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Flashcards in early vertebrates? primitive fish? Deck (24)
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1

What is a fish?

A vertebrate that isn't a tetrapod

2

Give 5 characteristics of the early Cambrian fossilised vertebrates

Cranium
W-shaped myomeres
Heart and fin rays
Lack mineralised tissues
Soft bodied

3

When are the early Camrbian fossils from?

535 mya

4

Where were the early Cambrian fossils found?

Chengjiang, China

5

When did mineralised tissue appear in the fossil records?

Late Cambrian

6

When did bone fragments appear in the fossil records?

Early Ordovician - 480 mya

7

When did complete fossils first appear in the record?

Late Ordovician

8

Where were the first complete fossils found?

Bolivia and Australia

9

Give an example of a complete fossil from late Ordovician Bolivia

Astraspis

10

Give 5 characteristics of Astraspis

Torpedo shaped
Jawless
External armour, head shield and bony plating
Gill openings
Sensory canals

11

What did the Astraspis use its sensory canals for?

Detecting changes in water pressure (like modern day fish)

12

Why may the Astraspis have needed external armour?

Protection from large marine invertebrates

13

What are conodonts?

Microfossils spanning fossil records from Cambrian to Triassic, turned out to be teeth

14

What are conodonts made of?

Apatite

15

What are jawless fish called?

Agnatha

16

What are the 2 classes of agnatha?

Myxinoidea
Petromyzontia

17

Give 8 general characteristics of jawless fish

Slender eel-like bodies
Naked skin (no scales)
Cartilaginous skeleton/cranium
Notochord persistent
No vertebrae or jaws
5-16 pairs of gills
Distinct brain
No distinct stomach

18

How many species of hagfish are there?

65

19

Why don't hagfish lose ions or water to the surrounding environment?

They have an osmotic equilibrium with seawater

20

How do hagfish defend themselves against predators?

They produce slime which clogs up a predator's mouth and gills, making it hard to breathe

21

Describe the hagfish circulatory system

Low pressure
1 main heart with 3 accessory hearts

22

What are Myxinoidea known as?

Hagfish

23

What are Petromyzontia known as?

Lampreys

24

Give 4 morphological characteristics of hagfish

Single nasal opening
Single semi-circular canal
Degenerate, skin-covered eyes
Mucoid bag