Classification of Mammals

BS Zoology
Mammalogy
Classification of Mammals
Lecture # 2

1. Classification of Mammals 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

20. 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.

21. 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

22. 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)

23. 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

24. A vampire bat ( Desmodus rotundus )

25. 4.Order Primate Primates

26. 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

27. 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

28. 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.

29. 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 .

30. Common Primates Traits

31. 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

32. Subgroups of Primates

33. Cladogram of Primates

34. 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.

35. Prosimians Classification

36. 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.

37. Lemurs

38. Lories

39. 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

40. ( Tarsius spectrumgurskyae )

41. 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 .

42. 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

43. 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.

44. 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.

45. Marmosets and Tamarins  

46. 2. Family Cebidae

47. 3. Family Cercopithecines (Old World Monkeys)

48. 4. Family Hylobatidae

49. 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 huma ns

50. 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 ).

51. 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

52. 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.

53. 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.

54. Rabbits Examples: