- Up to 500 dinosaur groups may remain undiscovered, yet
our knowledge of the creatures and how they were related is relatively
complete, a scientist says.
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- The figure of 500 may seem a lot, but this is a maximum
possible value.
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- The expert behind the study actually thinks the dinosaur
fossil record is between one-half and two-thirds complete, which is comparatively
good.
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- The data comes from an analysis of more than 250 dinosaur
groups and their family tree branches.
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- Julia Heathcote, a graduate student at Washington University
in St Louis, US, used statistical analysis to determine how much missing
data there might be on dinosaur groups to how much researchers actually
have.
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- She also calculated how well proposed splits in the dinosaur
family tree matched the fossil evidence over time.
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- Good record
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- The research was carried out in collaboration with researchers
from the Natural History Museum in London.
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- "The whole Dinosauria fossil record I would say
is moderately good, which was a surprise, because I thought it would be
much worse," said Ms Heathcote.
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- Although there had been previous attempts to analyse
evolutionary patterns with the dinosaur fossil record, she added, these
patterns could only be interpreted in a useful way when the ages of fossils
were taken into account.
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- Ms Heathcote claimed that her work could be added to
by other researchers as new dinosaur specimens are discovered and see where
the new discovery fits in with previous ones.
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- Another calculation gave how much missing data there
is to the minimum missing data possible if all dinosaur groups were arranged
in a family tree in order of age.
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- "[The analysis] draws together all of the data of
the past 150 years," said Ms Heathcote. "You can see how far
back these dinosaurs go, see their relationships with each other."
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- Previous studies have attempted to provide complete dinosaur
family trees. Researchers at the University of Bristol have combined 150
previously published evolutionary trees to form one supertree of 277 dinosaur
groups.
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- © BBC MMIV
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- http://news.bbc.co.uk/2/hi/science/nature/3475915.stm
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