BS Zoology Mammalogy Classification of Mammals Lecture # 2

1. Lecture #2
Naveed Akhtar
Assistant Professor of Zoology

2. General Characteristics of
Mammals

3. Classification of Mammals

4. Infraclass Eutheria (Placental
Mammals)

5.  General Characters of Eutherian Mammals
 Placenta:
 Placental mammal, any member of the mammalian
group characterized by the presence of a placenta, a
vascular organ that develops during gestation,
which facilitates exchange of nutrients and wastes
between the blood of the mother and that of the fetus.
 Although some authorities consider the marsupials
(cohort Marsupialia) to be placental mammals,
these animals have a less-developed, less-efficient type
of placenta that limits the gestation period

6.  The true placenta of the placentals allows for a longer
developmental period within the protection of the
womb, a factor considered to have contributed to the
evolutionary success of the group.
 Fossil evidence shows that the first placental mammals
evolved between about 163 million and 157 million
years ago during the Jurassic Period (201.3 million to
about 145 million years ago).

7. 1. Order Insectivora
 Insect eating mammals
 Relatively abundant in the past; represented today by a few
survivors Moles, shrews, hedgehogs
 The principal food is insects, worms or small invertebrates
 Represent examples of convergent feeding strategies -burrowers
and diggers -hunt for insects living in soil and in organic matter
that sits atop the soil
 Insectivores, widely distributed over the world except
Australia and New Zealand
 They are small, sharp-snouted animals with primitive characters
that spend a great part of their lives underground
 The shrews are among the smallest mammals known; 419
species

8.  Insectivores vary greatly in appearance
 they typically have a long snout, as evidenced by most
moles, shrews, and solenodons.
 Some are covered in a mouse-like fur with a hairy,
smooth tail, others are covered in spines and lack tails
entirely.
 Most insectivores have an excellent sense of smell,
touch, and hearing, but have a poor sense of sight.
They live in a wide variety of habitats, from streams to
open meadows to deep underground.

9.  Primitive traits of insectivores
 Flat-footed (plantigrade) stance
 Five toes
 Vibraseae
 Smooth cerebral hemispheres
 Small sharp pointed teeth with incisors, canines, and premolars
poorly differentiated
 Most insectivores lack a separate opening for the genitals and
anus, and instead have a cloaca, which serves as the genital,
urinary, and fecal system.
 Large embryonic allantois and yolk sac
 In some genera, testes are retained in the abdominal cavity and
not fully descended in any genera

10.  Habitat: Wide variety of habitats
 Mostly ground level or subterranean Moles live
underground Eat mainly insects and some
invertebrates Require a lot of energy to survive

11. Behaviour and Reproduction

12. Short Tailed Shrew

13. Lemur, Mole, Solendon, Hedgehog

14. 2. Order Xenarthra (Edentata)
 (ze-narthra) (Gr. xenos, intrusive, arthron, joint)
(formerly Edentata:WORD MEANS TOOTHLESS) [L.
edentatus, toothless])
 strange joints
 The lumbar vertebrae are “xenarthrous”; that is, they have
extra contacts (joints, or arthroses) that function to
strengthen the lower back and hips
 This aids use of the forelegs in activities not associated with
locomotion, such as digging—the primary method used by
anteaters and armadillos to obtain food
 anteaters, armadillos, sloths
 New world insectivores and more specialized than
members of order insectivora

15.  Many of these organisms do not have prominent teeth
 When present, teeth lack enamel
 Anteaters completely lack teeth
 Sloths, on other hand, are herbivores (folivorous ) that are
continuously growing teeth that are adapted to grinding plants
 Nearly all of the formerly
abundant megafaunal xenarthrans became extinct at the end of
the Pleistocene.
 Xenarthrans share several characteristics not present in other
placental mammals, which suggest their ancestors were
subterranean diggers for insects
 They have single-color vision
 Xenarthrans are also often considered to be among the most
primitive of placental mammals.

16.  Females show no clear distinction between the uterus
and vagina, and males have internal testicles, which
are located between the bladder and the rectum.
 Xenarthrans have the lowest metabolic
rates among therians
 Notable:
 Armadillo is only xenarthan that give birth to
quadruplets from as ingle fertilized egg
 They are only true bony armor mammals

17. Tree Sloth, Armadillo, Anteater

18. 3. Order Chiroptera
 (ky-roptera) (Gr. cheir, hand, pteron, wing)
 Bats are the second-most speciose group
of mammals, after rodents.
 The approximately 925 species of living bats make up
around 20% of all known living mammal species.
 In some tropical areas, there are more species of bats
than of all other kinds of mammals combined
 Bats are often divided into two major groups, usually
given the rank of suborders, Megachiroptera and
Microchiroptera.

