Extinction of species is a recent discovery

Transcription

1 Extinction

2 Extinction of species is a recent discovery Georges Cuvier ( ) Georges Cuvier, anatomist and naturalist at the Museum of Natural History, Paris, used comparative anatomy to prove that fossil bones belonged to a species (American Mammoth) that no longer existed Ohio Animal Mammoth vs. Indian elephant lower jaw vs. Indian Elephant

3 Extinction is normal >99% of all species that have ever existed are now extinct Extinction rates have varied quite a bit through time Different groups have different characteristic species durations: Mammals: ~ 2 million years Foraminifera: ~ 20 million years

4 Marine Animal Extinction rates over the past 540 million years Late Ordovician Permian-Triassic Pleistocene-Recent?

5 Potential drivers of extinction Background Competition Predation Habitat loss Disease Climate change Bad luck Mass Rapid climate change Sea level change Wholesale habitat loss Ocean acidification Anoxia/hypoxia Bolide Impacts Disease?

6 Selectivity of extinction: What traits might influence extinction risk under different scenarios? Individual Physiology Thermal tolerance Diet Home range size Reproduction Gestation period etc. Population Geographic range Latitudinal range Environmental range Population density Population growth rate Dispersal etc.

7 Selective signature of mass extinctions: what is unusual about extinctions relative to extinctions at other times? An analogy: age distribution of mortality Fig. 5. Deaths from pneumonia and influenza in USA in three influenza pandemics during a (adapted normal fromflu Dauer pandemic & Serfling (44); vs. data for 1892 for Massachusetts only) during the 1918 pandemic Dowdle, 1999, Bulletin of the WHO

8 The Late Ordovician Mass Extinction

9 Climate change & mass extinctions Number of genera of marine animals Extant genera Cret.-Pg. Tri.-Jur. Perm.-Tri. L. Dev L. Ord Cm O S D C P T J K Pg Ng class Archaeocyatha Bivalvia Brachiopoda Cephalopoda Conodonta Crinoidea Demospongea Echinoidea Gastropoda Graptolithina Gymnolaemata Ostracoda Rugosa Scleractinia Stenolaemata Stromatoporoidea Tabulata Trilobita z.other climate Warm Cool Millions of years before present 200 Millions of years before present 100 0

10 Trotter et al., 2008, Science The Late Ordovician Mass Extinction Marine invertebrate genera ~60% of marine genera disappear during the Katian ( mya) and Hirnantian ( mya) stages Two pulses: end-katian pulse coinciding with cooling & expansion of Gondwanan ice sheets, end-hirnantian pulse coinciding with warming & contraction of ice sheets No clear selective signature with respect to which taxonomic groups go extinct

11 The Late Ordovician globe Very limited life on land, High CO2, Low O2 Laurentia Siberia Baltica Gondwana Gondwana modified after R. Blakey:

12 The Ordovician Period: little or no animal life on land, but abundant marine life

13 Who was hit by the extinction? Trilobites Brachiopods Tabulate and Rugose Corals Mollusks Graptolites naming-fossils.html Crinoids action=item&prod_id=191& agaricocrinus-americanus-crinoid.html

14 Who was hit by the extinction?

15 Ultimate cause: glaciation and subsequent deglaciation of south polar Gondwana?

16 Late Ordovician glacial deposits in Morocco Le Heron et al., 2010, Sedimentary Geology

17 What caused cooling? Some ideas: May have been caused by movement of Gondwana over the south pole... Laurentia Siberia Baltica Gondwana Gondwana modified after R. Blakey:

18 Or, increased chemical weathering of silicate rock due to Taconic mountain-building The silicate weathering feedback: modified after R. Blakey:

19 Or, increased chemical weathering of continental silicate rocks by early terrestrial ecosystems Late Ordovician moss and fungal spores The silicate weathering feedback: wellman-research-pic-dec-07.jpg Science Sep 15;289(5486):

20 Late Ordovician North America (Laurentia) Anticosti Island modified after R. Blakey:

21 English Head Baie des Homards 49 45'N Point Laframboise Natiscotec Creek 49 30'N 49 15'N 64 30' Ordovician Silurian LEGEND Chicotte Jupiter Gun River Merrimack Becscie Ellis Bay Vauréal measured section 64 00' 63 30' kilometers 63 00' Salmon River Macaire Creek Lousy Cove Fox Pt ' 62 00'

22 Vauréal Canyon

23 Gun River Fm. 1 cm. Ellis Bay Fm. 1 cm. Becscie Fm. Vauréal Fm.

24 Stratigraphic ranges of orthide brachiopods on Anticosti Laframboise Mbr., Ellis Bay Fm. Jin and Zhan, 2008

25 Western Anticosti: Pt. Laframboise Shallow-water deposits Deep-water deposits

26 Western Anticosti: Pt. Laframboise Deep water deposits (Silurian) Reefs

27 CaCO3 shells record the chemistry of the water in which they grew... Korte et al., 2005

28 Stable isotope ratios in fossil shells -Isotopes of an element vary in number of neutrons, but have a fixed number of protons and electrons -Isotopes have identical chemical interactions, but are often sorted by mass δ 13 C : ratio of 13 C to 12 C, provides information about changes in carbon cycle δ 18 O : ratio of 18 O to 16 O, provides information about changes in climate

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30 Jones et al., 2011 Pt. Laframboise: δ 13 C, δ 18 O Height in section (m) Lousy Cove Laframboise Fox Point δ 18 Ocarb, δ 13 Ccarb (, VPDB) δ 13 Corg (

