
Range and ecology
The species ranged throughout the BlancanBlancan
The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...
period in North America. This stage is usually considered to start in the early-mid 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...
epoch and end by the early 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 ....
. It is thought to have inhabited terrain similar to that of the modern Gray Fox, including a mixture of forest, woodland and brushland.