Mammalian Biology and Evolution

A comprehensive set of flashcards covering key concepts in mammalian biology and evolution.

When did mammals first appear?

Mammals appeared in the early Mesozoic era, specifically the late Triassic period.

What did mammals evolve from?

Mammals evolved from an amniote ancestor.

What are sarcopterygian fishes?

Sarcopterygian fishes include coelacanths and lungfishes, which are ancestral to tetrapods.

What major groups comprise the tetrapods?

Tetrapods include the crown group tetrapods, batrachomorphs, reptiliomorphs, and amniotes.

What are synapsids?

Synapsids are a group of amniotes characterized by a single skull opening.

What is the significance of the dentary bone in early synapsids?

The dentary bone is the single bone in the lower jaw, which is an important feature of mammalian evolution.

Who are the cynodonts?

Cynodonts are a group of therapsids with characteristics that are retained in mammals.

What features define the mammalian jaw structures?

Mammals have a dentary-squamosal jaw articulation, while early synapsids exhibited a quadrate-articular joint.

What are three characteristics of the mammalian middle ear?

The mammalian middle ear has three ossicles: malleus, incus, and stapes, which transmit sound.

What is the function of mammary glands?

Mammary glands provide nourishment to developing young.

What is the primary function of hair in mammals?

The primary function of hair is insulation.

What are the types of hair found in mammals?

Guard hairs, underfur, vibrissae, and other specialized types.

What defines a mammal's heart?

Mammals typically have a 4-chambered heart.

What type of fertilization do most mammals exhibit?

Most mammals exhibit internal fertilization.

What is viviparous reproduction?

Viviparous reproduction is when mammals give birth to live young, as opposed to laying eggs.

Define altricial and precocial young.

Altricial young are born helpless and require significant parental care, while precocial young are more developed at birth.

Which mammals belong to the subclass Prototheria?

Subclass Prototheria includes monotremes, such as the platypus and echidna.

What is the difference between marsupials and placental mammals?

Marsupials have a short gestation period and give birth to underdeveloped young, while placental mammals (Eutheria) have a longer gestation with a more developed placenta.

What is a unique feature of some male mammals regarding reproduction?

Many male mammals possess a baculum (os penis), which is a bone in the penis.

How do mammals usually care for their young?

Mammals typically provide extensive parental care, including gestation and lactation.

What is the function of the epiphysis in long bone growth?

The epiphysis contributes to the growth of long bones and closes early in life.

What adaptations do aquatic mammals exhibit for locomotion?

Aquatic mammals have modified limbs into flippers and a fusiform body shape for efficient movement in water.

What is the term for mammals that spend equal time on land and in water?

Amphibious mammals are those that spend relatively equal time in water and on land.

What is unique about the respiratory system of birds compared to mammals?

Birds have air sacs to store and pump air through their stationary lungs, allowing for unidirectional airflow.

What are the primary functions of the mammalian social systems?

Predator/prey detection, communication, and detection of pheromones.

What do heterodont teeth refer to?

Heterodont teeth are differentiated teeth adapted for different functions, unlike homodont teeth which are uniform.

What is the primary function of incisors in mammals?

Incisors are primarily used for acquiring food.

What type of locomotion do ungulates exhibit?

Ungulates exhibit adaptations for running, which may include digitigrade or unguligrade postures.

What anatomical feature characterizes graviportal locomotion?

Graviportal locomotion is characterized by limbs positioned directly under the body to support heavy weight.

What adaptations do fossorial mammals exhibit?

Fossorial mammals have adaptations such as enlarged forelimbs and reduced eyes and ears for burrowing.

What does arboreal locomotion refer to?

Movement that occurs in trees, often requiring adaptations like elongated appendages and a prehensile tail.

What is piscivory?

The diet that primarily consists of fish.

What adaptations do herbivorous mammals have?

Herbivorous mammals tend to have hypsodont teeth, a diastema, and large complex digestive systems.

Define omnivorous mammals.

Omnivorous mammals eat a varied diet that includes both plant and animal material.

What type of teeth do herbivores typically have?

Herbivores usually have flat, grinding teeth suited for processing plant material.

Describe the molting process in mammals.

Molting refers to the shedding and replacement of fur, which can occur annually or seasonally.

What is the primary component of the mammalian circulatory system?

The mammalian circulatory system is characterized by a 4-chambered heart.

What adaptations contribute to effective mammalian hearing?

The external ears (pinnae) help focus and direct sound to the inner ear.

What part of the skull indicates a mammal is a synapsid?

A synapsid mammal has a lateral skull opening located ventrally.

How does the structure of hair contribute to insulation?

Hair traps air to provide insulation and reduce heat loss.

What are the three types of hair structures found in mammals?

Guard hairs, underfur, and vibrissae (whiskers).

How many orders are there in the infraclass Metatheria?

There are 7 orders in the infraclass Metatheria (marsupials).

What are the two types of hair growth patterns?

Definitive growth (fixed length) and angora growth (continual growth).

How are mammalian ears structured compared to early synapsids?

Mammalian ears evolved with three ossicles, while early synapsids had a different configuration.

What environmental conditions facilitated mammalian adaptive radiation during the Cenozoic?

The extinction of dinosaurs and the breakup of Pangaea allowed for adaptive radiation in mammals.

What role does the pectoral girdle play in mammalian anatomy?

The pectoral girdle supports the forelimbs.

What does the term 'saltatorial locomotion' refer to in mammals?

Saltatorial locomotion refers to jumping or hopping, often seen in certain mammals.

What is the primary function of olfactory adaptations in mammals?

Olfactory adaptations assist in predator/prey detection, food locating, and communication.

How do mammals exhibit unique adaptations for aerial locomotion?

Mammals possessing wings may exhibit elongation of bones in the forelimb and specialized musculature for flight.

Describe the developmental care provided by mammals to their young.

Mammals exhibit a high degree of parental care which includes gestation and lactation.