Micropaleontology – Science of Microfossils

• Microfossils are the tiny remains of bacteria, protists, fungi, Microfossils are the tiny remains of bacteria, protists, fungi, Microfossils are the tiny remains of bacteria, protists, fungi, Microfossils are the tiny remains of bacteria, protists, fungi, animals, and plantsanimals, and plantsanimals, and plantsanimals, and plants

• A fossil group with at least two third of its population is visible A fossil group with at least two third of its population is visible A fossil group with at least two third of its population is visible A fossil group with at least two third of its population is visible under the microscope is a microfossilunder the microscope is a microfossilunder the microscope is a microfossilunder the microscope is a microfossil

• These are a heterogeneous group of fossil remains studiedThese are a heterogeneous group of fossil remains studiedThese are a heterogeneous group of fossil remains studiedThese are a heterogeneous group of fossil remains studiedas a single discipline. Includes taxonomically unrelated groups as a single discipline. Includes taxonomically unrelated groups as a single discipline. Includes taxonomically unrelated groups as a single discipline. Includes taxonomically unrelated groups united solely on the basis of their study under the microscopeunited solely on the basis of their study under the microscopeunited solely on the basis of their study under the microscopeunited solely on the basis of their study under the microscope

• As a discipline it lacks homogeneity, most are protists As a discipline it lacks homogeneity, most are protists As a discipline it lacks homogeneity, most are protists As a discipline it lacks homogeneity, most are protists ––––unicellular plants and animalsunicellular plants and animalsunicellular plants and animalsunicellular plants and animals

• Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic • Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic Some are multicellular or microscopic parts of macroscopic formsformsformsforms

• These are calcareous, siliceous, organicThese are calcareous, siliceous, organicThese are calcareous, siliceous, organicThese are calcareous, siliceous, organic----walled and phosphatic walled and phosphatic walled and phosphatic walled and phosphatic in test composition. Their morphology as well as genetic in test composition. Their morphology as well as genetic in test composition. Their morphology as well as genetic in test composition. Their morphology as well as genetic characters are differentcharacters are differentcharacters are differentcharacters are different

• Thus, microfossils, unlike other kinds of fossils, are not grouped Thus, microfossils, unlike other kinds of fossils, are not grouped Thus, microfossils, unlike other kinds of fossils, are not grouped Thus, microfossils, unlike other kinds of fossils, are not grouped according to their relationships to one another, but only according to their relationships to one another, but only according to their relationships to one another, but only according to their relationships to one another, but only because of their generally small size and methods of study. For because of their generally small size and methods of study. For because of their generally small size and methods of study. For because of their generally small size and methods of study. For example, fossils of bacteria, foraminifera, diatoms, very small example, fossils of bacteria, foraminifera, diatoms, very small example, fossils of bacteria, foraminifera, diatoms, very small example, fossils of bacteria, foraminifera, diatoms, very small invertebrate shells or skeletons, pollen, and tiny bones and invertebrate shells or skeletons, pollen, and tiny bones and invertebrate shells or skeletons, pollen, and tiny bones and invertebrate shells or skeletons, pollen, and tiny bones and teeth of large vertebrates, among others, can be teeth of large vertebrates, among others, can be teeth of large vertebrates, among others, can be teeth of large vertebrates, among others, can be called microfossils. But it is an unnatural groupingcalled microfossils. But it is an unnatural groupingcalled microfossils. But it is an unnatural groupingcalled microfossils. But it is an unnatural grouping

• They are found in all the ecosystems in water (marine, river, They are found in all the ecosystems in water (marine, river, They are found in all the ecosystems in water (marine, river, They are found in all the ecosystems in water (marine, river, estuarine) and on landestuarine) and on landestuarine) and on landestuarine) and on land

• They live in shallow marine, bathyal and abyssal depthsThey live in shallow marine, bathyal and abyssal depthsThey live in shallow marine, bathyal and abyssal depthsThey live in shallow marine, bathyal and abyssal depths• Their minute size, abundant occurrence and wide geographic Their minute size, abundant occurrence and wide geographic Their minute size, abundant occurrence and wide geographic Their minute size, abundant occurrence and wide geographic

distribution in sediments of all ages and in almost every marine distribution in sediments of all ages and in almost every marine distribution in sediments of all ages and in almost every marine distribution in sediments of all ages and in almost every marine environment make them usefulenvironment make them usefulenvironment make them usefulenvironment make them useful

