Evidences for Evolution: Fossil Records PDF

Did you watch the news last July 2020, about a megalodon tooth found in Maribujok Bohol? Megalodon, (Carcharocles megalodon), member of an extinct species of megatooth shark (Otodontidae) that is considered to be the largest shark...

Did you watch the news last July 2020, about a megalodon tooth found in Maribujok Bohol? Megalodon, (Carcharocles megalodon), member of an extinct species of megatooth shark (Otodontidae) that is considered to be the largest shark, as well as the largest fish, that ever lived. Fossils attributed to megalodon have been found dating from the early Miocene Epoch (which began 23 million years ago) to the end of the Pliocene Epoch (about 2.6 million years ago).  Sources of Evidence for Evolution 1.Fossils are the traces of organisms that lived in the past and were preserved by natural process. Figure 2. Shark of Maribujoc: 2nd Tooth Fossil of Megalodon Found in Bohol Most fossils were found in the sedimentary rocks. They were from the hard part of organism’s body like the woody stem, shell, bones or teeth. Types of Fossils Fossils can be classified as to impression or compression. Impression is also known as imprint which are the shallow external molds left by animal with little or no organic materials present. Compression is a fossil preserved in sedimentary rock that has undergone physical compression and with more organic material.  Activity 1 Types of Fossils Paleontologist uses several methods in determining the age of the fossil. Relative dating is a method used to determine the age of the rocks by comparing them with the rocks in the other layer. Fossils found at the bottom layer are assumed to be the older than those on the upper layer. Carbon-14 dating is a method used to determine the age of rocks using the decay or radioactive isotope present in rocks. Geologic time scale shows the major events in the Earth history and the appearance of various kinds of organism in particular period of time. It is divided into four, namely Precambrian, Paleozoic, Mesozoic, and Cenozoic. Era is the largest division and it is further divided into Period. SOURCES OF EVIDENCE FOR EVOLUTION 1. Comparative anatomy is the study of the similarities and differences in the anatomy of different species. Scientists use bones to determine similarities and differences in comparative anatomy. There are two types of structure used in comparative anatomy. a. Homologous structure may perform different functions but it may have same origin. The example of homologous structure are the forelimbs of human, dog, cat, bat, frog, bird, lizard, and whale which are structurally the same but functionally different. Structures from different species which have similar internal framework and position are considered to be homologous. b. Analogous structure pertains to species with similar functions but different origin. Structure of unrelated species may evolve to look alike, because the structure is adapted to similar function. Examples are wings of butterfly, bird and bat and other insects that have the same function but different origin. c.Genetic information organisms have the basic heredity units for all life that consists of similar nucleotides and proteins. The biochemical analysis and amino acid sequence of the organisms provide evidence for evolution. DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are 1. Jean Baptiste de Lamarck was one of the first to believe that organisms change over time. He has developed three theories about evolution. A. theory of need. According to him organisms change in response to their environment. The ability of organisms to survive has helped them to adapt to the environment in which they live. B. Theory of Use and Disuse. According to him, the organs or parts of the body that are not used will be lost and the organs that are always used will be developed. Lamarck believed that giraffes used to have short necks but because of what they ate in the tall trees and they needed to survive they stretched their necks to reach the food and that is said to be the reason why the giraffe's necks are long. c. theory of Acquired Characteristics which according to Lamarck, the offspring inherited the acquired characteristics of having a long neck of giraffes and it is propagated to the next generation of giraffes. 2. Charles Darwin. Like Lamarck, Darwin believed that organisms change over time,. within any population of organisms, there were always individuals with different traits. Like in the giraffe species, originally had different neck lengths but due to natural selection, only giraffes with long necks survived because they could only reach tall trees for food. Theory of Natural selection is a process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. Charles Darwin means that some individuals have traits better suited to the environment than others. This is also known as “survival of the fittest” which states that organisms best adjusted to their environment are most successful in surviving and reproducing.  DARWIN’S THOUGHT ABOUT EVOLUTION In Charles Darwin's journey he realized the diversity of organisms. Because of this he developed the Theory of Natural Selection. Procedure: 1. Study and observe the sets of footprints in the diagram below. Guide Questions: 1. Look at diagram 1, how many sets of footprints do you see? What can you say about the organisms based on the size of footprints? ___________________________________________________________________________ ___________________________________________________________________________ 2. Create your own story about diagram 2, 3, and 4. Diagram 2: ___________________________________________________________________________ ___________________________________________________________________________ Diagram 3: ___________________________________________________________________________ ___________________________________________________________________________ Diagram 4: ___________________________________________________________________________ ___________________________________________________________________________ 3. How will you relate the story you created to the Theory of Natural Selection? ___________________________________________________________________________ ___________________________________________________________________________