Mount Blanco is a small white hill — an erosional remnant — located on the eastern border of the

Llano Estacado The Llano Estacado (), sometimes translated into English as the Staked Plains, is a region in the Southwestern United States that encompasses parts of eastern New Mexico and northwestern Texas. One of the largest mesas or tablelands on the North A ...

within

Blanco Canyon Blanco Canyon is a canyon located in the U.S. state of Texas. Eroded by the White River into the Caprock Escarpment on the east side of the Llano Estacado, the canyon runs for in a southeasterly direction, gradually widening from its beginning ...

Crosby County, Texas Crosby County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 5,133. The county seat is Crosbyton. The county was founded in 1876 and later organized in 1886. Both the county and its seat are named for ...

. With

, it is the type locality of the

Blanco Formation The Blanco Formation, originally named the Blanco Canyon Beds, is an early Pleistocene geologic formation of clay, sand, and gravel whitened by calcium carbonate cementation and is recognized in Texas and Kansas. After the Ogallala had lain e ...

of Texas and Kansas, as well as the

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 (NALMA), typically set from 4,750,000 to 1,806,000 years Before Present, BP, a period of .

fauna, which occurs throughout North America.

Geology

The term "Blanco Canyon beds", later shortened to "Blanco beds", was first applied to this formation in 1890 by William F. Cummins of the Geological Survey of Texas. The Blanco beds are considered to be of lacustrine origin – deposited in a Pleistocene lake basin set upon the

Ogallala Formation The Ogallala Formation is a Miocene to early Pliocene geologic formation in the central High Plains of the western United States and the location of the Ogallala Aquifer. In Nebraska and South Dakota it is also classified as the Ogallala Group. N ...

of Pliocene age, which underlies the upper surface sediments of the

. The thickness of the Blanco beds varies from around thick. The formation mainly consists of light-gray, fine-grained

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

, and some conglomerate. These light-colored sediments contrast sharply with the locally rust-colored sediments of the Ogallala Formation.

Fossil fauna

All fossil fauna are from Mount Blanco modified from Dalquest (1975) unless otherwise noted. * Class

Mammalia Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

** Order Perissodactyla *** Family

Equidae Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', ...

**** †'' Equus cumminsi'' **** †''

Equus simplicidens The Hagerman horse (''Equus simplicidens''), also called the Hagerman zebra or the American zebra, was a North American species of equid from the Pliocene epoch and the Pleistocene epoch. It was one of the oldest horses of the genus ''Equus'' and ...

'' **** †''

Nannippus ''Nannippus'' is an extinct genus of three-toed horse endemic to North America during the Miocene through Pleistoceneabout 13.3—1.8 million years ago (Mya), living around 11.5 million years. This ancient species of three-toed horse grew up to 3 ...

peninsulatus'' ** Order

Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

*** Family

Antilocapridae The Antilocapridae are a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids with which they comprise the superfamily Giraffoidea. Only one species, the pronghorn (''Antilocapra americana''), is li ...

*** Family

Camelidae Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, ...

**** †''

Blancocamelus ''Blancocamelus'' is an extinct genus of Terrestrial animal, terrestrial herbivores the family (biology), family Camelidae, endemic to North America during the Pliocene through Pleistocene—4.9 million years ago until 300,000 years ago, existing ...

meadei'' **** †''

Camelops ''Camelops''Being occasionally called ''Western Camel'' or ''Yesterday's Camel''. is an extinct genus of camels that lived in North and Central America, ranging from Alaska to Guatemala, from the middle Pliocene to the end of the Pleistocene. It ...

traviswhitei'' **** †''Canimartes cumminsi'' **** †''

Titanotylopus ''Titanotylopus'' is an extinct genus of terrestrial herbivore in the family Camelidae, endemic to North America from the late Hemphillian stage of the Miocene through the Irvingtonian stage of the Pleistocene. It was one of the last surviving ...

spatulus'' *** Family

Cervidae Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...

