Field Notes 
Some sighs of relief for GPR   A heads up for pterosaur research

Some sighs of relief for GPR

Since February, geoscientists using ground penetrating radar (GPR) for everything from finding lost utilities to inspecting highways and bridges have been waiting for some assurance from the Federal Communications Commission (FCC). Under a controversial new set of rules for ultra-wideband technology, the FCC restricted GPR usage to specific groups: law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies and construction companies (Geotimes, July 2002). Some of the waiting is now over as the FCC adopted an Order on July 12 that allows GPR users to apply for a blanket waiver to continue wide usage of GPR devices.

The FCC says that the new waiver procedure will provide an easy process for old GPR systems to comply with the new regulations. The Order clarifies that GPR users need not work for one of the groups stated in the original rules, as long as their purpose falls under one of those categories. For example, an independent geoscientist could legally use GPR to locate archaeological finds, even if that geoscientist does not work for a scientific institution. “These actions will permit the accommodation of existing products while ensuring that the authorized radio services are protected from harmful interference and that all new equipment complies with the appropriate standards,” says the FCC Order.

However, the new Order alleviates only some concerns of the GPR community. “People have started filing for waivers, but the turnaround time is expected to be 15 working days, so no one has an answer yet,” says Gary Olhoeft, a geophysics professor at the Colorado School of Mines.

The geoscience community also worries, Olhoeft says, that the FCC and the National Telecommunications and Information Administration (NTIA), who are handling the waivers, do not have enough staff to quickly process the requests. Also unclear is whether or not a waiver carries an expiration date. Moreover, Olhoeft points out that the waivers do not cover GPR manufacturers and no one knows how long it will take to develop a certification process that will allow the selling of equipment again.

While these questions still loom around the GPR controversy, the waiver process goes on. The application deadline for the FCC waiver is Oct. 15.

Contact the FCC for more. To read more about the GPR rulings, link to the July story, Narrowing the radio spectrum for geoscience.

Lisa M. Pinsker

A heads up for pterosaur research

A 110-million-year old pterosaur skull is generating interest in the paleontological community. Writing in the July 19 Science, Brazilians Alexander Kellner from the National Museum/Federal University and Diogenes de Almeida Campos from the Museum of Earth Sciences in Rio de Janeiro say they’ve discovered a pterosaur, Thalassodromeus Sethi, with the largest crest — three-fourths the size of the skull — and a unique scissors-like jaw.

“It’s a very unusual skull, even for a pterosaur. There’s a very large, thin and quite fragile crest. And the unusual jaw suggests specialization. It just demonstrates how bizarre pterosaurs are,” says Christopher Bennett, a paleontologist from the University of Connecticut.

Pterosaurs are one of the earliest winged animals. Paleontologists continue to debate how these creatures lived. “Once we are faced with a distinct anatomy, we try to compare it with other living and fossil species. In our case, the only animal that has such a scissors-like bill is the skimmer,” Kellner says, referring to the modern avian genus, Rynchops. These birds skim over water as they hunt for pelagic fish and crustaceans.

David Unwin, a paleontologist from the Museum of Natural History in Berlin, questions this claim. “Skimmers don’t have pointed jaw tips, as shown for Thalassodromeus, because this doesn’t work when the jaw is skimmed through water. Skimmers have a rather blunt jaw tip, as also seen in Rhamphorhynchus [another type of pterosaur, hypothesized to be a skimmer], which helps direct the water away to either side of the jaw as they skim.” Bennett has seen the specimen and is also wary. “In cross-section the jaw is not laterally compressed as is observed in skimmers,” he says.

But Kellner contends that the skull’s anterior is laterally compressed and maintains the model is a strong one. “All arguments against this interpretation would have to explain how a flying animal with a scissors-like beak would feed.” He suggests that the scientific debate will be more on the function of the crest.

Not only is the crest large, but it is also embedded with the impression of a network of blood vessels. “If this is correct — and there is nothing else I could make of them — then the crest was extensively irrigated by blood. Therefore we introduced the hypothesis that at least some pterosaurs might have used their crest in thermal regulation,” Kellner says.

Unwin doubts this, claiming that in particular species the crest size can vary from individual to individual: “Consequently, most pterosaur workers are coming round to the idea that crests often show dimorphism — probably sexual — and evolved primarily as signaling structures.” They may have had other secondary functions, such as temperature control, but these are more controversial, he explains.

While Bennett doubts the pterosaur was a skimmer, he believes that the interpretation for temperature regulation is plausible.

Salma Monani

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