What is paleobiology?
The study of the history and evolution of life, as revealed by the fossil record.
Why should we care?
Paleobiology provides us with a long-term historical perspective (a fourth dimension) on the remarkable and astonishing diversity of life today.
Gain that perspective mainly from fossils!!
What are fossils good for?
Fossils provide the only direct record of the history of life
What are fossils good for?
Indicate the discovery of kinds of organisms no longer living
What are fossils good for?
Provide direct evidence of ancient environments
What are fossils good for?
Can determine ancient continental positions and connections
What are fossils good for?
Fossils are the only practical means of telling time in geology
What are fossils good for?
Show us that life today is a product of a long, complex history
What are fossils good for?
Fossils are fascinating and beautiful!
What are fossils good for?
Macroevolution: can examine patterns and hypothesize mechanisms of evolutionary change over long periods of time - rates, trends, evolutionary
modes, etc.
Know what the average species longevity is
(how long it can live for)
1-25 million years
- Unaltered Remains
are not common. It's when organic matter is still present, like in mummification or encased in petroleum sediment.They usually consist of soft tissues like woolly mammoths eaten by humans and skeletons. Typically, DNA and protein are degraded but organic
- Altered Remains (more common):: Permineralization
when pores are filled with minerals; petrified wood and bone.
Altered Remains (more common):: Recrystallizatio
- change in minerals
ex:
a. inversion to less ordered state: ARAGONITE �> CALCITE
b. loss of Mg: CALCITE �> CALCITE
c. change in crystal size: SMALL �> LARGE
Altered Remains (more common).) Dissolution and replacement
- skeleton dissolves, leaves a void that defines a mold, which can be cast with sediment
Altered Remains (more common).Carbonization
- residue of coal-like carbon, from high organic material
More preserved.: ) ANATOMICAL
Organisms without mineralized skeletons are much less likely to be preserved as fossils. Preservation is more likely with hard (mineralized), thick/dense skeletons. Also with skeletons of one part (more difficult to break apart)
More preserved.: ) ANATOMICAL
molted skeletons: animal makes more than one in its lifetime, so its more likely to be preserved.
More preserved.: ) ANATOMICAL
also large body size!! �> easier to discover as a fossil, but less abundant originally
- EX: chiton has 8 plates and is easily disarticulated. Yet each individual chiton is more likely to be represented by at least one plate!
) ECOLOGICAL
- Abundant individuals
makes preservation more likely, but a single individual may be more difficult to discover as a fossil
ECOLOGICAL
Shallow marine habitat
#NAME?
BIOGEOGRAPHICAL
Geographically widespread species more likely to be preserved, somewhere
�> What something WON'T get fossilized
(less likely): no mineralized skeletons, rare and low abundance
- Igneous
: latin for ignis "fire"; cools and crystallizes from liquid rock (magma); seldom contains fossils because its too hot! However, their have been humans buried and found in volcanic ash, can be found in sierra mountains
Metamorphic
: change form; form fro pre-existing rock due to increase in temp (T) and press (P) which can change characteristics. Can form from any type of rock. Fossils are rare. These rocks can NEVER remelt!
Sedimentary
settle out; form at earth's surface from interaction of fluids (wind, water) and atmosphere on pre-existing rocks. Most fossils are found in sedimentary rocks.
Uniformitarianism
processes observed today were the same in the past
Relative Age = relative order of events
� Uniformitarianism = processes observed today were the same in the past
Relative Age = relative order of events
� Superposition = in an undeformed sequence of rocks (flat line of rocks), each bed is older than the one above and younger than the one below
Relative Age = relative order of events
� Original horizontality = layers are deposited in horizontal layers; tilting occurs after deposition!! bc gravity wouldn't allow
Relative Age = relative order of events
� Lateral continuity = strata often form laterally extensive horizontal sheets. subsequent erosion dissects once continuous layers
Relative Age = relative order of events
� Cross-cutting relationships = younger features truncate (cut across) older features �> dike= vertical igneous features
Relative Age = relative order of events
� inclusions = ALWAYS older than the material that encloses them
Relative Age = relative order of events- baked contact
� Baked contacts = an igneous intrusion cooks the invaded surround rocks; "pluton will be younger than baked contact
Absolute Age = actual number of years since event- rock composition
� rocks are made of minerals which are made of elements/compounds which are made of atoms
Absolute Age = actual number of years since event
� some elements are radioactive
Absolute Age = actual number of years since event - radioactive elements
� radioactive elements decay continuously, spontaneously, and at a predictable rate
Absolute Age = actual number of years since event - isotopes
Isotopes= elements that have varying numbers of neutrons
radioactive decay
� radioactive decay = a change in the number of neutrons and protons, and a change in atomic mass and/or atomic number
Half life
� half-life = amount of time it takes for half the parent atoms to transform to daughter atoms
Mass spectrometer
mass spectrometer = measuring parent: daughter ratio; � diff radioactive elements decay at diff rates
Absolute Age = actual number of years since event
� a composite column divided into tumed blocks
UNCOMFORMITIES
#NAME?
