A. Perissodactyls and artiodactyls are known as the ungulates

1. These are usually large, hoofed, terrestrial grazers

2. The two groups are united by the presence of the hooves and structure of the limbs

a. They walk on the tips of their toes

b. These end in hard, keratinized hooves

c. They usually have a reduced number of toes

3. They are fast runners

a. Often found in open areas and depend on running to outdistance predators

b. Usually found in grassy areas

B. The two orders are divided by the number of toes they have

1. The perissodactyls are the odd-toed ungulates

a. These flourished in the early to middle Tertiary and are a remnant group today

2. Artiodactyls are the even-toed ungulates

a. They are highly diverse today

b. They are economically the most important mammal group

i. Important as domesticated animals

ii. For sport hunting

iii. Ecotourism

iv. Many species are also on the brink of extinction due to poaching and habitat destruction

II. Perissodactyla

A. May have from 1-3 toes

1. However, the weight is borne primarily on the enlarged third (middle) toe

a. This is the only digit remaining in the equids (horses), which are more derived (and less closely related to) the other two families

B. Perissodactyls have a simple stomach, but an enlarged cecum with mutualistic microbes that assist in breaking down cellulose

1. Food passes through the gut of a perissodactyl about twice as fast as through a ruminating artiodactyl

a. Because of this, digestive efficiency is much less efficient in a perissodactyl than in an artiodactyl

b. Therefore, they consume more food than an artiodactyl

C. Fossil history

1. Both perissodactyls and artiodactyls descended from the Condylarthra

a. These were the dominant mammalian herbivores of the early Paleocene (~65 mya)

2. By the early Eocene (50 mya), several identifiable perissodactyls were in evidence

a. At this time, the perissodactyls outnumbered the artiodactyls

3. However, by the end of the Oligocene (25 mya), many perissodactyl families were extinct

4. The Tapiridae and Rhinocerotidae are each other's closest living relatives, and both had representatives in North America at one time

a. Tapirs migrated into South America, and rhinos did not

i. Today, tapirs survive in Central and South America and Asia

ii. Rhinos survive only in Asia and Africa

5. Fossil record of the Equidae is amongst the best documented of any mammalian family

a. Changes in morphology are depicted in fig. 19.4, p. 327

i. Horses have become progressively larger

ii. There has been a reduction in numbers of toes, so that horses have had a single toe (the third) since the Pliocene

iii. Jaws have become increasingly more muscular, reflecting shifts into more open habitat and more of a grazing lifestyle

iv. Occlusal surfaces of molars have become increasingly complex

b. Most of their fossil history occurred in North America, but they became extinct in North America about 10,000 years ago

i. Were re-introduced by Cortes in 1519

D. Economics and conservation

1. Horses are extremely important economically

a. Domesticated about 5000 yrs ago in southern Ukraine

b. Introduced throughout the world

c. Important for transportation throughout recorded history

2. Tapirs and rhinos are both near extinction, rhinos especially so

E. Equidae--zebras and horses

1. One genus (Equus), perhaps 8 species, although this is open to question

2. All of them look basically alike

3. Natural distribution: Eastern Africa, central Asia from Middle East to Mongolia

4. Inhabit short grasslands and desert scrublands

5. Social group of usually 10-15 individuals, with a single male, several females, and offspring

a. Males are highly territorial

6. Several species are endangered

a. Przewalski's horse and African ass may be extinct in the wild

b. Onager and Grevy's zebra endangered

c. Mountain zebra and Asiatic ass are threatened

d. Quagga of South Africa became extinct in 1872

F. Tapiridae: Four species in the genus Tapirus

1. Found in Mexico, Central and South America, and southeastern Asia

2. Look something like pigs, with a chunky body and short legs (fig. 19.6A, p. 329)

a. Have a long, flexible proboscis

b. Can be quite large, up to 300 kg

3. Inhabit forested areas and are nocturnal

4. Feed on understory shots, twigs, fruit, grass, sometimes on cultivated crops

5. Most are associated with water

6. Usually solitary

7. All are threatened by habitat loss and are declining in number and distribution

G. Rhinocerotidae

1. Four genera, five species

2. Characterized by their horns, which are agglutinated keratinized fibers, or fused hairs

a. These are conical and posteriorly curved

b. They are hunted for their horns, which are reputed to be aphrodisiacs

i. Horns sell for tens of thousands of dollars per kg

c. Horns are attached to the skin, not to underlying bone

3. White and black rhinos are found in sub-Saharan east and central Africa

a. Indian rhino occurred in Pakistan and northern India

b. Javan rhino was originally found in southeastern Asia

c. Sumatran rhino was also originally found in southeastern Asia

d. Ranges of all species are now greatly reduced

4. Found in a variety of habitats including tropical rain forest, floodplains, grasslands, scrublands

5. They are generally solitary

III. Artiodactyla

A. 10 families, 80 genera, ~220 species

1. Distributed almost worldwide

2. Great diversity in body size and structure, with 3 suborders

a. Suborder Suiformes, with three families

i. Suidae: pigs and warthogs

ii. Tayassuidae: peccaries

iii. Hippopotamidae: hippopotamuses

b. Tylopoda; with one family, the Camelidae (camels, llamas, vicuna)

c. Suborder Ruminantia, with 6 families (all have head ornamentation except members of the family Tragulidae)

i. Tragulidae (chevrotains, or mouse deer)

ii. Giraffidae (giraffe and okapi)

iii. Cervidae (deer)

iv. Moschidae (musk deer)

v. Antilocapridae (pronghorn)

vi. Bovidae (antelope, bison, goats, sheep, etc.)

