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HDSO Fossils > Trilobites > Flashcards

Trilobites Flashcards

1
Q

What are the 4 types of Trilobite

A

Calymene
Agnostus
Deiphon
Trinucleus

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2
Q

What is the phylum and class for Trilobites

A

Phylum - Arthropoda

Class - Trilobita

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3
Q

When did Trilobites evolve and become extinct

A

Evolved - Cambrian

Extinct - End of permian period

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4
Q

What is their exoskeleton made out of

A

Chitin

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5
Q

What does the exoskeleton act as

A

An anchorage for muscles

a suit of armour

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6
Q

What are the jointed legs and antennae known as

A

Appedages

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7
Q

What were the appendages used for

A

Moving

Feeding

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8
Q

What is a pleuron

A

Segment adjoining the axis

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9
Q

Each pleuron had a pair of what

A

Jointed legs

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10
Q

What did the legs have attached to them

A

Gills

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11
Q

What is the cephalon

A

The head

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12
Q

What role did the antennae have

A

Feeding

Sensory role

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13
Q

What is the cephalon made up of

A

Eyes
Facial structures
Free cheeks
Glabella

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14
Q

How would you describe the eyes and what did they consist of

A

Compound eyes

Many small lenses made of calcite

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15
Q

What may be attached to the glabella at the genal area

A

Spines for protection or spread the organisms mass

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16
Q

What is the thorax made up of

A

Thoracic segments

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17
Q

What does each thoracic segment possess

A

A pair of appendages and gills in life

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18
Q

What does each thoracic segment consist of

A

Two pleurae

A segment from the axis

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19
Q

What may each pleuron have

A

Spines extending from them

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20
Q

The thorax is made up of many what and making it what

A

Individual plates articulated together

Making it very flexible

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21
Q

Some trilobites were so flexible they could what

A

Enroll

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22
Q

What is the pygidium

A

Tail

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23
Q

What is the pygidium composed of

A

Several segments fused together

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24
Q

What is the process called by which a Trilobite sheds its skin

A

Ecdysis

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25
How did ecdysis occur
The exoskeleton fractured along the lines of weakness such as the facial structures. This separated the fixed cheek from the free cheek along the surface of the eye. The animal could then free its self then go on a period of rapid growth before the new exoskeleton was completely formed
26
What is adaptive radiaion
Its when Trilobites evolved to be a variety of different shapes and sizes probably as a response to the environment they lived in and the selection pressures in the environment
27
What is an example of a bethonic trilobite
Calymene
28
How big is the Trilobite Calymene
They are large
29
What do they show little of (Calymene)
Streamlining
30
What type of eyes do they have (Calymene)
Complex compound eyes
31
What did they have a lot of and what ability did it give them (Calymene)
Lot of pleura | The ability to enrol
32
mode of life for Calymene
Benthonic Epifaunal Living on the substrate Active hunters
33
Probable function for many pleura (Calymene)
Many pairs of legs for walking Supports many gills for respiration Can enrol for protection
34
Probable function for present-shaped compound eyes set high on the cheeks (Calymene)
Ability to see forward, backwards and sideways | Complex eyes may mean the animal was a hunter or scavenger
35
probable function for large and not streamline (Calymene)
Animal did not swim so no need to be small, light and streamline
36
What is an example of a pelagic trilobite
Agnostus
37
How big is the trilobite Agnostus
These are small and probably light trilobites
38
What did they lack (Agnostus)
Eyes
39
What did they have few of and what does this mean (Agnostus)
Pleura | Therefore few gills and legs
40
Where are they found (Agnostus)
They are widespread geographicaly
41
What type of sediments are they found in and what energy environment (Agnostus)
Shales | Low-energy deep waters
42
What is their mode of life (Agnostus)
Pelagic Planktonic Possible that their lack of eyes means a benthonic lifestyle in deep, cold water on ocean floor with no or minimal light
43
Probable function for no eyes or very small eyes (Agnostus)
Blind or nearly blind which means the animal did not hunt and its food source was filtered from the sea water or organic rich sediment
44
Probable function of inflated or large glabella and large pygidium (Agnostus)
Maybe filled with fat or gas | Seen as possible flotation device
45
Probable function for very small size (Agnostus)
Small to possibly stay afloat in water column
46
Probable function of few pleura (Agnostus)
Few legs which may be used as paddles or to steer animal | Limited flexibility and movement restricted
47
What is an example of a Nektonic trilobite
Deiphon
48
How big is the trilobite Deiphon
Small
49
What do they show (Deiphon)
Streamlining and have complex compound eyes on stalks
50
What is their mode of life (Deiphon)
Planktonic living in water column and nektonic Actively swimming possibly active hunters
51
Probable function for eyes on stalks (Deiphon)
Ability to see forwards, sideways, backwards and underneath | Complex eyes may mean the animal is an active hunter of scavenger
52
Probable function for inflated or large glabella (Deiphon)
May be filled with fat or gas which could be a possible flotation device
53
Probable function for very small size (Deiphon)
Small to stay afloat in water column
54
Probable function for numerous separated pleura, with spines (Deiphon)
Had many legs for swimming | The spines and separated pleura increased surface area to aid buoyancy
55
What is an example of a Burrowing trilobite
Trinucleus
56
What do these types of trilobites lack (Trinucleus)
Eyes
57
How was their cephalon modified (Trinucleus)
Shovel shaped with pits running along its margins
58
What is their mode of life (Trinucleus)
Benthonic Living on substrate as epifaunal or infernal organisms May have dug shallow borrows for protection or feed on organic rich sediment Lived at a 200M depth
59
Probable function of no eyes (Trinucleus)
Unlikely to hunt | Fed on organic rich sediment
60
Probable function of wide cephalic fringe (Trinucleus)
Maybe to spread was on soft substrate | Or as a digging tool
61
Extended genal spines (Trinucleus)
To spread mass | As a defence weapon
62
Pitted cephalic fringe (Trinucleus)
Pits may have housed sensory hairs in life | These may have been able to detect the movement of prey and water currents on the sea floor or temperatures or chemicals

HDSO Fossils (13 decks)

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