During their month long research trip to the Macquarie Ridge recently, scientists aboard the Research Vessel Tangaroa of New Zealand’s National Institute of Water & Atmospheric Research (NIWA), discovered an seemingly unlikely colony of starfish-like echinoderms called brittlestars living at the summit of a huge seamount. These critters take advantage of the dramatic 4km/hr ocean current of the dramatic 4km/hr ocean current at the summit, capturing prey as it is blown over the seamount. According to Dr. Mike Willams of NIWA, “This current is estimated to be 110 to 150 times larger than all the water flowing in all the rivers of the world.”
The Macquarie Ridge extends southwest of New Zealand and then curves southeast before ending at around 58 degrees south. Running along the Macquarie Fault Zone, a major right lateral-moving transform fault along the seafloor of the south Pacific Ocean, and also the tectonic plate boundary between the Indo-Australian Plate to the northwest and the Pacific Plate to the southeast the ridge is the result of the two abutting plates. Macquarie Island, along the ridge, was formed from the thrusting of the two plates. It does not have large-scale sediment, was not formed by a volcano and does not have suffered from glacial activities. The age of the rocks forming the island is extremely young geologically and there is much interest from scientists and geologists to study the island, the ridge, the trenches alongside it, and the life it supports.
Very few of the 100,000 seamounts which rise higher than 1km above the sea have been explored. It was originally thought that only corals and sponges covered the seamounts, so the discovery of the brittle stars was an exciting and significant find.
The Census of Marine Life seamount programme, CenSeam, hosted the trip. The voyage was largely funded by the New Zealand Foundation for Research, Science and Technology.
Sources
www.survivalmachine.org
http://censeam.niwa.co.nz
This ten year old organizations, mission is “to determine the role of seamounts in the biogeography, biodiversity, productivity, and evolution of marine organisms, and to evaluate the effects of human exploitation on seamounts.” A detailed account of the Tangaroa is on the site, along with similar expeditions and their outcomes. Very interesting reading, about the trips,t he people, and life on board.
Monday, June 9, 2008
245 Million-year-old Burrows of Land Vertebrates found in Antarctica
June 2008. For the first time paleontologists have found fossilized burrows of tetrapods (land vertebrates with four legs or leglike appendages) in Antarctica dating from the Early Triassic epoch, about 245 million years ago.
The fossils were created when fine sand from an overflowing river poured into the animals' burrows and hardened into casts of the open spaces. The largest preserved piece is about 14 inches long, 6 inches wide and 3 inches deep. No animal remains were found inside the burrow casts, but the hardened sediment in each burrow preserved a track made as the animals entered and exited. In addition, scratch marks from the animals' initial excavation were apparent in some places, said Christian Sidor, a University of Washington assistant professor of biology and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture at the UW.
"We've got good evidence that these burrows were made by land-dwelling animals rather than crayfish," said Sidor, who is lead author of a paper describing the find, which is being published in the June edition of The Journal of Vertebrate Paleontology.
Co-authors are Molly Miller, a geology professor at Vanderbilt University, and John Isbell, a geosciences professor at the University of Wisconsin-Milwaukee. The work was funded by the National Science Foundation.
Fossils of tetrapod bones from later in the Triassic period have been found in a section of Antarctica called Victoria Land, but the fossil burrows predate those bone fossils by at least 15 million years, Sidor said. The fossilized burrows were collected in 2003 and 2005-06 from the Fremouw Formation at Wahl Glacier and from the Lashly Formation at Allan Hills, both toward the outer edges of Antarctica.
Pangea
Despite the absence of fossil bones, the burrows' relatively small size prompted Sidor to speculate that their owners might have been small lizardlike reptiles called Procolophonids or an early mammal relative called Thrinaxodon. Burrows, some containing tetrapod bones, have previously been excavated in South Africa, which is considered to be perhaps the world's richest fossil depository, and those burrows are nearly identical to the fossils unearthed in Antarctica. During the Triassic period, Antarctica and South Africa were connected as part of a supercontinent called Pangea.
Because even at that time Antarctica was substantially colder than South Africa, and because sea levels likely were higher than today, it is much rarer to find fossils there that date from as far back as the Early Triassic.
"Everywhere has a spotty fossil record, but Antarctica has an extremely spotty fossil record because it is difficult finding exposed rocks amid all the ice," Sidor said.
Ice free Antarctic
At the time the burrows were dug, Antarctica would have been ice free. However temperatures still would have been quite cold, since both areas where the burrows were found are within the Antarctic Circle and so experience at least one day a year of complete darkness.
"We have documented that tetrapods were burrowing, making dens in Antarctica, back in the Triassic," Sidor said. "There are lots of good reasons for burrowing at high latitudes, not the least of which is protection from the elements."
The fossils were created when fine sand from an overflowing river poured into the animals' burrows and hardened into casts of the open spaces. The largest preserved piece is about 14 inches long, 6 inches wide and 3 inches deep. No animal remains were found inside the burrow casts, but the hardened sediment in each burrow preserved a track made as the animals entered and exited. In addition, scratch marks from the animals' initial excavation were apparent in some places, said Christian Sidor, a University of Washington assistant professor of biology and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture at the UW.
"We've got good evidence that these burrows were made by land-dwelling animals rather than crayfish," said Sidor, who is lead author of a paper describing the find, which is being published in the June edition of The Journal of Vertebrate Paleontology.
Co-authors are Molly Miller, a geology professor at Vanderbilt University, and John Isbell, a geosciences professor at the University of Wisconsin-Milwaukee. The work was funded by the National Science Foundation.
Fossils of tetrapod bones from later in the Triassic period have been found in a section of Antarctica called Victoria Land, but the fossil burrows predate those bone fossils by at least 15 million years, Sidor said. The fossilized burrows were collected in 2003 and 2005-06 from the Fremouw Formation at Wahl Glacier and from the Lashly Formation at Allan Hills, both toward the outer edges of Antarctica.
Pangea
Despite the absence of fossil bones, the burrows' relatively small size prompted Sidor to speculate that their owners might have been small lizardlike reptiles called Procolophonids or an early mammal relative called Thrinaxodon. Burrows, some containing tetrapod bones, have previously been excavated in South Africa, which is considered to be perhaps the world's richest fossil depository, and those burrows are nearly identical to the fossils unearthed in Antarctica. During the Triassic period, Antarctica and South Africa were connected as part of a supercontinent called Pangea.
Because even at that time Antarctica was substantially colder than South Africa, and because sea levels likely were higher than today, it is much rarer to find fossils there that date from as far back as the Early Triassic.
"Everywhere has a spotty fossil record, but Antarctica has an extremely spotty fossil record because it is difficult finding exposed rocks amid all the ice," Sidor said.
Ice free Antarctic
At the time the burrows were dug, Antarctica would have been ice free. However temperatures still would have been quite cold, since both areas where the burrows were found are within the Antarctic Circle and so experience at least one day a year of complete darkness.
"We have documented that tetrapods were burrowing, making dens in Antarctica, back in the Triassic," Sidor said. "There are lots of good reasons for burrowing at high latitudes, not the least of which is protection from the elements."
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