Fossils

• Fossils - are traces of organisms that lived in the past and were preserved by natural process or catastrophic events.
• They can be remains of organisms which include bones, shells, teeth and also feces embedded in rocks, peat, resin, and ice.
• Paleontologist is a person who studies fossils.
• Most fossils were commonly found in sedimentary rocks. They were form the hard parts of the organism like woody stem, bones, or teeth.
• Imprints are shallow external molds left by animal or plant tissues with little or no organic materials present.
• Compression is the other side with more organic material.
• Paleontologists make initial estimates of the age through the position in the sedimentary. Fossils found in the bottom layer are much older than those found in upper layer of rocks.
• Trilobite - An invertebrate, it lived in a shallow marine environment during Ordovician and Silurian periods.
• Crinoids - look like plants but are actually animals related to our modern day starfish. They belong to the Phylum Echinodermata and lived during the Triassic Period.
• Dinosaurs or giant reptiles - ruled the earth during the Jurassic Period under Mesozoic Era.
• Vascular Plant - This fossilized leaf is once part of an early vascular plant during the Carboniferous Period.
• Relative Dating - A method used to determine the age of the rocks by comparing them with the rocks in the other layer.
• Radiometric Dating - A method used to determine the age of rocks using the decay of radioactive isotopes present in rocks.
• Era - is the largest division of Geologic Time Scale, namely Precambrian, Paleozoic, Mesozoic, and Cenozoic. Each Era is further divided into Period.
• Homologous - Structures from different species which have similar internal framework, position, and embryonic development.
• Analogous - Structures of unrelated species may evolve to look alike, because the structure is adapted to similar function. Have similar functions but different origin.
• Divergent Evolution - The splitting of an ancestral population into two or more subpopulations that are geographically isolated from one another.
• Convergent Evolution - is an increase in similarities among species derived from different ancestors as a result of similar adaptation to similar environment.
• Embryo - is an early stage of development in organisms.
• Embryonic development include stages such as blastula, gastrula, and organogenesis.