1. Vertebral Column made of vertebrae
2. Cranium
3. Neural Crest Cells
4. Epidermal Placodes

A series of separate bones/cartilage blocks that are joined as a backbone.

• defines the major body axis.
• sep by intervertebral disks.
• As VC prominence increased, NC prominence decreased.

Skull: composite structure of bone/cartilage that supports the sensory structures in the head and encases the brain.

(Jaw devp is a key developmentary evolution of vertebrates)

1. Prevertebrate
2. Agnaths
3. Gnathostome

Suspension feeder that utilizes cilia pumps.

First predecesor to vertebrates.

Changes that occur:

1. Band of muscle encircles the pharynx
2. Cartilage replaced by collagen in the pharyngeal arches.

 Jawless fish with a muscular pump that increases effeciency of feeding allowing size increase and active food search.

Medial Fins (no paired fins/limbs)

Innear ear with 1-2 semicircular canals.

Endoskeleton and persistent NC.

No scales, smooth skin.

Ex: Cyclosomes.

Second predecesor to vertebrates.

• Jawed organisms (derived from pharyngeal arches) that allows for raptorial feeding which removes prey size limit.
• Two sets of paried fins supported by bone/cartilegenous girdles and controlled by muscles within the body.
•  Ex: Chondrocytes, Osteiohthyes, tetrapods.

Third predecesor to vertebrates.

Amniotes: Extra exmbryonic membranes aorund the embryo.

Anamiotes: Lack this extra embryonic membrane.

• Placoid Scales
• Cartinaginous skeleton with pieces of calcium that replaces the NC
• Bouyuncy from liver, pectoral fins, tail.
• Spiracle
• Replacement teeth.
• Ram ventilation

Water in the mouth and out the gills.

Propelled by constant swimming.

• Boney fish with an ossified internal skeleton.
• Swim bladder creates buoyancy.
• Overlapping scales cover the body.
• Fins are strengthened by rays.
• Opercular pump ventilates gills.
• Fins delicately control movement.

Ray-finned fish.

Fins are internally supported by ray muscles (within the body wall)

Lobe-finned fish.

Muscles that control fin movement are outside the body wall.

Fines are at the end of short, projecting appendages with bone and muscle.

(believed to give rise to tetrapods)

• Paired Appendages, Jaws, backbone, lungs, chiridium

A muscular limb with well-defined joints and digits.

Mammals, Reptiles, Amphibians, Birds compose tetrapods.

Adult Terrestrials.

Weight-bearing girdles are more ossified/stronger.

Vert Column increases in prominence.

Anamniotes.

Paired lungs are typical.

Moist, grandular skin.

Extra bone associated with the ear.

• Embroys are in an extraembryonic membrane.
• Chorion for outter gas exchange.
• Allantois for excretion and respiration.
• Yolk Sac surrounds the yolk and provides nutrition.
• Amnion.

Anapsids (no temp openings) and Diapsids (two temp openings)

Anapsids: turtles, first reptiles.

Diapsids: Squamates, dinosaurs, crocs, birds.

Birds, Aves

Reptiles

• scales comp of surface epid.
• No hair or feathers
• Absorb heat from environ
• Lungs for respiration

One temporal opening.

Considered the ancesters to mammals.

• quadripeds, 5 digit feet, diff teeth types, explit terrestrial habitats, legs more directly under the body.