iii. fossil and biochemical evidence
DESCRIPTION
III. FOSSIL AND BIOCHEMICAL EVIDENCE. TYPES 0F FOSSILS. PETRIFIED WOOD. MOLD. CAST. BONES. AMBER. IMPRINTS. PALEONTOLOGY -the study of fossils. Sedimentary rock. Figure 22.18. The Fossil Record. - PowerPoint PPT PresentationTRANSCRIPT
III. FOSSIL AND BIOCHEMICAL EVIDENCE
TYPES 0F FOSSILS
MOLD
BONES
IMPRINTS
PETRIFIED WOOD
CAST
AMBER
PALEONTOLOGY -the study of fossils
Sedimentary rock
Figure 22.18
The Fossil Record• The succession of forms observed in the fossil
record is consistent with other inferences about the major branches of descent in the tree of life.
• The Darwinian view of life– Predicts that evolutionary
transitions should leave signs in the fossil record
• Paleontologists– Have discovered fossils of many
such transitional forms
A. Fossils-relative and absolute dating methods
How Rocks and Fossils Are Dated
• Sedimentary strata– Reveal the relative
ages of fossils
Relative Dating Methods
• Index fossils– Are similar fossils found in the same strata in
different locations– Allow strata at one location to be correlated with
strata at another location
Figure 26.6
• The absolute ages of fossils– Can be determined by radiometric dating
Figure 26.7
1 2 3 4
Accumulating “daughter”
isotope
Ratio
of p
aren
t iso
tope
to
dau
ghte
r iso
tope
Remaining “parent” isotope
1
1
11
Time (half-lives)
2
4
816
Absolute Dating Methods
Magnetism Dating• Magnetic reversals of the north and south
magnetic poles:– Have occurred repeatedly in the past– Leave their record on rocks throughout the world– These marks are used for dating
Another Absolute Dating Method
The GeologicRecord
• By studying rocks and fossils at many different sites– Geologists
have established a geologic record of Earth’s history
B. A Discussion of what can be inferred from patterns in the fossil
record• The fossil evidence Is consistent with the idea
that today’s organisms evolved from a common ancestor.
• There have been catastrophic events that have affected the creation of new species.
• Geological events that alter environments– Change the course of biological evolution
• Conversely, life changes the planet that it inhabits
Figure 26.1
C. Biochemical SimilaritiesBetween Current & Past Species
Molecular Homologies• Biologists also observe
homologies among organisms at the molecular level– Such as genes that are shared
among organisms inherited from a common ancestor
1 2.4 3.14 5.18 6 7.15
XX1913.1710.169.128.11
1 2.19 3.8 4.16 5.14 6.7
XX15.1813.1711.129.10Figure 23.10
• Anatomical resemblances among species– Are generally reflected in their molecules, their
genes, and their gene products
Figure 22.16
Species
Human
Rhesus monkey
Mouse
Chicken
Frog
Lamprey 14%
54%
69%
87%
95%
100%
Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide
D. Shared Anatomical Structures• Homology– Is similarity resulting from common ancestry
• Homologous structures between organisms– Are anatomical resemblances that represent variations on
a structural theme that was present in a common ancestor
GILL SLITS
TAIL
All VETEBRATES
Similar Embryonic Development
• Comparative embryology– Reveals additional anatomical homologies not
visible in adult organisms
Figure 22.15
Pharyngealpouches
Post-analtail
Chick embryo Human embryo
VESTIGIAL STRUCTURES
Appendix
Are remnants of structures that served important functions in the organism’s ancestors