Lab 8 Flashcards
What three characteristics are seen in the mink? What clade of mammals is associated with these?
- tribosphenic molar, mobile scapula, lack coracoids
- Clade Theria
In the Order Carnivora, mammals like the mink, cat, and dog have specialized sheering teeth. What are they called?
carnassials
The foot pads on the soles of mammals is homologous to what in primates? What are they formed from?
- homologous to primate friction ridges (fingerprints)
- are formed of thickened stratum corneum, the outer layer of the skin
What is a unique feature found in mammals? Where can this be seen?
possess hair which grows on entire surface except soles of feet and rhinarium
What is rhinarium?
the bare patch around the external nares
True or false? Hair is homologous to reptilian scales.
False. Hair is not homologous to reptilian scales but developed as vibrissae (sensory structures) between scales and around face
True or false? Hair developed as a secondary insulative function.
True
What kind of adaptation of hair is seen in porcupines and hedgehogs?
hairs are enlarged and stiffened as quills
What kind of adaptation of hair is seen in pangolins?
hairs are agglutinated into overlapping scales
What kind of adaptation of hair is seen in rhinos?
horn of the rhino is formed of agglutinated hair
Which is the only truly armored mammal?
armadillos which have rows of dermal bone plates embedded in the skin with a few hairs, probably sensory, projecting between plates
Name offensive or defensive adaptations of mammals’ hair.
quills, agglutinated into overlapping scales, horn
What is the pinna? Functions?
- a fold of tissue at the opening of the external auditory meatus to funnel and focus sound waves onto the tympanum
- may have secondary function as a heat radiating surface in elephants
The pinna is seen in which mammals?
absent or very small in aquatic mammals and developed in terrestrial mammals differently
What structure can be seen on the mink that serves as a third eyelid? What is its function?
nictitating membrane for protection of the eye and keep it moist, 3D vision
How does the position of eyes of a cat compare to that of a deer? What advantage might the positioning of the deer’s eyes confer?
deer: eyes are larger and more to the side of their head which allows for a much wider range of vision than cats have (eyes are more centered on the face)
The Synapsida/Mammalia have what type of skull?
synapsid skull=lower temporal fenestrae only
The ridges found on the skull of mammals allow for what?
sites of muscle attachment
What does a cheetah have that the horse does not? What happens to the cheetah’s spine and scapula compared to the horse?
- has fast twitch muscles
- when it runs, scapula moves a lot more than the horse and its spine flexes way more when running
How many roots are found in the incisors and canines?
single root
Why are lips unique to mammals and what makes them so important?
- highly innervated and operated by specialized facial muscles
- an expressive feature
- permits manipulation of food
In mammals, what other characteristic other than hair and lips is unique, seen highly developed especially in females?
mammary glands are highly developed in females and are not evident except in lactating females
What is external evidence in males and females of the mammary glands?
nipples
In mammals, instead of the testes in the ventral cavity, where can they be found?
testes have descended from within the body cavity to the scrotum, a pair of sacs ventral to the anus
True or false? Skulls of mammals are kinetic.
False. They are akinetic=no movement between the upper jaw and braincase
The synapsid skull of mammals caused what type of modifications and these are associated to what type of development?
changes in sensory mechanisms, feeding mechanisms, increased metabolic rate associated with development of endothermy
What is the secondary palate?
the premaxillae, maxillae, and palatines developed ventromedial flanges which form the secondary palate
Function of the secondary palate?
encloses the nasal cavity and separates the mouth and air passages far back in the pharynx
What is the advantage of having a secondary palate?
able to eat and breathe at the same time
What are the ethmoaturbinates inside the nasal cavity covered by?
olfactory mucosa
What is the functions of ethmoturbinates? Is there a non-olfactory function for them?
for sense of smell and serve to heat and humidify the air that enters the nose
What is a rarity seen in evolution regarding the quadrate and articular of mammals?
quadrate and articular migrated into the auditory bulla (incus and malleus)
The auditory bulla is composed of what two components?
incus and malleus
Early mammals were nocturnal, therefore why would hearing and sense of smell evolution be important?
increased sense of smell and hearing would have enhanced survival under conditions when sight was less useful
What has happened to mammals’ postorbital bar seen in reptiles? What is this structure’s role? What about advanced primates?
- has been reduced to a lateral projection of frontal bone called the postorbital process
- protects the eye
- advanced primates rely heavily on sight so orbit again enclosed by bony analogue of postorbital bar
What structure provides a connection between the mouth and the vomeronasal organ?
incisive foramen
What is the function of the vomeronasal organ?
detects olfactory sensations from food in the mouth
What is the pterygoid fossa?
- extension of the nasal cavity
- covered by cartilage forming the soft palate
- separates the oral and nasal cavities
What is the glottis?
the opening of the trachea (windpipe)
What is the eustachian tube?
this tube connects the middle ear with the pharynx and provides a mechanism to equalize air pressure inside and outside the tympanum
In mammals, four elements of the occipital region are fused into one single occiptal. How does this compare to the turtle?
- mammals have two occipital condyles
- turtle has three elements of the occipital region that forms one single occipital
What is the name for the first cervical vertebra? Second? Functions? Articulation with?
atlas-permits nodding motion of the head (due to articulation with occipital condyles)
axis-rotation of the head (due to articulation with atlas)
What is the nuchral crest? Function?
- the ridge formed by the articulation between the occipital and the roofing bones of the skull
- for neck muscle attachment
What are the ridges on the skull for?
for muscle attachment
What canal passes through the lacrimal?
a canal which carries the tear duct between the eyelid and the nasal cavity
What is the function of the masseteric fossa?
for insertion of the masseter muscle
What are angular processes?
small caudal projections ventral to the condyles
What kind of dentition do mammals have?
heterodont dentition=several kinds of teeth in the jaw
Name the four types of teeth going from anterior to posterior.
incisors, canines, premolars, molars
In the upper jaw, where can the different types of teeth be found in the bone ? What about the lower jaw?
upper jaw: incisors on premaxilla, canines at junction of premaxilla and maxilla, premolars and molars on maxilla
lower jaw: all in dentary
Which teeth are rarely lost through evolution?
canines
What is carnassial specialization?
meat sheering specialization of teeth in carnivores
What is the diastema?
a gap that is needed to accommodate canines when mouth is closed
Many gnawing rodents like the beaver and porcupine have ever-growing incisors with enamel on only one side. What does this adaptation allow?
prolongs the life of the tooth and permits self sharpening since softer dentine is worn away as upper and lower teeth slide past one another
what is bunodont specialization?
omnivores have bunodont molars which are square with four cusps, and also have premolars to cut and crush
What is seen in the premolar (bicuspids) of adult humans?
have a buccal shearing edge and lingual crushing heel in lower jaw and two shearing edges in upper jaw
What kind of teeth specialization is seen in herbivores?
have moralized premolars with large grinding surfaces for grinding of tough food
Hoofed mammals like deer, cattle, horses have what kind of teeth specialization?
selenodont=molars and premolars have enamel folded into longitudinal ridges
Among elephants, what kind of teeth specialization is seen?
lophodont=transverse enamel ridges
What does it mean to have diphyodont dentition? What are baby molars?
- first set of teeth is not permanent, baby teeth are lost starting with incisors and replaced by a second permanent set
- baby molars are molarised premolars and analogous to adult molars
How are vertebrae in mammals divided?
cervical (neck), thoracic (articulating with ribs), lumbar (those that lack ribs), sacral (fused into sacrum), caudal (in tail)
How many cervical vertebrae are there?
seven (atlas and axis are first two)
The articular facets of the atlas articulate with which structure?
occipital condyles of the skull
What is the main difference between the atlas and axis?
atlas has no neural spine and its transverse processes are large for muscle attachment
axis has large neural spine
There is no zygapophyses between the atlas and axis. What does this allow for?
more flexibility and motion of the head, allows for nodding and side to side motion
How many thoracic vertebrae are there? How can you describe them?
