Category: Fossils & Ruins

Portable 3D laser technology preserves Texas dinosaur’s rare footprint

Post author By Margaret Allen
Post date November 2, 2009

Using portable 3D laser technology, scientists have preserved electronically a rare 110 million-year-old fossilized dinosaur footprint that was previously excavated and built into the wall of a bandstand at a Texas courthouse in the 1930s.

The laser image preserves what is called a “type specimen” footprint — an original track used many years ago to describe a new species of dinosaur, says paleontologist Thomas L. Adams at SMU.

Portable 3D laser scanners capture original fossil morphology and texture, making it possible to use the data for rapid 3D prototyping in foam or resin, Adams says.

The footprint embedded in the bandstand has been exposed to the elements for nearly 75 years, causing portions of it to erode, Adams says. Erosional loss has affected the outer edge of the toes and heel, altering the initial shape of the track impression.

The track of the ichnospecies Eubrontes glenrosensis was excavated in 1933 from a main track layer in a riverbed in what is now 1,500-acre Dinosaur Valley State Park in Somervell County near Glen Rose. Not long after the track was excavated, the citizens of Glen Rose built a stone bandstand and embedded the track within one of its walls.

The track was described in 1935 by Ellis W. Shuler, SMU’s first geology professor.

Adams says the footprint is that of a three-toed, bipedal, meat-eating dinosaur, with the most likely candidate being the theropod named Acrocanthosaurus, found mostly in Texas, North Carolina and Oklahoma.

“The track is scientifically very important,” says Adams, who is earning his doctoral degree in paleontology at SMU. “But it’s also a historical and cultural icon for Texas.”

Dinosaur Valley State Park boasts the ancient shoreline of a 113 million-year-old sea and is renowned for some of the best preserved dinosaur footprints in the world. The bandstand track is a popular draw for tourists passing through Glen Rose, which is one hour southwest of Dallas.

In an effort to preserve the specimen, as well as to compare its present state with the original description, Adams used a portable 3D laser scanner to perform in situ digitization of the track.

The scans were post-processed to generate high-resolution 3D digital models of the track. Finally the models were rendered in various media formats such as Quicktime VR Virtual Reality and Tagged Image File Format for viewing, publication and archival purposes.

Adams will make the raw scan data and industry-standard 3D object files format available for download.

The research demonstrates the advantages of using portable laser scanners to capture field data and create high-resolution, interactive models that can be digitally archived and made accessible to others via the Internet for further research and education.

“It’s a nice way to share scientific data,” Adams says.

Adams’ research was funded by the Institute for the Study of Earth and Man at SMU. He presented the research at a scientific session of the 2009 annual meeting of The Geological Society of America in Portland, Ore., Oct. 18-21. His co-researchers are Christopher Strganac, Michael J. Polcyn and Louis L. Jacobs, all three in the Roy M. Huffington Department of Earth Sciences at SMU. — Margaret Allen

Tags Dedman College, Ellis W. Shuler, Huffington Department of Earth Sciences, Michael J. Polcyn, Thomas L. Adams

Earth & Climate Fossils & Ruins Plants & Animals Researcher news

Polcyn in New Scientist’s “Real Sea Monsters: Hunt for Predator X”

Post author By Margaret Allen
Post date October 28, 2009

Paleontologist Michael J. Polcyn, director of the Visualization Laboratory in the SMU Huffington Department of Earth Sciences and SMU adjunct research associate, is quoted as an expert source in “Real Sea Monsters: The Hunt for Predator X.” The article by reporter James O’Donoghue was published in the October 2009 issue of the magazine New Scientist.

Polcyn is a world-recognized expert on the extinct marine reptile named Mosasaur.

His research interests include the early evolution of Mosasauroidea and adaptations in secondarily aquatic tetrapods. Polcyn’s research also includes application of technology to problems in paleontology.

Tags Dedman College, Huffington Department of Earth Sciences, Michael J. Polcyn

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Land snail fossils suggest eastern Canary Islands wetter, cooler 50,000 years ago

Post author By Margaret Allen
Post date October 27, 2009

Fossil land snail shells found in ancient soils on the subtropical eastern Canary Islands show that the Spanish archipelago off the northwest coast of Africa has become progressively drier over the past 50,000 years.

Isotopic measurements performed on fossil land snail shells resulted in oxygen isotope ratios that suggest the relative humidity on the islands was higher 50,000 years ago, then experienced a long-term decrease to the time of maximum global cooling and glaciation about 15,000 to 20,000 years ago, according to new research by Yurena Yanes, a post-doctoral researcher, and Crayton J. Yapp, a geochemistry professor, both in the Roy M. Huffington Department of Earth Sciences at SMU.

With subsequent post-glacial climatic fluctuations, relative humidity seems to have oscillated somewhat, but finally decreased even further to modern values.

Consequently the eastern Canary Islands experienced an overall increase in dryness during the last 50,000 years, eventually yielding the current semiarid conditions. Today the low-altitude eastern islands are characterized by low annual rainfall and a landscape of short grasses and shrubs, Yanes says.

The research advances understanding of the global paleoclimate during an important time in human evolution, when the transition from gathering and hunting to agriculture first occurred in the fertile Middle East and subsequently spread to Asia, North Africa and Europe.

“In the Canary Archipelago, land snails are one of the rare ‘continuous’ records of paleoclimatic conditions over the last 50,000 years,” Yanes says. “The results of this study are of great relevance to biologists and paleontologists investigating the evolution of plants and animals linked to climatic fluctuation in the Islands.”

The researchers’ isotopic evidence reflects changing atmospheric and oceanic circulation associated with the waxing, waning and subsequent disappearance over the past 50,000 years of vast ice sheets at mid- to high latitudes on the continents of the Northern Hemisphere.

The research also is consistent with the observed decline in diversity of the highly moisture-sensitive land snails.

Land snail shells are abundant and sensitive to environmental change and as fossils they are well-preserved. Measurement of variations in oxygen isotope ratios of fossil shells can yield information about changes in ancient climatic conditions.

The shells are composed of the elements calcium, oxygen and carbon, which are combined to form a mineral known as aragonite. Oxygen atoms in aragonite are not all exactly alike. A small proportion of those atoms is slightly heavier than the majority, and these heavier and lighter forms of oxygen are called isotopes of oxygen.

Small changes in the ratio of heavy to light isotopes can be measured with a high degree of accuracy and precision. Variations in these ratios are related to climatic variables, including relative humidity, temperature and the oxygen isotope ratios of rainwater and water vapor in the environments in which land snails live.

Yanes presented the research at a scientific session of the 2009 annual meeting of The Geological Society of America in Portland, Ore., Oct. 18-21.

The research was funded by the government of Spain’s Ministry of Science and Innovation and the National Science Foundation.

Tags Crayton Yapp, Dedman College, Huffington Department of Earth Sciences, Yurena Yanes

Earth & Climate Fossils & Ruins Researcher news

Ethiopia 27 million years ago had higher rainfall, warmer soil

Post author By Margaret Allen
Post date October 22, 2009

Thirty million years ago, before Ethiopia’s mountainous highlands split and the Great Rift Valley formed, the tropical zone had warmer soil temperatures, higher rainfall and different atmospheric circulation patterns than it does today, according to new research of fossil soils found in the central African nation.

Neil J. Tabor, associate professor of Earth Sciences at SMU and an expert in sedimentology and isotope geochemistry, calculated past climate using oxygen and hydrogen isotopes in minerals from fossil soils discovered in the highlands of northwest Ethiopia. The highlands represent the bulk of the mountains on the African continent.

Tabor’s research supplies a picture of the paleo landscape of Ethiopia that wasn’t previously known because the fossil record for the tropics has not been well established. The fossils were discovered in the grass-covered agricultural region known as Chilga, which was a forest in prehistoric times. Tabor’s research looked at soil fossils dating from 26.7 million to 32 million years ago.

Fossil plants and vertebrates in the Chilga Beds date from 26.7 million to 28.1 million years ago, Tabor says. From his examination, Tabor determined there was a lower and older layer of coal and underclay that was a poorly drained, swampy landscape dissected by well-drained Oxisol-forming uplands. A younger upper layer of the Chilga Beds consists of mudstones and sandstones in what was an open landscape dominated by braided, meandering fluvial stream systems.

Tabor is part of a multi-disciplinary team combining independent lines of evidence from various fossil and geochemical sources to reconstruct the prehistoric climate, landscape and ecosystems of Ethiopia, as well as Africa.

The project is funded with a three-year, $322,000 grant from the National Science Foundation. The team includes paleoanthropologists, paleobotanists and vertebrate paleontologists from the University of Texas at Austin, Miami University, Southern Methodist University, the Fort Worth Museum of Science and History, Washington University and the University of Michigan.

Tabor presented the research in a topical session at the Oct. 18-21 annual meeting of the Geological Society of America. The presentation was titled “Paleoenvironments of Upper Oligocene Strata, NW Ethiopian Plateau.” His co-researcher is John W. Kappelman, Department of Anthropology, University of Texas. — Margaret Allen

Tags Dedman College, Huffington Department of Earth Sciences, Neil Tabor

Earth & Climate Fossils & Ruins Plants & Animals Researcher news

Ethiopian fossils define prehistoric ecosystems, human evolution, climate change

Post author By Margaret Allen
Post date October 5, 2009

Leaf3%2Clr.jpg For paleobotanist Bonnie Jacobs standing atop a mountain in the highlands of northwest Ethiopia, it’s as if she can see forever — or at least as far back as 30 million years ago.

Jacobs is part of an international team of researchers hunting scientific clues to Africa’s prehistoric ecosystems.

The researchers are among the first to combine independent lines of evidence from various fossil and geochemical sources to reconstruct the prehistoric climate, landscape and ecosystems of Ethiopia in particular, and tropical Africa in general for the time interval from 65 million years ago — when dinosaurs went extinct, to about 8 million years ago — when apes split from humans.

Paleobotanist Bonnie Jacobs in Ethiopia.

While it’s generally held that human life began in Africa, ironically there is little known about changes in the continent’s vegetation during the time when humans were evolving.

The team’s work also will help climate scientists trying to model future global warming by providing data from the tropics that up to now did not exist.

The multi-disciplinary team is studying fossils they’ve found near Chilga, a small region in the agricultural highlands.

Contrary to the common notion that vegetation decomposes in the tropics too quickly to supply evidence, sediments there have preserved an abundant variety of 28 million-year-old fossils. These include fruits, seeds, leaves, woods, pollen and spores, says Jacobs, an associate professor of Earth Sciences at Southern Methodist University and director of the Environmental Science and Studies Programs.

“There are lifetimes of work to be done in Africa on plant fossils alone, and certainly a lot more to be done with vertebrates as well,” says Jacobs, who’s done research in Africa since 1980 in Kenya, Tanzania and Ethiopia. “There’s not a well established record of plant fossils, so there’s no real context. It’s all new — so whatever you find is interesting.”

With the permission of the Ethiopian government, Jacobs — along with Ellen Currano, in the Department of Geology at Miami University, and paleobotanist Aaron Pan, curator of science at the Fort Worth Museum of Science and History — is now studying more than 1,600 fossil leaves the team gathered from two age-equivalent sites to understand climate, precipitation, vegetation and the physical landscape.

Jacobs is calculating precipitation and temperature estimates for the two Ethiopian sites using leaf traits for size and shape. While the rainfall estimates are statistically identical, the temperature estimates are not, an informative reflection of the method itself.

Pan has identified palm fossils, which help to address a big question about the timeframe for a decline in the presence of palm trees in Africa. He’s also calculating past climate using species composition of fossil leaves, fruit and flowers.

Morediggers%2Clr.jpg Currano is looking at insect damage on fossil leaves, to see if the insect fauna is as diverse and as specialized as expected for tropical forests. Neil Tabor, associate professor of Earth Sciences at SMU and an expert in sedimentology and isotope geochemistry, is calculating past climate using oxygen isotopes in minerals from fossil soils.

“We’re using multiple independent lines of evidence to get at climate reconstruction during this time interval for a place — the tropics of Africa — for which there were few data before,” Jacobs says. “The lower latitudes are especially poorly documented for fossils, which tell us about climate, so the tropical regions of Earth are poorly documented for past climate as well.”

The project is funded with a three-year, $322,000 grant from the National Science Foundation. Paleoanthropologists and vertebrate paleontologists from UT Austin, Washington University and the University of Michigan have studied the fossil bones that co-occur with the plants.

Questions they will address:

When and how did Africa’s rain forests evolve into the present day savannas and how did that impact human evolution?
What happened to the prehistoric lowland forest that’s been hypothesized across Africa in the tropical belt?
When did the Great Rift Valley’s formation divide the forest into eastern and western components, and how did the process evolve?
Why is there evidence of a large diversity of palm trees at 33 million years ago in Africa, but certain species are missing by 28 million years ago?
Why were palm trees abundant and diverse 100 million years ago in Africa and South America, but now rare in present-day Africa, while still prolific in the tropical forests of Southeast Asia, South America and Madagascar?

SMU graduate student Daniel Danehy.

Jacobs will present her research in October at a seminar on “Cenozoic Evolution of African Landscapes” at Penn State. She and other members of the team will also report on the Ethiopian fossils in a Geological Society of America Topical Session called “Phanerozoic Paleoenvironmental Evolution of Africa,” which they’ve organized for the annual meeting from Oct. 18-21.

Jacobs’ research today expands on earlier work. She reported with her collaborators at the 2008 “Celebrating the International Year of Planet Earth” meeting of the Geological Society of America that palm trees were significant in Africa 28 million years ago

In a 2006 study that published in the “Botanical Journal of the Linnean Society,” Jacobs and lead author Pan reported that Chilga fossil leaves represent the earliest records of Africa’s characteristic palm genus “Hyphaene.”

The leaf fossils that Jacobs, Currano, and Pan are cataloging will be permanently housed in a new building now under construction at the National Museum of Ethiopia in Addis Ababa.

With a $21,600 supplemental grant from the National Science Foundation, cabinets for storing the plant and vertebrate fossils have been made in Ethiopia and Jacobs, Currano and Pan will return later this year to curate the collections. — Margaret Allen

Tags Bonnie F. Jacobs, Dedman College, Ellen Currano, Huffington Department of Earth Sciences, Neil Tabor

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