amniotes

what makes amniotes different

• amniotic egg

• dont need water to reproduce

• coverings on skin

amniotic egg

4 extraembryonic membranes, outer shell develops in moms uterus, eggs muct be layed on land

4 extraembryonic membranes,

1. yolk sac: provided nutrients

2. amnion fluid filled sac: cushions embryo 

3. allantois: connects the end of gut tube, stores waste 

4. chorion: aids in gas exchange

synapomorphies 

keratinized skin

ankle bone (astrogaus) 

more than 2 sacral bones 

costal breathing 

elongation of neck/trachea

keratinzied skin

thick, waterproof, non permeable

scales, hair, feathers formed by keratin and homologous to fish scales

costal breathing

intercostals opens ribs for inhalation, increases chest cavity

synapsids 

extant mammals, mammal like reptiles 

suaropsids

Lizards/snakes, turtles, crocs birds

distinction between synapsids and sauropsids

#of fenestration

anapsid: 0

synapsid: ONE on each side

diapsid: TWO on each side (living reptiles and sauropsids)

*turtles derived no fenestration

Locomotion

synapsid: quadrupedal, one lung can inflate at a time, legs under body, flex back up and down

suaropsid: bipedal, axial muscles not needed for locomotion,

lungs 

amphibian: simple sac w/ septa to increase SA

synapsid: trachae→ primary bronchus, secondary bronchii, tertiarry bronchi, bronchioles→ aveoli (old and new air mixes)

sauropsid: faveolar lung, faveoli in lung (cups/pockets), primary bronchi→ faveoli  

parabronchial lung (crocs)

primary bronchus → dorsal secondary bronchus→ parabronchi → past faveoli

gas exchange in faveoli → into ventral seconday bronchus

hearts

• evolved septum between ventricles, reduces mixing of oxygenated and deoxygenated blood

• low blood pressure: to lungs to protect delicate lung tissue

• high blood pressure: in systematic to get everywhere in the body

• ***** heart design in synapsids and suaropsids started different then derrived to be similar = analogous

skin

• both have alpha keratin in epidermis

• synapsids: smooth skin w/ hair from alpha keratin

• suaropsids: beta keratin adding rigid , forms hard surface → birds beaks, claws, feathers

excretory system

• fish ammonia in urine

• synapsids: convert ammonia into urea, less toxic, conserves water, reabsorption happens in nephrons, urinary bladder only stores urine

• suaropsids: converts citric acid, least toxic, conserves the most water but the most energetically costly, urinary bladder reabsorbs water

vision

• rods: rod shaped, peripheral, night vision, sense movement 

• cones: cone shaped, see color 

• synapsids: generally poor vision, mostly rods, 2 types( green blue)

• primates have 3 cones ( red, green, blue)

• sauropsids: good color vison, primarily cones, 4 types( red,green,blue, UV) ( 4 cones ancestral trait)