The Deep History of Life Andrew H. Knoll Harvard University James - - PowerPoint PPT Presentation

▶
the deep history of life
SMART_READER_LITE
LIVE PREVIEW

The Deep History of Life Andrew H. Knoll Harvard University James - - PowerPoint PPT Presentation

Apr 27, 2023 306 likes •694 views

The Deep History of Life Andrew H. Knoll Harvard University James Hutton (1788): Earth is a dynamic Planet Charles Darwin (1859): Populations are also dynamic. Percival Lowell (1908): Planetary change is directional . Earth preserves a

slide-1
SLIDE 1

Andrew H. Knoll

Harvard University

The Deep History of Life

slide-2
SLIDE 2

James Hutton (1788): Earth is a dynamic Planet

slide-3
SLIDE 3

Charles Darwin (1859): Populations are also dynamic.

slide-4
SLIDE 4

Percival Lowell (1908): Planetary change is directional.

slide-5
SLIDE 5

Earth preserves a record of its biological and environmental history.

slide-6
SLIDE 6

Comparative biology and evolutionary history

Teilhardina magnoliana

slide-7
SLIDE 7

Haikouichthys, ca. 520 Ma Yunnanozoan, ca. 520 Ma

542

slide-8
SLIDE 8

Earliest evidence of animals

slide-9
SLIDE 9

End of the trail for animals What happened back here?

slide-10
SLIDE 10

Comparative biology suggests a potentially long pre-animal history of life.

slide-11
SLIDE 11

Can a microbial history be captured by the fossil record?

slide-12
SLIDE 12
  • Carbonates, similar to

those deposited today on Bahama Banks

  • Lamination,

comparable to laminae formed today by microbial mats

  • Tepee structures

indicate exposed tidal flat

  • Early diagenetic chert

nodules preserve microfossils (below, each spheroid is ca. 4 microns)

slide-13
SLIDE 13

Microfossil Interpretation

  • Diagnostic Form
  • Life Cycle
  • Behavior (Orientation)
  • Environmental Setting
  • Taphonomy
  • Distinctive stalk-

forming fossils preserved in tidal flat cherts

  • Some form mono-

specific crusts

slide-14
SLIDE 14

Ancient-Modern Comparison

  • Modern Bahama Banks: close environmental

analog

  • Find stalk-forming cyanobacteria that build

crusts

  • Very close morphological, life cycle and

environmental comparison across 750-800 million years

slide-15
SLIDE 15

Microfossils record a broad diversity of life in the late Proterozoic ocean

slide-16
SLIDE 16

Stromatolites

slide-17
SLIDE 17

Modern stromatolites guide interpretation of ancient

Shark Bay, Australia; Cross- section courtesy of J.W. Schopf

slide-18
SLIDE 18

Biomarker Molecular Fossils

  • Preserved molecules
  • f known biosynthetic
  • rigin
  • DNA and proteins

rarely preserved, and not known from Precambrian rocks

  • Lipids preserve well
slide-19
SLIDE 19

Biological Influence on the Isotopic Composition of Seawater

  • Autotrophic organisms

take up CO2 containing 12C in preference to 13CO2 – a kinetic isotope effect

  • Fractionation, the

difference between the isotopic composition of C in carbonate and C in co-

  • ccurring organic matter,

preserves a record of biology

  • Sulfur isotopes preserve a

similar biogeochemical record

slide-20
SLIDE 20
  • Modern microbial ecosystems provide keys

to the physical and biological interpretation

  • f sedimentary rocks deposited before the

evolution of animals.

  • In 750-800 million year old rocks of

Spitsbergen, the fingerprints of biology are everywhere

  • What do we see in older rocks?
slide-21
SLIDE 21

Bil’yakh Group, northern Siberia (~1500 Ma)

slide-22
SLIDE 22

Widespread Evidence of Life

C and S isotopic signatures, molecular biomarkers

slide-23
SLIDE 23

North Pole, Australia: The Warrawoona Group (3.45 Ga)

slide-24
SLIDE 24

Stromatolites (plus C and S isotopes)

slide-25
SLIDE 25
  • Available evidence

suggests that life

  • riginated early in

Earth history

  • BUT, at present

few hard facts about the nature of early life

  • EXCEPT, that it

worked without

  • xygen
slide-26
SLIDE 26

Several lines of evidence indicate

  • xygenation 2.4 Ga
  • Banded iron formation
  • Detrital uraninite, siderite,

and pyrite

  • Paleosols
  • Sulfur isotopes

Our hero

slide-27
SLIDE 27

How much O2 accumulated?

Lyons et al. (2014)

slide-28
SLIDE 28

Life at Middle Age: Abundant and diverse cyanobacteria

* * * * * * * * * * * * * *

* Known from mid-Proterozoic rocks (Tomitani et al., 2006)

slide-29
SLIDE 29

50 µm

Early Eukaryotes

Satka favosa Valeria lophostriata

Tappania plana

50 µm Grypania spiralis

slide-30
SLIDE 30

Building Diversity

slide-31
SLIDE 31

Animals: 800 Ma origin but diversification after 600 Ma

Erwin et al. (2011)

slide-32
SLIDE 32

When did atmosphere/ocean begin its transition to a more modern state?

Partin et al. (2013)

slide-33
SLIDE 33

Carnivory links oxygen and ecology

Sperling et al. (2013)

slide-34
SLIDE 34
slide-35
SLIDE 35

Animals Anaerobic Bacteria and Archaea Eukaryotes Aerobic Metabolism

Surface OMZ High O2 Low O2 No O2 O2 Fe Fe (HS-) Fe

slide-36
SLIDE 36

Evolution plays out on a dynamic planet

slide-37
SLIDE 37

The Evolutionary Present

Jim Barry (MBARI)