From Simple English Wikipedia, the free encyclopedia
The
Cretaceous
?
Tertiary
extinction
event
, now called the
Cretaceous?
Palaeogene
extinction event
,
[1]
was about 65.5 million years ago.
[2]
It may be called the
K/T extinction event
or
K/Pg event
for short. This is the famous event which killed most of the
dinosaurs
at the end of the Cretaceous period.
It was a large-scale
mass extinction
of animal and plant species. The event marks the end of the
Mesozoic
era
and the beginning of the
Cainozoic
era.
[3]
[4]
Dinosaur
fossils
are only found below the K/T boundary. This shows they became extinct before, or during the event.
[5]
Mosasaurs
,
plesiosaurs
,
pterosaurs
and many species of plants and invertebrates also became extinct.
Mammalian
and
bird
groups got through the event with some extinctions. Those that survived became widespread and varied during their later
evolutionary
radiation
.
[6]
The K/T extinctions were so sudden and far-reaching that they must have been caused by something sudden and powerful. One or more massive
asteroid
or
meteor
impacts, and increased
volcanic
activity have been suggested.
How quickly animals died out around the world is an important clue.
[5]
Patterns in rocks also suggest causes. There are several
impact craters
and massive
volcanic activity
in the
Deccan Traps
in
India
dated to about the same time as the extinctions. Those impacts and volcanoes would have reduced sunlight and hindered
photosynthesis
, disrupting Earth's
ecology
.
[6]
The best supported theory is that the meteorite strike in the Yucatan was the main cause of the extinction at the end of the Mesozoic era.
[7]
There were several
impact event
s across the Cretaceous/Tertiary boundary, such as the
Chicxulub crater
in Mexico, Boltysh crater in
Ukraine
, Silverpit crater in
North Sea
, and the Shiva crater offshore western India.
[8]
[9]
The Shiva crater is a sea floor structure under the
continental shelf
in the
Indian Ocean
, west of
Mumbai
,
India
. It was named by paleontologist Sankar Chatterjee after
Shiva
, the
Hindu
god of destruction and renewal.
- ↑
Because the term "Tertiary" is out of date.
- ↑
Renne, Paul R.; Deino, Alan L.; Hilgen, Frederik J.; Kuiper, Klaudia F.; Mark, Darren F.; Mitchell, William S.; Morgan, Leah E.; Mundil, Roland; Smit, Jan (2013).
"Time scales of critical events around the Cretaceous-Paleogene boundary"
(PDF)
.
Science
.
339
(6120): 684?687.
Bibcode
:
2013Sci...339..684R
.
doi
:
10.1126/science.1230492
.
PMID
23393261
.
S2CID
6112274
. Archived from
the original
(PDF)
on 2017-02-07
. Retrieved
2018-11-14
.
- ↑
Fortey R (1999).
Life: A natural history of the first four billion years of life on Earth
. Vintage. pp. 238?260.
- ↑
With "Tertiary" being discouraged as a formal time or rock unit by the International Commission on Stratigraphy, the K/T event is now called the Cretaceous?
Palaeogene
extinction event by many researchers.
Gradstein F, Ogg J, Smith A.
A geologic time scale 2004
.
{{
cite book
}}
: CS1 maint: multiple names: authors list (
link
)
- ↑
5.0
5.1
Fastovsky, David E.; Sheehan, Peter M. (March 2005).
"The Extinction of the Dinosaurs in North America"
(PDF)
.
GSA Today
.
15
(3): 4?10.
doi
:
10.1130/1052-5173(2005)15<4:TEOTDI>2.0.CO;2
. Retrieved
2017-04-22
.
- ↑
6.0
6.1
MacLeod N.; et al. (1997).
"The Cretaceous?Tertiary biotic transition"
.
Journal of the Geological Society
.
154
(2): 265?292.
Bibcode
:
1997JGSoc.154..265M
.
doi
:
10.1144/gsjgs.154.2.0265
.
S2CID
129654916
.
- ↑
Schulte, Peter & others 2010. The Chicxulub asteroid impact and mass extinction at the Cretaceous?Paleogene Boundary.
Science
327
(5970): 1214?1218.
[1]
- ↑
Chatterjee, Sankar
et al
2003. Paper No. 60-8, Seattle Annual Meeting of
Geological Society of America
.
The Shiva Crater: implications for Deccan volcanism, India-seychelles rifting, dinosaur extinction, and petroleum entrapment at the K/T boundary
Archived
2008-10-12 at the
Wayback Machine
.
- ↑
Mullen, Leslie 2004.
Astrobiology Magazine
.
Deep impact -- Shiva: another K-T impact?