2FossilsA fossil is a feature which records organisms or plants in rocks. Fossils can include hard parts of the organism such as skeletons, bones, plant material, pollen or shells.Trace fossils record the activities of animals or plants, but do not include any hard parts. Trace fossils include burrows, footprints and feeding tracks.
3Bivalves TEETH UMBO SOCKET GROWTH LINES RIBS PALLIAL LINE MUSCLE SCARS THICK SHELLEVIDENCE FOR MODE OF LIFE?High energy, intertidal shorelines: Thick shell, large muscle scars, strong teeth and socket arrangements.
4Interior of a bivalve TEETH AND SOCKETS UMBO PALLIAL LINE MUSCLE SCARS The line of symmetry of bivalves runs BETWEEN the two valves.
5Pecten (scallop)Thin, light shell for floatingMode of life: Pectens float/swim between periods on the sea bedEARSStrong ribs to live in high energy waterThis bivalve is nearly symmetrical but the ears are not the same and the umbo leans slightly to the left.
6Bivalves in their life positions (life assemblage) St Bees sandstone, St Bees, Lake DistrictFlags on the Pennine WayMussels beds on a present day shore
7Burrowing bivalvesTEETH AND SOCKETSUMBO5cmGROWTH LINESMUSCLE SCARSBivalves which burrow are likely to be more elongated than those which live on the top of the sea-bed. They may also have a gape (the valves do not meet at one end) so that the siphons which enable them to feed can reach the surface of the sea-bed.
8BRACHIOPODS LINE OF SYMMETRY CUTS THROUGH THE VALVES GROWTH LINES PEDICLE OPENINGBrachiopods differ from bivalves in that they have a sessile mode of life – they live attached to the sea-bed by a pedicle, which is a tough ligament which emerges from the pedicle opening.
9Rhynchonella is a very common Jurassic brachiopod, with heavily ribbed valves. UMBOPEDICLE OPENINGLINE OF SYMMETRYRIBSRhynchonella has two valves which close together very tightly, suggesting that they lived on intertidal shorelines which had high energy breaking waves.
10Jurassic brachiopodsPicture from the Palaeontological Association
11Carboniferous brachiopods in black shales These valves of the brachiopod Productus are not broken up, but they are separated. That suggests that they have been transported by gentle waves or currents into the area of muds without being fragmented.Carboniferous brachiopods in black shales
12CORALSIn this Silurian coral, Halysites, the individual corallites have been linked together to form a coral colony, which would have been firmly attached to the sea-bed.
13These Carboniferous corals also form a colony, preserved in limestone in their position of growth. Septa are radiating plates of calcite that held the soft body of the coral animal (polyp) firmly inside the corallite. Corals live in high energy conditions with breaking waves where there are plenty of other organisms from which to feed.SEPTAPicture from the Palaeontological Association
14Solitary corals lived with the pointed end stuck into the sea-bed Solitary corals lived with the pointed end stuck into the sea-bed. The coral animal could reach food in the sea with its many tentacles.SEPTA
15CORAL ENVIRONMENTSCoral reef growth is only possible if these requirements are met:Marine conditionsWarm water (over 25oC)Clear waterShallow water (photic zone)High energy (breaking waves)Present coral reefs
16Coral reefs in the Red Sea Photos from Ellen Spencer
17GRAPTOLITESThe first graptolites were colonies of animals attached to each other on branches (stipes) and attached to the sea-bed by a hold-fast. They extracted their food from sea-water.STIPESHOLD-FAST
18TetragraptusSTIPEAs time passed, it became more efficient for graptolite colonies to float freely in the oceans to find food (pelagic floating). The number of stipes reduced and the trilobite animals on each colony decreased in number. Their chambers (thecae) became larger and are clearly seen in this picture.THECAE
19Didymograptus murchisoni TWO STIPESIn the Ordovician period the number of stipes per colony reduced to two. Often the thecae became more complex in structure.THECA
20MonograptusLater, in the Silurian period the two stipes of Didymograptus united and became one, but with thecae on both sides. Monograptus is only found in Silurian rocks and is therefore an excellent zone fossil to correlate rocks of this age.THECAE ON BOTH SIDES OF THE STIPESINGLE STIPE
21TRILOBITESTrilobites had segmented exoskeletons which allowed some species to roll up to protect themselves.Picture from the Palaeontological Association
22Trilobite morphology THORAX WITH SEGMENTS GLABELLA PYGIDIUM – fused segmentsCOMPOUND EYE – hidden in shadowTrilobite exoskeletons were made from protein and therefore were slightly flexible. The soft parts, like brain, breathing gills, guts and reproductive organs were protected by the exoskeleton.
23Calymene cephalon GLABELLA COMPOUND EYES These were made of many crystals of calcite, like present-day insect eyes.SEGMENT OF THE THORAX
24Spiny trilobiteSome trilobites developed elaborate spines, perhaps to protect themselves from predators or to stop their exoskeletons from sinking into soft sea-bed muds.
25TrinucleusTrinucleus had long genal spines (broken off in this fossil) which probably helped it to balance in soft mud.Trinucleus had no eyes. But the ribbed headshield is thought to be a sensitive organ which could enable Trinucleus to feel its way through mud to find its food by touch.
26Angelina sedgwickiiThis Lower Ordovician trilobite is always found in slates so has been deformed by metamorphism. It is therefore used by geologists as an indicator of the direction and size of pressure during mountain building periods which metamorphosed the shales, in which Angelina is found, into slates.
27AMMONITESWHORLSKEELThis specimen has very few ribs or growth lines on its shell.BODY CHAMBERAmmonite shells were made of calcite.
29Ammonite interiorEach chamber is separated from the next by a calcite septum secreted by the animal as it grows larger.These chambers have been filled with coarse calcite crystals when the shell was covered with sediments.SEPTA
31Outer shell and whorls original shell of the ammonite Shell broken away to show the infilling of the chambers by sediment
32Suture lines in ammonites developed very frilly edges to give the shell more strength. This allowed ammonites to become much larger and more competitive.6cmSEPTUM
33Ammonite suture lines FRILLY SUTURE LINES Both lobes and saddles developed frills. On this specimen it is not easy to see which is which because the fossil does not include the body chamber.SURFACE OF THE SEPTA
34GONIATITESGoniatites are the ancestors of the ammonites and were common in the Carboniferous period.They have simple suture lines and are usually small with very few whorls.
35Goniatites have simple suture lines LOBES POINT AWAY FROM THE BODY CHAMBERSADDLES POINT TOWARDS THE BODY CHAMBERBODY CHAMBER
36PLANTSThis tree trunk was found in its position of growth (in situ) in Appleton Quarry, Shepley. The tree grew in a swamp and became covered with fine muds, which are now laminated fissile black shales. The trunk has become carbonised and there is a thin black layer of carbon around the outside of the tree.4m
38Jurassic Gingko tree leaves fossilised in pale grey shale
39Plant branch fossilsLepidodendron has leaf scales which give it a diamond-shaped pattern.Calamites has a strongly ribbed trunk.
40Branches in Millstone Grit sandstone Flagstones on the Pennine WaySandstone in Ratten Clough, Todmorden
41RootletsThe thin coal seam represents the plants which have become compressed and carbonised as water and gases have been driven off as the rocks became lithified.Carbonised rootlets growing in a silica-rich soil, which would have developed in a tropical climate.
42THE ENDTHE ENDJurassic ammonite moulds and casts, Dorset