• They range from the Precambrian to the RecentThey range from the Precambrian to the RecentThey range from the Precambrian to the RecentThey range from the Precambrian to the Recent• Some are planktic living in top 200 m making them useful in Some are planktic living in top 200 m making them useful in Some are planktic living in top 200 m making them useful in Some are planktic living in top 200 m making them useful in

monitoring sea surface temperature, e.g. foraminifera, diatoms, monitoring sea surface temperature, e.g. foraminifera, diatoms, monitoring sea surface temperature, e.g. foraminifera, diatoms, monitoring sea surface temperature, e.g. foraminifera, diatoms, radiolaria, coccolithsradiolaria, coccolithsradiolaria, coccolithsradiolaria, coccolithsradiolaria, coccolithsradiolaria, coccolithsradiolaria, coccolithsradiolaria, coccoliths

• Some are benthic (vagile/sessile) Some are benthic (vagile/sessile) Some are benthic (vagile/sessile) Some are benthic (vagile/sessile) –––– foraminifera, bryozoa, foraminifera, bryozoa, foraminifera, bryozoa, foraminifera, bryozoa, ostracoda, diatomsostracoda, diatomsostracoda, diatomsostracoda, diatoms

• Some have both benthic and planktic phases in their Some have both benthic and planktic phases in their Some have both benthic and planktic phases in their Some have both benthic and planktic phases in their reproductionreproductionreproductionreproduction

• Spores and pollens derived from land plants, are strongly Spores and pollens derived from land plants, are strongly Spores and pollens derived from land plants, are strongly Spores and pollens derived from land plants, are strongly climate dependentclimate dependentclimate dependentclimate dependent

• A small amount of sediment sample can give rise to thousands A small amount of sediment sample can give rise to thousands A small amount of sediment sample can give rise to thousands A small amount of sediment sample can give rise to thousands of specimens of foraminiferaof specimens of foraminiferaof specimens of foraminiferaof specimens of foraminifera

Importance:Importance:Importance:Importance:

• Microfossils are perhaps the most important group of all fossils Microfossils are perhaps the most important group of all fossils Microfossils are perhaps the most important group of all fossils Microfossils are perhaps the most important group of all fossils ———— they are extremely useful in agethey are extremely useful in agethey are extremely useful in agethey are extremely useful in age----dating, correlation and dating, correlation and dating, correlation and dating, correlation and paleoenvironmental reconstruction, all important in the oil, paleoenvironmental reconstruction, all important in the oil, paleoenvironmental reconstruction, all important in the oil, paleoenvironmental reconstruction, all important in the oil, mining, engineering, and environmental industries, as well as in mining, engineering, and environmental industries, as well as in mining, engineering, and environmental industries, as well as in mining, engineering, and environmental industries, as well as in general geologygeneral geologygeneral geologygeneral geology

• Billions of dollars have been made on the basis of microfossil Billions of dollars have been made on the basis of microfossil Billions of dollars have been made on the basis of microfossil Billions of dollars have been made on the basis of microfossil studiesstudiesstudiesstudies

• Because they usually occur in huge numbers in all kinds of Because they usually occur in huge numbers in all kinds of Because they usually occur in huge numbers in all kinds of Because they usually occur in huge numbers in all kinds of sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily sedimentary rocks, they are the most abundant and most easily accessible fossilsaccessible fossilsaccessible fossilsaccessible fossils

• Indeed, some very thick rock layers are made entirely of Indeed, some very thick rock layers are made entirely of Indeed, some very thick rock layers are made entirely of Indeed, some very thick rock layers are made entirely of microfossils. The pyramids of Egypt are made of sedimentary microfossils. The pyramids of Egypt are made of sedimentary microfossils. The pyramids of Egypt are made of sedimentary microfossils. The pyramids of Egypt are made of sedimentary rocks, for example, that consist of the shells of foraminifera, a rocks, for example, that consist of the shells of foraminifera, a rocks, for example, that consist of the shells of foraminifera, a rocks, for example, that consist of the shells of foraminifera, a major microfossil groupmajor microfossil groupmajor microfossil groupmajor microfossil group

• Microfossils can also be very useful in teaching science at all levels. Microfossils can also be very useful in teaching science at all levels. Microfossils can also be very useful in teaching science at all levels. Microfossils can also be very useful in teaching science at all levels. Students are commonly fascinated by things they cannot see with their Students are commonly fascinated by things they cannot see with their Students are commonly fascinated by things they cannot see with their Students are commonly fascinated by things they cannot see with their naked eyes, especially when the objects are beautiful or interesting in naked eyes, especially when the objects are beautiful or interesting in naked eyes, especially when the objects are beautiful or interesting in naked eyes, especially when the objects are beautiful or interesting in their own right.their own right.their own right.their own right.

• Processing of micropaleontological samples is usually easy and safe Processing of micropaleontological samples is usually easy and safe Processing of micropaleontological samples is usually easy and safe Processing of micropaleontological samples is usually easy and safe enough for students to do themselves, or at least to watch.enough for students to do themselves, or at least to watch.enough for students to do themselves, or at least to watch.enough for students to do themselves, or at least to watch.

• Although plants and animals are the most obvious life around us today, Although plants and animals are the most obvious life around us today, Although plants and animals are the most obvious life around us today, Although plants and animals are the most obvious life around us today, they are not the most numerous nor the most important contributors of they are not the most numerous nor the most important contributors of they are not the most numerous nor the most important contributors of they are not the most numerous nor the most important contributors of microfossils.microfossils.microfossils.microfossils.

• Bacteria (prokaryotes) and protists far outnumber them, live in more Bacteria (prokaryotes) and protists far outnumber them, live in more Bacteria (prokaryotes) and protists far outnumber them, live in more Bacteria (prokaryotes) and protists far outnumber them, live in more diverse habitats, and leave a greater diversity of microfossils. diverse habitats, and leave a greater diversity of microfossils. diverse habitats, and leave a greater diversity of microfossils. diverse habitats, and leave a greater diversity of microfossils.

• Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest

• Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming Today these organisms live from Antarctic ice deserts to steaming volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest volcanic hot springs, and from the highest mountains to the deepest sea. Some cause diseases, such as malaria which infects 350sea. Some cause diseases, such as malaria which infects 350sea. Some cause diseases, such as malaria which infects 350sea. Some cause diseases, such as malaria which infects 350----400 400 400 400 million people today; others are useful to humans. million people today; others are useful to humans. million people today; others are useful to humans. million people today; others are useful to humans.

• Most simply live their lives unknown to us but contributing enormously Most simply live their lives unknown to us but contributing enormously Most simply live their lives unknown to us but contributing enormously Most simply live their lives unknown to us but contributing enormously to our well being through the production of oxygen, the degradation of to our well being through the production of oxygen, the degradation of to our well being through the production of oxygen, the degradation of to our well being through the production of oxygen, the degradation of waste materials, recycling of nutrients, production of food, and a waste materials, recycling of nutrients, production of food, and a waste materials, recycling of nutrients, production of food, and a waste materials, recycling of nutrients, production of food, and a multitude of other functions, some of which take place in our own multitude of other functions, some of which take place in our own multitude of other functions, some of which take place in our own multitude of other functions, some of which take place in our own bodies. Fungi, another group in modern environments that both benefit bodies. Fungi, another group in modern environments that both benefit bodies. Fungi, another group in modern environments that both benefit bodies. Fungi, another group in modern environments that both benefit and plague humans, have a long, but mostly unstudied, microfossil and plague humans, have a long, but mostly unstudied, microfossil and plague humans, have a long, but mostly unstudied, microfossil and plague humans, have a long, but mostly unstudied, microfossil record.record.record.record.

• Prokaryotes and protists are very well represented in the fossil record. • Prokaryotes are the oldest known fossils, and they were the only life on Earth for

most of its history — from 3.7 to 1.5 billion years ago. • Protists joined them at least 1.5 bya, and animals and plants were latecomers at

less than .57 bya. • All these microfossils provide insights to Earth and life history, and so are important

to study in paleontology.

Table 1. Some primary differences between prokaryotes and eukaryotesTable 1. Some primary differences between prokaryotes and eukaryotesTable 1. Some primary differences between prokaryotes and eukaryotesTable 1. Some primary differences between prokaryotes and eukaryotes(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)(from Lipps, 1992)

PROKARYOTES EUKARYOTESNucleus absent Nucleus presentMeiosis absent Meiosis1 basic genome Chromosome number 2-600Mitochondria absent Mitochondria presentChloroplasts absent Chloroplasts may be presentEndoplasmic reticulum absent Endoplasmic reticulum presentVacuoles absent Vacuoles present

Processing of SamplesProcessing of SamplesProcessing of SamplesProcessing of Samples

• Soak soft samples in water and half a spoon of baking sodaSoak soft samples in water and half a spoon of baking sodaSoak soft samples in water and half a spoon of baking sodaSoak soft samples in water and half a spoon of baking soda• If samples are hard, add few drops of 5 ml of dil. H2O2 (15%)If samples are hard, add few drops of 5 ml of dil. H2O2 (15%)If samples are hard, add few drops of 5 ml of dil. H2O2 (15%)If samples are hard, add few drops of 5 ml of dil. H2O2 (15%)• Allow a sample soaked for 8Allow a sample soaked for 8Allow a sample soaked for 8Allow a sample soaked for 8----10 hours10 hours10 hours10 hours• Wash wet samples over an 8” dia 63 micron size sieve with a jet Wash wet samples over an 8” dia 63 micron size sieve with a jet Wash wet samples over an 8” dia 63 micron size sieve with a jet Wash wet samples over an 8” dia 63 micron size sieve with a jet

of water to allow finer particles washed awayof water to allow finer particles washed awayof water to allow finer particles washed awayof water to allow finer particles washed away• Transfer sample to the same beaker and dry it in an electric Transfer sample to the same beaker and dry it in an electric Transfer sample to the same beaker and dry it in an electric Transfer sample to the same beaker and dry it in an electric

oven at 50oven at 50oven at 50oven at 50----60 degree Celsius60 degree Celsius60 degree Celsius60 degree Celsius• Transfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vials• Transfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vialsTransfer dry samples to labeled glass vials• Dry sieve sample over a 4 “ dia sieve of 125 micron size for Dry sieve sample over a 4 “ dia sieve of 125 micron size for Dry sieve sample over a 4 “ dia sieve of 125 micron size for Dry sieve sample over a 4 “ dia sieve of 125 micron size for

benthic foraminifera and 150 micron for planktic foraminiferabenthic foraminifera and 150 micron for planktic foraminiferabenthic foraminifera and 150 micron for planktic foraminiferabenthic foraminifera and 150 micron for planktic foraminifera• Radiolarian samples are washed over 53 micron size sieve Radiolarian samples are washed over 53 micron size sieve Radiolarian samples are washed over 53 micron size sieve Radiolarian samples are washed over 53 micron size sieve

because of small size of specimensbecause of small size of specimensbecause of small size of specimensbecause of small size of specimens• Examine the dry samples under stereozoom microscope, Examine the dry samples under stereozoom microscope, Examine the dry samples under stereozoom microscope, Examine the dry samples under stereozoom microscope,

identify the specimens and calculate their percentages for identify the specimens and calculate their percentages for identify the specimens and calculate their percentages for identify the specimens and calculate their percentages for population analysispopulation analysispopulation analysispopulation analysis

• Make plots of individual species for paleoenvironmental Make plots of individual species for paleoenvironmental Make plots of individual species for paleoenvironmental Make plots of individual species for paleoenvironmental interpretationsinterpretationsinterpretationsinterpretations

Microfossils

Marine Environments

Historical Review• Earliest mention is that of larger foraminifera Nummulites by Herodotus (5th

Century BC), Strabo (7th Century BC) and Pliny the Elder (1st Century AD)• Systemic study started with the discovery of microscope by Leeuwenhoek in

1660• Linne’s binommial system of nomenclature formed the basis of classification• d’Orbigny (1802-1875) published first comprehensive classification of

foraminifera in 1826, included foraminifera in cephalopoda. He is also known as father of micropaleontology

• French biologist Felix Dujardin (1835) described them as Rhizopoda since they possess a pseudopodia

• C.G. Ehernberg (1795-1876), a German biologist, made the first discovery and • C.G. Ehernberg (1795-1876), a German biologist, made the first discovery and description of silicoflagellates, ebridians, coccoliths, discoasters, dinoflagellates and numerous living protists. Also described radiolaria, diatoms and foraminifera. He suggested that foraminifera are Bryozoa – this view he maintained till 1858

• British school comprises of Reuss (1860s and 1870s), N.C. Williamson, W.K. Parker, T.R. Jones, W.B. Carpenter, H.B. Brady, and C.D. Sherborne

A largest impetus to descriptive micropaleontology• The voyage of H.M.S. Challenger (1873-1878) – collected dredge samples from

the world ocean• H.B. Brady published a monumental monograph in 1884• Revival of micropaleontological studies in the post-World War II period• Advent of JOIDES program in 1965 and its successor Deep Sea Drilling Project

(DSDP) in 1968 with the drilling ship D/V Glomar ChallengerCommercial

micropaleontology• The demand for oil during two world wars led to extensive use of micropaleotology.• Commercial micropaleontology is related to petroleum industry• Commercial micropaleontology is related to petroleum industry• During World War I, micropaleontology was introduced as a formal course in the

curriculum by Josia Bridge at the Missouri School of Mines and by H.N. Coryell at Columbia University and F.L. Whitney at the University of Texas

• J.J. Galloway began teaching micropaleontology at Columbia University in 1924• J.A. Cushman established Cushman Laboratory for Foraminiferal Research at

Shaorn, Massachusetts• H.G. Schenck introduced micropaleontology at Leland Stanford University in 1924• Before World War II, emphasis was on biostratigraphic correlation. After World War II,

the emphasis was on paleoecology and paleobathymetry

Main Microfossil GroupsClassified on the basis of test composition

A. Calcareous Microfossils1. Foraminifera (Cambrian to Recent)2. Calcareous Nannoplanktons (Jurassic to Recent) 3. Ostracodes (Cambrian to Recent)4. Pteropods (Late Cretaceous to Recent)5. Calpionellids (Late Jurassic to Early Cretaceous)6. Calcareous Algae (Precambrian to Recent)7. BryozoaB. Siliceous MicrofossilsB. Siliceous Microfossils8. Radiolaria (Cambrian to Recent)9. Marine Diatoms (Late Cretaceous to Recent)10. Silicoflagellates (Late Cretaceous to Recent) and Ebridians (Tertiary

to Recent)C. Phosphatic Microfossils11. Conodonts and other phosphatic microfossils (Cambrian to Triassic)D. Organic-Walled Microfossils12. Dinoflagellates (Silurian to Recent), Acritarchs (Precambrian to

Recent) and Tasmanitids (Cambrian to Tertiary)13. Spores and Pollens in the Marine realm14. Chitinozoa (Ordovician to Devonian)

Foraminifera

• Foraminifera are single-shelled belonging to Kingdom Protista, Phylum Protozoa, Class Sarcodina

• The word is from Latin foramen = hole, ferre = to bear• They possess pseudopodia• They have both benthic and planktic mode of life• Reproduction is through schizogony = asexual reproduction and gamogony=sexual

reproduction• Larger prolocus in individuals resulting from schizogony than resulting from

gamogony• Wall structure: Agglutinated, Microgranular, Calcareous hyaline, Calcareous

porcellaneousporcellaneous• Chamber shape and chamber arrangement: clavate, fistulose, globular, cuneate,

tubular, angular truncate, angular conical, lenticular biconvex, uniserial rectilinear, biserial, triserial, milioline, planispiral evolute, planispiral involute

• Pores – round, slit-like, or irregular openings• Ornamentations: ribs, ridges, furrows, spines, etc.• Ecology: study of the relationship between organisms and their environments• Physical Variables: water depth, temperature, hydrostatic pressure, light intensity• Chemical variables:

(i) salinity 35 psu to 45 psu. The genus Discorbinopsis can tolerate upto 57 psu(ii) Alkalinity(iii) Trace elements and nutrients

Distribution

Benthic foraminifera• Endobenthic – Bulimina aculeata Epibenthic – Epistominella exigua• Low oxygen, high organic carbon – Uvigerinids, Buliminids• Neritic species: Quinqulina seminulum, Ammonia beccarii

Benthic foraminifera: Marshes, Brackish environments, Carbonate platforms, reefs and back reefs, Continental shelf, open marinePlanktic foraminifera: Tropical to Polar

Microhabitat

• Bathyal species: Cibicides wuellerstorfi, Melonis barleeanum• Abyssal species: Nuttallides umbonifera, Epistominella exigua

Planktic foraminifera

• Tropical: Globorotalia menardii• Warm subtropical: Globigerinoides ruber• Cool subtropical: Globorotalia truncatulinoides• Subpolar: Globigerina bulloides• Polar: Neogloboquadrina pachyderma

Planktic Foraminifera(Jurassic to Recent)

Benthic Foraminifera(Cambrian to Recent)

Evolution of Foraminifera

• Late Precambrian witnessed a change in oxygen content leading to the evolution of organisms by adaptation

• Foraminifera evolved in Cambrian, prior to which forams existed as naked shells• Devonian is considered a period of extensive carbonate environments which were

invaded by foraminifera• Carboniferous was a period of radiation• In the late Carboniferous-Permian the first porcelaneous family ‘Agathamminidae’

appeared.• The Permian is termed the epoch of fusulinids• In the Triassic the diversification of foraminifera was slow. The Triassic is

considered an arid period marked by regressions of the sea• The Jurassic was the beginning of extensive transgressions, equable climates and

is known as the period of ‘milk and honey’• Cretaceous is considered to be the continuation of the period of “milk and honey”• The Cretaceous terminated with abrupt mass extinctions of majority planktons

and shallow dwelling benthic foraminifera• Cenozoic saw a revitalization of foraminiferal faunas• Early Tertiary had abundant calcareous foraminifera like Nummulites and

numerous smaller foraminifera

CALCAREOUS NANNOPLANKTONS

• The word is from Greek nano means dwarf• Unicellular, autotrophic marine algae/phytoplankton also

known as coccolithophores• Range from Jurassic to Recent• Cell secretes a skeleton of minute calcareous shields forming

coccosphere• Individual elliptical to circular shields or coccoliths range from ~1-15

microns• Discoasters also comprise this group• Discoasters also comprise this group

Historical review• First reference to the nannoplankton is by C.G. Ehrenberg in 1836, initially

called them as inorganic• In 1858, T.H. Huxley reported these in deep-sea oozes• G.C. Wallich and H.C. Sorby – another pioneers worked on this group• Wallich gave the name coccosphere & reported true nature of this group• In 1891, John Murray and A.F. Renard published work on sediments

collected during the voyage of HMS Challenger• Hans Lohmann worked on living nannoplanktons• M.N. Bramlette & W.R. Riedel worked on biostratigraphy of this group

