The analysis of a well-preserved skull from 54 million years ago contradicts some common assumptions about brain structure and evolution in the first primates. The study also narrows the possibilities for what caused primates to evolve larger brain sizes. The study is scheduled to appear online the week of June 22 in the Proceedings of the National Academy of Sciences.

The skull belongs to a group of primitive primates known as Plesiadapiforms, which evolved in the 10 million years between the extinction of the dinosaurs and the first traceable ancestors of modern primates. The 1.5-inch-long skull was found fully intact, allowing researchers to make the first virtual mold of a primitive primate brain.

“Most explanations on the evolution of primate brains are based on data from living primates,” said lead author Mary Silcox, an anthropologist at the University of Winnipeg and research associate at UF’s Florida Museum of Natural History. “There have been all these inferences about what the brains of the earliest primates would look like, and it turns out that most of those inferences are wrong.”

Researchers used CT scans to take more than 1,200 cross-sectional X-ray images of the skull, which were combined into a 3-D model of the brain.

“A large and complex brain has long been regarded as one of the major steps that sets primates apart from the rest of mammals,” said Florida Museum vertebrate paleontologist and study co-author Jonathan Bloch. “At our very humble beginnings, we weren’t so special. That happened over tens of millions of years.”

The animal, Ignacius graybullianus, represents a side branch on the primate tree of life, Bloch
said. “You can think of it as a cousin of the main line lineage that would have given rise ultimately to us.”

In previous research, Bloch and Silcox established that Plesiadapiforms were transitional species. Ignacius was similar to modern primates in terms of its diet and tree-dwelling but did not leap from tree to tree like modern fast-moving primates.

In many ways, the early primate behaved like living primates but with a brain that was one-half to two-thirds the size of the smallest modern primates. This means that factors such as tree-dwelling and fruit-eating can be eliminated as potential causes for primates evolving larger brain sizes, Silcox said, because “the smaller brained Ignacius was already doing those things.”

The mold suggests a “startling combination” of features in the early primate that requires a rethinking of primate brain evolution, said Florida State University anthropologist Dean Falk, who was not involved in the study.

“Hypotheses about early primate brain evolution often link keen smell with nocturnal insect-eating, and a more recently evolved increase in visual processing with fruit-eating in arboreal habitats,” Falk said.

The move to larger brain size occurred during an evolutionary burst that happened 10 million years after the extinction of the dinosaurs. At that point, visual features in the brain became much more prominent while the olfactory bulbs became proportionately smaller.

More than likely, Bloch said, this change in brain structure and size was related to primates living in closed canopy forests that brought trees closer together and allowed for more leaping. But answering that will require the discovery and analysis of new fossils.

Changes in brain size and brain structure in the early stages of primate evolution have generated enormous debates for decades. But until now, fossil evidence has been lacking.

Many models of the ancestral primate brain are based on tree shrews, which come from southeast Asia and are distantly related to humans. But with some 70 million years of evolution between them and humans, “it turns out tree shrew brains are not a good model,” Silcox said.

Led by Florida Museum of Natural History vertebrate paleontologist Larisa DeSantis, researchers examined fossil teeth from mammals at two sites representing different climates in Florida: a glacial period about 1.9 million years ago and a warmer, interglacial period about 1.3 million years ago. The researchers found that interglacial warming resulted in dramatic changes to the diets of animal groups at both sites. The study appears in the June 3 issue of PLoS ONE.

“When people are modeling future mammal distributions, they’re assuming that the niches of mammals today are going to be the same in the future,” DeSantis said. “That’s a huge assumption.”

Co-author Robert Feranec, curator of vertebrate paleontology at the New York State Museum, said scientists cannot predict what species will do based on their current ecology.

“The study definitively shows that climate change has an effect on ecosystems and mammals, and that the responses are much more complex than we might think,” Feranec said.

The two sites in the study, both on Florida’s Gulf Coast, have been excavated quite extensively, DeSantis said. During glacial periods, lower sea levels nearly doubled Florida’s width, compared with interglacial periods. But because of Florida’s low latitude, no ice sheets were present during the glacial period. Despite the lack of glaciers in Florida, the two sites show dramatic ecological changes occurred between the two periods.

Both sites include some of the same animal groups, allowing DeSantis, Feranec and Bruce MacFadden, Florida Museum curator of vertebrate paleontology, to clarify how mammals and their environments responded to interglacial warming.

The research examined carbon and oxygen isotopes within tooth enamel to understand the diets of medium to large mammals, including pronghorn, deer, llamas, peccaries, tapirs, horses, mastodons, mammoths and gomphotheres, a group of extinct elephant-like animals.

Differences in how plants photosynthesize give them distinct carbon isotope ratios. For example, trees and shrubs process carbon dioxide differently than warm-season grasses, resulting in different carbon isotope ratios. These differences are incorporated in mammalian tooth enamel, allowing scientists to determine the diets of fossil mammals. Lower ratio values suggest a browsing diet (trees and shrubs) while a higher ratio suggests a grazing diet (grasses).

Animals at the glacial site were predominantly browsing on trees and shrubs, while some of those same animals at the warmer interglacial site became mixed feeders that also grazed on grasses. Increased consumption of grasses by mixed feeders and elephant-like mammals indicates Florida’s grasslands likely expanded during interglacial periods.

Tooth enamel locks in the chemical signatures of the plants and water an animal consumes, allowing paleontologists to understand the diets and associated climate of fossil specimens that are millions of years old. To find these signatures, researchers run samples of tooth enamel through a mass spectrometer.

DeSantis and her collaborators analyzed enamel samples from 115 fossil teeth. For two of the specimens she took serial samples, small samples that run perpendicular to the growth axis and give insight into how the diet and climate changed over a specific period of time.

“That’s one of the cool things about using mammal teeth,” she said. “We can actually look at how variable the climate was within a year, millions of years ago.”

The study highlights the importance of the fossil record in understanding long-term ecological responses to changes over time, DeSantis said. While ecological studies of modern impacts can cover only limited spans of time, “this study emphasizes the importance of using the fossil record to look at how mammals and other animals responded to climate change in the past, also helping us gain a better understanding of how they might respond in the future.”

But a new University of Florida study, set to appear next week in the online edition of the Proceedings of the National Academy of Sciences, is helping shed light on the mystery with information about what the first flowers looked like and how they evolved from nonflowering plants.

“There was nothing like them before and nothing like them since,” said Andre Chanderbali, lead author of the study and a postdoctoral associate at UF’s Florida Museum of Natural History. “The origin of the flower is the key to the origin of the angiosperms (flowering plants).”

The goal of this research is to understand the original regulatory program, or set of genetic switches, that produced the first flower in the common ancestor of all living flowering plants, said Pam Soltis, study co-author and curator of molecular systematics and evolutionary genetics at the Florida Museum. Better understanding of these genetic switches could one day help scientists in other disciplines such as medicine or agriculture, including help in growing plants used to fight disease or developing more drought-resistant crops.

The flower is one of the key innovations of evolution, responsible for a massive burst of evolution that has resulted in perhaps as many as 400,000 angiosperm species. Before flowering plants emerged, the seed-bearing plant world was dominated by gymnosperms, which have cone-like structures instead of flowers and include pine trees, sago palms and ginkgos. Gymnosperms first appeared in the fossil record about 360 million years ago.

The new study provides insight into how the first flowering plants evolved from pre-existing genetic programs found in gymnosperms and then developed into the diversity of flowering plants we see today.

The study compares the genetic structure of two vastly different flowering plants to see whether differences exist in the set of circuits that create each species’ flower. Researchers examined the genetic circuitry of Arabidopsis thaliana, a small flowering plant commonly used as a model organism in plant genetics research, and the avocado tree Persea americana, which belongs to an older lineage of so-called basal angiosperms.

“What we found is that the flower of Persea is a genetic fossil, still carrying genetic instructions that would have allowed for the transformation of cones into flowers,” Chanderbali said.

Advanced angiosperms have four organ types: female organs (carpels), male organs (stamens), petals (typically colorful) and sepals (typically green). Basal angiosperms have three: carpels, stamens and tepals, which are typically petal-like structures. The researchers expected each type of organ found in Persea’s flowers would have a unique set of genetic instructions. Instead they found significant overlap among the three organ types.

“Although the organs are developing to ultimately become different things, from a genetic developmental perspective, they share much more than you would expect,” Chanderbali said. “As you go back in time, the borders fade to a blur.”

“With these facts established, we can now think about the vast space open to natural selection to establish ever more rigid borders,” said Virginia Walbot, a biology professor at Stanford University who is familiar with the research. The selection process arrived at a “narrow solution in terms of four discrete organs but with fantastic diversity of organ numbers, shapes and colors that provide the defining phenotypes of each flowering plant species.”

Researchers don’t know exactly which gymnosperms gave rise to flowering plants, but previous research suggests some genetic program in the gymnosperms was modified to make the first flower, Soltis said. A pine tree produces pine cones that are either male or female, unlike flowers, which contain both male and female parts. But a male pine cone has almost everything that a flower has in terms of its genetic wiring.

Douglas Soltis, chairman of the UF botany department, emphasized that the study highlights the importance of studying primitive flowering plants such as the avocado to gain insight into the early history of the flower. Survivors of ancient lineages represent a crucial link to the first flowers and provide insight that cannot be obtained by studying highly derived models such as Arabidopsis, he said.

For the last 150 years, some paleontologists have concluded the great white shark, Carcharodon carcharias, is a smaller relative of the line that produced Carcharodon megalodon, the largest carnivorous fish known. Other paleontologists disagree, arguing the great white shark evolved instead from the broad-toothed mako shark. The second group contends megalodon, which grew to a length of 60 feet, should have its genus name switched to Carcharocles to reflect its different ancestry.

The study in the March 12 issue of the Journal of Vertebrate Paleontology falls squarely into the mako camp. It concludes megalodon and modern white sharks are much more distantly related than paleontologists initially believed.

“I think that this specimen will clarify things,” said lead author Dana Ehret, a vertebrate paleontology graduate student at the Florida Museum of Natural History located on the UF campus. “When we only have isolated teeth to describe, it’s very hard to come to a definitive conclusion.”

The study is based on a remarkably well preserved 4- to 5-million-year-old fossil from Peru of an early white shark species: a complete jaw with 222 teeth intact and 45 vertebrae. Most ancient shark species are known only from isolated teeth. Based on tooth size and analysis of growth rings within the vertebrae, the shark was about 20 years old and 17 to 18 feet long, a size in the range of modern white sharks.

Having the teeth in place allows researchers to see important distinguishing characteristics that help determine a fossil’s genus and species, such as whether a tooth curves toward the outside of the jaw or its midline, Ehret said. He believes the fossil belongs to a white shark species closely related to Isurus hastalis, a broad-toothed mako shark that probably grew to 27 feet long and lived 9 million to 10 million years ago.

An olive-grove farmer trained in fossil collection discovered it near his home in the desert of southern Peru in 1988. It has since been part of a private collection and was donated to the Florida Museum of Natural History in December.

“It’s the only fossilized partial skull of a white shark that’s ever been found,” said Gordon Hubbell, the fossil’s owner and study co-author.

Hubbell purchased the fossil from the farmer during his first trip to Peru, which coincidentally occurred only a few days after the discovery.

The specimen came from an area known as the Pisco Formation, famous for its rich fossil beds dating from the late Miocene to Pleistocene, about 1 million to 9 million years ago. The region was once a sheltered, shallow marine environment ideal for preserving skeletons. The formation has produced articulated broad-toothed mako shark skeletons as well as fossils of whales, aquatic sloths and sea turtles.

The study strengthens the evolutionary link between the extinct mako and the modern white shark, said vertebrate paleontologist Kenshu Shimada, an associate professor at DePaul University in Chicago. Shimada said paleontologists now need fossil skeletons from megalodon and a shark from the extinct Otodontidae family such as Otodus, a large prehistoric mackerel shark that lived about 40 million to 60 million years ago.

“If we can demonstrate the strong link between Carcharocles and Otodus from such skeletal remains,” Shimada said, “we may be able to settle the evolutionary and taxonomic debates.”

Megalodon was first classified in the same genus as the modern white shark in the 1840s based on the similarity of tooth shape and serrations specialized for eating marine mammals. Mako sharks have no serrations because they feed primarily on fish.

Ehret says the shark fossil’s coarse serrations are evidence of a transition between broad-toothed mako sharks and modern white sharks.

“Here we have a shark that’s gaining serrations,” he said. “It’s becoming a white shark, but it’s not quite there yet.”

