Dear Kitty
Wednesday, June 08, 2005
Ancient DNA confirms single origin of Malagasy primates
Yale biologists have managed to extract and analyze DNA from giant, extinct lemurs, according to a Yale study published in a recent issue of the Proceedings of the National Academy of Sciences.
Radiocarbon dating of the bones and teeth from which the DNA was obtained reveal that each of the individuals analyzed died well over 1,000 years ago, according to the senior author, Anne Yoder, associate professor in the Department of Ecology and Evolutionary Biology.
Living lemurs comprise more than 50 species, all of which are unique to the island of Madagascar, which is the world's fourth largest island and east of Africa.
Evolutionary analysis of the DNA obtained from the extinct giants reveals that they, like the living lemurs, are descended from a single primate ancestor that colonized Madagascar more than 60 million years ago, Yoder said.
The biologists extracted DNA from nine subfossil individuals in two of the more bizarre extinct species, Palaeopropithecus and Megaladapis. The first has been likened to tree sloths and the second compared to koala bears.
Both ranged in body weights from 100 to 150 pounds, as compared to the largest living lemur, Indri indri, which weighs in at fewer than 15 to 17 pounds.
"The most important conclusion to be drawn from our study is that the phylogenetic placement of subfossil lemurs adds additional support to the hypothesis that non-human primates colonized Madagascar only once," Yoder said.
"However, the limited taxonomic success of our study leaves open the possibility that data from additional taxa will overturn this increasingly robust hypothesis."
Read more here.
Yale biologists have managed to extract and analyze DNA from giant, extinct lemurs, according to a Yale study published in a recent issue of the Proceedings of the National Academy of Sciences.Radiocarbon dating of the bones and teeth from which the DNA was obtained reveal that each of the individuals analyzed died well over 1,000 years ago, according to the senior author, Anne Yoder, associate professor in the Department of Ecology and Evolutionary Biology.
Living lemurs comprise more than 50 species, all of which are unique to the island of Madagascar, which is the world's fourth largest island and east of Africa.Evolutionary analysis of the DNA obtained from the extinct giants reveals that they, like the living lemurs, are descended from a single primate ancestor that colonized Madagascar more than 60 million years ago, Yoder said.
The biologists extracted DNA from nine subfossil individuals in two of the more bizarre extinct species, Palaeopropithecus and Megaladapis. The first has been likened to tree sloths and the second compared to koala bears.
Both ranged in body weights from 100 to 150 pounds, as compared to the largest living lemur, Indri indri, which weighs in at fewer than 15 to 17 pounds.
"The most important conclusion to be drawn from our study is that the phylogenetic placement of subfossil lemurs adds additional support to the hypothesis that non-human primates colonized Madagascar only once," Yoder said.
"However, the limited taxonomic success of our study leaves open the possibility that data from additional taxa will overturn this increasingly robust hypothesis."
Read more here.
Labels: Mammals
¶ 12:31 PM 0 comments
Tuesday, April 19, 2005
Exceptional Whale Fossil Found in Egyptian Desert
Mon Apr 18, 2005
CAIRO (Reuters) - An American paleontologist and a team of Egyptians have found the most nearly complete fossilized skeleton of the primitive whale Basilosaurus isis in Egypt's Western Desert, a university spokesman said on Monday.
Philip Gingerich of the University of Michigan excavated the well-preserved skeleton, which is about 40 million years old, in a desert valley known as Wadi Hitan (the Valley of the Whales) southwest of Cairo, spokesman Karl Bates told Reuters.
Read more here.
And here.
CAIRO (Reuters) - An American paleontologist and a team of Egyptians have found the most nearly complete fossilized skeleton of the primitive whale Basilosaurus isis in Egypt's Western Desert, a university spokesman said on Monday.
Philip Gingerich of the University of Michigan excavated the well-preserved skeleton, which is about 40 million years old, in a desert valley known as Wadi Hitan (the Valley of the Whales) southwest of Cairo, spokesman Karl Bates told Reuters.
Read more here.
And here.
Labels: Mammals, Science and health
¶ 12:25 AM 0 comments
Monday, April 18, 2005
Elephant seal pups suffer from ocean warming
Ocean warming has a negative impact on the condition of elephant seals, reveals a study published in the Open Access journal BMC Biology. High ocean temperatures observed from 1975 to the late 1990s are correlated with a 28% decrease in the weight of elephant seal pups. Elephant seals are shown to be sensitive to ocean temperature changes associated with both long-term 25-year cycles and short-term 3-4 year cycles such as those caused by El Niño.
Sea lions and fur seals that feed near their rookeries at the surface of the ocean are known to be very sensitive to water temperature changes, as an increase in water temperature usually causes their prey to migrate to cooler areas, depleting local food resources and resulting in pup starvation. Elephant seals, which feed in deep waters, were previously thought to be better buffered against ocean temperature changes than other sea mammals.
A study by Dr Burney Le Boeuf and Dr David Crocker from the University of California in Santa Cruz, shows that as waters get warmer the average weight of an elephant seal pup decreases.
Read more here.
Sea lions and fur seals that feed near their rookeries at the surface of the ocean are known to be very sensitive to water temperature changes, as an increase in water temperature usually causes their prey to migrate to cooler areas, depleting local food resources and resulting in pup starvation. Elephant seals, which feed in deep waters, were previously thought to be better buffered against ocean temperature changes than other sea mammals.
A study by Dr Burney Le Boeuf and Dr David Crocker from the University of California in Santa Cruz, shows that as waters get warmer the average weight of an elephant seal pup decreases.
Read more here.
Labels: Environment, Mammals
¶ 11:46 PM 0 comments
