Plant fossils give first real picture of earliest Neotropical rainforests

October 15th, 2009

Photos available

GAINESVILLE, Fla. — A team of researchers including a University of Florida paleontologist has used a rich cache of plant fossils discovered in Colombia to provide the first reliable evidence of how Neotropical rainforests looked 58 million years ago.

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 Cerrej√≥n 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. (more…)

54-million-year-old skull reveals early evolution of primate brains

June 22nd, 2009

Photos available at: http://news.ufl.edu/2009/06/22/primate-brain-multimedia/primate-brain-photos/

GAINESVILLE, Fla. — Researchers at the University of Florida and the University of Winnipeg have developed the first detailed images of a primitive primate brain, unexpectedly revealing that cousins of our earliest ancestors relied on smell more than sight.

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. (more…)

UF study finds ancient mammals shifted diets as climate changed

May 29th, 2009

Photos available

GAINESVILLE, Fla. — A new University of Florida study shows mammals change their dietary niches based on climate-driven environmental changes, contradicting a common assumption that species maintain their niches despite global warming.

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.” (more…)

Preserved shark fossil adds evidence to great white’s origins

March 12th, 2009

GAINESVILLE, Fla. — A new Florida Museum of Natural History study could help resolve a long-standing debate in shark paleontology: From which line of species did the modern great white shark evolve?

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. (more…)

UF study: Rapid burst of flowering plants set stage for other species

February 5th, 2009

GAINESVILLE, Fla. — A new University of Florida study based on DNA analysis from living flowering plants shows that the ancestors of most modern trees diversified extremely rapidly 90 million years ago, ultimately leading to the formation of forests that supported similar evolutionary bursts in animals and other plants.

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 worlds 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 UFs Florida Museum of Natural History. “Associated with some of the subsequent radiations is even the diversification of the primates.” (more…)

Small islands given short shrift in assembling archaeological record

October 30th, 2008

Photo available

GAINESVILLE, Fla. — Small islands dwarf large ones in archaeological importance, says a University of Florida researcher, who found that people who settled the Caribbean before Christopher Columbus preferred more minute pieces of land because they relied heavily on the sea.

“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. (more…)

Florida Museum study shows Isthmus of Panama formed as result of plate tectonics

July 30th, 2008

GAINESVILLE, Fla. — Contrary to previous evidence, a new Florida Museum of Natural History study shows the Isthmus of Panama was most likely formed by a Central American Peninsula colliding slowly with the South American continent through tectonic plate movement over millions of years.

The study, co-authored by Florida Museum 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.” (more…)

Mummy lice found in Peru may give new clues about human migration

February 7th, 2008

GAINESVILLE, Fla. — Lice from 1,000-year-old mummies in Peru may unravel important clues about a different sort of passage: the migration patterns of America’s earliest humans, a new University of Florida study suggests.

“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. (more…)

96-Million-year-old fossil pollen sheds light on early pollinators

December 20th, 2007

Photo available

GAINESVILLE, Fla. — The collapse of honeybee colonies across North America is focusing attention on the honeybees’ vital role in the survival of agricultural crops, and a new study by University of Florida and Indiana University Southeast researchers shows insect pollinators have likely played a key role in the evolution and success of flowering plants for nearly 100 million years.

The origins of when flowers managed to harness insects’ pollinating power has long been murky. But the new study, published online this week on the Proceedings of the National Academy of Sciences Web site and appearing in its Dec. 24 print edition, is the first to pinpoint a 96-million-year-old timeframe for a turning point in the evolution of basal angiosperm groups, or early flowering plants, by demonstrating they are predominantly insect-pollinated. (more…)

Ancient Global Warming Changed Earth From ‘Icehouse to Greenhouse’

December 17th, 2007

GAINESVILLE, Fla. — Earth literally turned over a new leaf 15 million years ago when an earlier version of global warming changed large parts of the planet from lush forests to open grasslands, a new study by scientists at the University of Florida and other institutions shows.

In a portent of today’s global warming, fossilized leaves tell the story of a carbon dioxide induced warm-up at the end of the Miocene age that melted much of the polar icecaps and led to the spread of animals that thrive in the wide open spaces, such as horses, camels and other grazers, said David Dilcher, a UF paleobotanist and one of the study’s authors.

“Our findings clearly demonstrate that past climate changes were tied to carbon dioxide fluctuations in the atmosphere, which influenced the major vegetation patterns occurring on earth and in turn affected the evolution of major animal groups,” Dilcher said. (more…)

Older Posts
Newer Posts