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BIOL 307 > Mammals > Flashcards

Mammals Flashcards

1
Q

What are non-mammalian synapsids?

A

“mammal-lie reptiles”

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2
Q

What are the most basal forms of non-mammalian synapsids?

A

Pelycosaurs. eg: sailbacks

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3
Q

What are the more derived non-mammalian synapsids?

A

Therapsids

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4
Q

How many species of extant mammals are there?

A

5588 (it is the least speciose lineage of tetrapods)

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5
Q

Traditionally, what classes are mammalia divided into?

A
  1. Allotheria (multituberculates = extinct, rodent-like, mesozoic)
  2. Prototheria (monotremes)
  3. Theria (divided into Metatheria=marsupials, and Eutheria=placentals*)
    * Placental is a misnomer because marsupials also have a .placenta
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6
Q

Traditional v.s. Modern naming of mammals:

A
  • Both systems still used today
  • Traditional (Linnaean) groups organisms based on similar traits.
  • Modern classifies organisms based on evolutionary relationships (determined using molecular tools)
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7
Q

What is systematics?

A

Study of the diversification of living forms, both past and present, and the relationships among living things through time.

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8
Q

What is phylogeny?

A

The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.

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9
Q

What is cladistics?

A

An approach to biological classification in which organisms are categorized in groups (“clades”) based on the most recent common ancestor. A valid clade is monophyletic.

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10
Q

What is a a monophyletic group or clade?

A 
A group of organisms that consists of all the descendants of a common ancestor.
Groups are typically characterized by shared
derived characteristics (synapomorphies), which distinguish organisms in the clade from other organisms.
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11
Q

What is a paraphyletic group?

A

A group of organisms descended from a

common evolutionary ancestor or ancestral group, but not including all the descendant groups.

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12
Q

What is a polyphyletic group?

A

Derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon.

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13
Q

What were the two hypothesized phylogenetic trees of mammals?

A

A) Based on morphology

B) Based on genetics

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14
Q

What are monotremes?

A

Name refers to the cloaca (One hole). Single opening for excretory and reproductive tracts.

  • Oviparous
  • Lack teeth as adults
  • Have a leathery bill or beak containing receptors that sense electromagnetic signals from the muscles of other animals.
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15
Q

What are the two families of monotremes?

A

1) Ornithorhynchida (rynchus = beak)—includes platypus

2) Tachyglossidae (tachy = fast, glossa = tongue) includes long and short nosed echidnas; 4 species in total.

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16
Q

What are the characteristics of Ornihorhynchida (platypus)?

A
  • Semi-aquatic
  • Feeds on aquatic invertebrates in streams of eastern Australia and Tasmania
  • Males have spur on hind leg attached to venom gland, which is used to poison rivals or predators (venom is rare in mammals)
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17
Q

What are the characteristics of Tachyglossidae (Echidna)?

A

-Eat mainly ants, termites,
earthworms
-Found in Australia and New
Guinea

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18
Q

What do marsupials include?

A

Includes 4 lineages equivalent in morphological and genetic diversity to the placental orders.
2 major divisions:
1) Ameridelphia - Opossums and rat opossums. Mostly North American species
2) Australidelphia- 5 orders of species found mostly in Australia.

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19
Q

What are some examples of extant marsupials?

A

a) North American opossum
b) Shrew opossum
c) Monito del monte
d) Tasmanian devil
e) Marsupial mole
f) Bilby
g) Honey possum
h) Koala
i) Long-nosed potoroo

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20
Q

What does ameridelphia include?

A
  • Dasyuromorphia—carnivorous, marsupial cats and mice, dog like forms (Tasmanian devil and Tasmanian tiger [Thylacine])
  • Peramelemorphia-insectivorous, bandicoots and bilbies insectivorous.
  • Diprotodontia—herbivorous or omnivorous
  • gliders, possums, phalangers, ringtails, cuscuses, honey possum;
  • koala & wombat, macropods (hopping marsupials—potoroos, wallabies, kangaroos)
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21
Q

What kind of grouping of placentals are supported by?

A

Geographical groupings

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22
Q

Why is there controversy about interrelationships in placentals?

A

Molecular phylogenies differ substantially from traditional morphology-based phylogenies.

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23
Q

What are the major divisions within placentals?

A
  • Afrotheria
  • Xenartha
  • Boreoarthra
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24
Q

What are Afrotheria?

A 
-African mammals
Orders are:
Afrosoricida: Tenrecs, otter shrews, golden moles 
-Macroscelidea: Elephant shrews
-Tubuilidentata: Aardvark
-Hyracoidea: Hyraxes (conies or dassies)
-Sirenia: Dugongs, manatees
-Proboscidea: Elephants
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25
Q

What are Xenartha?

A

-Simplified dental pattern, or lacking teeth
-Originated in South America (but have colonized North America)
Orders
• Cingulara: Armadillos
• Pilosa: Sloths & anteaters

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26
Q

What are Boreoeutheria?

A

“northern mammals”

Subdivided into: Glires, Eurchonta and Ferungulata

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27
Q

What are the clades of Glires?

A
  • Lagomorpha: rabbits, hares, pika

- Rodentia: rats, mice, squirrels, guinea pigs, capybara

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28
Q

What are the clades of Eurchonta?

A
  • Scandentia: Tree shrews
  • Primates: Lemurs, monkeys, apes, humans
  • Dermoptera: Flying lemur
  • Lipotyphla: hedgehogs, moles, shrews
  • Chiroptera: Bats
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29
Q

What are the clades of Ferungulata?

A

-Carnivora: Dogs, bears, raccoons, weasels, hyenas, cats, sea lions, walruses, seals (suborder Pinnipedia)
-Pholidota: pangolins (scaly anteaters)
-Perissodactyla: Odd-toed ungulates—horses, tapirs, rhinoceroses
-Artiodactyla: Even-toed ungulates—swine, hippopotamuses, camelids, deer, giraffes, antelopes,
sheep, cattle
-Cetacea: Porpoise, dolphins, sperm whales, baleen whales
*Now combined into Cetartiodactyla= whales and dolphins are technically ungulates, hippos are closest relatives.

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30
Q

What are the features that are shared by all mammals?

A
  • Lactation
  • Precise occlusion of teeth
  • Skeletomuscular characteristics underlying diverse functions
  • Skin and pelage characteristics control interactions with physical environments
  • Cardiovascular, respiratory and sensory systems still retain traces of the origin of mammals as nocturnal animals
  • Early mammals thought to have been nocturnal to avoid competition
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31
Q

What are the features of lactation?

A
  • Females of all mammals lactate
  • Mammary glands are absent from males or marsupials, but are present and potentially functional in male monotremes and placentals
32
Q

What is an example of male mammals lactate?

A

Two species of bats have males that lactate. Human males may produce milk in certain circumstances

33
Q

Why do therians have nipples?

A

So that the young can suckle directly from the breast rather than the mother’s fur.

34
Q

Skeletomuscular system- Cranial Features

A

Dermal bones which originally form the skull roof have grown down around the brain and completely enclose the braincase
-The bones that form the lower border of the synapsid temporal opening
are bowed out into a zygomatic arch (cheekbone)

35
Q

How is dentition divided?

A

Several types of teeth- incisors, canines, premolars and molars.

36
Q

How many sets of teeth do placental mammals have?

A

Two sets of teeth, milk teeth and permanent, adult dentition.

37
Q

What is unique about mammal teeth?

A

Mammals are the only animals that masticate (chew food) and swallow a bolus of food particles and saliva.

38
Q

Skeletomuscular system - Postcranial features:

A
  • Upright posture (generally—opossums have semi-sprawl)

- Ribs are restricted to the thoracic trunk vertebrae

39
Q

How do ankle joints of mammals differ from other animals?

A

Ankle joint differs from other amniotes: main site of movement is not within the bones of the ankle joint (metatarsal joint), rather it is between the tibia and one of the proximal ankle bones (the astragalus). Allows only fore-and-aft movement of foot, which is good for rapid
locomotion.
New projection of the other proximal ankle bone (calcaneum) to form the heel.

40
Q

What are some general features of the mammalian integument?

A
  • Highly variable among species
  • Hair is unique to mammals
  • Lubricant and oil producing glands secrete volatile substance, water and ions
  • Mammals keratinous structures include: nails, claws, hoofs, horns.
41
Q

How do epidermis cells differ between mammals?

A
  • Small rodents have epidermis a few cells thick; humans range from a few dozen cells thick over much of body to more than 100 cells on palms and soles; elephant skin = several 100s of cells thick.
  • Fur-covered, hairless, rough, or crinkled; tails may have epidermal scales (but lack hard beta keratin found in scales of birds and lizards)
42
Q

What are the functions of mammalian hair?

A

-Functions in insulation, camo, communication, and sensation via vibrissae (whiskers)

43
Q

Where do vibrissae grow?

A

Grow out of the muzzle, around eyes or on lower legs and associated touch receptors

44
Q

What is the function of fur?

A

Closely packed hairs, often produced by multiple hair shafts arising from a single complex root

45
Q

What is the significance of hair erections?

A

Serve for communication (warning, fear and anger) and for thermoregulation (trap more air when erect)

46
Q

What does most mammal fur do?

A

Fur (also called pelage) that grows and rests in seasonal phases (weather changes).

47
Q

What are the 3 main glands in the integument?

A
  • Eccrine glands
  • Sebaceous glands
  • Apocrine glands
48
Q

What is the function of eccrine glands?

A

Produce watery secretion from soles of feet, prehensile tails, to increase grip or tactile perception.
Uniquely found all over the body surface in primates, functioning as sweat glands.

