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Asteroid yang menyapu dinosaurus mungkin hampir
menghapus mamalia juga
Kisah klasik adalah bahwa mamalia naik men dominasi setelah dinosaurus
punah, namun sebuah studi baru menunjukkan bahwa beberapa mamalia yang paling
umum hidup bersama dinosaurus, para metatherians, kerabat punah marsupial ,
juga hampir musnah ketika sebuah asteroid menghantam planet 66 juta tahun yang
lalu.....read more
.........................
Asteroid that
wiped out dinosaurs may have nearly knocked off mammals, too
Date:
December 17, 2014
Source:
Pensoft Publishers
Summary:
The classic story is
that mammals rose to dominance after the dinosaurs went extinct, but a new
study shows that some of the most common mammals living alongside dinosaurs,
the metatherians, extinct relatives of living marsupials, were also nearly
wiped out when an asteroid hit the planet 66 million years ago.
.....................
The extinction of the dinosaurs 66 million years
ago is thought to have paved the way for mammals to dominate, but a new study
shows that many mammals died off alongside the dinosaurs.
Metatherian mammals -- the extinct relatives of living marsupials
("mammals with pouches," such as opossums) -- thrived in the shadow
of the dinosaurs during the Cretaceous period. The new study, by an
international team of experts on mammal evolution and mass extinctions, shows
that these once-abundant mammals nearly followed the dinosaurs into oblivion.
When a 10-km-wide asteroid struck what is now Mexico at the end of the
Cretaceous and unleashed a global cataclysm of environmental destruction, some
two-thirds of all metatherians living in North America perished. This includes
more than 90% of species living in the northern Great Plains of the USA, the
best area in the world for preserving latest Cretaceous mammal fossils.
In the aftermath of the mass extinction, metatherians would never recover
their previous diversity, which is why marsupial mammals are rare today and
largely restricted to unusual environments in Australia and South America.
Taking advantage of the metatherian demise were the placental mammals:
species that give live birth to well-developed young. They are ubiquitous
across the globe today and include everything from mice to men.
Dr. Thomas Williamson of the New Mexico Museum of Natural History and
Science, lead author on the study, said: "This is a new twist on a classic
story. It wasn't only that dinosaurs died out, providing an opportunity for
mammals to reign, but that many types of mammals, such as most metatherians,
died out too -- this allowed advanced placental mammals to rise to
dominance."
Dr. Steve Brusatte of the University of Edinburgh's School of GeoSciences,
an author on the report, said: "The classic tale is that dinosaurs died
out and mammals, which had been waiting in the wings for over 100 million
years, then finally had their chance. But our study shows that many mammals
came perilously close to extinction. If a few lucky species didn't make it
through, then mammals may have gone the way of the dinosaurs and we wouldn't be
here."
The new study is published in the open access journal ZooKeys.
It reviews the Cretaceous evolutionary history of metatherians and provides the
most up-to-date family tree for these mammals based on the latest fossil
records, which allowed researchers to study extinction patterns in
unprecedented detail.
Dr. Gregory Wilson of the University of Washington also took part in the
study.
The work was supported by the US National Science Foundation and the
European Commission.
Story Source:
The above story is based on materials provided by Pensoft Publishers. The original story is licensed under
a Creative
Commons License. Note: Materials may be edited for content and length.
Journal Reference:
1. Thomas E. Williamson, Stephen L.
Brusatte, Gregory P. Wilson. The origin and early evolution of
metatherian mammals: the Cretaceous record. ZooKeys, 2014; 465:
1 DOI: 10.3897/zookeys.465.8178