133 terms

Mammalogy Exam 1


Terms in this set (...)

What era do amniotes appear?
What is Sauropsida?
Gives rise to reptiles and birds
What does Synapsida give rise to?
Gives rise to mammals
What happened during Permian extinction?
90% of synapsids went extinct
Synapsid characters
Maxilla contacts quadratojugal bones; Caniniform maxillary teeth
Pelycosaurs characteristics
Narrow neural arches on trunk vertebrae
Mammals in pelycosaurs
Eothyrididae, Casedae, Varanopeidae, Sphenacodontidae
Eothyrididae characteristic
Large canine teeth
Top predators during Paleozoic
Therapsid Characteristics
Enlarged temporal opening; Sagittal crest and zygomatic arches; upper canines enlarged; jaw joint in live with occiput; more upright limp posture; feet shortened; deep acetabulum; external auditory meatus
Therapsid Animals
Biarmosuchia, Dinocephalia, Dicynodontia, Gorgonopsians, Cynodontia
Cynodont characteristics
More cheek teeth; different shaped teeth; Cusps on postcanine teeth; Dentary bone becomes lower jaw; Angular bone becomes part of hearing; Occipital condyles; Partial secondary palate; Ribs reduced; Heel present on foot
What mammals appear in Mesozoic period?
Stem Mammals (Mammaliaformes)
Teeth Characteristics in stem mammals
Dentary bone in lower jaw; Teeth fit together; Double rooted cheek teeth; 2 sets of teeth
Soft tissue characteristics of stem mammals
Mammary glands with nipples; Viviparity (Live young); Separate anal and urogenital openings; Muscles lower jaw
Traits of Therian mammals
Tribosphenic molars; Supraspinous fossa on scapula; Cochlea spiraled
What bones form from the atricular, quadrate, and angular bones?
Malleus, incus, and tympanic ring
What is the secondary palate?
Roof of the mouth; Thought to have evolved to facilitate in suckling
Mesozoic mammal characteristics
Small bodied; premolars and molars; large brain; insectivorous diet; nocturnal; lactation and suckling
Mammaliaforms; Herbivores; Large incisors, well developed molars
Mammaliaforms; Nocturnal, insectivorous, lay eggs
Mammaliaforms; Square like teeth, modern jaw
Monotremes; Electrosensory in nose, tribosphenic molar; ancestor to modern monotremes
Longest living mammal
Independent big toe used for grabbing; Big incisors; Blade like lower premolars
Early mammals that originated in the Northern Hemisphere and had tribosphenic molars
Earliest marsupial; 4 pairs of molars
Earliest placental mammal
Second earliest placental mammal
Mammals during the Paleocene
Condylarths, Creodonts, Pantodonts, Uintatheres, Mesonychids
Mammals during the Eocene
Diversity of Ungulates; Perissodactyls (Odd toed); Primates; Proboscideans (elephants)
Largest mammal
Ancestors to hippos
Ancestors to whales
Types of Primates during Eocene
Adapids and Omomyids
Mammals during the Oligocene
Amphicyonids, Protoceratids, Fayum (monkey)
Protoceratids characteristics
Even-toed ungulates; Deer-like; Unique horns; Lacked cannon bones (metacarpals/tarsals)
Mammals in the miocene
Greatest mammmal diversity; Gomphotheres (elephants), Nimravids (sabor toothed cats), Euteludonts (pigs), Apes
Mammals in the Pliocene
Many ungulates; Bipedal apes
Mammals in Pleistocene
Large mammals (easier to retain heat); Camels evolved in NA; Humans; Polar mammals
Glands in skin
Mammary, sweat, sebaceous, and scent glands
Sebaceous glands
Clean and lubricate hair
What muscle makes hair stand up?
Arrector pili muscles
Layers of hair
Cuticle, Cortex, medulla
What is the cortex layer in hair?
Contains living cells with melanin
Medulla layer of hair
Helps insulate animal; Filled with warm air
Definition of a mammal
Hairy, milk producing, endotherm that gives birth to live young
Traits of mammals
Endothermy/hair; Lactation; Sensory specializations; Heterodont dentition; skeletal simplification; Dentary jaw joint
What determines hair color
Advantages of pelage coloration
Countershading, Camouflage, Disruptive coloration, Warning coloration, Intraspecific communication
Circulatory System in mammals
4 chambered heart; Anucleate (no nucleas) Biconcave red blood cells; Varying heart rates
Respiratory System in mammals
Diaphragm-aids ventilation; Alveoli- increases surface area in lungs
Nervous system in mammals
Neopallum highly developed; Corpus callosum present
Neocortex (brain)
Where higher functions occur in mammals
Olfaction in mammals
Receptors distributed across the mucosal surfaces of the mesothmoid and vomeronasal organs
Function of vomeronasal organ
Picks up phremones
Hearing in mammals
High acuity; Range from intrasound to ultrasound; External pinna (ear) leads to auditory canal
Rods and Cones in eyes
Rods- gray color; Cones- Color
Digestive system in mammals
Salivary glands; Simple esophagus; Simple or complex stomach; Caecum
Function of caecum
May be site of Fermentation
4 chambers of stomach
Rumen, reticulum, omasum, and abomasum
Musculoskeletal system in mammals
Trunk muscles aid postural control and breathing; Superficial muscles allow skin to move; Simplification of skeletal elements; Greater ossification; Determinate growth
Superficial muscles function
Assist in suckling; Facial expression; Ear movements; Derived from constrictor cell muscles in neck
Why is there Determinate growth?
Diaphysis fuses with epiphysis once bone is done growing
Skeletal System in mammals
Akinetic skull- only lower jaw moves; Large Braincase; Zygomatic arch; Sagittal crest depending on diet; Secondary palate; Single craniomandibular jaw joint; Tympanic bullae (middle ear cavity); Turbinates in nasal cavity; Foramina in skull