The transition from megatooth sharks like megalodon to modern white sharks would require changes in body size and tooth serrations, thickness and enamel, Ehret said. By contrast, the transition from the broad-toothed mako shark to modern white sharks would require only the presence of serrations and a shift in the slant of a key tooth position.

This burst of speciation over a 5-million-year span was one of three major radiations of flowering plants, known as angiosperms. The study focuses on diversification in the rosid clade, a group with a common ancestor that now accounts for one-third of the world’s flowering plants. The forests that resulted provided the habitat that supported later evolutionary diversifications for amphibians, ants, placental mammals and ferns.

“Shortly after the angiosperm-dominated forests diversified, we see this amazing diversification in other lineages, so they basically set the habitat for all kinds of new things to arise,” said Pamela Soltis, study co-author and curator of molecular systematics and evolutionary genetics at UF’s Florida Museum of Natural History. “Associated with some of the subsequent radiations is even the diversification of the primates.”

The study appearing online in next week’s Proceedings of the National Academy of Sciences is the first to show the evolutionary relationships of these plants and provide evidence for their rapid emergence and diversification.

Because the diversification happened so quickly, at least in evolutionary terms, molecular methods were needed to sort out the branches of the rosid clade’s phylogenetic tree, a sort of family tree based on genetic relationships. Only after sequencing many thousands of DNA base pairs are genetic researchers able to tease apart the branches and better understand how plant species evolved.

Often, when scientists discuss the rapid radiation of flowering plants, they talk as if there had been one massive burst of early diversification, said Doug Soltis, co-author and chair of UF’s botany department.

“I think one thing that becomes very clear from our phylogenetic trees when you look at them closely is that it’s not just one big explosion of species within the flowering plants,” Doug Soltis said. “There’s a series of explosions.”

The rosid clade’s diversification is one of at least three bursts in the early evolution of flowering plants. More than 300,000 species of angiosperms exist, classified into an estimated 15,000 genera and more than 400 families. Understanding how these plants are related is a large undertaking that could help ecologists better understand which species are more vulnerable to environmental factors such as climate change.

“We really need to know on a finer scale how these species are related and on different parts of the planet how members of the clade are related,” Doug Soltis said. “That’s where the action is going to be in terms of how this clade responds to climate change. How members of this large clade respond is really going to determine the fate of most of the organisms on the planet.”

The study’s authors sequenced 25,000 base pairs of DNA and sampled a broad range of 104 species from the rosid clade. Using a phylogenetic tree to date the diversification of lineages requires the use of a molecular clock, which calibrates the degree of change that has occurred over time.

“You can assume that over time DNA sequences accumulate change, and things that are more similar to each other in general would have diverged from each other more recently than things that are more different,” Pam Soltis said.

But different genes have different rates of evolution, as do different clades. To compensate, the study used algorithms that accommodate the different rates. Rosid fossils selected by co-author Steven Manchester, the museum’s curator of paleobotany, were used to help calibrate that clock by setting minimum ages for member species.

The study’s first author is Hengchang Wang, who worked at the Florida Museum as a post-doctoral fellow but is now with The Chinese Academy of Science. Other authors include former post-doctoral fellows Michael J. Moore from Oberlin College and Charles D. Bell from the University of New Orleans. UF botany graduate students Samuel F. Brockington and Maribeth Latvis, former UF undergraduate Roolse Alexandre, and Charles C. Davis of Harvard University also contributed to the study.

GAINESVILLE, Fla. — The largest snake the world has ever known — as long as a school bus and as heavy as a small car — ruled tropical ecosystems only 6 million years after the demise of the fearsome Tyrannosaurus rex, according to a new discovery published in the journal Nature.

Partial skeletons of a new giant, boa constrictor-like snake named “Titanoboa” found in Colombia by an international team of scientists and now at the University of Florida are estimated to be 42 to 45 feet long, the length of the T-Rex “Sue” displayed at Chicago’s Field Museum, said Jonathan Bloch, a UF vertebrate paleontologist who co-led the expedition with Carlos Jaramillo, a paleobotanist from the Smithsonian Tropical Research Institute in Panama.

Researchers say the extinct snake was even larger than the wildest dreams of directors of modern horror movies.

“Truly enormous snakes really spark people’s imagination, but reality has exceeded the fantasies of Hollywood,” said Bloch, who is studying the snake at the Florida Museum of Natural History on the UF campus. “The snake that tried to eat Jennifer Lopez in the movie ‘Anaconda’ is not as big as the one we found.”

Jason Head, a paleontologist at the University of Toronto in Mississauga and the paper’s senior author, described it this way: “The snake’s body was so wide that if it were moving down the hall and decided to come into my office to eat me, it would literally have to squeeze through the door.”

Besides tipping the scales at an estimated 1.25 tons, the snake lived during the Paleocene Epoch, a 10-million-year period immediately following the extinction of the dinosaurs 65 million years ago, Bloch said.

The scientists also found many skeletons of giant turtles and extinct primitive crocodile relatives that likely were eaten by the snake, he said. “Prior to our work, there had been no fossil vertebrates found between 65 million and 55 million years ago in tropical South America,
leaving us with a very poor understanding of what life was like in the northern Neotropics,” he said. “Now we have a window into the time just after the dinosaurs went extinct and can actually see what the animals replacing them were like.”

Size does matter because the snake’s gigantic dimensions are a sign that temperatures along the equator were once much hotter. That is because snakes and other cold-blooded animals are limited in body size by the ambient temperature of where they live, Bloch said.

“If you look at cold-blooded animals and their distribution on the planet today, the large ones are in the tropics, where it’s hottest, and they become smaller the farther away they are from the equator,” he said.

Based on the snake’s size, the team was able to calculate that the mean annual temperature at equatorial South America 60 million years ago would have been about 91 degrees Fahrenheit, about 10 degrees warmer than today, Bloch said.

The presence of outsized snakes and turtles shows that even 60 million years ago the foundations of the modern Amazonian tropical ecosystem were in place, he said.

Fossil hunting is usually difficult in the forest-covered tropics because of the lack of exposed rock, Bloch said. But excavations in the Cerrejon Coal Mine in Northern Colombia exposed the rock and offered an unparalleled opportunity for discovery, he said.

After the team brought the fossils to the Florida Museum of Natural History, it was UF graduate students Alex Hastings and Jason Bourque who first recognized they belonged to a giant snake, Bloch said. Head, an expert on fossil snakes, worked with David Polly, a paleontologist at the University of Indiana, to estimate the snake’s length and mass by determining the relationship between body size and vertebral — backbone — size in living snakes and using that relationship to figure out body size of the fossil snake based on its vertebrae.

Harry W. Greene, professor in the department of ecology and evolutionary biology at Cornell University and one of the world’s leading snake experts, said the “colossal” ancient boa researchers found has “important implications for snake biology and our understanding of life in the ancient tropics.”

“The giant Colombian snake is a truly exciting discovery,” said Greene, who wrote the book “Snakes: The Evolution of Mystery in Nature.” “For decades herpetologists have argued about just how big snakes can get, with debatable estimates of the max somewhat less than 40 feet.”

So concludes a group of anthropologists in a new assessment of the demise of the coastal Peruvian people who built the earliest, largest structures in North or South America before disappearing in the space of a few generations more than 3,600 years ago.

“This maritime farming community had been successful for over 2,000 years, they had no incentive to change, and then all of a sudden, ‘boom,’” said Mike Moseley, a distinguished professor of anthropology at the University of Florida. “They just got the props knocked out from under them.”

Moseley is one of five authors of a paper set to appear next week in the online edition of the Proceedings of the National Academy of Sciences.

The people of the Supe Valley along the central Peruvian coast did not use pottery or weave cloth in the settlements they founded as far back as 5,800 years ago. But they flourished in the arid desert plain adjacent to productive bays and estuaries. They fished with nets, irrigated fruit orchards, and grew cotton and a variety of vegetables, according to evidence in the region unearthed by Ruth Shady, a Peruvian archaeologist and co-author of the paper. As director of the Caral-Supe Special Archaeological Project, Shady currently has seven sites in the region under excavation.

Most impressively, the Supe built extremely large, elaborate, stone pyramid temples — thousands of years before the better-known pyramids crafted by the Maya.

“They’re impressive, enormous monuments,” Moseley said.

The largest so far excavated, the Pirámide Mayor at inland settlement Caral, measured more than 550 feet long, nearly 500 feet wide and rose in a series of steps nearly 100 feet high. Walled courts, rooms and corridors covered the flat summit.

The Supe seemed to thrive in the valley for about 2,000 years. But around 3,600 years ago, an enormous earthquake — Moseley estimates its magnitude at 8 or higher — or series of earthquakes struck Caral and a nearby coastal settlement, Aspero, the archaeologist found. With two major plates scraping together not far offshore, the region remains one of the most seismically active in the world.

The earthquake collapsed walls and floors atop the Pirámide Mayor and caused part of it to crumble into a landslide of rocks, mud and construction materials. Smaller temples at Aspero were also heavily damaged, and there was also significant flooding there, an event recorded in thin layers of silt unearthed by the archaeologists.

But the flooding and temples’ physical destruction was just the dramatic opening scene in what proved to be a much more devastating series of events, Moseley said.

The earthquake destabilized the barren mountain ranges surrounding the valley, sending massive amounts of debris crashing into the foothills. Subsequent El Niños brought huge rains, washing the debris into the ocean. There, a strong current flowing parallel to the shore re-deposited the sand and silt in the form of a large ridge known today as the Medio Mundo. The ridge sealed off the formerly rich coastal bays, which rapidly filled with sand.

Strong ever-present onshore winds resulted in “massive sand sheets that blew inland on the constant, strong, onshore breeze and swamped the irrigation systems and agricultural fields,” the paper says. Not only that, but the windblown sand had a blasting effect that would have made daily life all but impossible, Moseley said.

The bottom line: What had for centuries been a productive, if arid, region became all but uninhabitable in the span of just a handful of generations. The Supe society withered and eventually collapsed, replaced only gradually later on — by societies that relied on the much more modern arts of pottery and weaving, Moseley said.

With much of the world’s population centers built in environmentally vulnerable areas, the Supe’s demise may hold a cautionary tale for modern times, the researchers said. El Niño events, in particular, may become more common as global climate change continues.

“These are processes that continue into the present,” said Dan Sandweiss, the paper’s lead author and an anthropology professor and graduate dean at the University of Maine.

Affirmed Moseley, “You would like to say that people learn from their mistakes, but that’s not the case.”

The other authors of the paper are David Keefer, a geologist and geoarchaeologist with the University of Maine’s Climate Change Institute, and Charles Ortloff, a consulting engineer who has spent the past three decades working in the Andes.

Distinguished by a long rostrum or “saw” that makes it a popular curio item and gives it its name, the sawfish has become a historical and cultural icon that is rapidly disappearing, said George Burgess, a UF ichthyologist and curator of both the International Shark Attack File and the newly expanded National Sawfish Encounter Database.

“Postcards from the turn of the 20th century often depicted this so-called monster that inhabited Florida waters, and if one goes back and looks at newspaper accounts from places outside Florida, every time a sawfish was caught it made the papers,” he said. “Today, it’s difficult to find a bar in South Florida that doesn’t have a sawfish ‘saw’ hanging on the wall.”

An important part of Florida’s fauna, the sawfish once swam in bays, lagoons and rivers extending from New York to the Rio Grande, Burgess said. Today, its American range has shrunk to Florida and its declining numbers have made it the first species of marine fish to be placed on the list of federally endangered species, he said.

Burgess and a team of scientists at the Florida Museum of Natural History on the UF campus plan to use information from the sawfish database to further enhance a management plan developed to help speed the species’ recovery.

The National Sawfish Encounter Database is a compendium of all known historical and current records of sawfish in the United States, Burgess said. Databases formerly housed with the Mote Marine Laboratory in Sarasota, the Florida Fish and Wildlife Conservation Commission and two private sawfish enthusiasts are being combined with existing Florida Museum of Natural History records, he said.

Data from the collections will reveal the known distribution of sawfish throughout the United States, he said. Burgess plans to add to it new research results as he and his team monitor the abundance of sawfish and use tags to track their movements within the Indian River Lagoon and Banana River along Florida’s east coast.

This area is critical to the recovery of the once widespread species, Burgess said. Historically, the region was full of sawfish, but the numbers drastically declined as development encroached on the creature’s coastal habitat and its encounters with humans rose, he said.

“Sawfish are disappearing all over the world for basically the same reason, which is that their big saws snag very easily in fishing nets,” he said. “They have become despised as net wreckers because obviously a fisherman doesn’t like getting one in his net. So over the years most sawfish that were captured were killed.”

