Synapomorphies

Question 1

Hemichordata

Answer 1

Stomachord, 3 segmented body

Question 2

Hemichordata - Chordata

Answer 2

Pharyngeal Gill Slits

Question 3

Chordata

Answer 3

1. Dorsal Hollow Nerve Chord
2. Notochord
3. Post-anal tail
4. Endostyle

Question 4

Urochordata

Answer 4

lack notochord, nerve cord becomes gland, tunic (cellulose-like)

Question 5

Cephelachordata

Answer 5

Illiocolic ring, Metapleural folds, wheel organ, midgut cecoem,

Question 6

Amniota

Answer 6

Amniotic egg (chorion, amnion, allantois), chevron bones

Question 7

Aves (birds)

Answer 7

enlarged sternum for breast (flight muscles), furcula (fused clavicle bones), fused pelvic girdle to synascrum,
fused caudal vertebrae to pygostyle

Question 8

Anurans (frogs)

Answer 8

Urostyle - fused caudal vertebrae

Question 9

Osteichthyes (bony fish)

Answer 9

opercular bone (cannot move head separate from body and protects
gills), segmented, boney (lepidotrichia) fin rays

Question 10

Tetrapods

Answer 10

sternum, limbs, loss of post temporal and opercular bones, sacroiliac joint (pelvic girdle
articulates with vertebral column), no fins

Question 11

Gnathostomes

Answer 11

pelvic and pectoral girdles, hemal and neural arches

Question 12

Amphibians

Answer 12

elongated ilium, cartilaginous pubic, columella ear bone

Question 13

Mammalia

Answer 13

three bones of pelvic girdle fused, three divisions of sternum, hair, ear bones (stepes, malleus, incus), placenta and umbilical cord,

Question 14

Deuterostomia

Answer 14

Blastopore -> anal opening, Enterocoelus coelom formation

Question 15

Protostomes

Answer 15

Blastopore -> mouth, schizocoelous coelom formation

Question 16

Agnatha (Petromyzontidae)

Answer 16

keratinized teeth, oral disk