discomformity
� disconformity - parallel strata bracketing non deposition; look at fossils for clues
nonconformity
� nonconformity - metamorphic or igneous rocks overlain by sedimentary strata
angular unconformity
angular unconformity - rocks below an angular unconformity were tilted or folded before the unconformity
� STRATIGRAPHIC CORRELATION
� lithologic correlation - based on rock type
STRATIGRAPHIC CORRELATION
� fossil correlation - based on fossils within the rocks
Know the age of the Earth
4.6 billion yo
what time the earliest fossils appear
3.5 billion year ago
when the first multicellular life appeared
700 million years ago
first abundant skeletonized multicellular life
550 million ya
Know the functions of mineralized skeletons
Protection
from predation
Know the functions of mineralized skeletons
- Mechanical
attachment for muscles
Know the functions of mineralized skeletons
-) Ion Storage
- energy, metabolism
Know the functions of mineralized skeletons
-Ion Purge
ridding body of unwanted shit
Know the functions of mineralized skeletons
-Gravity Perception
mineralized statocysts respond to force of gravity
major components of skeletons
A) Organic
-Proteins
crystalline polymers; long chains of amino acids.
i) Collagen = basic structural fiber in animals
ii) Silk - spider webs
iii) Keratin - claws, hair, horn
major components of skeletons: Polysaccharide
polymers of joined, simple sugars
i) Cellulose - plants (glucose)
ii) Chitin - 2nd most common structural fiber in animals
) Inorganic
Mostly crystalline, formed both intracellularly and extracellularly; most enclose or are enclosed by an organic matrix, Composed of major elements, minor elements, trace elements, and isotopes of elements
) Biologically-controlled (MOST ANIMALS)mineralization
...
) Biologically-controlled (MOST ANIMALS)mineralization
framework or template of organic components is formed by organism
) Biologically-controlled (MOST ANIMALS)mineralization
ions are actively induced to specific sites on template, then crystallize and grow
) Biologically-controlled (MOST ANIMALS)mineralization
mineral type, structure and orientation are genetically controlled BY ORGANISM
Biologically-induced (GREEN ALGAE ONLY) - Mineralization
organisms alter their immediate chemical microenvironment, thus inducing minerals to precipitate
Biologically-induced (GREEN ALGAE ONLY) - Mineralization
- not under strict genetic control �> this is not sensitive to environmental conditions; so you're not getting that consistency or same mineralized makeup, orientation, location, etc
Biologically-induced (GREEN ALGAE ONLY) - Mineralization
- organisms alter their immediate chemical microenvironment, thus inducing minerals to precipitate
minerals that make up organism skeletons
A) Phosphates
�> Apartite (biomineral in vertebrate skeletons)
minerals that make up organism skeletons
-Carbonates
Calcite (coccoliths, some brachiopods), High Magnesium Calcite (echinoderms), Aragonite (molluscs)
minerals that make up organism skeletons
-) Silica Minerals
�> Opals - hydrated form of silica (radiolaria, diatoms, sponge)
minerals that make up organism skeletons
-Iron Oxides
rare) �> magnetite; magneto tactic bacteria have these magnetite particles and align themselves to Earth's magnetic field
temperature affects oxygen isotopes & the isotopic ratio in skeletons (if we get isotope ratio measurements, what can we use this for?)
� oxygen isotopes can tell us about the temperature of formation of skeletons of marine organisms, seasonal growth periodicities, etc
temperature affects oxygen isotopes & the isotopic ratio in skeletons (if we get isotope ratio measurements, what can we use this for?)
� In winter, organisms living in seawater will have a heavier isotopic signal in skeletons bc the seawater is enriched in 18O �> In cool climates (glacial times; winters), more mobile 16O in the oceans will preferentially be taken up in evaporation and de
temperature affects oxygen isotopes & the isotopic ratio in skeletons (if we get isotope ratio measurements, what can we use this for?)
