Geology PAG 5: Investigating fossils

Suggested Activity 1: Identifying fossils

Instructions for teachers& technicians

This practical activity is composed of two parts; a teacher/technician section and the learner activity which can be found on page 7.This practical activity supports OCR AS/A Level Geology.

When distributing the activity section to the learners either as a printed copy or as a Word file you will need to remove the teacher instructions section.

This is a suggested practical activity that can be used as part of teaching the OCR AS and ALevel Geology specifications helping to fulfil the requirements of the Practical Endorsement.
These are not required activities, nor are they coursework tasks.
You may modify these activities to suit your learners and centre. Alternative activities are available from, for example, ESTA, Earth Learning Idea, CLEAPSS and publishing companies. Support for mapping activities to the requirements of the Practical Endorsement is available from OCR – see or email us at .
Students can collaborate during the activities but each student must individually demonstrate competence in each of the practical skills being assessed (see Practical Skills below).
It is possible for a student to achieve some but not all of the practical skills involved in an activity (and this can be recorded as individual skills in the OCR PAG Tracker).
Further details are available in the specifications (Practical Skills Topics).

OCR recommendations:

Before carrying out any experiment or demonstration based on this guidance, it is the responsibility of teachers to ensure that they have undertaken a risk assessment in accordance with their employer’s requirements, making use of up-to-date information and taking account of their own particular circumstances. Any local rules or restrictions issued by the employer must always be followed.

CLEAPSS resources are usefulfor carrying out risk-assessments: ().

Centres should trial experiments in advance of giving them to learners. Centres may choose to make adaptations to this practical activity, but should be aware that this may affect the Apparatus and Techniques covered by the learner.

This document may have been modified– if in doubt check the master version on OCR Interchange.

Version 1.0 – May 20171© OCR 2017

Introduction

Learners will use an identification system (dichotomous key) based on a hierarchy of symmetry to identify a range of fossils to phylum(orclass) level. A common misconception is where learners picture match specimens to force any fossil into a limited number of ideal archetypes, or to give up when a specimen is not perfect. By developing the skill of systematically working through the observable morphological characteristics they develop the skills to handle fossil material in the field and laboratory. Learners are expected to be familiar with different types of fossils (body, casts, impressions), fossil preservation and the concept of body symmetry.

Aims

  • to use a dichotomous key
  • to identify different types of fossil samples to phylum (orclass) level
  • toproduce scientifically annotated drawingsof fossils.

Intended class time

  • 1 hour

Practical Skills – competence assessed by the teacher

1.2.1 (b) safely and correctly use a range of practical equipment and materials

1.2.1 (c)follow written instructions

1.2.1 (d) make and record observations/measurements

1.2.1 (f) present information and data in a scientific way

1.2.2 (f) application of classification systems using distinguishing characteristics to identify unknown minerals and fossils

1.2.2 (g) production of annotated scientific drawings of fossils, or small scale features, from hand samples using a light microscope, or hand lens observation

1.2.2 (l) use of methods to increase accuracy of measurements, such as timing over multiple observations, or use of a fiducial scale (in photograph/field sketch).

CPAC – competence assessed by the teacher

(1)follows written procedures

(3)safely uses a range of practical equipment and materials

(4)makes and records observations.

Links to Specifications

2.2.1 (a) fossils as the preserved remains of living organisms or the traces of those organisms

2.2.1 (b)the nature and the reliability of the fossil record and the morphological definition of species

2.2.2 (b)the geochronological division of the geological column for the Phanerozoic into eras and systems using a biostratigraphic relative time sequence. To include basic identification of main invertebrate groups (trilobites, corals, brachiopods, bivalves, cephalopods)

7.1.2 (a)(i)the adaption of the basic trilobite morphology to occupy multiple marine niches during the Palaeozoic

7.1.2 (a)(ii) the application of the ecology of modern reef building (scleractinian) corals to interpret and compare fossil corals (tablulate, rugose) as palaeoenvironmental indicators of reef building in the geological record

7.1.2 (a)(iii)the adaption of the basic brachiopod morphology to occupy high energy and low energy marine environments

7.1.2 (a)(iv)the morphological similarities and differences between brachiopods and bivalves

7.2.3 (a)(iii)the zonation of the Welsh Basin using zone fossils (trilobites, corals and graptolites)

7.2.3 (b)(iii)the zonation and correlation of the Jurassic Period using ammonites and belemnites