Nutrition• Mostly photoautrophic• Some instances of ingestion of foreign organic material reported• Some are believed to be heterotrophic (utilizing both organic and

inorganic substances• Abundant in upwelling areas

Growth• Growth rates are relatively high, as some species multiply more than twice

in a day• Most species exist within narrow temperature range• Most species exist within narrow temperature range• Temperature range 7-27 degrees• Emiliania huxleyi has been observed at temperatures as low as 2 degrees• Made up of calcite and to a lesser degree aragonite

Function of coccoliths• Coccoliths shield the the enclosed cell from excessive sunlight• Equally popular is the opposing idea tha coccoliths concentrate light

toweards the cell interior• Also as floating devices, metabolic barriers, stabilizers, defensive shields

etc• Some think them as by-products of detoxification of carbonate

Ecology• Exclusively planktic marine• Euryhaline, occurring in lagoonal, littoral and estuarine environments• Can tolerate a salinity range of 16 to 45 psu• Photosynthetic living in upper 100-150 m or the photic zone• Rapidly decreases with depth

Biogeography• Greater concentration in zones of high organic productivity where

more nutrients are available due to upwellingmore nutrients are available due to upwelling• These zones are located north and south of 45 degrees

Paleoclimatic interpretations• Dissolution plays an important role• Reconstruction of Lysocline and water mass chemistry• Paleoproductivity

Geological distribution• First diversification occurred in Jurassic, at the end of Maastrischtian a

massive extinction of marine organisms, Taxa evolved from a small pool in the early Tertiary, the relative abundance and short stratigraphic range make them useful tool in biostratigraphy

OSTRACODES

•Range from Cambrian to Recent•Length between 0.15 and 2 mm•Bivalved (carapace), living in fresh, brackish, saline and hypersaline waters•Both benthic (abundant) and planktic (rare)•The oldest generic names given to ostracods are Cypris and Cythere by O.F. •The oldest generic names given to ostracods are Cypris and Cythere by O.F. Muller in the 1770's and 80's•H.B. Brady was the next pioneer worker. He published important monograph in 1880 describing material from H.M.S. Challenger•The first fossil ostracode was described in 1813•Interest in fossil ostracodes was stimulated in 1920s with increased demand for oil and became second to foraminifera•After World War II the study of ostracodes entered the stage of neontological and paleontological synthesis•Ostracodes are always divided into separate sexes. Not all of them, however, reproduce sexually

Ecology• Ostracodes probably originated in a marine environment• Largest number of species still inhabits the pelagic and benthic realms of the ocean from shoreline down to

several thousand meters• They are found from equator to the poles

Nutrition:• Both filter- and deposit-feeders• Numerous feed on marine plants and small living animals such as annelids or small crustaceans• Some eat detritus from decaying vegetal or animal tissues• Some are limnivorous eating bottom sediments without any selection• Some are commensals• Some are parasites living in the gills and nostrils of fishes

Distribution: physical, chemical and biological factorsDistribution: physical, chemical and biological factorsSalinity• Euryhaline (fresh to normal saline to hypersaline), StenohalineTemperature• Psychrospheric (deep-sea cold loving), Cryolophic (cold-loving shallow • species) and thermophilic (warm-loving)Substrate• Coarse grained sediments support a small population• Mud-mixed sands and pelitic sediments have a much larger populationDepth• In highl-energy shallow waters both diversity and density of ostracodes are lower than in deepser and more

stable offshore environments• Below photic zone, ostracode population becomes less diverseFood supply• High organic content of the sediment has been considered to be a factor controlling ostracode distribution

Geological Distribution

• Ordovician seas witnessed a great expansion of Ostracodes• In the Triassic ostracodes constitute one of the most important elements of the

microfauna• Many genera persist from Jurassic into early Cretaceous faunas• Cenozoic witnessed a different set of ostracode assemblage

PTEROPODS• Also known as sea butterflies, are marine gastropods

adapted to pelagic life• Range from late Cretaceous to Recent• Aragonitic shell and preserve between 700 and 3000 m water depth• Better preserved in basins having high bottom temperatures,

sluggish circulation and rapid rates of sedimentation such as the Red Sea and the Mediterranean Sea

• Known since the seventeenth century

Morphology• The animal is divisible into four regions(1) head, (2) foot, (3) visceral mass, and (4) mantle which secretes shell

