Category: Plants & Animals

World’s first full skeletal mount of Paluxysaurus jonesi dinosaur reveals new biology

Post author By Margaret Allen
Post date December 10, 2009

The Early Cretaceous sauropod Paluxysaurus jonesi weighed 20 tons, was 60 feet long and had a neck 26 feet long, according to the scientists who have prepared the world’s first full skeletal mount of the dinosaur.

The massive Paluxysaurus jonesi, prepared for the Fort Worth Museum of Science and History in Fort Worth, was unveiled Nov. 20 when the museum opened in a new $80 million facility. The Paluxysaurus mount enables Texans to see their state dinosaur in three dimensions for the first time.

The reconstructed skeleton is yielding clues to the biology of the animal and its relationship to other similar dinosaurs, says Dale Winkler, lead consultant for anatomy and posture on the skeletal mount.

Winkler is director of the Shuler Museum of Paleontology at SMU and a research professor in the Roy M. Huffington Department of Earth Sciences. Winkler has worked with Paluxysaurus bones since crews from SMU and the Fort Worth museum began to unearth them in the early 1990s.

In preparing the mount, Winkler said he was surprised at how extremely long the neck was — at 26 feet — compared to the tail, and he found the head especially striking.

“It was really exciting to see what the head looked like,” Winkler says. “Paluxysaurus had very high cheeks compared to its relatives. Once the bones defining the opening of the nose were connected, it showed that the nostrils were turned up on top of the snout, instead of out like Brachiosaurus.”

Skeletal mount reveals animal’s anatomy, size and stature
A relative of Brachiosaurus and Camarasaurus, Paluxysaurus lived about 110 million to 115 million years ago. The dinosaur was identified and named in 2007 by Peter J. Rose. The Fort Worth skeleton was assembled from a combination of actual fossil bones from at least four different dinosaurs found on private ranch land in North Central Texas and from cast lightweight foam pieces modeled on original bones. The mount enables scientists to better understand the animal’s anatomy, size and stature on questions like “How were the legs situated, and how did the shoulders relate to the hips?”

From the skeletal mount, the scientists learned that Paluxysaurus was more than 6 feet wide and nearly 12 feet tall at the shoulder, although built fairly light, Winkler says. Its teeth are a lot slimmer than those of its closest relatives, indicating Paluxysaurus gathered and processed food differently, using its teeth not for chewing, but to grab food, he says.

Paluxysaurus had a long neck like Brachiosaurus, and a tail almost as long, but wasn’t quite so gigantic. Scientists also learned Paluxysaurus had relatively long front arms, unlike Diplodocus, making its back more level. The dinosaur’s shoulder turned out fairly high, and the hips were wide, Winkler says, and it had reached a more advanced stage of evolution than Late Jurassic sauropods.

Paluxysaurus’ massive pelvis and its sacrum have never before been viewed by the public, he says. Its ilium, the largest bone in the pelvis, is similar to that of titanosaurids of the Late Cretaceous, mainly found in South America. However, one titanosaurid, called Alamosaurus, entered North America and is known from Big Bend National Park in southwest Texas.

The bones assembled for Fort Worth’s Paluxysaurus mount were recovered by students, faculty, staff and hundreds of volunteers over the past 16 years.

DFW’s ancient Cretaceous past included dinosaurs along a shallow sea
Most bones were found in masses of hardened sandstone dug from a Hood County quarry on the private ranch of Bill and Decie Jones.

It took more than a decade to remove the specimens because they were embedded in a hard sandstone matrix, said Louis L. Jacobs, a world-renowned paleontologist, dinosaur fossil hunter and a professor in the Earth Sciences department at SMU. Jacobs helped unearth and prepare the bones.

The end result is a skeleton that is “absolutely awe-inspiring,” Jacobs says. “Paluxysaurus and the plants and animals it lived among show us the truly unique position Texas held in the Cretaceous world. The exhibits at the Fort Worth museum tell that story to the people who now live where the giants used to walk.”

Sauropods weren’t common during the Early Cretaceous. The Fort Worth specimen is morphologically distinct from all other sauropods described and named in North America at that time, according to the research of Rose, who is now a doctoral student at the University of Minnesota. Rose identified the type specimen and named the animal while a graduate student in geology at SMU.

The Paluxysaurus dinosaurs lived near the shore of the rising Cretaceous seas that eventually covered Texas, amid large-trunked conifer trees that are now extinct. The semi-arid environment nurtured relatives of sago palms but few flowering plants, which were just beginning to spread out across the Earth, Winkler says.

The scientists say the Jones Ranch bone bed is one of the richest accumulations of sauropod bones in North America.

A group apparently died together there in a common death, perhaps a forest fire, according to earlier research of Winkler and Rose.

The quarry has produced hundreds of bones, all within an area of 400 square meters. Fossil hunters found 60 to 70 percent of the bones needed to reconstruct a single Paluxysaurus skeleton, says Aaron Pan, curator of the Fort Worth museum. Most of the bones, however, are too fragile or deformed to be mounted 15 feet in the air, Pan says.

“We were happy to have as much of it as we do,” Pan says, noting that the museum welcomes fossil researchers. “Most of our material is available. So if a researcher did want to see any of it, we’d be happy to have them come.”

Huge, multi-year project recreated skeleton with bones and casts
Paleontologists from both the museum and SMU helped exhibit fabricator and model-maker Robert Reid Studios, located near Fort Worth, mount the bones. About 15 percent to 20 percent of the skeleton is actual fossil bone, while the remaining bones are casts, says Pan.

Preparing the fossils for mounting and modeling was a huge, multi-year project. The cast bones were computer modeled using laser scanning, says Michael J. Polcyn, director of the Earth Sciences department’s image analysis lab at SMU.

“I was able to scan available bones in 3D and manipulate them in the computer to remove distortion, create mirrored pieces — for example right or left — and model missing portions,” Polcyn says. “I was then able to use the computer models to produce life-sized physical models of the bones using computer-controlled machining techniques.”

Many of the very large bones remain all or partially embedded in blocks of quarry rock, due primarily to the logistical challenge of removing them. For example, the 11-ton block containing the pelvis and sacrum required hoisting with an industrial crane. For some large blocks, tons of rock were painstakingly cut with diamond-blade saws from around the various bones to make them manageable in the SMU labs, Winkler says.

Rock was partially removed from the pelvis and sacrum so that Polcyn could scan them. The scientists then constructed a model using dense foam that was cut to form the basic shape. Crews from Robert Reid Studios coated them with epoxy resin to give them hardness, then added a layer of bone texture and painted them to match.

In the case of the long neck, much was preserved, but many of the bones were distorted by sediment load, which essentially crushed the bone, Polcyn says. He studied the neck vertebrae and made a model. Only two of the skull bones were recovered: the left maxilla and a nasal bone, which defined the top front of the face. Polcyn worked closely with a sculptor to reconstruct the skull by studying related groups of dinosaurs.

Preparation of the skeletal mount was funded by the Fort Worth Museum of Science and History. — Margaret Allen

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Tags Aaron Pan, Dale Winkler, Dedman College, Huffington Department of Earth Sciences, Louis L. Jacobs, Michael J. Polcyn, Paluxysaurus jonesi, Peter J. Rose

Fossils & Ruins Plants & Animals Slideshows Student researchers

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

Earth & Climate Fossils & Ruins Plants & Animals Slideshows Student researchers

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 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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