31 Jones et al., 2011 δ 13 C is controlled by global organic carbon burial Enhanced upwelling, productivity and organic carbon burial? Decreased organic carbon oxidation rate? Weathering of exposed carbonate rocks? Height in section (m) Lousy Cove Laframboise Fox Point δ 18 Ocarb, δ 13 Ccarb (, VPDB) δ 13 Corg (

32 Jones et al., 2011 δ 18 O is controlled by both local temperature and global ice volume Increased glaciation of the poles? Cooling of the tropics? Both? Height in section (m) Lousy Cove Laframboise Fox Point δ 18 Ocarb, δ 13 Ccarb (, VPDB) δ 13 Corg (

33 T Temperature and seawater δ 18 O trends from clumped isotope paleothermometry ian Brachiopod Trilobite Rugose coral Bryozoan Anticosti Cinci. Arch U. Miss. V. Temperature, C! 18 O seawater LGM Ice-free ORDOVICIAN SILURIAN Katian Hirn. Rhuddanian Aeronian Age, mya 445 Age, mya Age, mya 440 Finnegan et al., 2011, Science

34 Results: Inferred Ice Volumes* *Assuming mean δ 18 Oice equivalent to Last Glacial Maximum ORDOVICIAN SILURIAN Katian Hirn. Rhuddanian Aeronian Ice volume, 10 6 km Last Glacial Maximum Present Age, mya Present LGM

35 Rhuddanian (E. Sil.) Ordovician-Silurian boundary sections Atypical: Anticosti Island Typical: Kentucky Hirnantian (L. Ord.) Rhuddanian (E. Sil.) Katian (L. Ord.) Katian (L. Ord.)

36 Build-up of glaciers on land drains shallow marine habitats San Francisco Bay 18,000 years ago Image courtesy Lynn Ingram

37 Sedimentary rocks record changes in continental flooding through time

38 Late Ordovician-Early Silurian sedimentary rocks and fossil collections in Laurentia Gap-bound sedimentary packages from Macrostrat (Peters, 2005) Fossil occurrences from PBDB (Alroy et al, 2008) Whiterock Chazyan Blackriveran Kirkfield Shermanian Maysvillian Richmondian Hirnantian Rhuddanian Aeronian Telychian Wenlock Fig. 1. Maps of sedimentary rocks deposited across Laurentia from Middle Ordovician Mixed carbonate-clastic Chert (Dapingian) through the Early Silurian (Wenlockian) time. Red points Sandstone mark PaleoDB collections. Colored polygons indicate sedimentary rock distribution and lithotype. Blue ¼ carbonate, dark blue ¼ mixed carbonate-clastic, gray ¼ fine clastics, tan ¼ mixed clastics, yellow ¼ sand, orange ¼ coarse clastics, blue-green ¼ chert, pink ¼ evaporites, brown ¼ metamorphic indet., Carbonate Mixed clastic dark green ¼ igneous indet. Only the uppermost unit in each column is plotted. Fine clastic Evaporite Finnegan et al., 2012, PNAS

39 svillian Richmondian n late Katian Draining of shallow tropical seaways late Katian Hirnantian Hirnantian Shallow ocean Exposed land Salt basin 0 0 Open ocean Wenlock

40 l nvil yas n ia Draining of shallow tropical seaways nn nn tidaia Koan te m laich R Shallow ocean ttiiaa aann rirnn HHi Hirnantian late Katian Exposed land Salt basin 0 ckk llooc eenn WW Open ocean 0 Hypothesis: genera that had large areas of their Late Ordovician geographic ranges drained should have experienced exceptionally high extinction rates

41 Ranges reflect interaction of climate and geography Mean sea surface temperature Bivalve species latitudinal ranges

42 Changing temperatures would have imposed additional stresses on genera with limited thermal tolerance Modeled Late Ordovician sea surface temperatures Before glaciation During glaciation Modified from Herrmann et al., 2004, P 3

43 Changing temperatures would have imposed additional stresses on genera with limited thermal tolerance Modeled Late Ordovician sea surface temperatures Before glaciation During glaciation Modified from Herrmann et al., 2004, P 3 Hypothesis: genera with narrow latitudinal ranges should have experienced exceptionally high extinction rates

44 Determinants of marine invertebrate extinction risk B Polar Ice Volume Tropical Temperature % Habitat Loss C Finnegan et al., 2012, PNAS D

45 Selective Signature: 80 Dapingian-early Before mass extinction Katian late Mass Katian extinction Rhuddanian-Wenlockian After mass extinction Exclusively lowlatitude genera much harder hit than those with broad latitudinal distributions Mean Temperature ( C) % Extinction % Extinction % Extinction Maximum Maximum Paleolatitude paleolatitude Finnegan et al., 2012, PNAS Vandenbrouke et al., 2010

46 Conclusions: The Late Ordovician glaciation was at least as large, in terms of ice volumes, as the Pleistocene glaciation Tropical seawater temperatures fell by ~5º C during the Late Ordovician glacial maximum Growth of glaciers caused sea levels to fall and drove a massive reduction in the area of shallow seaways Reduction of shallow seaways combined with cooling temperatures led to large-scale habitat loss and resulting extinction

47 Why did Late Ordovician glaciation cause a major mass extinction, but not subsequent glaciations? Late Ordovician Sea level, continental configuration & biogeography Mio-Pliocene R. Blakey: