Miracinonyx
Encyclopedia
Miracinonyx is an extinct genus of the family
Felidae
, endemic to North America
during the Pleistocene
epoch (1.8 mya—11,000 years ago), existing for approximately .
There were at least two species of feline
morphologically
similar to the modern cheetah
. Living from three million to ten or twenty thousand years ago in North America
, these cats are known only from fragments of skeletons. The two species commonly identified are Miracinonyx inexpectatus and M. trumani. Sometimes a third species, M. studeri, is added to the list, but it is more often listed as a junior synonym of M. trumani. Both species are similar to the modern cheetah, with faces shortened and nasal cavities expanded for increased oxygen capacity, and legs proportioned for swift running. However, these similarities may not be inherited from a common ancestor, but result from either parallel
or convergent
evolution.
and re-analyzing morphology, has suggested reversing the reclassification: the American cheetah developed cheetah-like characteristics through convergent evolution
, but it is most closely related to Puma and not to the modern cheetah of Africa
and Asia
. The supposed American origin of the modern cheetah is thus equivocal; however, it is believed to have evolved from cougar-like ancestors, whether in the Old or New World
.
The cougar and M. trumani are believed to have split from a cougar-like ancestor around three million years ago; where M. inexpectatus fits in is unclear, although it likely is a more primitive version of M. trumani.
s and plains of western America, it was likely a predator of hoofed plains
animals such as the pronghorn
. In fact, predation by Miracinonyx is thought to be the reason that pronghorns evolved to run so swiftly, their 60 mph top speed being much more than needed to outrun extant American predators such as cougars and gray wolves.
The similarity between M. trumani and the cheetah is an example of parallel evolution
. As grasslands became more common in both Africa-Eurasia and North America, cougar-like cat species from both continents evolved to catch the new fleet-footed herbivore
s. The claws of M. trumani had even become only partially retractable, to be used for better grip at high speeds.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Felidae
Felidae
Felidae is the biological family of the cats; a member of this family is called a felid. Felids are the strictest carnivores of the thirteen terrestrial families in the order Carnivora, although the three families of marine mammals comprising the superfamily pinnipedia are as carnivorous as 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 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 ....
epoch (1.8 mya—11,000 years ago), existing for approximately .
There were at least two species of feline
Felinae
Felinae is a subfamily of the family Felidae which includes the genera and species listed below. Most are small to medium-sized cats, although the group does include some larger animals, such as the Cougar and Cheetah....
morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similar to the modern cheetah
Cheetah
The cheetah is a large-sized feline inhabiting most of Africa and parts of the Middle East. The cheetah is the only extant member of the genus Acinonyx, most notable for modifications in the species' paws...
. Living from three million to ten or twenty thousand years ago 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...
, these cats are known only from fragments of skeletons. The two species commonly identified are Miracinonyx inexpectatus and M. trumani. Sometimes a third species, M. studeri, is added to the list, but it is more often listed as a junior synonym of M. trumani. Both species are similar to the modern cheetah, with faces shortened and nasal cavities expanded for increased oxygen capacity, and legs proportioned for swift running. However, these similarities may not be inherited from a common ancestor, but result from either parallel
Parallel evolution
Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.-Parallel vs...
or convergent
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
evolution.
Taxonomy and evolution
Research into the American cheetah has been contradictory. It was originally believed to be an early cougar representative, before being reclassified in the 1970s as a close relative of the cheetah. This suggested that ancestors of the cheetah diverged from the Puma lineage in the Americas and migrated back to the Old World, a claim repeated as recently as Johnson et. al. (2006). Other research by Barnett, however, examining mitochondrial DNAMitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
and re-analyzing morphology, has suggested reversing the reclassification: the American cheetah developed cheetah-like characteristics through convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
, but it is most closely related to Puma and not to the modern cheetah of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. The supposed American origin of the modern cheetah is thus equivocal; however, it is believed to have evolved from cougar-like ancestors, whether in the Old or New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
.
The cougar and M. trumani are believed to have split from a cougar-like ancestor around three million years ago; where M. inexpectatus fits in is unclear, although it likely is a more primitive version of M. trumani.
Miracinonyx trumani
M. trumani was the most similar to true cheetahs in morphology. Living on the prairiePrairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...
s and plains of western America, it was likely a predator of hoofed plains
Great Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
animals such as the pronghorn
Pronghorn
The pronghorn is a species of artiodactyl mammal endemic to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the prong buck, pronghorn antelope, or simply antelope, as it closely resembles the true antelopes of the Old World and...
. In fact, predation by Miracinonyx is thought to be the reason that pronghorns evolved to run so swiftly, their 60 mph top speed being much more than needed to outrun extant American predators such as cougars and gray wolves.
The similarity between M. trumani and the cheetah is an example of parallel evolution
Parallel evolution
Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.-Parallel vs...
. As grasslands became more common in both Africa-Eurasia and North America, cougar-like cat species from both continents evolved to catch the new fleet-footed herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s. The claws of M. trumani had even become only partially retractable, to be used for better grip at high speeds.