Mammals Flashcards
Name seven synapomorphies of mammals.
1) heterodonts and diphyodonts (two sets of teeth)
2) turbinates
3) sweat and mammary glands
4) four-chambered heart
5) Diaphragm
6) single bone in the lower jaw
7) three middle ear bones
Name four integumentary glands and what they do in mammals.
1) Sweat glands - involved in heat regulation
2) Scent glands - marking territories, warning, defence
3) Sebaceous glands - associated with hair follicles
4) Mammary glands - provides milk for offspring
What is the purpose of underhair? Describe it.
Underhair is used for insulation.
It traps a layer of insulating air.
It is soft and dense.
It is extremely dense in aquatic animals.
What is guard hair? Describe it.
Guard hair is long and coarse. It is used for protection from wear and for colouration.
it can also be used for touch and sense, like the whiskers in a cat.
Define acrodont, pleurodont and thecodont.
Acrodont - teeth attached to occlusal surface (e.g. snake)
Pleurodont - teeth attached to side (e.g. lizard)
Thecodont - teeth set in sockets (e.g. alligator, mammal)
Define bunodont, lophodont and selenodont.
Bunodont - cusps form rounded peaks (e.g. primate, pig)
Lophodont - cusps form ridges (e.g. horse, rhino, rodent)
Selenodont - crescent-shaped cusps (e.g. camel, deer)
Most mammal are _____________.
Use one of the following words to fill in the blank:
monophyodont
polyphyodont
diphyodont
hypselodont
Name three exceptions to this.
Monophyodont or diphyodont.
Three exceptions are the elephant, kangaroo and manatee.
The malleus and incus are thought to be homologous to the _________ and __________ in reptilians.
Articular and quadrate.
The stapes evolved from the hyomandibular
What do the middle ear ossicles do?
Act as a lever and amplify sound more efficiently.
What divides the nasal cavity from the oral cavity in mammals?
The bony secondary palate.
What are turbinates?
Complex bony scrolls within the nasal chamber.
They act as countercurrent exchangers to conserve heat and water.
Olfactory turbinates are covered in sensory epithelium.
What are pelycosaurs?
Primitive synapsids found in the late Carboniferous and Permian.
They showed signs of early thermoregulation.
Two types of teeth; sharp and sheering.
Early transition from reptilian gait to more upright gait.
What are therapsids?
Advanced synapsids found in lower Permian to Cretaceous.
They had an erect gait, symmetrical feet.
They had incisors, canines and molars.
Beginnings of the secondary palate.
Fossil evidence of skin glands.
What is the ancestral jaw articulation?
Articular-quadrate
What is the jaw articulation of mammals?
Dentary-squamosal
