Researchers from the Smithsonian Institution and UF, among others, found that many of the dominant plant families existing in today’s Neotropical rainforests — including legumes, palms, avocado and banana — have maintained their ecological dominance despite major changes in South America’s climate and geological structure.

The study, which appears this week in the online edition of the Proceedings of the National Academy of Sciences, examined more than 2,000 megafossil specimens, some nearly 10 feet long, from the Cerrejón Formation in northern Colombia. The fossils are from the Paleocene epoch, which occurred in the 5- to 7-million-year period following the massive extinction event responsible for the demise of the dinosaurs.

“Neotropical rainforests have an almost nonexistent fossil record,” said study co-author Fabiany Herrera, a graduate student at the Florida Museum of Natural History on the UF campus. “These specimens allow us to actually test hypotheses about their origins for the first time ever.”

Herrera said the new specimens, discovered in 2003, also provide information for future studies that promise to provide an even stronger understanding of the plants that formed the earliest Neotropical communities.

Many previous assumptions and hypotheses on the earliest rainforests are based on studies of pollen fossils, which did not provide information about climate, forest structure, leaf morphology or insect herbivory.

The new study provides evidence Neotropical rainforests were warmer and wetter in the late Paleocene than today but were composed of the same plant families that now thrive in rainforests. “We have the fossils to prove this,” Herrera said. “It is also intriguing that while the Cerrejón rainforest shows many of the characteristics of modern equivalents, plant diversity is lower.”

The site, one of the world’s largest open-pit coal mines, also yielded the fossil for the giant snake known as Titanoboa, described by UF scientists earlier this year.

“These new plant fossils show us that the forest during the time of Titanoboa, 58 million years ago, was similar in many ways to that of today,” said Florida Museum vertebrate paleontologist Jonathan Bloch, who described Titanoboa but was not part of the rainforest study. “Like Titanoboa, which is clearly related to living boas and anacondas, the ancient forest of northern Colombia had similar families of plants as we see today in that ecosystem. The foundations of the Neotropical rainforests were there 58 million years ago.”

Megafossils found at the Cerrejón site made it possible to use leaf structure to identify specimens down to the genus level. This resolution allowed the identification of plant genera that still exist in Neotropical rainforests. With pollen fossils, specimens can be categorized only to the family level.

Researchers were surprised by the relative lack of diversity found in the Paleocene rainforest, Herrera said. Statistical analyses showed that the plant communities found in the Cerrejón Formation were 60 percent to 80 percent less diverse than those of modern Neotropical rainforests. Evidence of herbivory also showed a low diversity level among insects.

The study’s authors say the relative lack of diversity indicates either the beginning of rainforest species diversification or the recovery of existing species from the Cretaceous extinction event.

The researchers estimate the Paleocene rainforest received about 126 inches of rainfall annually and had an average annual temperature greater than 86 degrees. The Titanoboa study, which used different methods, estimated an average temperature between 89 and 91 degrees. Today the region’s temperatures average about 81 degrees.

Herrera is now comparing fossils from the Cerrejón site to specimens from other Paleocene sites in Colombia to see how far the early rainforest extended geographically. He is also examining fossils from a Cretaceous site to determine differences in composition before and after the extinction event.

GAINESVILLE, Fla. — The story of Christopher Columbus and the people he encountered when he arrived in the Caribbean has yet to be truthfully conveyed in books used by elementary school students, a new University of Florida study finds.

Long before Columbus Day arrives Oct. 12, an overwhelming majority of books used by children in libraries and classrooms have presented outdated information and outright distortions about the explorer’s expeditions, said UF researcher Donna Sabis-Burns. She did the study for her doctoral dissertation in the school of teaching and learning in UF’s College of Education.

“Picture books are usually the first time children are exposed to the story of Columbus, so they need to be truthful,” she said. “Unfortunately, these books are telling our children a history that is filled with omissions and misrepresentations.”

Referring to the native people as savages when Columbus kidnapped hundreds into slavery and his shipmates raped local women are among the most glaring examples of falsehoods, said Sabis-Burns, who is now a team leader with the U.S. Department of Education’s School Support and Technology Program in Washington, D.C.

Within the sample, most of the books are widely outdated at more than 10 years old, Sabis-Burns said. Less than 2 percent of the volumes contain more readily available information that became increasingly visible in 1992 as scholars released new findings to coincide with the 500th anniversary of Columbus’ first expedition to the New World, she said.

The week after Columbus Day in 2008, Sabis-Burns sent an online survey to school districts, teachers and national education listservs in 39 states about which reading materials they used on the explorer. She received responses from 189 teachers and 89 librarians, who provided a list of 182 books, which she analyzed for content.

Six out of 10 books failed to identify the native Taino people whom Columbus encountered by their tribal affiliation, calling them simply “Indians” or “natives” and even “gentle heathens” or “naked, red-skinned savages,” Sabis-Burns said.

“Without these people, Columbus never would have survived,” she said. “Had it not been for the Tainos, his voyages would not have been successful.”

The Tainos showered Columbus with much-needed food and showed him how to navigate the Caribbean islands, Sabis-Burns said.

Many of the books claim that the Tainos became extinct, even though about 600 descendants survive in small pockets of Cuba’s Guantanamo Mountains, she said.

While book publishers are beginning to release books for older children with more details about the Tainos, the practice has not extended to the picture book genre shared in today’s classrooms within the survey sample, she said.

Seventy-seven percent of picture books analyzed in the study use either oversimplified descriptions or primitive depictions of the native people, Sabis-Burns said. Less than half describe Taino trading items, traditional dress, agricultural practices or other aspects of their culture, many of which were never documented as belonging to the Taino, she said.

“It is not my intent to load picture books with men raping women or murdering them in the illustrations,” she said. “My point is that the books don’t tell what happened to the Taino at the hands of the Spanish.

“On his first voyage Columbus kidnapped several Tainos and shipped them back to Spain to be sold into slavery because he was afraid he would not have enough riches to compensate Spanish royalty for financing his trip,” she said.

On his next trip, Columbus seized hundreds more Tainos as slaves, many of whom died and were tossed overboard before his ships reached Spain, she said.

The Tainos killing of 39 men left behind after Columbus’ ship crashed into a reef on the island of Hispaniola was not unprovoked as presented in some of the sample picture books, Sabis-Burns said. Before Columbus returned a year later to the La Navidad settlement to find his men gone, the Europeans forced the Taino to work the fields and raped women, she said.

Sabis-Burns said the two most widely used books were written in 1980 and 1992, despite the publication of at least 150 picture books on Columbus since 1992.

“Dr. Sabis-Burns has brought this country’s deep resistance to correcting the story of Columbus taught to our children to the surface with her research,” said Nancy Rankie Shelton, an education professor at the University of Maryland, Baltimore County. “Year after year, schools across our nation celebrate Columbus Day with the youngest of our citizens, never once thinking about or teaching the destruction he caused the Taino people.”

Reed, an associate curator of mammalogy at the university’s Florida Museum of Natural History, will use the five-year, $934,498 grant to trace the evolutionary history of lice, and he hopes the study will shed light on human migration, development and evolution.

“Parasitic lice have evolved alongside, but much faster than their human hosts,” Reed said. “The lice have given researchers a more detailed look at the process of species migration and evolution.”

The study also will analyze genetic similarities between the evolution of lice and humans as they have evolved over time. Reed said human and chimpanzee lice branched from a single evolutionary line at about the same time their hosts did and the study will use DNA sequencing data to more closely examine other similarities between the two types of lice.

The study will require samples from around the world, collected with the help of medical professionals. The grant also provides funding to support a postdoctoral fellow, two graduate students and up to 10 undergraduates, and includes a training program to teach UF graduate students how to communicate their research to lay audiences.

“Scientists often lack the skills needed to translate their technical research findings into information that is relevant to a broad public audience, “which is why we are creating this graduate opportunity,” Reed said. “Being able to employ both graduate and undergraduate students is a real benefit to the department and the university.”

The research opportunities will provide training in skills such as collecting specimens, working in the molecular lab and conducting genetic analysis, allowing students to enter the work force with specialized skills.

Human lice have been a nuisance for centuries. The rapid changes that make lice ideal candidates for a study centered on evolutionary processes also play havoc on everyday life among the general human population.

Head lice in school children, one common form of parasitic lice, have built a resistance to insecticidal shampoos in developed countries, which is why their numbers are increasing in the U.S. In underdeveloped countries where insecticidal treatments are not widely used, lice are still susceptible and easily controlled with existing medicines, Reed said.

The grant also includes the purchase of a high definition imaging system to document, compare and study specimens collected worldwide for the project.

The National Science Foundation is an independent federal agency created by Congress in 1950 and currently funds about 20 percent of all federally supported research at U.S. colleges and universities. NSF creates about 10,000 new awards each year including the Faculty Early Career Development Award, which is given to researchers who exemplify the teacher-researcher role.

In a paper appearing this week in the online edition of the Proceedings of the National Academy of Sciences, UF biology professor Brian McNab concludes that contrary to common belief, dinosaurs didn’t attain their colossal body sizes because they had more food to eat. Instead, McNab says, like Popeye with his spinach-induced bulging muscles, dinosaurs simply converted more of the energy in their food to body mass.

“Dinosaurs used energy in a different way than mammals use it. Mammals use much of their energy for body maintenance, temperature regulation and activity, and less of it for growth,” McNab says. “Dinosaurs used more energy for growth and less for maintenance.”

McNab argues that the conifers, ferns and other prehistoric plants that proliferated during the Mesozoic era ending 65 million years ago largely constituted “garbage food” that required a lot of energy to digest and provided little energy in return. Despite this limitation, dinosaurs were able to grow as much as eight times bigger than modern mammals, with the largest herbivores reaching weights of 40 to 80 tons or more – six to eight times an elephant’s weight of about 7 tons. (A large rhinoceros relative that lived in the Miocene weighed 11 to 15 tons and was the largest terrestrial mammal.)

Most of today’s herbivorous mammals can eat grasses, which were not present in the Mesozoic, and are a high-energy, more readily digestible forage, McNab noted. At the other end of the scale, plankton have a high energy content and are easy to digest, which is why the largest whales can reach weights of 160 tons, eclipsing the sizes of even the largest dinosaurs, he said.

McNab says dinosaurs attained their gigantic proportions because their biology apparently combined characteristics of modern warm-blooded and cold-blooded animals. On the one hand, they could regulate their own body temperature because of their large size and small relative surface area, he concludes. On the other, their metabolic rates were only about a quarter of those of mammals, but four times those of most reptiles.

Among modern animals, McNab says, those whose metabolisms most closely match those of dinosaurs are the varanid lizards, which include the Komodo dragon and other Monitor lizards.

“If you extrapolate varanid lizards’ metabolic rate up the metabolic rates of elephants, you get an animal that weighs 60 to 80 tons,” he says. “That’s the size of the biggest dinosaurs, the sauropods.”

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.