**** †''

Odocoileus ''Odocoileus'' is a genus of medium-sized deer (family Cervidae) containing three species native to the Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South Am ...

brachyodontus'' *** Family Tayassuidae **** †''

Platygonus ''Platygonus'' ("flat head" in reference to the straight shape of the forehead) is an extinct genus of herbivorous peccaries of the family Tayassuidae, endemic to North and South America from the Miocene through Pleistocene epochs (10.3 million ...

biccalcaratus'' **** †''Tanupolama blancoensis'' ** Superorder

Edentata Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Extin ...

*** Family †

Glyptodontidae Glyptodonts are an extinct subfamily of large, heavily armoured armadillos. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best- ...

**** †''

Glyptotherium ''Glyptotherium'' (from Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Early Pliocene, about 4.9 million years ago, to the Early Holocene, around 7,000 years ...

texanum'' *** Family

Megalonychidae Megalonychidae is an extinct family of sloths including the extinct ''Megalonyx''. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is actually one possible find dating ...

**** †''

Megalonyx ''Megalonyx'' (Greek, "large claw") is an extinct genus of ground sloths of the family Megalonychidae, native to North America during the Pliocene and Pleistocene epochs. It became extinct during the Quaternary extinction event at the end of the ...

leptostomus'' *** Family †

Mylodontidae Mylodontidae is a family of extinct South American and North American ground sloths within the suborder Folivora of order Pilosa The order Pilosa is a clade of xenarthran placental mammals, native to the Americas. It includes the anteaters a ...

**** †''

Glossotherium ''Glossotherium'' is an extinct genus of mylodontid ground sloths of the subfamily Mylodontinae, which includes large ground-dwelling sloths. It represents one of the best known members of the family, along with ''Mylodon'' and ''Paramylodon''. ...

chapadmalens'' ** Order

Lagomorpha The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ� ...

*** Family

Leporidae Leporidae is the family of rabbits and hares, containing over 60 species of extant mammals in all. The Latin word ''Leporidae'' means "those that resemble ''lepus''" (hare). Together with the pikas, the Leporidae constitute the mammalian order ...

**** †''

Hypolagus ''Hypolagus'' is an extinct genus of lagomorph, first recorded in the Hemingfordian (early to middle Miocene) of North America. It entered Asia during the early Turolian and spread to Europe not much later, where it survived until the Middle Plei ...

'' sp. **** †''Nekrolagus progressus'' ** Order

Proboscidea The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...

*** Family †

Gomphotheriidae Gomphotheres are any members of the diverse, extinct taxonomic family Gomphotheriidae. Gomphotheres were elephant-like proboscideans, but do not belong to the family Elephantidae. They were widespread across Afro-Eurasia and North America during ...

**** †''

Stegomastodon ''Stegomastodon'' ('roof breast tooth') is an extinct genus of gomphotheres, a family of proboscideans. It ranged throughout North America from the early Blancan ~4 Ma, to the early Irvingtonian (~1.2 Ma). The South American species have be ...

mirificus'' ** Order

Carnivora Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...

*** Family

Canidae Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found within th ...

**** †''

Borophagus ''Borophagus'' ("gluttonous eater") is an extinct genus of the subfamily Borophaginae, a group of canids endemic to North America from the Middle Miocene epoch through the Early Pleistocene epoch 12—1.8 Mya. Evolution ''Borophagus'', like o ...

diversidens'' **** †''

Canis lepophagus ''Canis lepophagus'' (Latin: : 'dog'; : 'hare' or 'rabbit'; suffix : '-eating'; hence hare-eating dog) is an extinct species of canid which was endemic to much of North America during the Early Pliocene. It is notable because its lineage is prop ...

'' *** Family

Felidae Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the ...

**** †''

Felis ''Felis'' is a genus of small and medium-sized cat species native to most of Africa and south of 60° latitude in Europe and Asia to Indochina. The genus includes the domestic cat. The smallest ''Felis'' species is the black-footed cat with a he ...

'' cf.'' lacustris'' **** †''

Dinofelis ''Dinofelis'' is a genus of extinct sabre-toothed cats belonging to the tribe Metailurini or possibly Smilodontini. They were widespread in Europe, Asia, Africa and North America at least 5 million to about 1.2 million years ago (Early Pliocene t ...

palaeoonca'' **** †''

Homotherium ''Homotherium'', also known as the scimitar-toothed cat or scimitar cat, is an extinct genus of machairodontine saber-toothed predator, often termed scimitar-toothed cats, that inhabited North America, South America, Eurasia, and Africa during th ...

