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Dinosaur record and extinction scenarios + other papers



Ben Creisler
bcreisler@gmail.com

A number of recent papers that may be of interest from

GSA Special Papers 505, 2014
Volcanism, Impacts, and Mass Extinctions: Causes and Effects
edited by Gerta Keller & Andrew C. Kerr
Table of Contents

http://specialpapers.gsapubs.org/content/505.toc

***
J. David Archibald (2014)
What the dinosaur record says about extinction scenarios.
GSA Special Papers 2014, v. 505, p. 213-224
doi: 10.1130/2014.2505(10)
http://specialpapers.gsapubs.org/content/505/213.short

The record of dinosaurs over the last 10 m.y. of the Cretaceous, as
well as surrounding the Cretaceous-Paleogene boundary, helps to define
extinction scenarios. Although Late Cretaceous dinosaur fossils occur
on all present-day continents, only in North America do we find a
terrestrial vertebrate fossil record spanning the Cretaceous-Paleogene
boundary, although promising work may yield comparable records in
South America, India, China, and Europe. For the present then, the
North American record represents the proxy for our knowledge of
dinosaur extinction. Over the last 10 m.y. of the Cretaceous (late
Campanian to late Maastrichtian) in the northern part of the western
interior of North America, the number of nonavian dinosaur species
dropped from 49 to 25, almost a 50% reduction, even though a 16%
greater extent of fossil-bearing exposures record the last dinosaurs
in the latest Cretaceous in the western interior. Important, but
less-well-exposed, nonavian-dinosaur–bearing units suggest this drop
occurred around, or at least commenced by, the Campanian-Maastrichtian
boundary. These losses began during climatic fluctuations, occurring
during and possibly in part caused by the last major regressive cycle
of the Cretaceous, which also reduced the expanse of the low coastal
plains inhabited by nonavian dinosaurs. The pulse of Deccan Trap
emplacement that began some time later in the latest Cretaceous was
also likely a major driver of climatic change. As for the dinosaur
record near the Cretaceous-Paleogene boundary, even the best-known
records from North America remain enigmatic and open to
interpretation. Newer studies suggest some decline in at least
relative abundance approaching the Cretaceous-Paleogene boundary, but
the cause (or causes) for the final extinction (if it was the case) of
non-avian dinosaurs remains unresolved, although the Chicxulub impact
undoubtedly played a major role.
===

Guntupalli V.R. Prasad and Ashok Sahni (2014)
Vertebrate fauna from the Deccan volcanic province: Response to
volcanic activity.
Geological Society of America Special Papers, 2014, 505, p. 193-211
doi:10.1130/2014.2505(09)
http://specialpapers.gsapubs.org/content/505/193.abstract

During the last two decades, extensive paleontological research in the
main Deccan volcanic province has led to a better understanding of
biodiversity close to the Cretaceous-Paleogene boundary. Several
infratrappean localities exposed in Jabalpur, Kheda, Balasinor,
Rahioli, Dohad, and Bagh in the Narmada Valley (India) preserve one of
the most geographically widespread dinosaur nesting sites known in the
world. The well-studied intertrappean beds, such as those of Naskal on
the southern margin, Asifabad and Nagpur on the eastern margin,
Kisalpuri and Mohgaon Kalan on the northeastern margin, and Anjar on
the northwestern margin of the main Deccan volcanic province, have
yielded Maastrichtian fish (Igdabatis) and dinosaur remains and
palynofossils (Aquilapollenites-Gabonisporites-Ariadnaesporites),
either separately or in association, that suggest a Maastrichtian age
for these beds. Only two intertrappean sections, Papro on the northern
margin and Jhilmili on the northeastern margin of the main Deccan
volcanic province, have produced Paleocene fossils. The fossil record
from the infratrappean and intertrappean beds demonstrates that the
dinosaurs survived the early phase of volcanism, though there was an
apparent decline in their diversity, and that freshwater vertebrate
fauna was least affected by the initial volcanic activity. The
episodic nature of Deccan volcanism may possibly explain the survival
of many freshwater and terrestrial communities during the periods of
quiescence. In addition, as in the case of the late Maastrichtian
sections in eastern Montana, North America, detritus-feeding
freshwater vertebrate communities possibly had greater potential for
survival than the terrestrial communities dependent on primary
productivity. A close examination of the vertebrate faunal
distribution across the two stratigraphic intervals (infratrappean and
intertrappean) suggests that sampling bias in the infratrappean beds
may have also masked the actual diversity of these beds.
===


OPEN ACCESS

Adrian P. Jones (2014)
Impact volcanism and mass extinctions.
Geological Society of America Special Papers, 2014, 505, p. 369-381
doi:10.1130/2014.2505(19)
http://specialpapers.gsapubs.org/content/505/369.abstract

For asteroid or comet impacts, the mass of the projectile or bolide
and its velocity control the scale of damage and secondary
catastrophes induced, and the impact flux can be used to determine
whether such an impact was likely to occur at the time of interest.
Impact cratering processes are still orders of magnitude more deadly
than volcanism when considering the potential for atmospheric loading
of deleterious particulate and gaseous materials, due to the
extraordinarily rapid transfer of energy. Based on impact flux, there
could have been sufficient large impactors to cause one or more of the
“Big Five” mass extinctions in the last 300 m.y. The best contender so
far is the Chicxulub event, but this did not trigger massive volcanism
in situ, and the Deccan volcanism was not located correctly to be its
antipodal pair. The combination of volcanism with impact cratering is
a real possibility for the end-Cretaceous extinction, but there is no
established connection. This contribution reviews the wider aspects of
impact volcanism, including impact fluxes, impact melting, crater
thermal anomalies, and secondary impact crises like antipodal
volcanism in the context of Phanerozoic mass extinctions.