Mathematical Skills – learning opportunity within activity

  • Mathematical skills must be applied in the recording of the data and calculations, and in analysing the data. These steps require the appropriate application of the following mathematical skills:
  • M1.1Recognise and make use of appropriate units in calculations.
  • M1.3Use an appropriate number of significant figures.
  • M1.5Make order of magnitude calculations.
  • M2.11Plot two variables from experimental or other linear data.
  • M4.2Visualize and represent 2D and 3D forms, including 2D representations of 3D objects

Chemicals

Label / Identity / Hazard information
none used / — / —

Equipment

Each learner or group will require:

  • access to a tray of fossils containing both on and off specification examples. Ideally there should be two contrasting samples for each particular group(e.g. whole and partial, body and mould, morphologically different). Plaster casts may also be included fossils. Loan teaching sets may be available through your local museum service. Specimens may include
  • dichotomous key – resource sheet
  • callipers or ruler
  • hand lens
  • access to reference material (e.g. British Mesozoic Fossils, NHM)

Health and Safety

  • Health and safety should always be considered by a centre before undertaking any practical work. A full risk assessment of any activity should be undertaken including checking the CLEAPSS website (

Notes

Centres are advised to trial this activity before using it with students. In particular:

  • being able to use the key is more important than being able to sight identify fossils,
  • this activity has been adapted from Davis, L.E. and Eves, R.L., 1988 Identification of Common Fossil Organisms for Introductory Geology: Journal of Geological Education, v36, p253-255,
  • learners may initially need support to get their eye in rather than expect perfectly prepared museum examples; the centre should try the experiment in advance with the sample tray and a non-specialist using the key,
  • learners will need to be made familiar with the following technical terms: radial and bilateral symmetry; cone, horn and tusk-shaped; low and high spire; coiling and partitioning (simple diagrams may help). Nearly all organisms have some type of symmetry at some level, but for some organisms (such as colonial corals) this may be difficult to observe, these are included as having no apparent symmetry.

Answers and Guidance to Extension Activities

  1. Learners may need direction in selecting the appropriate NHM fossil guide book. The object is for learners to experience that detailed analysis or identification to species level is difficult. Once launched later in 2017 will be a suitable alternative online resource.
  2. Palaeontology is a specialised field and most geologists will be unfamiliar with most fossils below class or order. Without experience of which morphological characteristics should be used using photographs or drawings can be easily misinterpreted. Using a geological field guide it is possible to learn the common fossils at a site but not all fossils everywhere. Your local museum will have a reference collection which can be used to identify fossils from the local area.
  3. Where the body of the fossil has been directly preserved the wall of the fossil will show structure and organisation; the pore spaces may be filled with secondary minerals that encase the shell material.Where the shell has been recrystalised (e.g. aragonite by calcite) internal microstructure will be changed and crystal size will be larger. Replacement results in the shell material being replaced by a different mineral (e.g. silica).
  1. The characteristics chosen may be gross form such as length or based on the key. Where appropriate this activity could be used to demonstrate competence in 1.2.2(j)use of appropriate apparatus to record a range of quantitative measurements (to include mass, time, volume, temperature and length).This activity can be used to support Learning objective 2.2.1(b) the morphological definition of species. If insufficient fossils are available then recent shell material can be used and by selecting individuals a sample can be produced to demonstrate a continuous or discontinuous growth curve, or to show two morphologically distinct species (by choosing muscle and cockle shells).A single species will typically show one growth curve even where there is sexual dimorphism, missing growth stages (mother and child but no immature individuals) or grouping intoecdysis/moulting stages. There may be overlap between the characteristics chosen however species will be defined based on multiple characteristics.

Records

As evidence for the Practical Endorsement, learners:

  • should not need to re-draft their work, but rather keep all of their notes as a continuing record of their practical work, dating their work clearly,
  • should produce correctly annotated drawings of their specimens – this means the drawings need to be drawn with a sharp pencil with no sketching, be labelled with a ruled line, include a scale bar and be correctly titled.

Extension questions help learners develop their understanding of the underlying geological theoryand are a preparationfor the written examinations. They also help learners to develop the practical science skills assessed indirectly in the written examinations and they should be encouraged to record their data appropriately, for example showing full workings in calculations, and stating final answers to the appropriate number of significant figures.

Document updates

v1.0May 2017Original version.

This document may have been modified– if in doubt check the master version on OCR Interchange.

Version 1.0 – May 20171© OCR 2017

This document may have been modified– if in doubt check the master version on OCR Interchange.

Version 1.0 – May 20171© OCR 2017

Geology PAG 5: Investigating fossils

Suggested Activity 1:Identification of fossils

Learner activity

Introduction

In this practical activity you will be using a classification system (dichotomous key) to identify fossils down to phylum (or class)level.What is important is being able to identify and systematically use the morphological features of fossils to classify them rather than matching gross shape or identifying by sight. Unless they have been prepared by a conservator most fossils are not perfect and it will take practice to get your eye in to see detail.

You are expected to be familiar with different types of fossils (body, casts, impressions), fossil preservation and the concept of body symmetry. You will need to be able to identify certain morphological characteristics: radial and bilateral symmetry; cone, horn and tusk-shaped; low and high spire; coiling and partitioning.

You will be producingscientific drawing(s) of what you see. You will be expected to use standard scientific practice including adding annotations anda scale bar to your drawing(s).

Aims

to use a dichotomous key

to identify different types of fossil samples to phylum (or class) level

to produce scientifically annotated drawingsof fossils.

Intended class time

1 hour

Equipment

access to a tray of fossils containing contrasting samples for some particular fossils. Some of the fossil samples may be plaster casts

dichotomous key

callipers or ruler

hand lens

access to reference material – for use with extension activities

Health and Safety

  • Handling fossils should not introduce any additional risk to the class environment. You should follow your centre’s practice on handling environmental and geological materials.

This document may have been modified– if in doubt check the master version on OCR Interchange.

Version 1.0 – May 20171© OCR 2017

Procedure

Before starting your practical work, read the information below.

  1. Scan through the dichotomous keyand make sure that you understand the language in the classification statements.
  2. Select a sample fossil and compare it to the first set of statements in the key. Based on your observations decide whether the whole fossil has radial symmetry, only bilateral symmetry or no apparent symmetry.
  3. Work through the key and classify the phylum (or class) of the sample fossil.
  4. Repeat the activityfrom step 2 with a contrasting fossil sample. Work through the procedure until you are confident using the dichotomous key.
  5. Select a contrasting pair of fossils that you have classified. These may be the same group or similar overall shape or contrasting preservation
  6. Produce a scientific drawing of what you see. Use the hand lens to identify fine detail and add a scale bar to your drawing. Annotate the drawing identifying the morphological characteristics used to classify the two fossils.

Extension opportunities

  1. Using the reference material available in class attempt to identify the fossils that you have drawn to class, order, family or species.
  2. Suggest why geologists will refer samples to a specialist palaeontologist to identify them to a higher degree (for example to species rank)?
  3. Select a fossil where you can clearly see the mineral crystals in the fossil. Examine the fossil with your hand lens and produce a scientific drawing of what you see. Based on your observations suggest whether the minerals have been directly preserved (secreted by the organism) or have been replaced or recrystallised after death.
  1. (a) Select a fossil for which you appear to have multiple examples (this may be recent shell material). Select two measurable morphological features that appear characteristic and measure both characteristics for all the individuals in the sample.

(b) Plot the two variables on a scattergraph with an appropriate scale.

(c) Describe the distribution that you observe. Based on your observations suggest whether these individuals are a single species and whether they are a complete community or a subsample of a particular age group.

Records

As evidence for the Practical Endorsement, you need records of:

  • your annotated drawings of the contrasting fossil specimens,
  • any modifications to supplied procedures, or notes you have made to assist you in using the dichotomous key.

All work should be clearly dated.

In addition you should have considered the above questions as the answers to these questions will aid you in preparation for your written examinations.

This document may have been modified– if in doubt check the master version on OCR Interchange.

