CHAPTER 4 Flashcards
sprawling stance
an animals humerus and femur project horizontally, with elbows and knees strongly bend.
Erect stance
an animals humerus and femur project vertically, such that the limbs point straight down from their girdles
advantage and disadvantage to an erect stance
Advantage:
- positions the limb bones directly under the body, this allows to passively support the body weight
-Better for fast locomotion and allows all limbs to contribute to the length of a stride
disadvantage:
- requires muscle to do not my work then a sprawling stance would do.
what do all tetrapods share a common ancestor with
a common ancestor with a sprawling stance.
were dinosaur erect or sprawling
erect
advantages and disadvantages for sprawling stance
advantages:
- less energy is spent to support body weight
Disadvantage: unable to move fast and
Cursorial limbs
are limbs specially adapted for fast locomotion. tend to have very long lower legs bones
digitigrade posture
stand on their own toes
plantigrade posture
stand simultaneously on our toes and the flat part, and our heels
graviportal limbs
- specially adapted for supporting extremes body weight.
- have bones that are robust and heavy. limbs tend to be short and bend as little as possible when walking
- tend to have large fleshy pads to provide solid support base and help absorb impacts
obligate bipeds
animals that almost always walk and run on two legs.
obligate quadrupeds
animals that almost always walk and run on four legs.
facultative bipeds
walk on all four legs, but rise on two legs to run.
what was the walking stance of the ancestor for all dinosaurs
obligate biped
caudofemoralis
- a large muscle that pulls backwards on the hid leg,
- is anchored to the under surface of the ilium, to the caudal vertebrae, it attaches via tendon and femur
trochanter
a prominence of bone,
what does a larger caudofemoralis indicate ?
that the dinosaur was most likely a fast runner and was adapted for greater hindlimb power.
where is the caudofemoralis located on most theropods
located high on the femur
Ichnofossils
fossils that record traces of biological activity, like fossil footprints and tooth mark and burrows.
how does a footprint fossilize ?
1) must be made in soft mud
2) mud must dry out and Harden
3) must be buried and then eventually re-exposed for the palaeontologist to find
trackways
an entire series of footprints found.
what were hadrosaurs and iguanodons?
facultative bipeds
were dinosaurs cold or warm blooded
warm blooded
which is ectotherm
cold-blooded
which is endotherm
warm-blooded
Ectotherms
animals that adjust their internal body temperatures through behaviours that depends on temperature differences within their environments
Endotherms
animals that regulate their body temp through metabolic activity
disadvantage of endotherms
In order to maintain a constant body temp, a lot of energy is spent to do this.
are most organism ectotherms or endotherms
ectotherms
advantages to endotherms
- can survive in the cold.
- always ready for actions, cold or warm, day or night.
- instead of spending time sunbathing like ectotherms, they spend that time eating and gaining energy.
do endotherms or ectotherms benefit from feathers and shit
endotherms because it helps them hold o to body heat.
Histology
a technique of slicing samples of bones into very thin sections
osteons
bone cells
which group grow their bones quicker then the other
endotherms from bones faster then ectotherms. they also have their osteons in a different arrangement.
giganthermic
instead of being endotherms, large dinosaurs ectothermic, but with their low ratio of surface area to volume, it would have prevented them fro losing significant energy to the outside world. they could live endothermic-like lives without actually needing to produce body heat by burning energy.
cube square law
the larger the animal is, then they have relatively less surface area to volume ratio.
Dinosaurs that are obligate quadrupeds
- sauropods
- ankylosaurs
- stegosaurs
what were prosauropods walking stance
probably bipedal, but whether they were obligate or facilitative is unknown.
where does the caudofemoralis attach to
it attaches to the trochanter.
how do we know dinosaur have caudofemoralis
Dinosaurs have a femurs with trochanters (prominence of bone)
how can you determine whether a dinosaurs had a large cuadofemoralis
based on the size of the various anchor points.
where is the caudofemoralis located on carnivores?
higher on the femur. this increase the speed.
where is the caudofemoralis located on hadrosaurs
lower on the femur. this slowed down the speed but better endurance.
who benefits from having higher endurance
herbivores recuasse hey are always on the move.
what can trackways determine?
can determine how fast dinosaurs moved.
how can trackways be used to determine a dinosaurs speed.
estimate dinosaur leg lengths from the proportions of their footprints. full speed cannot be determine because they had to run through mud.
