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Emory Researcher Finds Crayfish Fossils Provide Missing Evolutionary Link
February 07, 2008Crayfish body fossils and burrows discovered in Victoria, Australia, have provided the first physical evidence that crayfish existed on the continent as far back as the Mesozoic Era, says Emory University paleontologist Anthony Martin, who headed up a study on the finds.
"Studying the fossil burrows gives us a glimpse into the ecology of southern Australia about 115 million years ago, when the continent was still attached to Antarctica," says Martin, a senior lecturer in environmental studies at Emory and an honorary research associate at Monash University in Melbourne. During that era, diverse plants grew in what is today Antarctica and dinosaurs roamed in prolonged polar darkness along southern Australia river plains. The period is of particular interest to scientists since it is believed to be the last time the Earth experienced pronounced global warming, with an average temperature of 68 degrees Fahrenheit - just 10 degrees warmer than today.
On Feb. 2, the earth science journal Gondwana Research published online the results of the crayfish study, which was conducted by Martin and a consortium of Australian scientists, including Thomas Rich and Gary Poore of the Museum of Victoria; Mark Schultz and Christopher Austin of Charles Darwin University; and Lesley Kool and Patricia Vickers-Rich of Monash.
The crayfish body fossils consist of an abdomen and two claws, and the fossil burrows are nearly identical to those made by modern crayfish in southeastern Australia. "Comparing these fossil burrows to those made by modern crayfish in Australia shows us that their behavior hasn't changed that much," says Martin, who specializes in trace fossils.
Biologists have long been fascinated by crayfish, due to their wide range - the freshwater decapods are found on almost every continent and have adapted to extremely diverse environments. Thomas Huxley, a colleague of Charles Darwin, was the first scientist to ponder how crayfish, which cannot survive in saltwater, could have spread to so many continents, according to Martin. Such studies helped lay the groundwork for plate tectonics, which revolutionized the earth sciences in the 1960s through the theory that the continents were once connected. More recently, molecular biologists have theorized that all Southern Hemisphere crayfish originated in southeastern Australia.
"The evolution of Southern Hemisphere crayfish has challenged researchers since the 1870s," Martin says. "Only now, 140 years later, are we starting to put together the physical evidence for this evolution through the discovery of fossils."
Emory University
The crayfish body fossils consist of an abdomen and two claws, and the fossil burrows are nearly identical to those made by modern crayfish in southeastern Australia. "Comparing these fossil burrows to those made by modern crayfish in Australia shows us that their behavior hasn't changed that much," says Martin, who specializes in trace fossils.
Biologists have long been fascinated by crayfish, due to their wide range - the freshwater decapods are found on almost every continent and have adapted to extremely diverse environments. Thomas Huxley, a colleague of Charles Darwin, was the first scientist to ponder how crayfish, which cannot survive in saltwater, could have spread to so many continents, according to Martin. Such studies helped lay the groundwork for plate tectonics, which revolutionized the earth sciences in the 1960s through the theory that the continents were once connected. More recently, molecular biologists have theorized that all Southern Hemisphere crayfish originated in southeastern Australia.
"The evolution of Southern Hemisphere crayfish has challenged researchers since the 1870s," Martin says. "Only now, 140 years later, are we starting to put together the physical evidence for this evolution through the discovery of fossils."
Emory University
Crayfish Current Events and Crayfish News RSSBiological invasions increasing due to freshwater impoundments, says CU-Boulder study
The growing number of dams and other impoundments is increasing the number of invasive species and the speed at which they spread, putting natural lakes at risk, says a study led by the University of Colorado at Boulder.
Study: DNA barcoding in danger of 'ringing up' wrong species
DNA barcoding is a movement to catalog all life on earth by a simple standardized genetic tag, similar to stores labeling products with unique barcodes. The effort promises foolproof food inspection, improved border security, and better defenses against disease-causing insects, among many other applications.
480-million-year-old fossil sheds light on 150-year-old paleontological mystery
Discovery of an exceptional fossil specimen in southeastern Morocco that preserves evidence of the animal's soft tissues has solved a paleontological puzzle about the origins of an extinct group of bizarre slug-like animals with rows of mineralized armor plates on their backs, according to a paper in Nature.
New map outlines risk of zebra mussel invasion
The spread of two invasive alien freshwater mussel species - the zebra mussel and the quagga mussel - appears to be controlled in part by calcium levels in streams and lakes and a new risk assessment based on water chemistry suggests the Great Plains and American Southwest could be next in line for invasion.
What gives us sunburn protects crayfish against bacteria
The production of melanin gives us sunburns, but it also helps invertebrate animals to encapsulate attacking fungi and parasites.
Ritualized submission and pseudo-copulation reduce aggression among male crayfish
Pseudo-copulation-an interaction that mimics sexual copulation-is a behavior known in mammalian communities that reduces aggression and signifies social dominance, particularly among males.
Fatty fish consumption associated with lower risk of kidney cancer in women
Preliminary research suggests that higher consumption of fatty fish in women is linked with a lower risk of renal cell carcinoma, a common form of kidney cancer.
Study shows hope for ridding lakes of clawed invader
The rusty crayfish-a voracious, bullying exotic that has visited ecological havoc on numerous Wisconsin lakes-may have finally met its match.
Sea Grant warns of dumping seafood
In its latest outreach campaign, MIT Sea Grant has developed an educational pamphlet to encourage people not to release or dump live and fresh seafood and seafood waste into the wild.
Elusive salamanders have role in developing new sampling models
Rare salamanders at a Georgia military base are the guinea pigs for Oak Ridge National Laboratory researchers whose goal is to develop methods to better determine whether a species has vanished.
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