Lecture 9 Part 1 Flashcards
What is the principle of uniformity?
The processes that shape the world today are the same as the ones from the past
Snakes swallow their prey how?
whole
How do komodo dragons eat?
their pointy teeth that angle slightly backwards allow them to grab on to prey and rip their flesh into smaller easy to swallow pieces, the teeth are sharp and spaced out so stringy materials do not get stuck between them
How can snakes and komodo dragons move their jaws?
They can move their jaws really wide (wide gape) to seize, kill, and/or dismember their prey depending on what they are eating
What bone allows snake to acheive it’s wide gape?
the quadrate, it suspends lower jaw and is able to rotate which allows the snake to open it’s jaw very wide
the acieve a wide gape, the jaw joint is at what level with the tooth row?
in line, this creates a stable joint that does not allow the jaws to move side to side
The quadrate jaw joint being in line with the tooth row is good for predation because?
because it resist thrashing prey, can hold onto it better
How do the jaws work like scissors?
the jaw joint in position with the tooth row gets a sequential shear and allows them to tear flesh but not chew
What three unique features allow herbivores to chew?
The herbivorous skull is divided into 3 main parts:
1. The cropping section (blade like teeth called incisors bite off chunks of food)
2. The diastema (a ~toothless gap for food manipulation by the tongue)
3. The cheek teeth (called molars in mammals, a place for grinding down food into a paste
What are adaptions for chewing in mammals? (5)
- An expansion of bone called the coronoid process for jaw muscle attachment
- closely packed teeth with flat grinding surfaces (no space between teeth)
- teeth occlude, (fit tightly together for efficient grinding)
- an inset tooth row to support cheeks (can accomodate food items)
- Jaw joint is above the
tooth row, allowing all the
upper and lower teeth to
make contact at the same
time (like water pump
pliers)- less stable then shearing jaws
What is the skull morphology of non chewers versus chewers?
Non chewers: chewers:
gape: Wide gape Small gape
Tooth spacing: Spaced-out teeth, Closely-packed teeth
Nature of contact
between upper and lower
teeth:
Teeth with limited
grinding surfaces (pointy,
narrow, peg-like or other),
Cheek teeth with large
grinding surfaces. Teeth
occlude (contact top and
bottom).
Position of jaw joint; Jaw joint in the plane of
the tooth row, Jaw joint below or above the plane of the tooth
row. Large coronoid
process.
Carnivore or herbivore? Usually carnivores (rarely
herbivores), Herbivores and omnivores
How do carnivores break down their food? What characteristics do their digestive systems have?
Through stomach acid not chewing, carnivores have simple, single-chmabered stomachs, short digestive tracts, and typically slim torsos (v-shaped)
How do herbivores and omnivores break down food?
through chewing and digestive enzymes, have a large barrel shaped gut that accommodate long digestive tracts to enhance the break-down of plant matter - act like fermentation chambers to break down large volumes of vegetation.
Were dinos gassy?
yes especially herbivorous ones
What are gastroliths?
animals that don’t chew digest stones to help mechanically process food and as a weight to provide stability (ballast).
Sometimes animals pass them and some animals retain them