19.  General Characters
 The are pterosaurs and birds are the only known craniates to have
achieved true flight
 The wing or Patagium is a double membrane of skin extended along
length of the body between trunk, forelimbs and hind limbs and till
tail
 It incorporates four greatly enlarged clawless fingers
 Second to fifth digits are elongated to support a thin integumental
membrane for flying. The first digit (thumb) is short with a claw
 The hind limbs are weak with five clawed digits and knee is directed
backwards
 The external ear or pinna is large and eyes are small with very weak
sight . Facial glands are large giving the head bizarre appearnace

21.  Pectoral muscle are strong and sternum is keeled
(not in birds)
 All bones are slender but not pneumatic (with out
air spaces)
 Nipples are usually a single pair and limited to the
thoracic wall
 The humblebee bat (2 gm) is the smallest
mammal on earth.

22.  Geographic Range:
 Bats are found throughout the world in tropical and temperate
habitats.
 They are missing only from polar regions and from some isolated
islands.
 Although bats are relatively common in temperate regions, they reach
their greatest diversity in tropical forests
 Habitat:
 Bats can be found in many terrestrial habitats below the polar regions.
Typical habitats include temperate and tropical forests, deserts, open
fields, agricultural areas, and in suburban and urban environments.
 Many bats forage near freshwater streams, lakes and ponds, preying on
insects as they emerge from the water. Generally, if a terrestrial habitat
provides access to sufficient roost sites and appropriate food, one or
more species will be found there

23.  Food Habits
 They eat a wide variety of food types. The majority of
species eat insects, either taking them on the wing or
picking them off of surfaces.
 Species specialized for eating fruit, nectar, or pollen
are especially abundant and diverse in tropical regions.
Some bats eat vertebrates like frogs, rodents, birds, or
other bats.
 Some are sanguinivorous (suck blood of other
mammals or birds)

24.  Reproduction
 Mating systems vary among bat species. Many temperate bats
mate in the fall as they aggregate near their winter hibernacula.
 These bats are generally promiscuous. Pteropodids also tend to
have promiscuous mating systems. These bats often aggregate
in large groups in one or a few trees and mate with various
nearby individuals. In many neotropical microchiropterans, one
or two males defend small harems of females.
 Juveniles grow quickly and can usually fly within 2 to 4 weeks of
birth. They are weaned shortly thereafter. Thus, lactation is
relatively short
 Adult can live between 10 to 25 yearss

25. A vampire bat (Desmodus
rotundus)

26. 4.Order Primate
Primates

27. General Characteristics
 Order Primates (pry-mayteez) (L. prima, first)
 The difference of the order primate from other
mammalian order is that its existing members fall
into a graded series or scale of organization which
suggests an actual evolutionary trend leading
from the most primitive to the most advance
(humans)
 This order stands first in the animal kingdom in
brain development, with especially large cerebral
hemispheres.
 Prosimians, Monkeys, Apes, Humans

28.  Most species are arboreal, apparently derived from
tree-dwelling Cretaceous insectivorous stock.
 Primates represent the end product of a line that
branched off early from other mammals and have
retained many primitive characteristics
 It is believed that their tree-dwelling habits of agility
in capturing food or avoiding enemies were largely
responsible for their advances in brain structure
 As a group they are generalized with five digits (usually
provided with flat nails) on both forelimbs and
hindlimb

29.  All except humans have their bodies covered with hair.
 Separated big toes and thumb for grasping:
 Among the primate specialization is the Prehensile grasping
hand built so that the thumb can touch the tips of the other
fingers of same hand. The big toe is opposable in most primates
and at least some digits have nails instead of claw.
 The group is singularly lacking in claws, scales, horns, and hoofs.
 Generally one pair of nipples
 Flatfoot stance, Five digits, a large clavicle, a central carpal bone
in the writs of the many primates
 A rotating shoulder joint: This is due to secure ball joints and
strong clavicles or collarbones, which have allowed them to use
their arms very effectively in climbing trees.

30.  Long pre- and post-natal life periods with greater
reliance on learning.
 In general, primates are highly social animals.
 Almost all primates are diurnal.
 There are two suborders
 1. Suborder Prosimii
 2. Suborder Anthropopoidea
 ; 223 species.

31. Common Primates Traits

32. Classification of Primates
 Classification of primates is primarily based on the
similarities and dissimilarities of external morphology,
although phylogenetic classifications have also
been done. Primates consist of two suborders:
Strepsirrhini and Haplorrhini

33. Subgroups of Primates

35. Cladogram of Primates

36. Suborder Strepsirhini or
Prosimians
 (strepsuh-ry-nee) (Gr. streps|, to turn, twist, rhinos, nose)
Prosimians means “Pre-Monkey”.
 They have moist, large hairless nose tip.
 Mostly are arboreal and nocturanl found in the tropics of the old
world
 They were the first of the suborders of primate to evolve.
 They are also called “lower Primates” and also referred to as
“Prosimians”
 Laterally placed eyes
 Short gestation and maturation period
 Lemurs, Lorises and related animals are included in this group.
 They are inhabited in most tropical regions of the earth.

37. Prosimians Classification

38. Lemurs (Latin: Ghost)
Unlike other primates, they have the long axis of the
head in line of the vertebral column
The largest lemur is the size of the domestic dog
 There are almost 22 arboreal species of lemurs
living today.
 There are five surviving families of lemur.

40. Lemurs

41. Lories

42. Tarsius
 Tarsiers of Southeast Asia are large rat size.
 They possess both prosimian and monkey-like traits. Yet,
they differ significantly from both the groups in genetic makeup.
 Their natural habitat is southern Philippines, Borneo and the
Celebes islands.
 There are at least seven surviving species of tarsiers who mostly
depend on vision and hearing with reduced ability to smell.
 Able to produce ultrasounds for their internal communications.
 Able to rotate their heads more than 180°.
 All fingers have nails as do all toes except Second and Third
 Their placenta is deciduate ; the fetal membranes become
rooted into wall of the maternal uterus as in Anthropoids
 Strictly Nocturnal and carnivores

43. (Tarsius spectrumgurskyae)

45. 2. Suborder Anthropoidae or
Haplorhini
 (haplo-rynee) (Gr. haploos, single, simple rhinos, nose) primates
with dry noses
 Larger brain and body size
 Reduced reliance on the sense of smell
 Greater degree of color vision
 Bony plate at the back of the eye socket
 Longer gestation and maturation period
 Only has nails
 Marmosets, New and Old World monkeys, gibbons, gorilla,
chimpanzees, orangutan, humans
 New world monkeys
 Old world monkeys Monkeys
 The suborder Haplorhini is divided into two infraorders, three
sub families and five families.

47.  1. Family Callitrichidae (New World Monkeys)
 Give birth to twins •
 Live in families composed of a mated pair or a female
and two adult males, plus the offspring.
 Males are involved with infant care
 Found only in the tropical forests of Central and South
America. It includes the marmosets and tamarins.
 Marmosets and tamarins are among the smallest
primates
 The face is very sparsely furred or naked

48.  The pelage is soft and silky, and often includes
characteristic tufts of hair on the head
 Coloration is variable and in some cases quite striking
to the human eye. Unlike many other New World
primates, marmosets do not have a prehensile tail.
 In form, callitrichids resemble other primates that
cling vertically to trees. The forelimbs are shorter than
the hind limbs, but most locomotion is quadrupedal.
The hands and feet resemble those of squirrels.

49.  The thumb and big toe are not opposable. The
surfaces of the hands and feet are long relative to the
digits. Additionally, all of the digits except
the hallux have sharp claws, not the flattened nails
found in many other primates. Callitrichids use these
claws to dig into the bark of trees.

50. Marmosets and Tamarins

51. 2. Family Cebidae

52. 3. Family Cercopithecines (Old
World Monkeys)

53. 4. Family Hylobatidae

54. 5. Family Hominidae
 Family Hominidae contains four genera and five
species: Gorilla (one species), Pan (two species of
chimpanzees), Pongo (one species of orangutan),
and Homo (one species, humans)
 The first three of these four genera were formerly
placed in the paraphyletic family Pongidae; the
family Hominidae contained only humans
 This separation is not recognized by cladistic
taxonomy because the most recent common ancestor
of the family Pongidae is also the ancestor of humans

55. 5. Order Lagomorpha
 (lagomorfa) (Gr. lagos, hare, morphƒ, form): rabbits,
hares, pikas
 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).

56.  General Characteristics
 Lagomorphs are similar to other mammals in that they all have hair,
four limbs (i.e., they are tetrapods), and mammary glands and
are endotherms.
 Large hairs up to 4 inches
 They can see up to 360
 Move by hopping o find legs
 Lagomorphs possess a moderately fused postorbital process to
the cranium, unlike other small mammals.
 Lagomorphs have four incisors in the upper jaw
 Lagomorphs are almost strictly herbivorous cosmopolitan distribution;
80 species
 Their incisor teeth grow continuously throughout their lives, thus
necessitating constant chewing on fibrous food to prevent the teeth
from growing too long

57.  Lagomorphs have no paw pads, instead the bottoms of
their paws are entirely covered with fur.
 Lagomorphs are small to medium-sized animals that
in many ways resemble large rodents. They have a
rudimentary or short tail. Folds of skin on the lips can
meet behind the incisors so that gnawing can take
place with the mouth cavity closed. Other flaps of skin
are able to close the nostrils.

58.  All lagomorphs are terrestrial. They occupy a wide
diversity of habitats, ranging from tropical forest to
arctic tundra.
 All are herbivores that feed on grasses and other small
plants. Lagomorphs have the ability to produce two
types of fecal material, one that is wet and eaten again
for further nutrient absorption, and one that is dry and
discarded.

59. Rabbits
 Examples: