Fossils are the remains of organisms; either their preserved remains or some trace of their existence. How does an organism become a fossil? Most are preserved in rock layers beneath the surface of the Earth. Let's look at one of the common ways that organisms can be preserved into fossils. Below, put the images and descriptions in the correct sequence. You'll need to scroll to see all of the images and descriptions. An ammonite (a shellfish with a spiral-shaped shell) dies and falls to the bottom of the sea where it is covered by sediments. More sediment covers and squeezes the shell. It may undergo mineralization or other processes that make it more stone like. After millions of years, movement of the Earth's crust may push the layer of sedimentary rock containing the fossil upwards towards the surface. Weathering and erosion eventually wear away some of the rock, exposing the fossil. Fossils are often found in quarries or other dig sites.
Added by Peter L.
Close
Step 1
An ammonite (a shellfish with a spiral-shaped shell) dies and falls to the bottom of the sea where it is covered by sediments. (Image 1) Show more…
Show all steps
Your feedback will help us improve your experience
Supreeta N and 88 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
A paleontologist is a scientist who studies the fossils of ancient animals. Fossils are very important pieces of evidence of evolution because the fossils prove that the animals today have always been present on Earth. The fossils show that there are similarities in body structures between living and dead animals. The fossils also show that there would be DNA similarities among living and dead.
Rupsa S.
Fossils provide our best direct evidence for the evolutionary changes that have occurred throughout Earth's history. Fossils are preserved remains or traces of once living organisms, which span the geologic record and are made up of organisms from microscopic to macroscopic. But how do they form? For an organism to become a fossil, the once living organism must be covered in a layer of sediment, in a process known as sedimentation, before the organism begins to decompose. Petrified fossils If the buried organism is sufficiently starved of oxygen, the decomposition process will nearly halt. With adequate sedimentation and hindrance of decomposition, the organic material of that organism will begin to become infiltrated with minerals, in a process known as mineralization. Fossils of this nature are known as petrified fossils. Woody plants and animals are by far the most common petrified fossils. This is due to the dense nature of the wood in trees and bones in vertebrates. Draw a sequence of events that would lead to a petrified fossil. Preserved fossils Fossils are not always petrified remains of once living organisms. In rare cases, organisms can be entombed by a sticky substance that eventually solidifies. These fossils are known as preserved fossils. The most common preserved fossils are encapsulated by sticky resin excreted by plants. The main difference between petrified and preserved fossils is that preserved fossils still contain organic matter, whereas petrified fossils are composed of minerals that infiltrated the organism. Draw a sequence of events that would lead to a preserved fossil.
Adi S.
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD