The Evolutionary History of Sharks
By: Alana J. Cameron
Student Number: 250752208
Earth Science 1083F-001 Tutorial 004
Sharks are an animal group that have existed on Earth for quite a long time. This essay will
focus on the long term evolution of sharks
To Be or Not to Be:
Fossilization and Information Loss
Fossilization tends to be the exception for
dead remains rather than the rule!
Less than _% of all remains of all living
things make it into the fossil record !
Contrary to popular b
Skeletons in the Closet:
the Evolution of Hardparts in Metazoa
(and the Cambrian Explosion)
Additional Comments on Ediacaran Fauna
Remember earliest complex
metazoa (Ediacaran fauna) were
all soft bodied (no _
All preserved as _.
Discovery of Edi
Darwins Big Breakthrough:
Natural Selection as a
Fundamental Driving Force in Evolution
Shell shape different on separate islands
Common ancestor, but different forms now separated
geographically, so interbreeding
The Dancing Plates:
The Plate Tectonic Revolution
How Can Rock Cycle Be Explained ?
Prior to the early 1900s, it was
thought that Earths exterior was
The conditions necessary for the
formation of the three rock
classes were fairly well
Survey of the Invertebrates
(Differentiated Multicellular Animals)
An Overview of the Major Groups
How Do We Classify Life ?
Note: Kingdoms Eubacteria and Archaea formerly
classified as Kingdom Monera
Earth Rocks: Rock-Forming Environments
Part 1: Igneous Environments
So far, we have looked at the
relationship of atoms to minerals.
We will now look at the relationship
of rocks to stated in the last couple
lectures processes that act with
Earths Rocks: Rock-Forming Environments
Part 2: Sedimentary and Metamorphic Environments
Sedimentary rocks are formed by the accumulation and
hardening of sediment.
Three kinds of sediment:
Clastic sediment - consisting of particles (cla
Earth Science Lecture 7: Some Quirks of Heterochrony.
A Bit of a Diversion: Heterochrony
The rapid and brief ontogeny is a condensed synopsis of the long and slow history of the
Early development stages among various animals (i
Earth Science Lecture 5: Modern Synthesis of Evolution and Punctuated
Watson and Crick
Outlined the coiled, helical structure of DNA, which provides a molecular basis for
inheritance and evolution.
o Beginning of reductionist evolut
Earth Science Lecture 5: Mendel to Modern Synthesis
Struggle for existence and only the fittest survive. Wondrous Monsters with new
advantageous traits will eventually replace less adapted individuals, giving rise to another
Earth Sci Lecture 4:
Darwins Big Breakthrough
Due to the difference between Saddleback and Domed back turtles (in their shells)
interbreeding was impossible.
Land Iguana and Marine Iguanas: Differ in colour to blend with different
The Earth System
and an Introduction to
The Earth System
Earth is a complex system of interconnected natural
For convenience, we can consider
these processes to affect four
main components (subsystems in
Geosphere (solid E
Rocks as time machines:
principles of geologic time
Determining geological ages
Relative dating placing rocks and events in their proper
_ of formation
Numerical (absolute) dating specifying the actual number
of _ that have passed since an event occurre
Earth Sciences 1083F:
Life on Planet Earth
The Joy of Rex:
Why Study the History of Life ?
Fossils are cool !
We want to know where we came from !
Humans (and all other organisms on Earth) are the products of at
least 3.5 billion years of evolution. Many
The Holy and the Heretical:
Pre-Darwin Concepts of Fossils and Evolution
An early interpretation of dinosaur remains?
Thoughts on Fossils and Earth
Aristotle (384-322 B.C.E.)
Mystic forces produced
(resembling living things)
Remember that Darwins theory of natural selection
claimed that there is a struggle for existence and that
in that struggle, the fittest survive
Natural selection therefore implies that an organism that
is best-equipped to survive the rigo
Tales of Seasick Naturalist:
Charles Darwin, the Beagle, and Early
Thoughts on Natural Selection
Charles Darwin (1809-1882)
Born: Charles Robert Darwin, February 12, 1809
(The Mount, Shrewsbury)
Father: Robert Darwin (physician)
- Son of Erasm
All Along the Ivory Tower: The Modern Synthesis of
Evolution (and Punctuated Equilibrium)
Tricking the Clock: Some Quirks of Heterochrony
Francis Crick and James Watson (1953) outline the coiled,
helical structure of DNA, which provides a molecular b
Primordial Soup in the
Kitchen of Life:
The Origin of Life
How Do We Classify Life ?
And Viruses ?
And nanobacteria ?
Nanobes growing on clay ?
Nanobacteria about 1,000 x smaller than regular bacter
Lungs for Land: Evolution of Amphibians
Middle to Late Devonian: Rhipidistians
Lungs were developed in two
groups of lobe-finned fishes Rhipidistians and lungfishes .
The Rhipidistians are considered
to be the ultimate ancestors of
the _ (vertebrate
Of Microbes and Martians:
Earths Earliest Life
Origin of Life: Recap
The answer to the ultimate question of how (and where) the
first living cell came into being remains elusive, but a few
1. That the essential ingredients for life we
What is a Mineral ?
Defining characteristics of minerals:
Inorganic (or at least never alive)
Ordered, repetitive internal structure (crystalline)
Definite chemical composition (allowing for small
Sex and the Simpleton:
Evolution of Sex and the Rise of the Eukaryotes
Two Main Types of Organisms
Prokaryotes (include Archaea and Bacteria),
distinguished by lack of a true nucleus
-term derived from Greek pros meaning before and
karyon meaning nut (ref
Sole Mates: Evolution of Fishes
The origin of fishes
can be traced to the
Pikaia or the modern
which lacked a
possessed a flexible
rod of tissue called a
Like other chordates,
Earth Science Lecture 3
Confessions of a Seasick Naturalist: Charles Darwin, the Beagle and Early Thoughts on Natural
Darwin believed that changes in organisms occurred over the accumulation of years and