Introduction to Paleontology Lecture 1 PDF

Introduction to Paleontology (Lecture 1)  General Paleontology LECTURE 1: INTRODUCTION Different branches of geology: geology has many sciences as (Mineralogy – Paleontology – Palynology – Hydrogeology – Paleoec...

Introduction to Paleontology (Lecture 1)  General Paleontology LECTURE 1: INTRODUCTION Different branches of geology: geology has many sciences as (Mineralogy – Paleontology – Palynology – Hydrogeology – Paleoecology - Sedimentology – Igneous rocks – Metamorphic rocks – Lithostratigraphy – Biostratigraphy – Chronostratigraphy - Petroleum geology – Economic geology - Remote sensing – Geophysics – etc….). Paleontology: The word paleontology (derived from the Greek) signifies the study of ancient life. Thus, generally paleontology deals with fossils. Paleontology: Is the study of life through geologic time, and therefore is based on the principals and methods of both biology and geology (Boardman et al., 1987). Paleontology, also spelled Palaeontology, scientific study of life of the geologic past that involves the analysis of plant and animal fossils, including those of microscopic size, preserved in rocks. Importance o Paleontology - It is concerned with all aspects of the biology of ancient life forms: their shape and structure, evolutionary patterns, taxonomic relationships with each other and with modern living species, geographic distribution, and interrelationships with the environment. - Paleontology has played a key role in reconstructing Earth’s history. - Data from paleontological studies, moreover, have aided petroleum geologists in locating deposits of oil and natural gas. - The occurrence of such fossil fuels is frequently associated with the presence of the remains of certain ancient life-forms (fossils).  History of paleontology Xenophanes of Colophon Paleontology was known by the first author since (570 – 475 Before Common Era BCE). then it was studied by many other author as Leonardo da Vinci, Robert Hooke, William Smith, Mary Anning and so on till now  Branches of paleontology Paleontology: 1- Micropaleontology 2- Macropaleontology a- vertebrate paleontology b- invertebrate paleontology 1- Micropaleontology: the study of microfossils, is a division of paleontology. Microfossils are fossils usually lesser than 1 mm and they are two types: organic walled and mineral walled. The organic walled forms are spore, pollen, acritarchs, chitinozoans, whereas mineral walled are further divided into calcareous foraminifera, Ostracoda, bryozoa, calcareous nannoplankton, calcareous algae, dinoflagellates; siliceous diatoms, radiolaria, silicoflagellates; and phosphatic conodonts. 2- Macropaleontology - Generally in cm, m size. - They are visible to the eye. - They can be found in abundance. - They can give reliable results. - It can be used at economical values. The invertebrate macrofossil groups are as: Brachiopods, Mollusca: (Cl: Bivalves, Cl: Gastropods, and Cl: Cephalopods), and Echinodermata vertebrate  LECTURE 1 General Paleontology Fossil and Fossilization Fossils What is the fossil?  LECTURE 1 General Paleontology Fossils: are the remains or traces of living organisms (animals or plants) that lived in the geologic ages and have been buried and preserved in the sediments by natural causes. Fossilization: is the transfer of the organism from the biosphere to the lithosphere.  LECTURE 1 General Paleontology Requirements of fossilization 1- Hard body parts such as skeletal bones or exoskeletons. In spite of this, there are rare cases of soft skeleton preservation. 2- Rapid burial within the suitable sediments, (less porous and permeable).  LECTURE 1 General Paleontology Types of remains a. Unaltered soft parts: Rare fossil cases in which both soft and hard parts are preserved without alteration as Mammoth and Insects in Amber. Soft organic remains (insects) are 40,000-year- old frozen baby mammoth preserved in amber (fossil tree sap) found in Siberia in 1971. hair around the feet is still visible.  LECTURE 1 General Paleontology b. Unaltered hard parts: Shells of Invertebrates or bones of Vertebrates are preserved without alteration. (Skeletal remains that are composed of stable minerals (e.g. calcite, calcium phosphate) can be preserved without significant change in chemical make up or internal structure).  LECTURE 1 General Paleontology c. Altered hard parts: Shells of Invertebrates or bones of Vertebrates are showing various degrees of alteration. There are many types of preserved fossils with alteration in the hard skeletons as following:- 1- Carbonization: Carbonization refers to the process of carbon enrichment of organic-rich remains through their burial and heating. Organic remains, when buried to relatively shallow (few kms) depths, are lightly heated due to higher temperatures closer to the center of the Earth. During this low-grade cooking, the volatile elements in the original organic molecules such as oxygen, hydrogen, and nitrogen are released as gasses, while carbon (non- volatile) is left behind. As a result, the remains are increasingly enriched in carbon. Coal is the typical product of this process.  LECTURE 1 General Paleontology 1- Carbonization Soft organic materials (leaves, graptolites, worms) are preserved as a thin (black to brown) carbon film in sedimentary rocks.  LECTURE 1 General Paleontology 2- Permineralization: Skeletal material can be quite porous. If the pores are filled in by foreign minerals that precipitate out of solution, the fossil is said to be permineralized. (Permineralized boons)  LECTURE 1 General Paleontology 3- Recrystallization: Although some hard parts can be preserved with minimal change, most experience at least some degree of recrystallization after burial (crystals tend to increase in size due to the higher temperatures encountered below Earth’s surface). With burial, and over time, the very fine crystals of the original skeleton tend to increase in size, and/or change to more stable crystal morphologies. Increased size of crystals Due to the coarser overall texture of the skeleton, finer textural details (e.g. ribs in this case) will be lost or obscured.  LECTURE 1 General Paleontology 4- Replacement: In some cases, organic matter or minerals of an organism can be replaced by different mineral substances. This replacement occurs at a microscopic (molecule for molecule) level. Calcareous (calcitic and aragonitic) shells are commonly replaced by silica minerals (silicon dioxide), pyrite (iron sulphide), or calcium phosphate minerals. So, Mineral replacement can be defined as: This occurs when skeletal material is replaced, molecule by molecule, with some alien material. This process occurs gradually over a long period of time as the original mineralogy dissolves away and a new mineral precipitates in its place.  LECTURE 1 General Paleontology Examples of Replacement include: (1) Silicification: when calcium carbonate is replaced by silica. (2) Pyritization: when calcium carbonate is replaced by pyrite. (3) Phosphatization: replacement by calcium phosphate. Silicification (Petrified wood)  LECTURE 1 General Paleontology Pyritized brachiopod Original calcitic brachiopod  LECTURE 1 General Paleontology Molds It is a removal by a dissolution of organic material buried in sediment; a void left in the rock is a mold. Molds can be internal (expressing the shape of the inside of a shell or other feature) or external (expressing the shape of the outside of the object). Internal External mold mold Note: the original shell of this ammonite has completely dissolved away, but its former presence is indicated by external and internal moulds.  LECTURE 1 General Paleontology External mould Internal mould 1. Sediment is surrounding the shell and filling the shell 2. Shell is dissolved cavity hardens  LECTURE 1 General Paleontology Cast: a filled-in external mold  LECTURE 1 General Paleontology Trace fossils: (Tracks, Trails, Burrows, Borings and Coprolites) Track: an impression made by a single foot. Trackway: number of tracks made during a single trip. Trail: an impression made by a tail or other “non-foot”. Burrows: a hole or holes (Excavations) an animal (As worms) dug into loose sediment (like mud). Borings : Drilled holes, bored through shells by predator snails or other organisms. Coprolites: excrement that has become fossilized. LECTURE 1 General Paleontology  LECTURE 1 General Paleontology Burrows Trail  LECTURE 1 General Paleontology Borings Coprolites  LECTURE 1 General Paleontology Types of fossils Index fossils: It is also called Guide fossils or Zonal fossils; are those fossils used for correlating and dating geologic strata found in different parts of the world. Index fossil characterized by 1- Short stratigraphical (vertical) range; so, the time between its appearance and extinction is short. 2- Wide geographic range (horizontal distribution); so, it is found in many places around the globe. Facies fossils: those fossils which are facies controlled (long stratigraphical range.  General Paleontology Importance of fossils Determination of the relative geologic age of the sediments containg them (Relative Chronology). Correlate the strata containing them. Determination of the paleoenvironment of the sediments containg them. Studying of the Paleoecology, Paleogeography, and paleoclimatology. Study of the evolution of life on earth. Determination of the localities of oil and some economic resources.  Homework 1 1- Define the following terms: (Paleontology- Fossils- Fossilization - Index fossil – Cast – Track - Trackway – Trail – Burrows – Borings – Coprolites) 2- Answer the following questions: a. What is the importance of paleontology? b. What are the requirements of fossilization? c. Mention the types of remains d. Give some examples of replacement e. Give five importance of fossils 3- Complete the missing words: 1. Foraminifera lives in ………... environment of …………. geologic age. 2. Ostracoda lives in ………... environment of …………. geologic age. 3. Calcareous nannoplankton lives in ………... environment of ………. geologic age. 4. Radiolaria lives in ………... environment of …………. geologic age. 5. Pteropods lives in ………... environment of …………. geologic age. 6. Diatoms lives in ………... environment of …………. geologic age. 7. Conodonts lives in ………... environment of …………. geologic age. 8. Spores/Pollens lives in ………... environment of …………. geologic age. 9. Dinoflagellates lives in ………... environment of …………. geologic age. 10. Silicoflagellates lives in ………... environment of …………. geologic age. 11. Chitinozoa lives in ………... environment of …………. geologic age. 12. Acritarchs lives in ………... environment of …………. geologic age. Thank you