WSU CVA bio 324 2026 Exam 2

Aerial Locomotion Types (5)

1. Jumping, parachuting, gliding- evolved in all classes of vertebrates

2. Jumping- fish, mammals, reptiles, amphibians

   1. short distances, escape predators

3. Parachuting- flying squirrels, flying frog, pygmy opossum, fish, mammals, reptiles, amphibians

   1. trap air, soften impact

4. Gliding- fish, mammals, reptiles, amphibians

   1. Deflect the line of fall

5. Flailing

   1. Increases distance, steering

6. Powered flight- birds, bats, pterosaurs, 3 independent lineages

   1. New lifestyle

Gliding/Parachuting

ex- pygmy opossum-parachuting marsupial

loose flap of skin is called a patagium, extends to wrist and catches air to slow

tail is used as a rudder

ex-Colugo-flying lemurs, largest patagium and best gliders, patagum from tips of tail to tips of digits

ex- flying frog-webbed toes trap air

ex-flying lizard, flares out ribs and loose flaps of skin

ex- flying snake, flattens ribs and body

ex- flying fish, enlarged pectoral fins, extended to deflect air

Powered flight

ex- bats

long digits make up the wing and patagium

thin, elongated scapula along body axis, 1 free digit (thumb)

ex- pterosaurs

elongated 5th digit akes leading edge of wing and digits 2,3,4 are used as hooks and 1 is in the patagium and similar to the bat

some winged dinos had spans of 20ft

ex-birds

most efficient fliers, thousands of miles, 100mph+, flight first originated in dinos but only one of the lineages became the birds

gave rise to the lineage of flightless birds (ostrich, penguins, elephant bird

Modern birds have flight feathers and reduction of digits

Archaeopteryx looked like a dino for everything else (had two traits above)

Origin of flight (3 hypotheses)

1. Arboreal- tree down

Ground up- cursorial

1. Insect-net

2. climbing

Ground up- cursorial

Cursorial/Insect-net theory

Running with short hops

Wings used to catch insects or small prey

Climbing theory

Wing assisted incline running (WAIR)

Aerodynamics- Bernoulli’s principle

Bernoulli’s principle

As fluid velocity increases, pressure in the fluid decreases

Airfoil shape

cambered wing with airflow over the top forms lower pressure on the top of the wing and higher pressure on the bottom which provides lift

cambered wing/airfoils-asymmetical wing that is curved slightly at the top

Angle of Attack

Lift -airflow going over bird, must overcome m*g or weight

Drag-

Thrust- must overcome drag

Weight- mass*gravity

Birds can change angle of attack with muscles to alter lift and drag

pilots change AOA with whole plane, risk is that it can stall with no lift and fall out of the sky

Flight feathers

Primary-attach to manus/wrist

Secondary-attach to forearm, radius+ulna

Soaring vs Thrust Bone formation

Hummingbird-short upperarm and forearm with long manus for primary feathers (thrust), rapid flapping, can’t soar, will drop

Albatross-medium upper arm and long forearm for secondary feathers (lift) and short manus, soaring for days, endurance

Shape of wings

Elongated- lift (shearwater

Short, robust- maneuverable (pheasant)

Streamline- fast (swallow)

Intermediate- (rough legged hawk)

Bone Tradeoffs for flight

light bones need less energy and thrust and lift

Penguins- thick bones for swimming against water

Auk- sea bird that dives for fish but still has to fly

Sea gull- soaring

Aerodynamic adaptations

Sclerotic ring- prevents deformation of eye while flying

Feathers- streamlining, contour feathers (body) to reduce drag

Rigid synsacrum and axial skeleton to resist aerodynamic forces, dont need as many axial muscles to lighten body, metabolically good, fusion of bones means resisting twisting forces is easier

Tubular/hollow bones- lighten skeleton, trabeculae are strings of bone tissue and theres no marrow

Why flight?

