Lecture 9 Flashcards
(53 cards)
What is the biggest difference between like in water and life on land?
The effect of gravity on support and locomotion
What must land animals have in terms of support?
They must have a bony skeleton capable of transmitting backwards force to substrate and resisting forces
Describe the structure of land animal bone
Not uniform, dense on the outside, soft & spongey in the middle
What are joints covered in and what is it for?
Small layer of articular cartilage to reduce friction
Where does bone length growth occur?
At the epiphyses
What is the zygapophyses and what does it do?
They’re processes on the vertebrae & interlock to prevent twisting and bending
What’s changed in the axial muscles from sea to tetrapods?
Were used for locomotion in fishes & assumed 2 new roles in tetrapods. Postural support of body & ventilation for lungs
Name the two axial muscles in tetrapods
Nuchal ligament & Rectus abdominus muscle
Explain the path of evolution of axial muscles
Differentiation of epaxial then hypaxial muscles followed by development of transverse abdominus
What does the transverse dominus do?
Forces air out, amphibians still have this
Summarise the evolution of the appendicular skeleton
Limbs and limb girdles evolved, tetrapod limbs were derived from the fin of fishes
What girdle works well in water but not on land and why?
The pelvic girdle because it wasn’t attached to the skeleton
What did jointed limbs form for tetrapods?
Form holdfasts
What parts of the body was locomotion supported by?
In primitive tetrapods, locomotion via axial musculature
What happened to the pelvic girdle when changing for life on land?
It fused with modified sacral vertebrae
What connected the three paired bones on each side of early tetrapod to the vertebrae?
Ilia
What was no longer used to support the head and jaw muscles like in fishes?
The pectoral girdle
Name the two types of bones lost in tetrapods that fish have
Opercular & gular bones
What do tetrapods have instead of the opercular and gular bones?
A flexible neck
What holds the girdle to the sternum and the ribs?
Muscles & connective tissue
What does not articulate directly with the vertebral column?
The pectoral girdle
Name the function that the appendicular muscles had in fishes?
Hydrodynamic lift, steering and breaking
What occurred in regards to musculature between life in sea and life on land and what was still present?
More complex musculature began to appear as limbs took on new roles but ancestral pattern was still present
In regards to locomotion, which one is more expensive to move on/in?
Land
