Geol 5, Lab #11: Fossils and Their Living Relatives: Mollusks, Arthropods, Echinoderms, Graptolites, and Plants

Please note that not all of these questions have been assigned during the current semester. Feel free to check your answers or try to answer other questions using the present key.

MOLLUSKS: Bivalves

question 4, page 127

Heavy-shelled bivalves are mainly nearshore dwellers because they evolved in a high-energy environment (where waves break). In such an environment, thin-shelled bivalves could not survive, unless they evolve into a more resisting form.

question 6, page 127

Filter feeders means that bivalves feed by filtering nutrients out of water.
From page 124: "Incoming water moves over the gills where food particles are trapped and carried into the digestive system"

MOLLUSKS: Gastropods

question 4, page 128

Only Euomphalus, Maclurites, and Bellerophon

MOLLUSKS: Cephalopods

question 2, page 131

a - Most cephalopods coil in a plane, while the majority of gastropods are helicoids.
b - The cephalopod conch is divided into chambers by septa, and the animal lives in the last chamber.

question 6, page 133

Cephalopods diversified quickly
Cephalopods were nektonic
Cephalopods were mostly predators

question 7, page 134

When the miners reach the abrupt end of the coal seam at point A, they are moving along a time surface (our coal layer). The geologist, as you read in the question, describes a rock containing belemnites, similar to the one described before, across the fault plane. This means that the younger belemnite-containing rock has been brought down to the same level of the coal seam. Or, the hanging wall moved downward with respect to the footwall.

As a consequence:

The prospects for additional recovery of coal across the fault are bad: in order to find coal again you have to dig vertically by the same distance encountered in the original, vertical mine shaft
The fault is a (dip-slip) normal fault

ARTHROPODS: Trilobites

question 2, page 136
Compound eyes

question 3, page 136
Just sketch any of the trilobites from our collection or from page 137, and label your drawing according to the question

question 4, page 136

Trilobites grow by molting
Because of that, it is possible to have several fossil trilobites from a single individual

question 6, page 139
You sketched these divisions on the drawing for question number 4. Here they are again, in order:

The two pleural lobes and the axial lobe
The cephalon, the thorax, and the pygidium

ARTHROPODS: Ostracoda

question 2, page 140
For instance, brachiopods and bivalve mollusks.
They are different in size and chemical composition of the shell

ECHINODERMS

question 4, page 147
The stem, the calix, and the arms (brachioles)

GRAPTOLITES

question 1, page 149
They live in cup-like thecas arranged in narrow branches called stipes, either attached to sthe seafloor, suspended from floating objects, or following a planktonic life style

question 2, page 149
Graptolites differ from corals because, among other things:

They are grouped into colonies
They have a chitinous skeleton
They can live suspended from floating object

question 3, page 150
The living habits of graptolites contribute to their being good index fossils because of:

Their worldwide distribution
Their rapid evolution

FOSSIL PLANTS

question 3, page 154

Gymnosperms do not need to be in constant contact with water
Gymnosperms reproduce sexually

question 4, page 154
This is sort of an open answer, and you will get credit as long as what you write makes sense.