Purpose of zygomatic arches
Opening for chewing muscles
Function of turbinates
Warms and humidifies air in nasal cavity
Purpose of foramina in skull
Passage of cranial nerves and vessels
Purpose of hyoid bone
Support tongue; Aid in swallowing
Axial skeleton in mammals
Vertebral column; Cervical, Thoracic, Lumbar, Sacral, and Caudal vertebrae; Ilium projects forward and ischium and pubis extend backward; Scapula and clavicle
Purpose of atlas
Holds up head; Provides up and down movement of head
Purpose of axis
Provides side to side movement of head
What holds the tooth in place?
Cementum and pariodontal ligaments holds tooth in place
Pulp cavity in tooth
Contains living cells
What starts the formation of the tooth
Dermal papilla- Made from neural crest cells of mesoderm
Upper molar cusp names
Basins on lower tribosphenic molar
Trigonid and Talonid basins
Chewing movements; Initially crush and puncture food then sliced by shearing surfaces of molars
Reorganization of jaw adductors (muscles)
1)External mandibular adductor (therapsids)
2)Temporalis and masseter (ealry cynodonts)
3)Temporalis, deep masseter, superficial masseter (late cynodonts)
Interpret this dental formula: (3/3, 1/1, 4/4, 2/3)
3 incisors, 1 canine, 4 premolars, 2/3 molars
Brachydont teeth
short-crowned teeth
Hypsodont teeth
high-crowned teeth
Special molars in carnivores
Bunodont teeth
Rounded cusps on molars
Lophodont teeth
Ridges from left to right; Found in rodents
Selenodont teeth
Vertical Ridges; Found in gazelles
Zalambdodont teeth
V-shaped crest; Found in moles and solenodons
Dilambdodont teeth
W-shaped crest; Found in shrews, moles, bats
Quadrate teeth
4 cusps on molar; Found in hedgehogs
What cells form enamel?
What cells form dentin?
What animals do testes remain abdominal in?
Monotremes, edentate (ant eaters), elephants, sirenians (manatee), and cetaceans
What does sperm competition result in?
Increased ejaculation volume and formation of copulatory plugs
Monotreme uterus
Retain cloaca; Two uterues both empty into urogenitial sinus
Metatherian uterus
Two vaginas and uteri; Birth occurs through pseudovaginal canal
Eutherian uterus
Single vagina; Two ovaries
Animals with Duplex uterus
Found in rodents and rabbits
Animals with bipartite uterus
Pigs, marine mammals, mice
Animals with bicornuate uterus
Bats, cows, horses
Animals with simplex uterus
Higher primates, humans
Monotreme reproduction process
Fertilized in infundibulum; Mucoid coating added in fallopian tube; Thin shell of ovokeratin added at base of fellopian tube; Second shell membrane added in uterus; Uterine secretions aid embryogenesis; Third shell layer added just prior to birth
Monotreme offspring
Altricial offspring-born unfinished
Estrous Cycle
1) Proestrus
2) Estrus
3) Metestrus
4) Diestrus
Development of ovian follicles and endometrium (lining of uterus)
Ovulation; Occurs from surge of luteinizing hormone
Formation of corpus luteum (releases progesterone)
Triggers production of endometrium; Prepares for implantation
Spontaneous ovulation
Ovulation under hormonal control; Without copulation
Induced ovulation
Ovulation only occurs after copulation
Type I Estrus Cycle in Marsupials
Gestation shorter than estrous cycle; Postpartum ovulation suppressed during lactation
Type II Estrus Cycle in Marsupials
Gestation equal to estrus cycle; Postpartum estrus and ovulation occur; Embryonic diapause
Type III Estrus Cycle in Marsupials
Same as type 2, but embryonic development can occur during lactation
Embryonic Development in Marsupials and Eutherians
Fertilization occurs in oviduct; Zygote begins cleavage divisions; Blastocyst reaches uterus in 3-4 days; Outer layer adheres and erodes endometrium; Trophoblast forms placenta; Inner cell mass forms embryo
Purpose of Placenta
Allows for nutritional, respiratory, and excretory exchange; Barrier for large molecules and bacteria; Contains hormones
Two layers of fetal tissue and maternal tissue
One layer of fetal tissue
No separate blood vessels on maternal layer, just blood sinus
Rudimentary lungs
Gas exchange occurs over skin
What does rise in estrogen levels result in?
Contraction of uterus, increase sensitivity of uterus to oxytocin; softening of cervix
Nondeciduous placenta
No bleeding; Villi completely detach from uterus
Deciduous placenta
Tissues not easily separated from uterus; Bleeding
Lactation hormone
Inhibited by progesterone; Milk simulated by prolactin
Cost of reproduction
Energy; Decrease in activity; Metabolize fat; Anatomical changes
Postnatal growth characteristics
Smaller the mammal, the faster the growth
Delayed Fertilization
Females store sperm in uterus; Fertilization occurs in spring; Hibernating bats
Delayed implantation
Fertilization occurs, but implantation is delayed until an optimal time
Obligate delayed implantation
Occurs every year; Species that hibernate
Facultative delayed implantation
Occurs only if female is nursing a litter
Delayed development
Implantation occurs, but development is delayed
Photoperiod with reproduction
Increase in day length increases melatonin which decreases reproduction
Bruce effect
The presence of an unfamiliar male will terminate the pregnancy
Males die when they reproduce because it costs lots of energy
Precocial young
Eyes and ears functional; Capable of locomotion right after birth