49
Q

What is the function of sebaceous glands?

A

Produce oily sebum, which lubricates and waterproofs hair and skin. Found all over body

50
Q

What is the function of apocrine glands?

A

Produce secretions for chemical communication. Restricted distribution. E.g., in humans found in armpit and pubic regions. In ungulates, used for sweating and distributed across body.
Mammary glands are also derived from basal apocrine glands.

51
Q

What is the significance of claws, hooves, nails and horns?

A
  • Locomotion, defense, offence and display

- They are accumulations of keratin hat protect the terminal phalanx of the digits.

52
Q

What are horns composed of?

A

Part keratin, may have a bony core

53
Q

What is an ungulate hoof made of?

A

Modified nail covering the third phalanx.

54
Q

Internal anatomy- what is adipose tissue?

A

(white fat) = subcutaneous fat, functions in energy storage, cushioning organs and insulation.

55
Q

What are adipoctyes and what do they do?

A

Fat cells. Secrete a wide variety of messenger molecules that coordinate metabolic processes.

56
Q

What is brown fat?

A

A type of adipose tissue that is unique to mammals. It is adapted to generate heat and can break down lipids or glucose to generate energy.
This is critical in thermoregulation of newborn mammals and for adults during hibernation.

57
Q

What is the function of cardiovascular system of mammals?

A
  • Heart has complete ventricular septum
  • Erythrocytes (RBCs) lack nuclei in their mature condition (unique among vertebrates)
  • Sinus venosus is incorporated into the right atrium as the sinoatrial node, which now acts as the heart’s pacemaker.
58
Q

What are the features of mammalian respiratory systems?

A
  • Large, lobed, aveolar lungs

- Diaphragm aids ribs in inspiration

59
Q

What are the features of mammalian urogenital systems?

A
  • Mammals retain the original tetrapod bladder (which is lost in many Sauropsids)
  • Excrete relatively dilute urine
  • Therians have separate openings for the urogenital and alimentary systems.
60
Q

What is the Loop of Henle?

A

-Loop of Henle is unique to mammalian kidney—allows
excretion of urine that has
higher concentration of salt
than the body fluids

61
Q

What are the features of sex determination and sex chromosomes in mammals?

A
  • Always have distinct sexes

- Sex determination is genetic, with distinctive sex chromosomes.

62
Q

Why is sex determination unclear in platypus?

A

-Unclear sex determination in platyus, males have 5X and 5Y chromosomes.

63
Q

What are some characteristics of the mammalian sensory systems?

A
  • Mammals have exceptionally large brains

- Mammals are reliant on hearing and olfaction more than vision

64
Q

What are features of the olfactory system in mammals?

A
  • Keen sense of smell likely related to nocturnal behaviour
  • Olfactory receptors are located on the epithelium on the scroll-like nasoturbinal and ethmoturbinal bones in the nose
  • Primates have relatively poor senses of smell and small is very reduced or absent in whales
65
Q

What are some features of mammal vision?

A

-We evolved as nocturnal animals, so vision in dim light (visual sensitivity) was more important than visual acuity.

66
Q

What are mammalian retinas composed of?

A

Primarily rod cells which have high sensitivity to light, but are poor at acute vision.

67
Q

Where is acute vision possible in the retina?

A

The all-cone fovea

68
Q

What is the unique mammal that has good colour vision?

A

Anthropoid primates.

69
Q

What are the general features of hearing in mammals?

A
  • 3-boned middle ear

- Long cochlea also contributes to auditory acuity (it is coiled to save space)

70
Q

What is the function of the external ear (pinna)?

A

Helps to determine sound direction

71
Q

What have cetaceans reduced or lost?

A

Pinnae, instead they use lower jaw to channel sound waves to the inner ear.

72
Q

Where are mammalian convergences seen?

A

In body form and habits between placental and marsupial mammals

73
Q

How did the linking of North America and South America change mammalian history?

A

The Great American Biotic Interchange.

74
Q

What are the differences in reproduction between therians and monotremes?

A

Therians give birth to live young, monotremes lay eggs

75
Q

What are some differences between therian and montremes?

A

In contrast to monotremes, therians have mammae with nipples, a cochlea in the inner ear with at least 2.5 coils, an external ear (pinna), and tribosphenic molars

76
Q

What are the differences in the shoulder girdle between therians and monotremes?

A

Shoulder is girdle is similar to ancestral condition in monotremes, but more derived in therians.

  • Therian shoulder girdle has lost ventral elements; the coracoid and interclavicle bones
  • Therians have expanded scapula with addition of new area of bone (supraspinous fossa)
  • Clavicle (collarbone) is retained in most therians, but lost in running- adapted placentals (e.g., dogs, horses)
  • Reduction of ventral elements of shoulder girdle allows greater stride length during locomotion

BIOL 307 (8 decks)

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