Even those sawfish lucky enough to be tossed back into the water were often released without their saws, as people came to value these body parts as curio items, Burgess said.

Although the sawfish’s body resembles a shark, the sawfish belongs to a class of fish called rays. Its elongated blade-like snout is used to stun and kill prey.

“Sawfish get lots of ooh’s and aah’s because humans tend to gravitate to the more charismatic megafauna, as it is characterized,” he said. “We place more values on whales than their kin the field mice or the brown-eyed seal more than we do some wood rat.”

Part of the sawfish’s appeal may also be its increasing rarity, said Burgess, who estimates there are only a few thousand sawfish left in Florida.

It takes longer for the sawfish population to recover than other species because of its unusually slow growth, late onset of sexual maturity and low reproductive potential, Burgess said. Although the sawfish has a long life span of 30 years or more, it is a live-bearer. As such, it has a prolonged gestation period and produces very few young, he said.

Anyone who sees a sawfish is asked to contact Burgess’s team at 352-392-2360 or sawfish@flmnh.ufl.edu so they can record the sighting’s location. Mapping the sawfish’s distribution is important in fine-tuning a management plan developed to protect the endangered species, he said.

More information about how to file a sawfish sighting report and what kind of details to include can be obtained from the museum’s Web site at http://www.flmnh.ufl.edu/fish/sharks/sawfish/.

“We’ve written history based on the bigger islands,” said Bill Keegan, a University of Florida archaeologist whose study is published online in the journal Human Ecology. “Yet not only are we now seeing people earlier on smaller islands, but we’re seeing them move into territories where we didn’t expect them to at the time that they arrived.”

Early Ceramic Age settlements have been found in the U.S. Virgin Islands and Montserrat, for example, but are absent from all of the larger islands in the Lesser Antilles, Keegan said. And all of the small islands along the windward east coast of St. Lucia have substantial ceramic artifacts — evidence of settlement — despite being less than one kilometer, or .62 mile, long, said Keegan, who is curator of Caribbean archaeology at the Florida Museum of Natural History on the UF campus.

It was thought that people preferred larger islands because the land mass of bigger islands could support a more diverse range of habitats and greater numbers of animal species for humans to subsist on, Keegan said. In addition, the focus of long-term evolutionary patterns has favored large islands, he said.

But small islands had coastlines rich with fish, and the absence of dense woodlands made them more suited to farming and hunting small prey such as iguanas, tortoises and hutias, a cat-sized rodent, he said.

“In the short term, small islands often are superior to larger islands, and for a variety of reasons, they were actually people’s first choice,” Keegan said. “They had better wind flow, fewer mosquitoes and more plentiful marine resources. With sufficient water and a relatively small amount of land to grow certain kinds of crops, they had everything one would need.”

Because prehistoric people were drawn to these small islands, they may tell scientists more than settlements on larger islands about early patterns of life, Keegan said. To date, most archaeological excavations have taken place on bigger islands in such countries as Cuba, Dominican Republic and Puerto Rico, he said.

Much of Keegan’s research focused on Grand Turk, Middle Caicos and very small cays in the Turks and Caicos Islands, along with Carriacou in the Grenadine Islands, he said.

Pottery remains he found that were analyzed at the Florida Museum of Natural History’s ceramic technology lab shows that humans often left large islands for small ones, probably initially to take advantage of abundant marine resources along the coastline, he said.

Ceramic pottery sherds recovered from the smaller Turks and Caicos islands, for example, were actually found to have come from Haiti, he said. “Traveling to the Turks and Caicos gave these people an opportunity to get sources of food that weren’t locally available to them,” he added.

In another case, pottery remains were found on an extremely tiny island in the Turks and Caicos that had little soil and was accessible only by a sand spit, Keegan said.

“The island looks just like a rock,” he said. “To think that anyone would have any reason to be out there is just beyond believability. But the island is named Pelican Cay, so people may have gone there to capture sea birds and their eggs.”

People were drawn by the large varieties of fish, tortoises, iguanas and sea turtles that were in much greater supply on Grand Turk than the island of Hispaniola at the time, Keegan said. Remains from loggerhead turtles as big as 1,000 pounds were excavated from Grand Turk, although sea turtle sizes eventually declined to 60 pounds with overexploitation, he said.

“The high rates of return from capturing these animals far outweighed the costs of getting to Grand Turk,” he said. “Such human migration patterns made good economic sense.”

It was probably easier to sail to other islands than traverse from one end of an island to the other through the overgrown vegetation of tropical woodlands, he said.

“Most island archaeologists today, including those in the Caribbean, recognize that the sea was their ancient highway,” he said.

And the smaller the island, the better. “Based on our work, it is clear that marine resources on smaller islands in the Caribbean were abundant, heavily exploited and even sought after by the native peoples,” Keegan said. “You could say that ‘small is beautiful’ or ‘size doesn’t matter.’”

But ancient settlements in the Amazon, now almost entirely obscured by tropical forest, were once large and complex enough to be considered “urban” as the term is commonly applied to both medieval European and ancient Greek communities.

So says a paper set to appear Friday in Science co-authored by anthropologists from the University of Florida and Brazil, and a member of the Kuikuro, an indigenous Amazonian people who are the descendants of the settlements’ original inhabitants.

“If we look at your average medieval town or your average Greek polis, most are about the scale of those we find in this part of the Amazon,” said Mike Heckenberger, a UF professor of anthropology and the lead author of the paper. “Only the ones we find are much more complicated in terms of their planning.”

The paper also argues that the size and scale of the settlements in the southern Amazon in North Central Brazil means that what many scientists have considered virgin tropical forests are in fact heavily influenced by historic human activity. Not only that, but the settlements — consisting of networks of walled towns and smaller villages, each organized around a central plaza — suggest future solutions for supporting the indigenous population in Brazil’s state of Mato Grosso and other regions of the Amazon, the paper says.

“Some of the practices that these folks hammered may provide alternative forms of understanding how to do low level sustainable development today,” Heckenberger said.

Heckenberger and his colleagues first announced the discovery of the settlements in a 2003 Science paper. The largest date from around 1250 to 1650, when European colonists and the diseases they brought likely killed most of their inhabitants.

The communities are now almost entirely overgrown. But Heckenberger said that members of the Kuikuro, a Xinguano tribe that calls the region home, are adept at identifying telltale landscape features that reveal ancient activity. These include, for example, “dark earth” that indicate past human waste dumps or farming, concentrations of pottery shards and earthworks. Also assisted by satellite imagery and GPS technology, the researchers spent more than a decade uncovering and mapping the obscured communities.

The new paper reports that the settlements consisted of clusters of 150-acre towns and smaller villages organized in spread out “galactic” patterns.

None of the large towns was as large as the largest medieval or Greek towns. But as with those towns, the Amazonian ones were surrounded by large walls – in their case, composed of earthworks still extant today. Among other repeated features, each Amazonian settlement had an identical formal road, always oriented northeast to southwest in keeping with the mid-year summer solstice, connected to a central plaza.

The careful placement of the like-oriented settlements is indicative of the regional planning and political organization that are hallmarks of urban society, Heckenberger said.

“These are not cities, but this is urbanism, built around towns,” he said.

The findings are important because they contradict long-held stereotypes about early Western versus early New World settlements that rest on the idea that “if you find it in Europe, it’s a city. If you find it somewhere else, it has to be something else,” Heckenberger said.

“They have quite remarkable planning and self-organization, more so than many classical examples of what people would call urbanism,” he said.

But the research is also important because it means at least one area of “pristine” Amazon has a history of human activity. That could change not only how scientists assess the flora and fauna, but also how conservationists approach preserving the remains of forest so heavily cleared it is the world’s largest soybean producing area. “This throws a wrench in all the models suggesting we are looking at primordial biodiversity,” Heckenberger said.

Around the communities the scientists found dams and artificial ponds that indicate inhabitants farmed fish near their homes. They also found the remnants of open areas and large compost heaps suggesting widespread near-town cultivation.

The research has been funded by the National Science Foundation.

The study, co-authored by Florida Museum of Natural History researchers Michael Kirby, Douglas Jones and Bruce MacFadden, is published in the July 30 issue of PLoS ONE, the online journal of the Public Library of Science. The study uses geologic, chemical and biologic methods to date rocks and fossils found in sides of the Gaillard Cut of the Panama Canal. The results show that instead of being formed by rising and subsiding ocean levels or existing as a string of islands as scientists previously believed, the Isthmus of Panama was first a peninsula of southern Central America before the underlying tectonic plates merged it with South America 4 million years ago.

“Scientists knew Panama was a North American peninsula, possibly as early as 19 million years ago because fossils that are closely related to North American land mammals, such as rhinos, horses, peccaries and dogs have been found in the Panama Canal during ongoing maintenance,” said Kirby, lead author of the study. “But we were not certain when this peninsula first formed and how long it may have existed.”

The canal’s maintenance also exposes sediment layers and marine animal fossils, as well as strata of rocks and clay specific to numerous environments, including lagoon, delta, swamp, woodland and dry tropical forest.

Previous studies placed marine sediment as the youngest layers, suggesting the peninsula was submerged before finally joining with South America. The current study revises the time order of strata, however, and concludes that the Panamanian peninsula joined with South America roughly 4 million years ago.

Deep-sea deposits in one sediment layer suggest a short-lived strait may have existed across the Panama Canal Basin between 21 and 20 million years ago,” said Jones, director of the Florida Museum of Natural History. “However, these short-lived straits probably had little impact on the long-term evolution of Central America’s flora and fauna.”

Kirby explained that because of numerous geologic faults resulting from tectonic plate movement that continues today, there is no area in Panama that allows a full view of the strata making up the land.

“We realized there was a problem with our previous understanding of the stratigraphy, or layering of sediments, in Panama,” Kirby said.

The authors used alternative methods such as strontium isotope dating of fossils and re-analysis of vertebrate fossils to better determine the geologic sequence of the Canal.

“There’s always missing information, like pages out of a book, when it comes to figuring out which layers came first and which were formed later,” Kirby added.

Anthony Coates, a staff scientist emeritus at the Smithsonian Tropical Research Institute in Panama who has extensively studied the geological history of the rise of the Central American isthmus, said the study brings together a diverse array of geologic evidence that convincingly suggests Central America was a peninsula and not a group of islands.

“They have made an important contribution to the land-based geologic evidence of the plate tectonic history of the formation of the Isthmus,” said Coates, who did not participate in the study. “Their results have important consequences for the nature of the global change engendered by the rise and closure of the isthmus.”

One of the major effects of the formation of the Isthmus of Panama was the intensification of the Gulf Stream in the Atlantic Ocean. While the area that is now Panama was still a peninsula, ocean currents moving north along the north coast of South America spilled over to the Pacific Ocean through the wide Central American Seaway, also called the Atrato Seaway. As tectonic plate movement joined the peninsula with South America to form the present-day Isthmus of Panama, equatorial ocean currents between the Atlantic and Pacific were cut off, forcing water northward into the Gulf Stream current.

“The strengthened Gulf Stream, in turn, delivered enough moisture to allow the formation of glaciers across North America,” Kirby said.

The complete text of the study is available on the publication’s Web site, www.plosone.org/doi/pone.0002791.

Falcons would seem to have evolved together with hawks and eagles, but the species are not close kin, appearing to have acquired their hawk-like characteristics completely independently from their look-alikes.

The largest group of birds, the passerines — which include such common North American birds as mockingbirds, blue jays and wrens — may be most closely related to a group not common at all in our latitudes: parrots.

These are among the surprising findings of the largest-ever study of the evolution of birds described in an article set to appear Thursday in Science. The study — conducted in large part by five institutions, including the University of Florida — challenges current bird classifications, alters understanding of avian evolution and provides a valuable resource for studying the evolutionary history of birds.

“We basically tried to make the next big step in understanding how different types of birds are related to each other,” said Rebecca Kimball, an associate professor of zoology at UF and one of three lead authors of the Science paper. “There has still been a lot of controversy about this issue. Some people have suggested that it is an unsolvable problem.”

Birds are among the most studied and loved animals, and much of what is known about animal biology — from natural history to ecology, speciation and reproduction — is based on birds. Nevertheless, the avian tree of life has remained elusive — until now.

For more than five years, the Early Bird Project has been examining DNA from all major living groups of birds. So far, scientists have built a dataset of more than 32 kilobases — a kilobase is a DNA fragment containing 1,000 base pairs — from 19 different locations on the DNA of each of 169 bird species. The result is equivalent to a small genome project.

“Our study and the remarkable new understanding of the evolutionary relationships of birds that it affords was possible only because of the technological advances of the last few years that have enabled us to sample larger portions of genomes,” said co-lead author Shannon Hackett of The Field Museum in Chicago. “Our study yielded robust results and illustrates the power of collecting genome-scale data to reconstructed difficult evolutionary trees.”

The study’s results are so broad that the scientific names of dozens of birds will have to be changed, and biology textbooks and birdwatchers’ field guides will have to be revised. The study resulted in a number of new or expanded findings about bird evolution:

• Birds adapted to diverse environments several distinct times because many birds that now live on water did not evolve from a different waterbird group, and many birds that now live on land did not evolve from a different landbird group.
• Distinctive bird lifestyles, such as birds that are nocturnal or raptorial, evolved several times. For example, contrary to conventional thinking, colorful, daytime hummingbirds evolved from drab nocturnal nightjars.
• Shorebirds are not an early evolutionary group, which refutes the widely held view that shorebirds gave rise to all modern birds.

“We have come a long way, but we haven’t answered every question,” Kimball said, adding that the study both confirmed and rejected traditional ideas about bird evolution. For example, she said, researchers confirmed the results of several other studies showing that chickens and turkeys are closely related to ducks and geese. But the study’s finding that passerines are close relatives of parrots is new and surprising, because parrots are anatomically very different from the birds in the passerine group.

Kimball said labs at each of the major institutions involved in the study took charge of sequencing separate genes from the same bird species. Because of the enormous amount of data involved in the sequencing work, the UF researchers, led by zoology assistant professor Edward Braun, sought to predict how many genes were needed for a satisfactory result.

“We actually tried to simulate the evolutionary process,” she said. “If we hypothesize that birds evolved in this rapid evolution, how much data would we need to have a chance to start to find those bits of information that would help us piece together these relationships? We used that simulation as our guide in how we set up the project.”

The UF portion of the research was funded with a $455,000 grant from the National Science Foundation through its Assembling the Tree-of-Life Research Program. Other UF authors were Braun and David Steadman, a UF ornithologist, both co-principal investigators on the project with Kimball. Graduate students Andrew Cox, Kin-Lan Han and postdoctoral researcher Tamaki Yuri also served as co-authors.

Using multiple techniques of geochemical analysis, scientists reconstructed 28 million years of the Altiplano portion of the central Andes’ ancient upward march due to movements in the earth’s tectonic plates miles below. But the peaks didn’t grow slowly and steadily, according to University of Florida researcher Bruce MacFadden, a co-author of the study published June 6 in the journal Science.

“Instead of the Altiplano rising little by little each year, like conventional theory might indicate, we found two cycles of spasmodic or punctuated uplift interspersed by millions of years of stability,” said MacFadden, a vertebrate paleontology curator at the Florida Museum of Natural History.

Geologists have long known mountains are born when continental crust shortens and thickens as one tectonic plate slides beneath another, so conventional theory held that the Altiplano rose gradually in sync with the moving of the earth’s plates. But the study reports an unexpected process. Lead author Carmala Garzione, a geologist at the University of Rochester, said the Nazca tectonic plate sliding beneath the South American continental plate caused the dense lower crust to accumulate material at deep depths.

“But when the dense material is removed rapidly — by downward dripping which is a convective process, or by another process called delamination — it caused rapid surface uplift,” Garzione said. “Our findings will force geologists to acknowledge that removal of lower lithosphere material could be an important process that causes rapid surface uplift in different mountain belts worldwide and over geologic time.”

To reconstruct the Altiplano’s sequential rise, the researchers coaxed geochemical clues in the form of oxygen isotopes from ancient soil nodules made of calcium carbonate. The nodules were sampled from layered soil deposits between 5 million and 28 million years old. Oxygen isotopes serve as reliable proxy indicators for the actual temperatures in which they formed — so the researchers used them to reconstruct ancient temperature records, and then linked these records to known temperature clines associated with vertical elevation gain. They also analyzed magma and sediment as additional proxies.

Dork Sahagian, a professor of earth and environmental sciences at Lehigh University who did not participate in this study, said that while weaknesses were inherent when single proxy methods were used, the multiple methods used in this study made the results robust.

“Remarkably, the rapid recent uplift scenario presented here is similar to what I found for the Colorado Plateau,” Sahagian said. “The greatest novelty in their study is the number of proxies they brought to bear on the problem. This is the right way to go about it.”

In 2005, Sahagian organized a national workshop to refine and strengthen paleoelevation techniques. Garzione presented the beginnings of her Altiplano work there and later, she contacted MacFadden to tap his three decades of research on stratigraphy and fossils from the Bolivian Andes. Over the past few years, MacFadden led Garzione and her team to several key fossil sites in the Altiplano where he had established geological age sequences decades ago. While Garzione’s interest was grounded in geology, MacFadden was interested in understanding how the birth of the Andes may have affected South America’s ancient animals and climate.

“The big-picture question is: When did the Andes grow high enough to become drivers of the South American climatic regime? Because this event obviously had cascading effects upon plant and animal life across the continent,” MacFadden said. “If we could rewind a video of their formation, we’d see how they grew into an immense force, affecting the distribution and abundance of moisture across large portions of South America.”

Today, the Andes’ massive mountain belt snakes 4,400 miles along the continent’s western edge and is the longest unbroken terrestrial chain on the planet, with peaks soaring to 22,841 feet. The world’s driest desert, the Atacama, lies to its west and the world’s largest collection of wetlands form the Pantanal to its east.

Additional study co-authors include: Gregory Hoke, University of Rochester; Julie Libarkin and Saunia Withers, Michigan State University; John Eiler, California Institute of Technology; Prosenjit Ghosh, Center for Atmospheric and Oceanic Science; and Andreas Mulch, Universität Hanover in Germany.

Except for 1987, when there were no fatalities, the last year a single human death occurred from a shark attack was in 1985, said George Burgess, director of the International Shark Attack File housed at UF’s Florida Museum of Natural History. By comparison, there were four deaths each in 2005 and 2006, and seven in 2004.

“It’s quite spectacular that for the hundreds of millions of people worldwide spending hundreds of millions of hours in the water in activities that are often very provocative to sharks, such as surfing, there is only one incident resulting in a fatality,” he said. “The danger of a shark attack stays in the forefront of our psyches because of it being drilled into our brain for the last 30 years by the popular media, movies, books and television, but in reality the chances of dying from one are infinitesimal.”

