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RE: The role of meteors in the mass extinction events

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Seismosaurus@seznam.cz
> Sent: Monday, September 22, 2008 12:47 PM
> To: dinosaur@usc.edu
> Subject: The role of meteors in the mass extinction events
> Good day to all listmembers,
> I'd like to ask what's the current general opinion on the 
> role of meteors in the mass extinctions events (and not just 
> the KT one)? Also, I'like to make myself clear about the 
> possible correlation of meteor craters and recognized 
> extinction events in the geological past. In David M. Raup's 
> book "Extinction: Bad Genes or Bad Luck?" appear some 
> interesting data (published back in 1990). I've already 
> mentioned these on the list before. Firstly, there's a short 
> list of all strata containing iridium anomalies (as for 1990 
> state of knowledge), I've updated the time estimates:
> Frasnian (Devonian) 375 mya

Little support for meteorites here, and extinction is just one of a sequence
at different levels in the Late Devonian. Here are some recent references:
# Algeo, T.J., & S.E. Scheckler. 1998. Terrestrial-marine teleconnections in
the Devonian: links between the evolution of land plants, weathering
processes, and marine anoxic events. Philosophical Transactions of the Royal
Society B 353: 113-130.
# Bond, D.P.G., & P.B. Wignall. in press. The role of sea-level change and
marine anoxia in the Frasnian-Famennian (Late Devonian) mass extinction. in
# Copper, P. 2002. Reef development at the Frasnian/Famennian mass
extinction boundary. Palaeogeography, Palaeoclimatology, Palaeoecology 181:
# Goddéris, Y. and Michael M. Joachimski. 2004. Global change in the Late
Devonian: modelling the Frasnian?Famennian short-term carbon isotope
excursions. Palaeogeography, Palaeoclimatology, Palaeoecology 202: 309-329.
# House, M.R. 2003. Strength, timing, setting and cause of mid-Palaeozoic
extinctions. Palaeogeography, Palaeoclimatology, Palaeoecology 181: 5-25.
# McGhee, G.R., Jr. 2001. The 'multiple impacts hypothesis' for mass
extinction: a comparison of the Late Devonian and the late Eocene.
Palaeogeography, Palaeoclimatology, Palaeoecology 176: 47-58.
# Peterhänsel, A., & B.R. Pratt. 2001. Nutrient-triggered bioerosion on a
giant carbonate platform masking the postextinction Famennian benthic
community. Geology 29: 1079?1082.
# Racki, G. 1999. The Frasnian?Famennian biotic crisis: How many (if any)
bolide impacts? International Journal of Earth Sciences 87: 617-632.
# Streel, M., M.V. Caputo, S. Loboziak & J.H.G. Melo. 2000. Late
Frasnian?Famennian climates based on palynomorph analyses and the question
of the Late Devonian glaciations. Earth-Science Reviews 52: 121-173. 

> Callowian (Jurassic) 161 mya
> Cenomanian (Cretaceous) 94 mya

Neither of these extinctions are well understood at present. Callovian is
far, far, far less severe than a typical mass extinction.

> KT boundary 65.5 mya

The biggie. Yep, very very very strongly correlated with an impact.

> Eocene (Tertiary) 34 mya

# Hansen, T.A., Pa.H. Kelley, & D.M. Haasl. 2004 Paleoecological patterns in
molluscan extinctions and recoveries: comparison of the Cretaceous?Paleogene
and Eocene?Oligocene extinctions in North America. Palaeogeography,
Palaeoclimatology, Palaeoecology 214: 233-242.
# Retallack, G.J., W.N. Orr, D.R. Prothero, R.A. Duncan, P.R. Kester & C.P.
Ambers. 2004. Eocene-Oligocene extinction and paleoclimatic change near
Eugene, Oregon. Geological Society of America Bulletin 116: 817?839. 

Evidence for impacts not compelling.

> Miocene (-"-) 12 mya
> Pliocene (-"-) 3 mya

Do not qualify as mass extinctions under any reasonable criteria. Dramatic
climate changes at 3 Ma closely associated with development of well-known
oceanographic barriers (between Indian and Pacific and between Pacific and
Atlatic) and consquent rise of the Oceanic Conveyor Belt and modern style

> + Pleistocene (Quaternary) 12kya

Blargh. See recent postings on this list about the "evidence" for Younger
Dryas extinctions.

> Manson (Iowa) 38 km, 74 mya (65.5 KT event, not likely)

Not merely not likely, but demonstrably a mid-Campanian event (by work of
Izett and colleagues in mid 1990s).

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA