Geology PAG 5: Investigating fossils

Suggested Activity 1: Identifying fossilsInstructions for teachers & techniciansThis 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 A Level 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 www.ocr.org.uk/positiveaboutpractical or email us at PASS@ocr.org.uk.

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 useful for carrying out risk-assessments: (http://science.cleapss.org.uk).

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.

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IntroductionLearners will use an identification system (dichotomous key) based on a hierarchy of symmetry to identify a range of fossils to phylum (or class) 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 (or class) level to produce scientifically annotated drawings of fossils.

Intended class time 1 hour

Practical Skills – competence assessed by the teacher1.2.1 (b) safely and correctly use a range of practical equipment and materials1.2.1 (c) follow written instructions1.2.1 (d) make and record observations/measurements 1.2.1 (f) present information and data in a scientific way1.2.2 (f) application of classification systems using distinguishing characteristics to identify unknown minerals and fossils1.2.2 (g) production of annotated scientific drawings of fossils, or small scale features, from hand samples using a light microscope, or hand lens observation1.2.2 (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 Specifications2.2.1 (a) fossils as the preserved remains of living organisms or the traces of those organisms2.2.1 (b) the nature and the reliability of the fossil record and the morphological definition of species2.2.2 (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 Palaeozoic7.1.2 (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

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7.1.2 (a)(iii) the adaption of the basic brachiopod morphology to occupy high energy and low energy marine environments7.1.2 (a)(iv) the morphological similarities and differences between brachiopods and bivalves7.2.3 (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:o M1.1 Recognise and make use of appropriate units in calculations.o M1.3 Use an appropriate number of significant figures.o M1.5 Make order of magnitude calculations.o M2.11 Plot two variables from experimental or other linear data.o M4.2 Visualize and represent 2D and 3D forms, including 2D representations of

3D objects

ChemicalsLabel Identity Hazard information

none used — —

EquipmentEach 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 (http://www.cleapss.org.uk).

NotesCentres 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,

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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 Activities1. 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 http://www.palaeocast.com/vnhm/ 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).

4. 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 into ecdysis/moulting stages. There may be overlap between the characteristics chosen however species will be defined based on multiple characteristics.

RecordsAs 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 theory and are a preparation for 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.

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Document updatesv1.0 May 2017 Original version.

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OCR Resources: the small printThis formative assessment resource has been produced as part of our free A Level teaching and learning support package. All the A Level teaching and learning resources, including delivery guides, topic exploration packs, lesson elements and more are available on the qualification webpages.

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Geology PAG 5: Investigating fossils

Suggested Activity 1: Identification of fossils

Learner activityIntroductionIn 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 producing scientific drawing(s) of what you see. You will be expected to use standard scientific practice including adding annotations and a scale bar to your drawing(s).

Aims to use a dichotomous keyto identify different types of fossil samples to phylum (or class) levelto produce scientifically annotated drawings of fossils.

Intended class time1 hour

Equipmentaccess to a tray of fossils containing contrasting samples for some particular fossils. Some of the fossil samples may be plaster castsdichotomous keycallipers or rulerhand lensaccess 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.

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ProcedureBefore starting your practical work, read the information below.

1. Scan through the dichotomous key and 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 activity from 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 preservation6. 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 opportunities1. 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.

4. (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.

RecordsAs 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.

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RESOURCE SHEETGeology PAG 5.1 Identifying fossilsKey for Identification of Common Fossil Organisms1 Displays radial or imperfect-radial symmetry go to 2

Displays bilateral symmetry in at least one plane go to 6Displays no apparent symmetry go to 13

2 Tapering; cylindrical; cigar- or cone-shaped go to 3Composed 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 7Non-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 9Shell halves unequal in size and shape go to 10Circular- to heart-shaped; flattened disc or domed go to 10Tapering, cone, tusk, or horn shaped go to 11Body segmented into distinct head, thorax (body), and tail regions go to 12Leaf- 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

Based on Davis and Eves (1988)

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 14Not 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 16Irregular cone-shaped; longitudinal and radial walls or partitions go to 16Composed of radiating mass of polygonal or circular tubes go to 16Resembles a clam or oyster shell; shell not symmetrical go to 17Cup-shaped; branching arms; flower-like; may have attached stem go to 17Lace-like; usually thin sheets go to 17Branching, twig-like go to 18Resembles 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; commonly appears 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

Bilateral symmetry

Based on Davis and Eves (1988)

No apparent symmetry

Based on Davis and Eves (1988)