CLASS: MAMMALIA

Kingdom: AnimaliaPhylum: Chordata

MAMMALIA

Mammals (formally Mammalia) are a class of vertebrate, air-breathing animals whose females are characterized by the possession of mammary glands while both males and females are characterized by hair and/or fur, three middle ear bones used in hearing, and a neocortex region in the brain. Some mammals have sweat glands, but most do not.

MAMMALIA

1. Mammals are divided into 21 groups. Scientists do not yet agree on the exact number of mammal groups. some of the better known mammal groups include Primates Marsupials Bats Cetaceans Carnivores Lesser known mammals include the hyraxes Monostremes Pangolins

MAMMALIA

2. There are between 4,500 and 5,000 species of mammals of all mammal groups.

the most diverse are the mammal group are: Rodents (1,700 species.) bats (977 species), primates (356 species), insectivores (365 species), marsupials (292 species). Mammal groups with the fewest number of species: the aardvark (1 species), dugongs and manatees (4 species), flying lemurs (2 species).

MAMMALIA

3. The first mammals appeared approximately 200 million years ago during the Jurassic Period.

The ancestors of mammals were a group of reptiles known as the therapsids. The first true mammals to have evolved diverged from the therapsids during the Jurassic Period. Of all the mammal groups alive today, the monotremes are the oldest, followed by the marsupials.

4. Mammals are tetrapods. Mammals have four limbs, a characteristic that places them among the

group of animals known as tetrapods. It should be noted that although some mammals such as whales, dugongs, and manatees have lost their hind limbs during the course of evolution, they are tetrapods by descent.

5. Mammals are warm-blooded. Mammals are warm-blooded or 'endothermic' which means they

generate their own internal heat.

MAMMALIA

6. All mammals have hair. Hair is a defining characteristic of mammals, no

other organisms possess true hair and all mammals have hair covering at least part of their body at some time during their life.

7. Mammals are amniotes. Amniotes are a terrestrial vertebrates whose eggs

are characterized by having several layers of protective membranes (the amnion, chorion and allantois). Reptiles, mammals, and birds are all amniotes.

MAMMALIA

8. The Cenezoic Era is the 'Age of Mammals'. The Cenezoic Era (65 million years ago until the present

day) is considered to be the Age of Mammals because it represents the time period during which mammals diversified and became the dominant land vertebrates.

9. The largest mammal is the blue whale. The blue whale is the largest mammal and is also the

largest animal alive today. It may even be the largest animal ever to have lived. Blue whales weigh between 110–160 tons (110—176 tons) and mature individuals measure in the range of 20–30 m (66–98 ft).

MAMMALIA

10. The smallest mammal is the bumblebee bat.

The bumblebee bat, also called the Kitti's hog-nosed bat, is the smallest of all mammals, measuring just over an inch in length and weighing a mere 2g. The bumblebee bat is a vulnerable species that inhabits limestone caves in Thailand and Burma.

3 INFRACLASS TAXA

MONOTREMES

MARSUPIALS

PLACENTALS

MONOSTREMES

From the Greek word monos means single, trema means hole

are mammals that lay eggs Divided into the orders

1. Platypoda-the platypus along with its fossil relatives

2. Tachyglossa-the echidnas, or spiny anteaters

MONOSTREMES

PlatypusFossil range: Late

Cretaceous to Recent

Echidnas(ant eaters)Fossil range: Miocene–Recent

MARSUPIALS

are an infraclass of mammals, characterized by a distinctive pouch (called the marsupium), in which females carry their young through early infancy.

MARSUPIALS

KangarooFossil record:

Early Cretaceous to

recent

PLACENTA

Also known as Eutheria, Greek: true/good beasts

is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals (such as humans) than to living marsupials (such as kangaroos)

One of the major differences between placental and non-placental eutherians is that placentals lack epipubic bones, which are present in all other fossil mammals and living mammals (monotremes and marsupials).

PLACENTA

Fossil of Eomaia,

the oldest known eutherian

MAMMALIA

Most mammals, including the six largest orders, belong to the placental group. The six largest orders, in descending order,

1. Rodentia (rodents)2. Chiropeta (bats)3. Soricomorpha (shrew-form, moles)4. Carnivora (dogs, cats, bears)5. Cetartiodactyla (dolphin, whale)6. Primates (humans, apes)

RODENTIA

CHIROPTERA

No mammals other than bats have true wings and flight

SORICOMORPHA

CARNIVORA

CETARTIODACTYLA

PRIMATES

EVOLUTION

MAMMALIAFORMES

Mammaliaformes (mammal-shaped) is a clade that contains the mammals and their closest extinct relatives.

MAMMALIAFORMES

ADELOBASILEUS

Adelobasileus cromptoni is a species of an extinct genus of proto-mammals from the Late Triassic (Carnian), about 225 million years ago. It is known only from a partial skull recovered from the Tecovas formation in western Texas.

SINOCODON

Ancient proto-mammal that appears in fossil record in the late Triassic period, about 208 million years.

MORGANUCUDON

Morganucodon (“Glamorgan tooth") is an early mammalian genus which lived during the Late Triassic. "It was a small animal with a skull 2-3 cm in length and a presacral body length of about 10 cm [4 inches]. In general appearance it would have looked like a shrew or mouse

MORGANUCUDON

DOCODONTA

Docodonta is an order of extinct proto-mammals that lived during the mid- to late-Mezosoic era. Their most distinguishing physical features were their relatively sophisticated set of molars, from which the order gets its name. In the fossil record, Docodonta is represented primarily by isolated teeth and bits of jawbones.

DOCODONTA

HADROCODIUM

Hadrocodium wui is an extinct basal mammal species that lived during the Lower Jurassic.

Hadrocodium was a mere 3.2 cm (1.35 in) in length (about 2 grams), and is one of the smallest mammals of either the Mesozoic or Cenozoic eras.

MAMMALIA

EVOLUTION

Comparison reveals that, although placental and marsupial mammals formed seperate lineages, they still evolved similar adaptations. In some cases, placental and marsupial mammals physically resemble each other: the pouched marsupial mouse and the harvest mouse, the marsupial mole and the common mole, the marsupial wombat and the marmot, the tasmanian wolf and the wolf.

Definitions The discussion above illustrates the following evolutionary concepts: divergent evolution-occurs when a single group of organisms splits into two

groups and each group evolves in increasingly different directions parallel evolution-occurs when a group of organisms evolve into two distinct

but similar lineages and continue to adapt in similar ways for a long period of time, often in response to a similar environment

convergent evolution-evolutionary change in two or more unrelated organisms that results in the independent development of similar adaptations to similar environmental conditions

ANATOMY and MORPHOLOGY

Skeletal system

The majority of mammals have seven cervical vertebrae (bones in the neck); this includes bats, giraffes, whales, and humans. The few exceptions include the manatee and the two-toed sloth, which have only six cervical vertebrae, and the three-toed sloth with nine cervical vertebrae.

ANATOMY and MORPHOLOGY

Respiratory system

The lungs of mammals have a spongy texture and are honeycombed with epithelium having a much larger surface area in total than the outer surface area of the lung itself. The lungs of humans are typical of this type of lung.

ANATOMY and MORPHOLOGY

Nervous system

All mammalian brains possess a neocortex, a brain region that is unique to mammals.

FEEDING

Most mammals have teeth, although some, like the baleen whales, do not. Since mammals range widely in habitat and food preferences, they have a wide range in feeding styles and preferences.

In marine mammals, whales feed using teeth or baleen, and on a variety of prey, including small fish, crustaceans and sometimes other marine mammals. Pinnipeds feed using teeth, usually eating fish and crustaceans. Sirenians also have teeth, although they also use the power of their strong lips when grasping and ripping aquatic vegetation.

REPRODUCTION

Mammals reproduce sexually and have internal fertilization. All marine mammals are placental mammals, meaning they give birth to live young, and the unborn young are nourished in the mother's uterus by an organ called the placenta.

THE END.