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