ECOLOGY• Are exclusively marine and generally live in open ocean, swimming in

the uppermost 500 m• Salinity, temperature, food, oxygen and water depth control their

distributionTemperature• They are dominant in the tropics• Two polar seas are dominated by one pteropod speciesSalinity• Salinity is an important controlling factor• Salinity is an important controlling factor• Can tolerate salinity as high as 40 psuPaleoecology• The Pleistocene is marked by glacial-interglacial intervals• Population of pteropods vary on glacial-interglacial time scales• Avoid carbonate corrosive waters where surface production is high

like upwelling regions

CALCAREOUS ALGAE• Important in micropaleontology as records of ancient life• Calcium carbonate depositing benthic red and green algae• Significant producers of carbonate sediment• Algae represent a large and diversified assemblage of aquatic

photosynthetic plants, varying from a minute plankton to huge marine benthif plants

• Considered by petrographers as rock constituents and sedimentary structures

• Investigations of calcareous algae traditionally have included only the benthic forms and have excluded planktic calcareous algae –benthic forms and have excluded planktic calcareous algae –coccolithophores

General aspects• Algae are aquatic, autotrophic, nonvascular plants• The plant body of an alga is called thallus• Algae contain chlorophyll a, require oxygen for respiration and

produce oxygen during photosynthesis• Extreme variation in size, morphology, cellular organization,

biochemistry and reproduction

Classification of fossil algae

• Fossil algae can be distinguished into two major categories(1) Preserved skeletal remains representing direct or indirect evidence of algal

tissue : (a) Blue-green algae (Cyanophyta)(b) Red algae (Rhodophyta)(c) Green algae (Chlorophyta)(d) Charophyta(2) Non skeletal biosedimentary structures, generally called stromatolites

Blue-green algaeBlue-green algae• Are some of the most common marine and nonmarine algae since the

Precambrian• Build laminated sedimentary structures or stromatolites in a variety of

environments but most often in shallow marginal waters• Prefer muddy substrate• Tropical to polarRed Algae• Marine• Prefer reef and rocky substrate• Tropical to polar

Green Algae• Marine, preferring sandy and muddy substrates• Most abundant in relatively shallow, protected lagoonal environments• Tropical to subtropicalCharophytes• Fresh and brackish water• TropicsSTROMATOLOTES• Include a variety of external shapes ranging from flat-lying laminations

to domical and columnar structures, some with branching or digitate habitshabits

• Flat-lying laminae are called “algal-laminate sediments”• Most dominant in the Archaen• Decline in the Phanerozoic has been attributed to the expansion of

grazing and burrowing animals that destroyed algal laminae

SILICEOUS MICROFOSSILS

• Cambrian to Recent• First published description of Radiolaria by F.V.F. Meyen in 1834• C.G. Ehrenberg published extensively between 1838 and 1875• Johannes Mueller and Richard Hertwig studied living specimens from the

Mediterranean• Mueller coined the name ‘Radiolaria’• Hertwig (a noted biologist) was the first to firmly establish the unicellular

nature of radiolarians• The oceanographic expeditions of the late nineteenth and early twentieth

RADIOLARIA

• The oceanographic expeditions of the late nineteenth and early twentieth centuries initiated an explosion in the study of radiolarians

Reproduction• Simple cell division and sexual reproductionNutrition• Feed on various kinds of planktic organisms including microflagellates and

other protozoans, diatoms and possibly copepods• Symbiotic algae also contribute to radiolarian nutritionEcology• Exclusively marine, found in all the oceans• Planktic living at all depths• Characteristically open ocean organisms

Biogeography• Antarctic Convergences• Below CCD and upwelling zonesPaleoecology• Play an important role in the silica cycle in the oceans• Form radiolarian ooze• Help in understanding the role of igneous activity as volcanism

contribute indirectly to skeletal preservation• They accumulate in abundance in equatorial sediments where surface

productivity is high• Also rich under high-latitude productivity belts – around Antarctica • Also rich under high-latitude productivity belts – around Antarctica

and in the North Pacific• Radiolaria are generally very rare or absent in continental margin

sediments where they are diluted by large influxes of terrigenous material which also provide chemical sink for silica

Application

MARINE DIATOMS

• Range from Cretaceous to Recent• Abundant in high latitudes and in low latitude upwelling zones• Useful as biostratigraphic marker and paleoecologic proxy – indicators of

water chemistry, paleosalinity, paleodepth, paleotemperature, paleonutrient concentrations and paleocurrents

• Diatoms are photosynthetic, single-celled algae and inhabit many aquatic and subaquatic environments

• Diatoms may be free-floating (planktic) or attached to some foreign surface (sessile)

• They alongwith coccoliths make up bulk of marine phytoplankton mass• They alongwith coccoliths make up bulk of marine phytoplankton massSkeletal construction• Diatoms secret an external shell, the frustule – often compared to a pill box• Frustules are composed of opaline silica and larger of the two valves is called

the epitheca while the other is called the hypothecaValve Structure• Diatoms are of two types: Centric and pennate forms• Centric forms may be circular, triangular or oblong, but the main distinguishing

feature is that the surface markings radiate from a central area.• Pennate forms have one long axis and two short axes with the surface

markings at right angles to the long axis

Marine diatoms (contd….)Reproduction• Diatoms reproduce by simple cell division• Just before division, the epitheca and hypotheca move slightly away

from each other and separation of two valves takes place• New valves are formed on the exposed protoplasm from the central

area otwards• Thus original two valves both become epitheca in the new individuals• A steady decrease in valve diameter occurs with each succeeding

generationNutrition• Three nutrients are considered essential – phosphorus, nitrate, silica• When any of the three nutrients is missing, diatom growth and

reproduction ceases• Any are of upwelling in the ocean will bring a constant supply of these

nutrients to the surface and thus cause productivity blooms• Coastal regions receiving high concentration of nutrients from run-off

and rain will support diatom population• Some require vitamins like cobalamin (vitamin B12) and thiamin (B1).

Sulphur, iron and manganese are also considered essential

Habitats• Both fresh-water and marine waters• On land they are found in soils and occasionally on wetted rocks

and plants• In streams, lakes and ponds they are found attached to rocks and

plants as well as in bottom muds• Both planktic and benthic• Holoplanktic, Meroplantic and TychopelagicBiostratigraphic and paleoecologic importance

SILICOFLAGELLAGES

• Tiny creatures, phytoplanktons, small size population

PHOSPHATIC MICROFOSSILS

Includes the following groups:• Conoidal Shells: conical tubes 5-15 mm in length, Early Cambrian-Ordovician• Horny Brachiopods: Cambrian and early Ordovician• Horny ostracode-like arthropods: Cambrian• Remains of Vertebrates: Bone fragments, spines, scales and teeth of vertebrates,

sometimes used as index fossils around Silurian-Devonian boundary

• CONODONTS:• By far the most important and biostratigraphically important group of phosphatic

microfossils• Range in size from 200 microns to 6 mm• Cambrian to Triassic in age• First described by C.H. Pander in 1856 and coined the term ‘Conodont’• Consist of an organic matrix in which crystallites of apatite similar to the mineral francolite

are imbededMorphology:

Morphologically divided into:1. Simple cones2. Bar-type conodonts3. Blade-type conodonts4. Platform conodonts

Importance:Important as biostratigraphic markers, used in lower Himalayan biostratigraphy; can be used inthe exploration of phosphatic deposits

PHOSPHATIC MICROFOSSILS

PHOSPHATIC MICROFOSSILS

Microfossils in Petroleum Exploration

Applied Micropaleontology

Figure: Discrimination of marineenvironments by cross-plots of foraminiferal morphogroups, (fromMurray, 1973).

Figure: Variation in the ratio ofplanktonic to benthic foraminifera withdepth, (from Hayward, 1990).

The advantages of using microfossils for subsurface biostratigraphy

• Small Size• Abundance

Review of Techniques

• Correlation• Age determination• Unconformity Identification• Application to sequence stratigraphy analysis• Application to sequence stratigraphy analysis• Sequence stratigraphy models• Sequence analysis of well• Characterization of formations (“fingerprinting”)• Palaeoenvironmental interpretation

Role of Micropaleontology in hydrocarbon exploration and development programmes

Requirements for hydrocarbon accumulation: • Reservoir: biostratigraphy + sedimentology• Trap: biostratigraphy + seismic mapping• Seal: lithostratigraphy + biostratigraphy• Source: geochemistry + biostratigraphy

Appraisal of discoveries• Well correlation• Reservoir distribution and reserve estimation• Trap evaluation• Field development

Pitfalls in biostratigraphic correlation• Factors affecting data quality• Reworking and caving• Age Interpretations• Taxonomic nomenclature• Preparation techniques• Microfossil and zonal identification• Paleoenvironmental controls• Practical correlation and biostratigraphy

How can Micropaleontology help to find oil?

Marine Micropaleontology – An Introduction

• Includes taxonomically unrelated groups united solely on the basis of their study under the microscope

• As a discipline, it lacks homogeneity• Most microfossils are protists – unicellular plants and animals• Some are multicellular or microscopic parts of macroscopic forms• Their minute size, abundant occurrence and wide geographic distribution in

sediments of all ages and in almost every marine environment make them useful

• They range from the Precambrian to the Recent• Some are planktic living in top 200 m making them useful in monitoring sea

surface temperature – e.g. radiolaria, silicoflagellates, some foraminifera, diatoms, coccoliths, etc.

• Some are benthic (vagile/sessile) – some foraminifera, bryozoa, ostracoda, diatoms

• Some have both benthic and planktic phases in their reproduction –dinoflagellates

• Spores and pollens derived from land plants, are strongly climate dependent