� In warm climates (interglacial times; summers), glaciers (snow) melt, releasing the16O in the ice back to the ocean. Skeletons of organisms living in the ocean at this time will be relatively depleted in 18O (and thus relatively enriched in 16O), with a
Biostratinomy
decade, disarticulation, deposition
a) biological - bacterial decay, borers, scavengers
b) chemical - dissolution, mummification
c) physical - abrasion, borings, disarticulation, transport
Diagenesis
#NAME?
Lagerst�tten: : Burgess Shalee
early, soft-bodied organisms, Pikaia; KNOWN FOR ITS GREAT PRESERVATION; found in british colombia, canada. (middle cambrian) about 500 million years old. one of the most famous fossil sites;
Lagerst�tten :Mazon Creek
Carboniferous (300 MY),
fossil plants in ILLINOIS
Lagerst�tten :Holzmadene
Jurassic (160 MY), Germany
ichthysaurs
Lagerst�tten : Solnhofen
Upper Jurassic (145 MY), Southern Germany
archaeopteryx aka FIRST BIRD; limestone and isolated lagoons
Lagerstatten : Messel
0
An entity persisting through a finite period of time, with change
ontogeny
Scales of description (microstructure) Chemical composition (biomineralization) Behavior (trace fossils) Position in space (habitat; biogeography) Position in time (biostratigraphy)
Know examples of ways to describe organisms
Types of growth 1) Addition of skeletal material to existing structures (accretion)
Younger skeleton is a major component of next older skeleton
Growth lines form
Gradual shape change usually results
2) Types of growthAddition of new parts to old parts.
Echinoderms, foraminifera, vertebrates Less common than accretion alone; often also involves accretion
Types of growth Molting
Arthropods Can regenerate parts, can eat molts for nutrition Eliminating entire skeleton periodically, leaves organism vulnerable Allows rapid change to occur during growth, less efficient mode of growth
Types of growth : Remodeling
Vertebrate bone, molluscs, brachiopods Continual mineralization and resorption Allows considerable change in shape; also from response to stress
How do organisms vary?
Types of variation within population
Sexual dimorphism Ecophenotypic variation Taphonomic distortion
Morphometrics
Quantitative descriptions (measurements) of individuals in 1D, 2D, and 3D =
Allometry
AllometryChange in shape that accompanies an increase in size Results from competing requirements of:
o surface area o cross-sectional area o volume
Different parts grow at different rates; proportions vary Scaling Effect
Allometry
Before log transforming, data plot as a curved line, or as a straight line not through the origin After log transforming, data plot as a straight line with slope NOT equal to 1
Isometry
Increase in size with NO change in shape �> geometric similarity After log transforming, special case where: a (slope of line) = 1
Interpretation of change in shape is more interesting than simply documenting change in shape � asking WHY?
Example: respiration is dependent on surface area. As size increases isometrically, ratio of surface area to volume decreases (1/1; 1/2; 1/3; 1/4; etc.); respiration becomes progressively less effective. Surface area must increase MORE than it would isome
Populations
A group of individuals living close enough to each other that each individual of a particular sex has an approximately equal chance of mating with a certain individual of the other sex. In other words, Groups of conspecific organisms that occupy a more or
Natural selection
Variation exists; is heritable; differential survival. Will increase those gene frequencies that are more "fit" in some environments
(more adaptive). Most influential force in large populations.
. Genetic drift
chance fluctuation in gene frequency
inbreeding -
reduces genetic variability within populations
Migration
mixing together prevents genetic divergence
Mutation
occur spontaneously; ultimate source of genetic variation
Modes of speciation How do species originate?, Allopatric
speciation (conventional model) requires geographic isolation
Divergent selection pressures act on geographically isolated populations
Modes of speciation How do species originate?, Parapatric
speciation
Speciation occurs in adjacent geographic areas Gene flow is reduced, clines can form
Modes of speciation How do species originate?, Sympatric
speciation
Speciation occurs in one geographic area Isolating mechanisms at work are NOT based on geography.
What patterns of speciation do we see in the fossil record?
Patterns of morphological change in the rock/fossil record interpreted as different modes of speciation:,, : Anagenesis
gradual change in fossil populations over time
What patterns of speciation do we see in the fossil record?
Patterns of morphological change in the rock/fossil record interpreted as different modes of speciation:,, Cladogenesi
splitting of lineages; like allopatry in time