Advances in medical treatment, greater attention to beach safety practices and increased public awareness about the danger of shark attacks are all likely reasons the fatality rate so far for the 21st century, at 7.6 percent, has been lower than the 12.3 percent recorded for the 1990s, Burgess said.

The number of shark attacks overall increased from 63 in 2006 to 71 in 2007, continuing a gradual upswing during the past four years, he said.

“One would expect there to be more shark attacks each year than the previous year simply because there are more people entering the water,” he said. “For baby boomers and earlier generations, going to the beach was basically an exercise in working on your suntan where a swim often meant a quick dunking. Today people are engaged in surfing, diving, boogie boarding and other aquatic activities that put them much closer to sharks.”

Occasionally, the number of attacks may drop in a particular year because of changes in meteorological or oceanographic conditions that affect water temperature and salinity, such as the frequency of hurricanes and tropical storms, Burgess said. But scientists don’t put too much stock in these year-to-year fluctuations, preferring to look at long-term trends, he said.

Traditionally, about half of the world’s attacks occur in United States mainland and Hawaiian waters, but the proportion was greater in 2007, Burgess said. Last year’s total of 50 attacks returned to 2000 and 2001 levels of 53 and 50, respectively, after dropping from 30 to 40 for each year between 2003 and 2006, he said.

Elsewhere, there were 12 attacks in Australia, up from seven in 2006 and 10 in 2005, but down slightly from the 13 attacks recorded in 2004. There were two attacks each last year in South Africa and New Caledonia, with single incidents reported in Fiji, Ecuador, Mexico and New Zealand.

There also was an upswing in attacks along the Florida coast, jumping from 23 in 2006 to 32 in 2007. There has been a gradual increase in human-shark skirmishes in the Sunshine State since they dropped from 37 in 2000 to an 11-year-low of 12 in 2004, he said.

Within Florida, Volusia County continued its dubious distinction as the world’s shark bite capital with 17 incidents, its highest yearly total since 2002, Burgess said. Attractive waves off New Smyrna Beach on the central Atlantic coast are popular with surfers, he said.

Additional U.S. attacks were recorded in Hawaii — seven — marking a five-year-high, along with South Carolina, five; California, three; North Carolina, two; and Texas, one.

Fifty-six percent of the 2007 victims were surfers and windsurfers; followed by swimmers and waders, 38 percent; and divers and snorkelers, 6 percent.

Last year’s Sept. 30 fatal attack involved a 23-year-old woman from France who was snorkeling off the Loyalty Islands archipelago in French New Caledonia and became separated from a friend, Burgess said. She was a nurse who had just finished a hospital contract in Noumea and was taking a brief vacation before flying home, he said.

“We advise not getting yourself isolated because there is safety in numbers,” he said. “Sharks, like all predators, tend to go after solitary individuals, the weak and the infirm, and are less likely to attack people or fish in groups.”

Last year had few spectacular attacks or heartwarming rescue stories, Burgess said. “It was mostly minor injuries,” he said. “There weren’t too many made-for-movie moments.”

“It’s kind of quirky that a parasite we love to hate can actually inform us how we traveled around the globe,” said David Reed, an assistant curator of mammals at the Florida Museum of Natural History on the UF campus and one of the study’s authors.

DNA sequencing found the strain of lice to be genetically the same as the form of body lice that spawns several deadly diseases, including typhus, which was blamed for the loss of Napoleon’s grand army and millions of other soldiers, he said.

The discovery of these parasites on 11th-century Peruvian mummies proves they were infesting the native Americans nearly 500 years before Europeans arrived, Reed said. His findings are published this week in an online edition of the Journal of Infectious Diseases.

“This definitely goes against the grain of conventional thought that all diseases were transmitted from the Old World to the New World at the time of Columbus,” he said.

It came as a surprise to Reed and his research team that the type of lice on the mummies was of the same genetic type as those found as far away as the highlands of Papua, New Guinea, instead of the form of head lice that is widespread in the Western Hemisphere, Reed said. This latter version, the bane of many school children, accounts for more than half the cases of lice that appear in the United States, Canada and Central America, he said.

“Given its abundance in the Americas on living humans, we thought for sure that this form of lice was the one that was here all along and had been established in the New World with the first peoples,” he said.

“We hope to be able to understand human migration patterns by investigating their parasites since people have carried these parasites with them as they moved around the globe,” he said. “Called a parascript, it’s a whole other transcript of our evolutionary history that can either add to what we know or in some cases inform us about things we didn’t know.”

Looking at evidence from parasites’ perspectives, for example, may yield valuable clues about when the first Americans arrived on the continent and which route they took, Reed said. Building upon this DNA sequencing work, scientists may be able to link the 1,000-year-old lice found in the Western Hemisphere with those in Siberia or Mongolia, confirming existing theories that America’s earliest residents originated there, he said.

Had these immigrants traveled by land masses, there was a very small window of time, about 13,000 years ago, when the glaciers retreated enough to allow passage through the Bering Strait on the way to South America, Reed said. Another proposed theory is a seafaring route, but this would have required sophisticated oceangoing vessels for which no evidence from the time exists, he said.

Being able to chart these early migration patterns would give insight into how these early immigrants lived, Reed said. “If you’re skirting the edge of glaciers, it’s obviously a very cold time period and humans would have needed certain creature comforts just to stay alive, such as tight clothing to maintain warmth,” he said.

Today, the people who don’t have the opportunity to change their clothes are the ones at risk for epidemic typhus, which along with the lesser-known diseases of relapsing fever and trench fever are carried by body lice, Reed said. These pests lay their eggs in clothing fibers and washing the clothes is all it takes to get rid of them, he said.

“The disease pops up primarily in refugees who have been displaced from their homeland with the clothes on their backs and nothing else,” he said. “They’re living in crowded conditions where hygiene is poor.”

Reed said he hopes the team’s lice research might someday increase human understanding of typhus by pinpointing where the disease originated.

Studying parasites to learn about their hosts’ history has been around for only about 20 years, Reed said. “By looking at things like tapeworms, pinworms, lice or bedbugs that humans have carried around for at least tens of thousands of years, and in some cases millions of years,” he said, “we can learn much more about human evolutionary history.”