Mammalian Characteristics

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Questions and Answers

What is the function of the sebum secreted by sebaceous glands associated with hair roots?

To nourish the hair

To change the color of hair

To provide insulation

To waterproof hair (correct)

What is the temperature of a monotreme's body?

37 degrees

35 degrees

32 degrees

30 degrees (correct)

What is the function of the placenta in mammalian development?

To produce milk for the baby

To produce sebum for hair

To regulate body temperature

To provide oxygen and nutrients to the developing embryo (correct)

What is the characteristic of the jaw articulation in modern mammals?

Dentary-squamosal connection Signup and view all the answers

What is the function of the mammary glands in mammalian mothers?

To nourish the baby with milk Signup and view all the answers

What is the characteristic of the lower jaw in modern mammals?

Formed of a single bone Signup and view all the answers

What is the function of the quadrate and articular bones in modern mammals?

To form the hammer and anvil in the ear Signup and view all the answers

What is the characteristic of hair in mammals?

Made of keratin protein Signup and view all the answers

What is the benefit of the new jaw attachments in modern mammals?

Allows for greater digestion within the mouth Signup and view all the answers

What is the characteristic of the subclass Theria?

Subclass Theria Signup and view all the answers

What is the primary function of the alpha keratin protein in mammals?

To insulate the body Signup and view all the answers

What is the primary difference between the body temperatures of monotremes and placentals?

Monotremes have a lower body temperature Signup and view all the answers

What is the purpose of the umbilical cord in mammalian development?

To supply oxygen and nutrients to the developing embryo Signup and view all the answers

What is the result of the quadrate and articular bones losing their function in jaw articulation?

They became smaller and eventually migrated into the ear region Signup and view all the answers

What is the characteristic of the hair found in mammals?

It is made of the protein alpha keratin Signup and view all the answers

What is the primary function of the squamosal and dentary bones in modern mammals?

To make the connection with the lower jaw Signup and view all the answers

What is the primary difference between the jaw articulation of modern mammals and that of reptiles and amphibians?

Modern mammals use the dentary-squamosal connection Signup and view all the answers

What is the benefit of the modification of hair in mammals?

It provides greater insulation to the body Signup and view all the answers

What is the characteristic of the subclass Prototheria?

It includes monotremes Signup and view all the answers

What is the primary function of parental care in mammals?

To provide nourishment to the young Signup and view all the answers

Study Notes

Mammalian Classification

Mammals are classified into subclass Prototheria (monotremes) and subclass Theria, which is further divided into infraclass Marsupialia (marsupials) and infraclass Placentalia (placentals/eutherians)

Mammalian Characteristics

Mammals have hair made from the protein alpha keratin, which helps to insulate the body
Endothermy allows for different body temperatures, e.g., monotremes (30°C), armadillos (32°C), marsupials and hedgehogs (35°C), humans (37°C), and rabbits and cats (39°C)
Hair is often composed of guard and soft underfur and is waterproofed by sebum, the oily secretions of sebaceous glands associated with their roots
Hair can be modified to serve various functions

Parental Care

Mammalian mothers nourish their babies with milk produced from mammary glands
Each baby in the uterus is attached via an umbilical cord to the placenta, which supplies oxygen and nutrients to the developing embryo
Mammals have a longer gestation period compared to other animals

Skull and Jaw Evolution

Modern mammals use the squamosal and dentary bones to make the connection between the skull and lower jaw
The quadrate and articular bones, which were used in reptiles, amphibians, and earliest synapsids, have become smaller and migrated into the ear region, forming the 'hammer' and 'anvil' of the ear
The new jaw attachments allow for greater digestion within the mouth, enabling a higher metabolic rate and maintenance of a high body temperature

Dental Characteristics

Mammals have teeth that come in a variety of shapes and sizes, adapted for biting and chewing many kinds of food
Mammals are diphyodontic, meaning they have two sets of teeth: milk/deciduous and adult
Mammals are heterodontic, meaning their teeth are diversified in function, typically consisting of incisors, canines, premolars, and molars

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Description

Test your knowledge of mammalian characteristics, including hair composition, body temperature regulation, and adaptations such as waterproofing. Learn about the different types of mammals, including monotremes, marsupials, and placentals. Discover the unique features that define mammals.