Version 1.0 – May 20171© OCR 2017

RESOURCE SHEET

Geology PAG 5.1 Identifying fossils

Key for Identification of Common Fossil Organisms

1 / Displays radial or imperfect-radial symmetry  go to 2
Displays bilateral symmetry in at least one plane  go to 6
Displays no apparent symmetry  go to 13
2 / Tapering; cylindrical; cigar- or cone-shaped  go to 3
Composed of segments or plates; may or may not taper go to 4
3 / Smooth, cigar-shaped; radiating calcite needles in cross-section = MOLLUSCA (Cephalopods)
Poorly developed radial symmetry; tapering; irregular horn or cone-shape; several may grow together as a colony = CNIDARIA (Corals)
Small (1-5mm); football-shaped = PROTISTA (Forams)
4 / Tapering; stacked circular segments = MOLLUSCA (Cephalopods)
Non-tapering; stacked discs or plates; discs may have small protrusions; may have hole in centre of discs = ECHINODERMATA (Crinoid Stems)
Composed of interlocking segments or plates  go to 5
5 / Rosebud-shaped = ECHINODERM (Blastoids)
Cup- or flower-shaped; cup may have many branching appendages (arms); may be attached to crinoid stem = ECHINODERMATA (Crinoids)
6 / Coiled forms, snail-like  go to 7
Non-coiled forms  go to 8
7 / Coiled in plane of bilateral symmetry; may show internal walls or partitions = MOLLUSCA (Cephalopods)
Perfect to irregular coil perpendicular to plane of symmetry; may show internal walls or partitions; snail like = MOLLUSCA (Gastropods)
8 / Shell halves equal or nearly equal in shape and size  go to 9
Shell halves unequal in size and shape  go to 10
Circular- to heart-shaped; flattened disc or domed  go to 10
Tapering, cone, tusk, or horn shaped  go to 11
Body segmented into distinct head, thorax (body), and tail regions  go to 12
Leaf- or fern-like; commonly found on bedding surfaces of mud/siltstones = LEAF FOSSIL
9 / Plane of symmetry parallel to shell half = MOLLUSCA (Bivalves)
Plane of symmetry perpendicular to shell, as well as parallel to shell half = MOLLUSCA (Bivalves)
10 / Shell halves unequal in size and shape; larger shell half often shows a prominent beak with strong ridge; smaller half often has a prominent depression = BRACHIOPODA (Brachs)
Circular- to heart-shaped; flattened disc or domed; star pattern on upper surface; like a sand dollar
= ECHINODERMATA (Echinoids)
11 / Cone- or horn-shaped (may be irregular); transverse walls or partitions (like spokes on a wheel)
= CNIDARIA (Corals)
Tusk-shaped; smooth or ribbed external surface; opening at both ends; no internal walls or partitions
= MOLLUSCA (Scaphapods)
12 / Bug-like; divided into three body lobes; may have appendages; often only semi-circular head and tail regions are preserved = ARTHROPODA (Trilobites)
Appendages often very distinct; resembles crab, shrimp, or crayfish = ARTHROPODA (Crustaceans)
13 / May show coiling, but without internal transverse walls or partitions go to 14
Not coiled go to 15
14 / Coiled like a horn; low spired; opening of shell very large; ribbed surface (may be concentric); two mirror image shells may be present = MOLLUSCA (Bivalves)
Tightly coiled; most are high spired; looks like a snail = MOLLUSCA (Gastropods)
Solid spiral ridge around a central axis; resembles a corkscrew = BRYOZOA (Ramose Bryozoa)
15 / Resembles a narrow saw blade; straight or curved; may be joined like branching leaves go to 16
Irregular cone-shaped; longitudinal and radial walls or partitions go to 16
Composed of radiating mass of polygonal or circular tubes go to 16
Resembles a clam or oyster shell; shell not symmetrical go to 17
Cup-shaped; branching arms; flower-like; may have attached stem go to 17
Lace-like; usually thin sheets go to 17
Branching, twig-like go to 18
Resembles woody material; commonly replaced by quartz; wide variety of colours = PETRIFIED WOOD
16 / Resembles a narrow saw blade; straight or curved; may be joined like branching leaves; commonlyappears as carbon film on flat surfaces of shales and slates = HEMICHORDATA (Graptolites)
Irregular cone-shaped; longitudinal and radial walls or partitions = CNIDARIA (Corals)
Composed of radiating mass of polygonal or circular tubes containing radial walls or partitions
= CNIDARIA (Colonial Corals)
17 / Resembles a clam or oyster shell; shell not symmetrical = MOLLUSCA (Bivalves)
Cup-shaped; branching arms; flower-like; may have attached stem = ECHINODERMATA (Crinoids)
Lace-like; usually thin sheets = BRYOZOA (Fenestrae Bryozoa)
18 / Covered with minute pores or openings = BRYOZOA (Ramose Bryozoa)
Evenly distributed 1-4mm openings or pores; radial partitions in openings = CNIDARIA (Corals)

Radial symmetry