'' *** Family

Ursidae Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Nort ...

**** †''

Arctotherium ''Arctotherium'' ("''bear beast''") is an extinct genus of the Pleistocene short-faced bears endemic to Central and South America. ''Arctotherium'' migrated from North America to South America during the Great American Interchange, following the f ...

''? *** Family Hyaenidae **** †''

Chasmaporthetes ''Chasmaporthetes'', also known as hunting or running hyena, is an extinct genus of hyenas distributed in Eurasia, North America, and Africa during the Pliocene-Pleistocene epochs, living from 4.9 million to 780,000 years ago, existing for about ...

ossifragus'' *** Family

Mustelidae The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in ...

**** †''Canimartes cummins'' **** †''

Spilogale The genus ''Spilogale'' includes all skunks commonly known as spotted skunks. Currently, there are four accepted extant species: ''S. gracilis'', ''S. putorius'', ''S. pygmaea'', and ''S. angustifrons''. New research, however, proposes that ther ...

rexroadi'' ** Order

Rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

ia *** Family

Sciuridae Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

**** †''Paenemarmota barbouri'' **** ''

Spermophilus ''Spermophilus'' is a genus of ground squirrels in the Sciuridae, squirrel family. As traditionally defined the genus was very species-rich, ranging through Europe, Asia and North America, but this arrangement was found to be paraphyletic to ...

''sp. **** †''Spermophilius howelli'' *** Family Geomyidae **** ''Geomys'' sp. *** Family

Heteromyidae Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within the gen ...

**** †''

Perognathus ''Perognathus'' is a genus of pocket mouse. Like other members of their family they are more closely related to pocket gophers than to true mice. Characteristics The silky pocket mice are small animals with soft pelage, long tails, and small f ...

parlettensis'' **** †''Perognathus rexroadensis'' **** †''Prodipomys centralis'' *** Family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has m ...

**** ''

Baiomys ''Baiomys'' is the genus of New World pygmy mice. Together with '' Scotinomys'', it forms the tribe Baiomyini. It currently contains two extant species: *Southern pygmy mouse, '' Baiomys musculus'' *Northern pygmy mouse, '' Baiomys taylori'' ...

''sp. **** †'' Bensonomys'' sp. **** †''

Neotoma A pack rat or packrat, also called a woodrat or trade rat, are any species in the North and Central American rodent genus ''Neotoma''. Pack rats have a rat-like appearance, with long tails, large ears, and large, black eyes. Pack rats are notice ...

quadriplicatus'' **** '' Onychomys'' sp. **** †''

Peromyscus ''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''Mu ...

kansasensis'' **** ''

Reithrodontomys ''Reithrodontomys'' is the genus of groove-toothed New World harvest mice. Species This genus contains these species: *Baker's small-toothed harvest mouse, ''Reithrodontomys bakeri'' *Short-nosed harvest mouse, ''Reithrodontomys brevirostris'' * ...

'' sp. **** †'' Sigmodon medius'' * Class

Reptilia Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

** Order

Testudinata Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Jacob The ...

*** Family Testudinidae **** ''

Geochelone ''Geochelone'' is a genus of tortoises. ''Geochelone'' tortoises, which are also known as typical tortoises or terrestrial turtles, can be found in southern Asia. They primarily eat plants. Species The genus consists of two extant species: A ...

'' sp.

Images

File:Mt_Blanco_1891.jpg, Early photo of Mount Blanco (1891)Cummins, W.F. 1892. Report on the geography, topography, and geology of the Llano Estacado or Staked Plains. In: Dumble, E.T. (ed), Third annual report of the Geological Survey of Texas 1891, pp. 129-223. File:Mt Blanco 2002.jpg, Mount Blanco viewed from east (2002)

References

External links

Mt. Blanco Fossil Museum
* {{Texas Geology of Texas Landforms of Crosby County, Texas Rock formations of Texas Cenozoic paleontological sites of North America Paleontology in Texas

Geology

Fossil fauna

Images

See also

References

External links