Trilobites Flashcards

1
Q

Phylum and class?

A

Arthropoda

Trilobita

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Exoskeleton?

A

Chitin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Three main body parts

A

Cephalon, thorax, pygidium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does it breathe?

A

Gills attached, underneath pleuron with appendages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe morphology of cephalon

A

Several structures, compound eyes, facial sutures, free cheek, fixed cheek and glabella. Spines may be attached at genal angle, for defence or to spread mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe morphology of the thorax

A

Made up of thoracic segments, each has pair of appendages and gills, two pleurae and segment from axis. Many articulated plates which may enable it to enroll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe morphology of the pygidium

A

Several segment fused together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is ecdysis?

A

Exoskeleton cannot grow so is shed. Fractured along lines of weakness like facial sutures, separated fixed cheek from free cheek, animal wriggles out, period of rapid growth before new skeleton forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When did trilobites live?

A

Cambrian to Permian-died at end Permian extinction, peaked in Ordivician

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Example of epifaunal trilobite

A

Calymene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What morphological features did Calymene posses?

A

Many pleura, to support many legs and gills, flexible so could enroll
Compound eye, ability to see 360 degrees, so safe from predation, may be active hunter
Large and not streamlined, didn’t need to swim or float, walked on sea floor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Name a pelagic trilobite

A

Agnostus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What morphological features did Agnostus possess?

A

No eyes, did not need to hunt for food as filter feeder
Very small and light, so could easily float in water column
Inflated glabella, filled with gas for buoyancy
Few pliers, didn’t swim, limited flexibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Name a nektonic trilobite

A

Dephion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the morphological features of Dephion?

A

Eyes on stalks, could see all around it
Inflated glabella for flotation
Very small size, light to stay afloat
Numerous separated pleura with spines, could be used to paddle, increase surface area for buoyancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name a burrowing, infaunal trilobite

A

No eyes, unlikely to hunt, couldn’t see in sediment
Wide cephalic fringe, spread mass on soft sediment
Extended genal spines, defence and to spread mass
Pitted cephalic fringe, sensory hairs