Cursorial
Encyclopedia
Running
Running is a means of terrestrial locomotion allowing humans and other animals to move rapidly on foot. It is simply defined in athletics terms as a gait in which at regular points during the running cycle both feet are off the ground...
. It is typically used in conjunction with an animal's feeding habits or another important adaptation. For example, a horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
can be considered a "cursorial grazer", while a wolf may be considered a "cursorial predator". The term is typically applied to animals adapted to long-distance running at high speeds, rather than animals with high acceleration over short distances - a 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...
is considered cursorial, while a leopard
Leopard
The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...
is not. Within vertebrates, the term is rarely applied to animals under 1 kg of mass, as such organisms typically move in a series of short bursts rather than at a constant speed. All extant curosial vertebrates are endothermic
Endothermic
In thermodynamics, the word endothermic describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat. Its etymology stems from the prefix endo- and the Greek word thermasi,...
, allowing high metabolic rates and high endurance, though it is possible some extinct species were ectothermic.
Some species of spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s are also considered cursorial, as they walk much of the day, looking for prey. The oldest fossils of jumping spiders are from Baltic amber
Baltic amber
The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite, with about 80% of the world's known amber found there. It dates from 44 million years ago...
dated at .
Locomotion of terrestrial vertebrates
Adaptions for cursorial locomotion include:- Increased stride length by:
- Increased limb bone length
- Adoption of digitigrade or unguligrade stance
- Loss of clavicle in mammals, which allows the scapula to move forwards and backwards with the limb and thereby increase stride length.
- Increased spinal flexion during galloping
- Decreased distal limb weight (in order to minimize moment of inertiaMoment of inertiaIn classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...
:- Increase in mass of proximal muscles with decrease in mass of distal muscles
- Increase in length of distal limb bones (the manus and pes) rather than proximal ones (the brachium or thigh).
- Longer tendons in distal limb
- Decreased ability to move limbs outside of the saggital plane, which increases stability.
- Loss of digits.
- Loss of ability to pronate and supinate the forearm
- Hooves, hoof-like claws, or blunt claws for traction (as opposed to sharp claws for prey-capture or climbing)
Locomotion of spiders
Spiders maintain balance when walking, so that legs 1 and 3 on one side and 2 and 4 on the other side are moving, while the other four legs are on the surface. To run faster, spiders increase their stride frequency. Jumping spiderJumping spider
The jumping spider family contains more than 500 described genera and about 5,000 described species, making it the largest family of spiders with about 13% of all species. Jumping spiders have some of the best vision among invertebrates and use it in courtship, hunting and navigation...
s can also jump up to 50 times their own length by powerfully extending the third or fourth pairs of legs.
Cursorial taxa
Several notable taxa are cursorial, including some mammals (such as wolves, cheetahCheetah
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...
s, ungulates, agouti
Agouti
Agouti refers to a number of species of rodents as well as a number of genes affecting coat coloration in several different animals. Agouti fur contains a pattern of pigmentation in which individual hairs have several bands of light and dark pigment with black tips.* When referring to a rodent,...
s, and kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s) and birds (such as the ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
), as well as some dinosaurs (such as theropods, and Heterodontosauridae
Heterodontosauridae
Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal members of the group...
). Several extinct archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
s were also cursorial, including the crocodylomorphs Pristichampsus
Pristichampsus
Pristichampsus is an extinct genus of pristichampsid crocodylian that grew to approximately three metres in length....
, Hesperosuchus
Hesperosuchus
Hesperosuchus is an extinct genus of crocodylomorph reptile that contains a single species, Hesperosuchus agilis. Remains of this sphenosuchian have been found in Late Triassic strata from Arizona and New Mexico....
, and several genera within Notosuchia
Notosuchia
Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Cretaceous. Fossils have been found from South America, Africa, and Asia...
.
Jumping spiders and other non-web based spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s generally walk throughout the day, so that they maximize their chances of a catch, and web-based spiders run away if threatened.
In evolutionary theory
The cursorial (or Ground-Up) theoryTheory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
of the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
of flight is the theory that bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s evolved from ground-living theropods
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
, as opposed to arboreal species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. This refers to the presumed cursorial nature of theropod dinosaurs, and that the flight apparatus may have been adapted to improve hunting by lengthening leaps and improving maneuverability.
The evolution of the horse
Evolution of the horse
The evolution of the horse pertains to the phylogenetic ancestry of the modern horse from the small dog-sized, forest-dwelling Hyracotherium over geologic time scales...
is one of the most widely-known sequences of transitional fossils, depicting all stages of evolution between a small, unspecialized grazer to a large, cursorial mammal capable of extremely high speeds.
Several Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
spiders were members of the Mesothelae
Mesothelae
The Mesothelae are a suborder of spiders that includes the extinct families Arthrolycosidae and Arthromygalidae and the only extant family Liphistiidae....
, a primitive group now represented only by the Liphistiidae
Liphistiidae
The spider family Liphistiidae comprises 5 genera and 85 species from Southeast Asia, China, and Japan. They are among the most basal living spiders, belonging to the suborder Mesothelae...
. The mesothelid Paleothele montceauensis, from the Late Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
over , had five spinnerets. Attercopus
Attercopus
Previously interpreted as the world's oldest spider, Attercopus fimbriunguis belongs to an extinct order of arachnids named Uraraneida; thought to be close to the origins of spiders...
fimbriunguis, from in the Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
period, bears the earliest known silk-producing spigots, and was therefore hailed as a spider. However, this may not have been a true spider as it shows no sign of having spinnerets, whose mobility is important in the building of webs, and Attercopus probably used silk for lining nests or producing egg-cases rather than for building webs. The oldest fossils of jumping spiders are from Baltic amber
Baltic amber
The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite, with about 80% of the world's known amber found there. It dates from 44 million years ago...
dated at , in the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
.