14 and have spines which project from them and have prezygaphophyses and postzygapophyses
How many lumbar vertebrae are there? How can you describe them?
6 have large transverse projections to incorporate remnant of rib into vertebrae
How many sacral vertebrae are there? How can you describe them?
3 are fused into the sacrum to articulate with ilium
What does a longer neural spine indicate?
- indicates larger forces can be applied to the area of vertebral column
- confers stability
Is the cervical or thoracic vertebrae subject to more force?
Thoracic vertebrae have longer neural spines so are subject to more force
What are the two articular surfaces of the ribs?
one articulates with the centrum at the proximal end and another articulates with the diapophysis
Each rib is composed of what and articulates with which structures?
composed of a bony vertebral segment articulating with the vertebral column and a ventral cartilaginous portion articulating with the sternum
There are no lumbar ribs in mammals. What is the advantage of the absence of these?
allows for a diaphragm for respiration (more efficient method of ventilation)
Why do minks and cats have an upright position?
limbs are brought under the body and in alignment with direction of travel
Mammals have lost certain elements of which girdle? What is the only remaining dermal element? Endochondral element?
- pectoral girdle
- clavicle (reduced in carnivores) has no connection with axial skeleton and has ligamentous connection with scapula
- scapula which has scapular spine
What is the function of epicondyles?
provide attachment sites for forearm muscles
What is the trochlear notch?
allows articulation of the ulna with the humerus
What three elements are fused together to form the pelvic girdle?
ilium, ischium and pubis
What are trochanters?
allows for insertion of thigh muscles
Which shank muscle is heaviest?
tibia
What is the name for the large “heel” bone?
calcaneus
Metatarsals are longer than metacarpals. What advantage might this confer?
more movement in the foot
Digitigrade vs plantigrade vs unguligrade
digitigrade=mink’s stance where only the digits are in contact with ground (longer limbs)
plantigrade=humans whole foot, digits, metatarsals and some tarsals bear weight
unguligrade=hoofed mammals bear their weight on tips of phalanges (longer limbs)
Longer limbs means what for stride and speed?
longer strides and more speed
What is the function of vibrissae?
sensory function
The auditory bulla is derived from?
articular and quadrate
In male cats, what can be said about the sagittal crest and their muscles?
larger in males and larger temporalis
What is the main roofing of the skull?
parietal
In what order is the rabbit from?
Order Lagomorpha
What is the difference between the mandibular fossa and coronoid of the horse vs the tiger?
are smaller in the horse
in tiger, it allows for wide gape
What does the glenoid fossa articulate with in the cat skeleton?
with humerus
The femur is held in the acetabulum (articular socket) which allows for which movement?
mostly in longitudinal plane
What is the function of the masseter?
mastication, rotation of jaw in herbivores
Where does the masseter originate and insert?
originates on the zygomatic arch and inserts on the lower jaw
Which has a bigger masseter relative to head size, the rabbit or mink?
rabbit has larger masseter than mink since herbivore
Action of the temporalis?
adduction of the jaw
clydo
shoulder
clydomastoid
runs between shoulder and jaw
sterno
chest
sternohyoid
runs from chest to neck area
Match.
Ethmoturbinates, auditory bulla, sagittal crest, zygomatic arch, coronoid process
high surface area bone extension in nasal cavity which is covered in mucosal tissue, ridge on skull to which the temporal muscles attach, derivative of the quadrate and articular, cheekbone formed by the squamosal and jugal, projection on the dentary to which the temporal muscles attach
Ethmoturbinates-high surface area bone extension in nasal cavity which is covered in mucosal tissue
auditory bulla-derivative of the quadrate and articular
sagittal crest-ridge on skull to which the temporal muscles attach
zygomatic arch- cheekbone formed by the squamosal and jugal
coronoid process-projection on the dentary to which the temporal muscles attach