3. All have a single characteristic that defines the order

a. The main weight-bearing axis passes through the third and fourth digits

i. This is termed paraxonic, as opposed to the mesaxonic foot of the perissodactyls

ii. So, they have two hooves instead of one (two-toes, the 3^rd and 4^th)

iii. The 2^nd and 5^th digits are reduced in size and non-functional; or they may be absent

4. The more derived families are the cervids and bovids, and these have ruminant stomachs

a. The most primitive families are the suids and tayassuids, which do not have ruminant stomachs

B. Families

1. Suidae: 5 genera and 16 species; the pigs

a. Simple stomachs, with large, ever-growing canines

b. Short legs, heavyset bodies

c. Thick skin with coarse pelage

d. Small eyes

e. The snout is used to root for food, and is often heavily muscularized

f. Distribution: Europe, Africa (except Sahara), and Asia

i. Introduced to North and South America, Australia, New Zealand

ii. Found in a wide variety of habitats

g. Gregarious, forage in groups

h. Economics and conservation

i. Feral hogs cause a lot of damage in many areas

ii. The pygmy hog and babirusa are both endangered

2. Tayassuidae (peccaries): 3 genera, 3 species

a. Least specialized of the suiforms

b. Superficially, they resemble pigs, but they are smaller

c. Only found in New World, from southwestern U.S. to central Argentina

i. Found from desert scrub into tropical rain forest

d. Generally, they are diurnal and herbivorous, although they can be found abroad at night

i. They also root just like pigs

e. They also form small groups just like pigs

f. One species is endangered, one (collared peccary) is hunted in Texas, New Mexico, and Arizona

i. Collared peccary populations appear to be secure in these areas

3. Hippopotamidae: 2 genera, 2 species

a. These two differ greatly in size, with the pygmy hippo being the more primitive of the two

b. Both species are highly aquatic

i. They walk along the bottom of rivers, lakes, and estuaries, feeding on plants

ii. They can dive for up to 30 minutes at a time

c. Both are restricted to Africa south of the Sahara

d. They have highly glandular skin and easily dry out

e. The hippo forms large aggregations of up to 40 individuals, while the pygmy hippo is generally solitary or found in pairs

f. The hippo has been extirpated from parts of its range, while the pygmy hippo has never been common and is currently considered threatened

i. Hippos became extinct on Madagascar within the last 1000 years

4. Camelidae: 3 genera, 6 species

a. Like the hippos, members of this family differ greatly in size

i. The family includes members that exist solely in domestication and may be hybrids

b. The dromedary (one-humped) camel exists solely in domestication

i. It is the only domesticated mammal for which no information on wild or fossil forms has been found

c. The bactrian (two-humped) camel originally ranged throughout central Asia but is now restricted in the wild to the western Gobi Desert

d. Guanacos and vicunas are South American

e. All are gregarious, diurnal, and herbivorous

i. They can eat plants with high salt content not tolerated by other grazers

ii. They can also conserve water, losing up to 40% of their body mass without harm

f. Humps are used for fat storage

g. The family arose in North America

i. It was restricted to this continent, then expanded to Eurasia and South America, going extinct in North America

h. They are very important for meat and as pack animals

i. The llama and dromedary have been domesticated for at least 5000 years

ii. The Bactrian camel and vicuna are both threatened

5. Tragulidae: 3 genera, 4 species

a. Most primitive of the extant ruminants

b. Found in west-central Africa, India, southeast Asia

c. Basically, look like tiny deer

i. However, they have curved upper canines and no antlers

d. Solitary and nocturnal

e. The world's smallest artiodactyl

6. Giraffidae: 2 genera, 2 species; the giraffe and okapi

a. Giraffe is found in savanna, grasslands, and open woodlands in sub-Saharan Africa

b. Okapi restricted to dense forest of the Republic of Congo (Zaire)

c. Both look fairly similar, with okapi somewhat smaller

i. See fig. 19.16, p. 336, for a picture of an okapi (this looks like a young individual)

7. Cervidae: 16 genera, 42 species

a. These are widely distributed, absent only from sub-Saharan Africa and Antarctica

i. Introduced to Australia and New Zealand

ii. Various species have been introduced to many other areas

b. Habitat is also highly variable; they are found in all kinds

c. Males are well-known for their antlers, and antler shape and size is highly variable from species to species

i. Examine fig. 19.18, p. 337, for examples of antlers

d. Deer have been hunted for many thousands of years

i. Many species are domesticated

ii. Others have been introduced to a variety of areas, sometimes with negative effects on local wildlife

iii. Others are endangered from overharvest and habitat destruction

8. Antilocapridae: monotypic; includes only the pronghorn

a. Endemic to western North America

b. The horns consist of a keratinized sheath over a bony core

i. The bony core is an extension of the frontal bone

c. Found in open grasslands and semidesert areas

d. Forage on grasses, forbs, low shrubs, sagebrush

e. The fastest New World mammal, reaching maximum speeds of 86 km/h

9. Bovidae: largest artiodactyl family, with 45 genera, ~137 species

a. From 5-10 subfamilies have been proposed

b. A glimpse of the variety of the bovids is offered in fig. 19.20, p. 339

c. The bison is amongst the largest of the bovids, at about 1000 kg

d. All bovids have ruminating stomachs

e. All have a pair of horns (except one 4-horned antelope)

i. These are present on males and sometimes females

ii. These horns have a bony core; an extension of the frontal bone

iii. It is covered by a keratinized sheath that is rarely shed

f. Bovids are found naturally worldwide except South America and Australia

i. Domesticated species have been introduced worldwide

ii. Center of the bovid radiation appears to be Africa and Eurasia

g. All are herbivores

h. Have a variety of social systems

i. Larger species tend to be more gregarious

i. Cattle, sheep, and goats have been domesticated for >5000 yrs

j. Many species are considered endangered from habitat loss and overharvest