Midterm 1

Question 1

Agnathans

Answer 1

Vertebrate lacking jaws (myxinoidea and petromyzonidae)

Extant do not have ribs

Lack sternum

Question 2

Gnathostomes

Answer 2

Creatures with jaws

Question 3

Myxinoidea

Answer 3

Cartilaginous jawless notochord having hagfish; lack vertebrae

Question 4

Petromyzontida

Answer 4

Cartilaginous, jawless, notochord having, cartilaginous limbs having

Question 5

Chondrichthyes

Answer 5

Elasmobranchii (sharks and rays) and holocephali (chimeras or ratfish)

Cartilaginous skeleton - griddles and paired fin rays - pectoral and pelvic griddle doesn’t attach to skull or vertebral column, instead muscle

Lack sternum
Claspers of fins transfer sperm

Question 6

Holocephali

Answer 6

Cartilaginous bone structure - lack ribs lack centra

Question 7

Elasmobranchii

Answer 7

Cartilaginous skeleton - ribs often greatly reduced, centra have narrow canal for notochord, in between each vertebrae the notochord thickens to provide a pad - stops bones from grinding spinal chord protected

Vertebral column - 2 regions trunk and caudal

Paire

Question 8

Acinopterygii

Answer 8

(Telestei)

Bony skeletons - endochondral bone, each vertebra has a centrum where the notochord passes through narrow hole- spinal chord protected

Vertebral column has caudal and trunk

Griddles and paired ray fins supported by radials

Pectoral griddle attached to dorsal posterior of skull - pelvic attaches to muscle

Lack sternum

Gas bladder provides buoyancy

Question 9

Sarcopterygii

Answer 9

Dipnomopha and tetrapoda

Gas bladders act as lungs

Question 10

Dipnomorpha

Answer 10

Grouped with actinopteryii (bony fish)

Have both lungs and gills

Centra are either small or not there, neural arch and hemal arch rest on large notochord

Vertebral column has caudal and trunk

Has griddles and paired fleshy fins that articulate using the humerus

Lack sternum

Pectoral griddle attached to dorsal posterior region of skull

Question 11

Tetrapoda

Answer 11

Limbs - paired muscular appendages with joints and digits

Notochord during development, but eventually gets lost

Vertebrae is endochondral bone - articular ends of centra coated with intervertebral bodies (disks in mammals and contain parts of notochord) for shock absorption

Axial skeleton suspended from pectoral griddle by muscles

Anterior vertebra is atlas - lacks centrum, allows skull to rock

Cervical and sacral region differentiated

Most have sternum, but vary across the taxa

Limbs - sprawled or erect

Vertebrae have zygapophyses which interlocks them and stops twisting

Marrow filled bones

Question 12

Teleostomi

Answer 12

Bony fish and tetrapods

Adjustable gas bladder

Question 13

Amphibia

Answer 13

Aquatic larval stage with gills, grow into semi or fully terrestrial adults

Lungs for gas exchange

Only one cervical vertebra - atlas

Ribs don’t articulate with sternum

Sprawled limb posture

Anamniotes

Question 14

Amniotes

Answer 14

Produce amnion, chorion, allantois and yolk sack as embryos

Vertebral ribs articulate with sternum

Sternal ribs articulate with sternum

2 cervical bones, anterior atlas, then axis

Question 15

Sauropsida

Answer 15

Amniotes

Testudinata, lepidosauria and archosauria (crocodilia and aves)

Question 16

Mammalia

Answer 16

Monotremata-egg laying
Therians(metatherians-marsupials,eutheian-young born later in development)-free living young

Intervertebal disks have remnants of notochord

Many have erect limbs

Question 17

Testudinata

Answer 17

Bony shell, carapace dorsal , plastron ventral

Question 18

Lepidosauria

Answer 18

Snakes and lizards

Hemipenis

Sprawled

Question 19

Archosauria

Answer 19

Crocodilia and aves

Question 20

Crocodilia

Answer 20

Sprawled limbs

Question 21

Aves

Answer 21

Erect limbs

Feathers, endothermy (warm blooded)