65 juta tahun yang lalu?
Tapi 'ssetiadi" yang dungu kayak anjing itu percaya saja kepada kibulan Bible
yang bilang alam semesta ini baru diciptakan oleh tuhan, yang nota bene tidak
berbukti ada, kurang dari 10.000 tahun yang lalu.
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Web address:
http://www.sciencedaily.com/releases/2010/09/
100916145131.htm
Tyrannosaurus Redux: T. Rex Was More Than Just a Large Carnivore at Top of Food
Chain, New Findings Reveal
enlarge
This is an adult Tyrannosaurus from the American Museum of Natural History.
(Credit: AMNH)
ScienceDaily (Sep. 17, 2010) We've all heard this story: the Late Cretaceous
of Asia and North America -- about 65 million years ago -- was dominated by
several large-headed, bipedal predatory dinosaurs like Tyrannosaurus rex and
Tarbosaurus that had tiny arms. But a decade of new fossil discoveries that
have more than doubled the number of known tyrannosaur species has changed this
tale. Older and smaller tyrannosaurs have made the evolutionary tree of this
group richer and more complex. Furthermore, a series of innovative research
projects on topics like bone growth and biomechanics have added an enormous
amount of information about tyrannosaurs, so much so that the group could now
be considered an exemplar for studying many themes in paleontology research.
A new paper describing recent research and a new evolutionary tree is published
in the journal Science.
"T. rex is the most iconic of all dinosaurs," says Mark Norell, curator in the
Division of Paleontology at the American Museum of Natural History. "Its star
power has allowed a research focus into questions not normally undertaken with
fossils, questions like bone growth, biomechanics, and neurology."
"We know more about tyrannosaurs than any other group of dinosaurs -- even more
than some groups of living organisms," says Stephen Brusatte, a graduate
student affiliated with the Museum and first author of the paper. "Over the
past year, five new species of tyrannosaurs have been described, and over the
last ten years we have found the oldest and smallest members of the group. Now
we can understand the family tree of tyrannosaurs in unprecedented detail."
The Science paper combines a new analysis of tyrannosaur phylogenetics, or
their genealogy, with a review of recent research into their biology. After
scoring 19 well-documented tyrannosaur fossils for over 300 different traits,
the researchers developed the most comprehensive evolutionary tree of this
group to date. This essentially redefined tyrannosaurs, at least when compared
to the popular perception of them as large meat-eaters. Tyrannosaurs have a
long evolutionary history of which the largest, T. rex, Albertosaurus, and
Tarbosaurus, represent species that were ecologically dominant only during the
Late Cretaceous in Asia and North America. Earlier tyrannosaurs, on the other
hand, lived up to 100 million years before the large apex (top) predators,
which were often small in size (some one-one hundredth of the size of T. rex
and akin to a lynx in body mass), and lived all over the world.
"T. rex is really just the tip of the iceberg of tyrannosaur diversity, and
honestly, is quite abnormal when compared with other members of the group. For
most of their evolutionary history, tyrannosaurs were small and living in the
shadow of other giant apex predators," says Brusatte. "They stayed small until
the end of the Cretaceous -- the final 20 million years of dinosaur history."
The new paper also reviews exciting research on tyrannosaurs, including
biomechanical analyses of how quickly they could run (work of co-author John
Hutchinson of the Royal Veterinary College in the U.K.), how quickly they grew
(work of co-author Gregory Erickson of Florida State University and Norell),
demographics of the population (Erickson), and reconstructions of the brain and
neurology (work of co-authors Amy Balanoff of the American Museum of Natural
History and Gabe Bever of Yale University).
"The work on tyrannosaurs underscores how much can be done using modern
techniques to understand the biology of fossil organisms," says Norell. "Many
of us in the field now look at ourselves as biologists who just happen to work
on dinosaurs."
In addition to Norell, Brusatte (who is also affiliated with Columbia
University), Hutchinson, Erickson, Bever, and Balanoff, authors include Jonah
Choiniere of the American Museum of Natural History, Thomas Carr of Carthage
College, Peter J. Makovicky of the Field Museum, and Xing Xu of the Chinese
Academy of Sciences (People's Republic of China). This research was funded by
the National Science Foundation, the American Museum of Natural History,
Natural Environment Research Council of the U.K., the National Natural Science
Foundation of China, and Special Funds for Major State Basic Research Projects
of China.
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by American Museum of Natural History, via
EurekAlert!, a service of AAAS.
Journal Reference:
1. Stephen L. Brusatte, Mark A. Norell, Thomas D. Carr, Gregory M. Erickson,
John R. Hutchinson, Amy M. Balanoff, Gabe S. Bever, Jonah N. Choiniere, Peter
J. Makovicky, and Xing Xu. Tyrannosaur Paleobiology: New Research on Ancient
Exemplar Organisms. Science, 2010; 329 (5998): 1481-1485 DOI:
10.1126/science.1193304
Need to cite this story in your essay, paper, or report? Use one of the
following formats:
APA
MLA
American Museum of Natural History (2010, September 17). Tyrannosaurus redux:
T. rex was more than just a large carnivore at top of food chain, new findings
reveal. ScienceDaily. Retrieved September 17, 2010, from
http://www.sciencedaily.com /releases/2010/09/100916145131.htm
Note: If no author is given, the source is cited instead.
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