Travel great distances (thousands of miles) and migration, energy efficient

Catch prey or escape predators

Better access to food resources or others

Cranial Skeleton

Splanchnocranium

Dermatocranium

Chondrocranium

Modern vertebrate skull made of 3 components

Old skull theories (wrong)

Source of skull is the continuation of vertebrae

no fossil evidence of ancestor with vertebrae in head

Composite skull structure

Multiple components and they come together to form the skull

Remodeling from three evolutionary sources

Splanchocranium- (digestive prefix) branchial support structures of pharynx of protochordates, cartilage or bone

Chondrocranium- brain support in early fishes

Dermatocranium- dermal bone or armor of ostracoderms/placoderms (early fish)

Splanchnocranium

Jaws of early gnathosomes, linker bones for jaws, hyoid support for base of skull and gills and or respiratory muscles, inner most part of skull

Chondrocranium

Supports and protects brain, sensory capsule, top part of inside skull

mesenchyme to cartilage, spenoids and ethmoids are the only endochonral bone, rest are dermal

cartilage to bone, except chondrichythes

Dermatocranium

Protection of the head, entire casing of fish skull basically, came from dermal bone plate ontop and it wrapped around

1. Derived from Dermal armor

2. Embryological Change

3. Function-protect the brain!

Embryology +catilage

Condensations of cartilage

Grow into plates

Ossify

General Functions of Chondrocranium

1. Adult braincase (chondrichythes)

   1. Support and protect brain

2. Scaffold (most vertebrates)

   1. Centers for ossification

      1. Neurocranium- if ossified

General Functions of the Splanchnocranium (visceral cranium)

1. Support respiration (fish, amphibian larvae)

2. support feeding apparatus (tongue, hyoid apparatus)

3. Jaws and jaw connectors (later)

   1. Derived from anterior branchial arches (mandibular arch/1st branchial arch)

      1. Evidence: embryology, supply of blood vessels, nerves, musculature

FISHY jaws

Agnathans-jawless

Gnathostomes- jawed

General Functions of Jaws

1. Prey Traps

2. Crushing/Tearing food

Without jaws- options are filter feeding, parasitic, and suspension feeding

ex-lamprey (jawless) can latch and suck blood

Hypothetical Ancestor- Agnathan

Jawless

Origin of jaws are from front branchail arches

Also gave rise to connective bones that attach to jaws

Shark Embryo Skull

Serial vs Composite hypotheses

Mandibular arch=first branchial arch

Alfred Romer- (serial)

Arch 1 became jaws, and arch 2 became hyoid arch

Erik Jarvik- (composite)

Other pieces of cartilage join up,not just first mandibular arch 1

Jaw Suspension Types (3)

Hyostyly-primary hymandibula (sharks, fish)

Amphistyly two primary articulations, hyomandibula and directly to skull via ligament, more primative (placoderms)

Autostyly-without hyomandibula ex-quadrate to articular (reptiles)

Lineages

Mammals, primitive mammals, therapsids (premammals, limbs rotated forward, jaw attachment changed, mammal like reptiles), pelycosaurs (synapsids, sail back), CENTRAL DIVERGENCE cotylosaurs, amphibians

Changes in synapsid jaw articulation

Reduction in articular and increase in dentary

3 bones turned into middle ear ossicles for sound amplification

transmit vibrations through middle ear into inner ear

act as a lever system amplified between each bone, amplifies about 40x

quadrate→incus

articular→malleus

hyomandibula→stapes

Cuvier dilemma

Animals function as wholes and parts fit/work together, so if you remove/ change one part, others will fail. How to change jaw articulations without jaw system failing?

ancestreal=articulat to quadrate

Probainognathus-early synapsid

Had two jaw articulations and could lose the quadrate/articular without problems

Skull Fenestrae

cons- Weaken Skull

1. Lighten skull

2. Increase surface area for muscle/connective fissue

3. Space allows for bulging of muscles when it contracts

Anapsid-0

Synapsid-1

Diapsid-2

Skull Functions

Primary

1. Protection

2. Feeding

3. Prey traps

4. Swallowing, respiration

Secondary

1. Heat exchange- airflow would cool boood circulating to nasal cavity if overheating

2. sound resonance- sound transmitted through nasal cavity (changes when you are sick)

Skull Function Feeding Methods (aquatic and land)

1. Filter feeders (A)

2. Suspension feeders (A)

3. Suction feeders (A)

4. Prehension- grab with jaws

(A) is aquatic only

Filter Feeders (aquatic)

1. Benthic- feed at or near bottom

2. Small sized particles- not efficient for larger vertebrates

3. Tight coupling of feeding/respiration

Early Agnathans:ostracoderms raised and lowered pharynx to bring water into oral cavity, not efficient

