Snowball Earth
and the
Evolution of
Animals.
Alex L. Sessions
Division of Geological and Planetary
Sciences
Caltech Alumni Seminars, May 2006
A Brief History of Life on Earth
Cenozoic
millions
of years Eon Era
0
100
Period
Tertiary
Mesozoic
Cretaceous
Jurassic
300
Phanerozoic
200
Triassic
Permian
400
Paleozoic
Carboniferous
Devonian
Silurian
Ordovician
500
Cambrian
Caltech Alumni Seminars, May 2006
A Brief History of Life on Earth
Cenozoic
millions
of years Eon Era
0
100
Period
Tertiary
Mesozoic
Cretaceous
Jurassic
300
Phanerozoic
200
Triassic
Permian
400
Paleozoic
Carboniferous
Devonian
Silurian
Ordovician
500
Cambrian
Caltech Alumni Seminars, May 2006
A Brief History of Life on Earth
100
Period
Tertiary
0.5
Mesozoic
Paleozoic
Jurassic
Triassic
Permian
2.0
Carboniferous
2.5
Devonian
3.0
Silurian
Ordovician
Proterozoic
1.0
3.5
Meso
Paleo
Archaean
Mesozoic
Phanerozoic
Era
Neo
1.5
Paleozoic
400
Eon
Cretaceous
200
300
billions
of years
0
Phaner.
Cenozoic
millions
of years Eon Era
0
500
4.0
4.5
Hadean
Cambrian
Caltech Alumni Seminars, May 2006
A Brief History of Life on Earth
100
Period
Tertiary
0.5
Mesozoic
Paleozoic
Jurassic
Triassic
Permian
2.0
Carboniferous
2.5
Devonian
3.0
Silurian
Ordovician
Proterozoic
1.0
3.5
Meso
Paleo
Archaean
Mesozoic
Phanerozoic
Era
Neo
1.5
Paleozoic
400
Eon
Cretaceous
200
300
billions
of years
0
Phaner.
Cenozoic
millions
of years Eon Era
0
500
4.0
4.5
Hadean
Cambrian
Caltech Alumni Seminars, May 2006
A Brief History of Life on Earth
100
Period
Tertiary
0.5
Mesozoic
Paleozoic
Jurassic
Triassic
Permian
2.0
Carboniferous
2.5
Devonian
3.0
Silurian
Ordovician
Proterozoic
1.0
3.5
Meso
Paleo
Archaean
Mesozoic
Phanerozoic
Era
Neo
1.5
Paleozoic
400
Eon
Cretaceous
200
300
billions
of years
0
Phaner.
Cenozoic
millions
of years Eon Era
0
500
4.0
4.5
Hadean
Cambrian
Caltech Alumni Seminars, May 2006
an
op
yr
s
41
ccu
ssp
ma
s
pla
o
rm
e
Th
hrax
Methano
spirillum
mari
n
e
SBAR
pSL
p pGr
5
12 GrtA tC26
4
Py
ro Sul
Th dicti folob
us
er um
m
op
ro
te
us
0.10 changes/site
Co
p
Tri
t
mo
Gi
na
s
a
ita
m
Entomoeba
ia
pler
Neo
ar
di
a
ph
or
im
ir
Va
modified from Pace (1997)
ho
Evolutionary
relationships
between the three
domains of life,
based on 16SrRNA sequences.
Anatomical diversity
belies a great deal
of biochemical
diversity.
xa
He
Dichyostelium
ric
a
um
om
ar
os
ys
an
Ph
ryp
T
lena
Eug
Eucarya
Po
r
Para phy
mec ra
ium
Babosla
rin
u
Homo s
Zea onas
hom
p
y
ria
Cr
ya sta
l
h
Ac
Co
ha
Arc
us
lob
g
eo
Halot
m
ilu
of
m
er 50
Th pSL 2
2
pSL
Root
8
pJP 7
pJP 27
Th
Th erm
er us
m
o
pO tog
Aq PS a
u 56
EM ifex
17
us
oco
us
m
teriu erm
th
th
no
m
Me
ha
et
M
riu
te
dr
io
De n
ch sulf
lo
ov
Syne ropla ibrio
choc st
oc
Gloeobcus
Chlamydia acter
Chlorobium ma
e
Lepton tridium
Clos
illus
Bac rium ter
e
ac
9
ct
ba hrob PS1
o
i
l
t
e
r
O
H
A
p ium
ob
c
ir
m
mo
er
Th
han
on
Archaea
Thermococcus
ch
c
ba
ro
Ag
ito
ac
anob
Meth
m
Met
Bacteria
lus
ocyc
Rhod Planctomyces
Flexibacter
Flavo
bacte
rium
Phylogenetic Tree of Life
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Early Animal Divergence
535
579
549
604
634
664
494
546
Dendraster
Encope
Eucidaris
Asterina
Antedon
Ptychodera
Saccoglossus
Mytilus edulis
Mytilus californianus
Modiolus
Nucula
Haliotis
Crepidula
Chaetopterus
Nereis
Amphiporus
Lineus
Cerebratulus
Lestes
Enaliagma
Drosophilia
Anopheles
Priapulus
Obelia
Metridium
Scypha
Leucosolenia
Microclona
Ephydalia
Trochospongilla
Saccharomyces
Arabidopsis
modified from Peterson & Butterfield (2005)
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Neoproterozoic Changes
1st Taxa
∆34S (‰)
δ13C (‰)
BIF
Ice
Archaean
Anoxic
2500
2000
Meso
Proterozoic
1500
1000
Age (millions of years)
Paleo
Anoxic/
Sulfidic
3000
Neo
Oxic
543
-8
0
+12
-60
modified from Anbar & Knoll (2002)
0
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Snowball Earth?
Neoproterozoic glacial deposits are found at virtually
all latitudes. Was this a global glaciation?
modified from Evans (2000)
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Snowball Earth?
courtesy of www.snowballearth.org
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Fossils
Morphologic fossils
OH OH OH
OH OH
Chemical fossils
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Biomarker Analyses
2. Solvent
extraction.
1. Crush rocks.
3. GC/MS
analysis.
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GC/MS Data
Chromatogram
tells us relative
abundances of
compounds.
Mass spectrum
tells us identity
of peaks.
Caltech Alumni Seminars, May 2006
Vazante Formation, Brazil
Lapa
sub Landim sub Member
Mbr
38
10
Morro do
Calcario
sub Mbr
Mocombo sub Member
Vazante Fm
Lapa Fm
46
Phanerozoic
Neoproterozoic
(São Francisco Supergroup)
18
Mesoproterozoic
(Espinhaço Supergroup)
Paleoproterozoic-Archean
(Basement)
Sample Site
Brazil
Caltech Alumni Seminars, May 2006
Vazante Formation, Brazil
TOC (%)
Lapa
sub Landim sub Member
Mbr
Morro do
Calcario
sub Mbr
Mocombo sub Member
Vazante Fm
Lapa Fm
0
4
759
783
805
810
812
2x
816
2x
817
858
Retention Time
Caltech Alumni Seminars, May 2006
Rogue’s Gallery of Biomarkers
R
Hopanes - aerobic Bacteria
2-Methylhopanes - Cyanobacteria
R
Steranes - Eukaryotes
Gammacerane - Protists
Arylisoprenoids - Green sulfur bacteria
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Shimen Section, South China
Doushantuo Fm
105oE
hu
i
Datangpo Fm
Gucheng Fm
An
Shimen section
Weng'an
Hunan
Guizhou
Gu
an
gx
i
20oN
ck
i
25oN
120oE
be
n
Ya
oc
l
b
115oE
Hu
o
Nantuo Fm
e
z
gt
30 N
k
110oE
ia
s
y
o
bl
ha
t
a
C
500 km
Cathaysia block
Yangtze block: platform facies
Yangtze block: shelf slope facies
Yangtze block: basinal facies
Xieshuihe Fm
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Shimen Biomarkers
nC19
Doushantuo Fm
nC26
Nantuo Fm
Datangpo Fm
Gucheng Fm
Xieshuihe Fm
Caltech Alumni Seminars, May 2006
Conclusions
• Biomarkers show no evidence of biotic crisis associated with glaciations.
• Repeated ecological
shifts are associated with
glaciations. Phytoplankton
more predominant.
• Nutrient delivery a possible mechanism to connect
these phenomena. Nutrients → phytoplankton →
oxygen → animals
Caltech Alumni Seminars, May 2006
Acknowledgements
Collaborators:
Chao Li, Alison Olcott,
Frank Corsetti (USC),
Ping’an Peng (GIG)
Funding: NSF Earth
Sciences Directorate
More information:
www.gps.caltech.edu/~als
Caltech Alumni Seminars, May 2006