Exam 1 Chapter 3A:

Question 1

In addition to The Five Basic Chordate Characteristics, what other traits do vertebrates have?

Answer 1

skull, vertebrae

Question 2

Agnatha

Answer 2

• A-without
• Gnath: jaws

Question 3

Earliest vertberates known?

Answer 3

• From Agnatha
• Both segmented, have myomeres
• Haikouella – nerve cord district
• Haikouichthys – well developed nerve cord

Question 4

In Conodonts, what structure gives them their name?

Answer 4

o Named from their teeth
o Lots of cone-shaped teeth
o Skeleton cartilaginous

Question 5

Where do Ostracoderms get their name?

Answer 5

o “shell-skin”
o External “armor” covering of dermal bone(bones that form into the skin)

Question 6

Name defining traits of Ostracoderms

Answer 6

o Internal skeleton simple, made of cartilage
o No jaws - some had moveable mouthplates
o More derived forms had anterior paired fins
o vertebrate

Question 7

2 examples of living agnathans

Answer 7

Myxinoidea and Petromyzontida

Question 8

Myxinoidea

Answer 8

Hagfishes
o Deep sea marine organisms
o Not eels
o Mostly cartilaginous
o Produce slime from glands on body, prevents predation

Question 9

Petromyzontida

Answer 9

: Lampreys
o Seven porelike gill openings, well developed eyes, no paired fins
o No jaws: disc shaped mouth lined with keratinized teeth

Question 10

What characterizes placoderms?

Answer 10

o Paired appendages (fins)
o Movable jaws (derived from the 1st gill arch)
o Active predators
o No teeth (bony plates)
Heavy dermal shields

Question 11

What does Chondrichthyes mean?

Answer 11

Chon- cartilage
ichthyes - fish

Question 12

2 chondrichthyan groups

Answer 12

Elasmobranchii and Holocephali

Question 13

Elasmobranchii

Answer 13

well developed cartilaginous internal skeleton

Question 14

Holocephali

Answer 14

: example Chimaera
o Gill slits: covered by a fleshy operculum
o Teeth: grinding plates (lack enamel, slow replacement)
o No scales, except for small denticles on back and on claspers
o Palatoquadrate fused to cranium = holostylic jaw suspension

Question 15

Teleostomi

Answer 15

all bony fished and tetrapods

Question 16

Acanthodii defining traits

Answer 16

o Large eyes and short blunt heads, wide mouth
o Spiny fins
o Head, body protected by dermal armor (and small diamond-shaped scales)
o The skeleton composed of both bone and cartilage
o Large operculum

Question 17

How do members of the Actinopterygii differ from the Sarcopterygii ?

Answer 17

• Actinopterygii have ray fins, and Sarcopterygii have lobe fins

Question 18

Name traits that all bony fish have in common

Answer 18

• Operculum: covers and protects gills, help fish pump water over gills
• swim bladder: regulates fish boyuancy
• • Gas added and recycled gas used in order to promote helatheir environmet

Question 19

Actinopterygii

Answer 19

• Thin, membranous fins supported by fin rays that radiate out from the body wall
• A bony operculum covering their gills
• Most have a swim bladder

Paleonisciformes

Question 20

Plaeonisciformes

Answer 20

• primitive ray finned fishes, from skeleton structures (basic)
• bichirs, sturgeons, and spoonbills

Question 21

Bichirs

Answer 21

Ganoid scales
o An ossified skeleton
o A spiracle (reduced 1st gill slit)

Question 22

Sturgeons

Answer 22

o 5 rows of bony scutes (modified ganoid scales)
o A cartilaginous skeleton
o A spiracle (reduced 1st gill slit)

Question 23

Spoonbills

Answer 23

o No scales
o A cartilaginous skeleton
o A spiracle (reduced 1st gill slit)

Question 24

Neopterygii

Answer 24

includes holosteans and teleosts

Question 25

Holosteans: what sets them aparts from teleosts?

Answer 25

o Primitive neopterygians
o Ossified skeleton except for the braincase (a.k.a. neurocranium) which remains cartilaginous
o Gars, Bowfins

Question 26

Teleosts

Answer 26

o Cycloid/ctenoid scales
o Highly mobile jaws (more later)
o Currently make up 99% (20,000 species) of the living fish
o Tigerfish, pufferfish

Question 27

Defining traits of Sarcopterygii?

Answer 27

• Fleshy pelvic and pectoral fins with:
• single basal skeletal element
• central supporting elements
• muscular lobes
• Internal nares (or “choana”) that opens directly into the oropharyngeal cavity
• A swim bladder
• A bony operculum

Question 28

Groups of Sarcopterygians

Answer 28

Actinistia, Dipnoi, Rhipidistians

Question 29

Actinistia: Are there any living members of this group?

Answer 29

Only Coelacanth remains

Question 30

Dipnoi: What unique respiratory adaptation does this group posess?

Answer 30

o They have lungs! Lungfishes
o Cosmoid scales
o Skeleton mostly cartilage
o Prominent notochord

Question 31

Examples of Dipnoi

Answer 31

*Protopterus and Lepidosiren require access to air to get enough oxygen, or else they’ll suffocate
*both dig deep burrows in the mud and spend the dry, hot season (when the waters start to dry up), in a state of aestivation (a state of lowered metabolic activity)

Neoceratodus relies on its gills except in cases when the oxygen content on the water is too low

Question 32

Rhipidistians

Answer 32

o Their importance: common ancestor of tetrapods
o Direct ancestor of land birds
 The skeletal elements within the fin lobes of the Rhipidistians are very similar to the proximal skeletal elements of early tetrapod limbs
 The skull is similar to that of the first amphibians (Tiktallik!!)

Question 33

What is the significance of Tiktallik roseae?

Answer 33

Saw gap in the fossil record of about 10 million years
o Strong conclusion of transition from water to land
o - First fish like animal with gap between pectoral girdle and fused head bones