-not effcienent for large vertebrates (excludes blue whales- only eats krill/suspension feeders)

Suction feeders (aquatic)

1. Gape ‘n suck

   1. Ingest larger food

   2. More efficient

2. Use the inertia of water- pulls water in and inertia also bring the food in

3. Coupled to respiration

Facial muscles contract and move one bone which push/move others via flexible joints, sides of skull flare outwards and creates negative pressure (Cranial Kinesis)

Prehension

Use jaws to grab, bite, tear

Mandibular arch rides forward on its suspension via hyomandibula which increases the gape

Skull Function Feeding (air)

1. Lingual Feeding

   1. Using tongue (sticky mucus, ex-salamanders and lizards)

2. Jaws (prehension)

   1. Grab with jaws

Lingual Feeding

Mucus covered sticky tongue, muscles at base of tongue and it is used first to bring food into the mouth

Hyoid bone (with long lingual process and tongue muscles

Glossohyal (retractor muscle), tendon, lingual process, accelerator muscle using the method of a hand squeezing a bar of soap

Prehension (air)

Adaption is a jaw joint

Bone articulations/muscles to open and close

Quadrate and mandible allow wider gape

Skull Function-Swallowing

1. suspension, filters

   1. ex-baleen whales filter water from krill

2. whole, often with a gizzard

   1. snake, lizard, bird pebbles in crop grind

3. mastication, chewing

   1. ex-mammals

Mastication (chewing)

Primary palate- top of nasal cavity (early synapsid)

Secondary palate- allows continual chewing while breathing, top of oral cavity

Mammals have two cavities, Separate nasal and oral cavities, more efficient

If there is no secondary palate then reptiles must top eating to breathe and cows can rechew because they have a secondary palate

Mastication (teeth)

1. Precise occlusion of teeth (alignment)

2. Specialized teeth (piercing, tearing, grinding)

3. Diphyodont (two sets of teeth-mammals-baby and permanent) and polyphyodont (constant replacement-sharks)

Akinetic: no relative motion of skull bones across joints allows precise alignment of specalized teeth

Cranial Kinesis

Not fused tightly to allow for movement

Not good for chewing or crushing

Allows for

1. rapid change in size and configuration of buccal cavity

   1. feeding methods

2. alter tooth position

   1. Skull can flex bones and therefore teeth for better grip on prey

   2. appying even force on top and bottom prevents prey from shooting out like a bar of soap

ex-fish, snakes, lizards, birds

Akinetic- amphibians, turtles, crocs, mammals

Snake Kinetic Skull

Ex- Snakes Can swallow prey larger than their head,very flexible jaw 90 degrees, unfused mandible in the front with stretchy ligament

Rattlensake strike

raise.rotate whole maxilla to raise.erect fangs and strike

use muscles of head to move skull bones

MUSCLESSSSS (3, and their subs+ 1 bonus)

Skeletal

1. Supply power for moving skeletal system

2. Restrain/restrict movement

3. Heat production/shivering

Smooth

1. Walls of hollow organs/tubes

   1. Digestive tract (mixing, peristalsis)

   2. Blood vessels (regulate diameter)

Cardiac

1. Wall of heart (pumping blood)

Specalized

1. Electric organs

Electric Organs

blocks of specialized skeletal muscle

Round disc shaped cells, stack (skeletal muscle is normally rod shaped)

contraction will produce a small charge

more rows and stacks will add current

some use low surrounding voltage for navigation and feeling changes

higher voltage for stunning prey or defense

AKA torpedo organs because first found in the torpedo ray

Skeletal muscle/connective tissue

Muscle organ (encased by epimysium)

Perimysium are around the fassicles

Fassicles are the bundles of muscle cells

Endomysium encases the muscle cell (chunks of myofybril)

Epimysium, perimysium, endomysium are all conective tissue

Tendons

Attach muscle to bone, continuous with connective tissue covering of bone and distribute force of muscles over long distances

Function

1. reduce blood supply

2. metabolically cheap

3. lighten distal limb

force generation without weight, not much vascularization or require blood/o2

Support Structures of muscles

Retinaculum- wrap around tendons for support

Bursae- fluid filled pouches to reduce friction