Drexel News Blog It’s almost time for Tiktaalik roseae to make another appearance on television. Ted Daeschler, vice president for collections at the Academy of Natural Sciences and an associate professor in Drexel’s College of Arts and Sciences, with Tiktaalik fossils Tiktaalik is already extremely … Continue reading With “Your Inner Fish”, Tiktaalik Gets Its Close-Up—On TV, Online and in Philly
Originally posted on DrexelNow.
“As soon as those two halves came together, like puzzle pieces, you knew it,” said Ted Daeschler, PhD, associate curator of vertebrate zoology and vice president for collections at the Academy of Natural Sciences of Drexel University.
That surprising puzzle assembly occurred in the fall of 2012, when Jason Schein, assistant curator of natural history at the New Jersey State Museum, visited the Academy’s research collections to better identify and describe a recently-unearthed fossil. The discovery linked scientists from both museums to their predecessors from the 19th century, while setting the stage to advance science today.
The partial fossil bone that Schein had brought to the Academy was a recent discovery by amateur paleontologist Gregory Harpel. Harpel thought the bone seemed strange and out of place when he noticed it on a grassy embankment, a bit upstream from his usual fossil-hunting haunt at a brook in Monmouth County, N.J. Visiting the brook to search for fossil shark teeth is a weekend hobby for Harpel, an analytical chemist from Oreland, Pa. “I picked it up and thought it was a rock at first – it was heavy,” Harpel said.
When he realized it was indeed a fossil, certainly much larger and possibly a lot more scientifically significant than shark teeth, he took it to the experts at the New Jersey State Museum, to which he ultimately donated his find.
Schein and David Parris, the museum’s curator of natural history, immediately recognized the fossil as a humerus – the large upper arm bone – from a turtle, but its shaft was broken so that only the distal end, or end nearest to the elbow, remained.
Parris also thought the fossil looked extremely familiar. He joked with Schein that perhaps it was the missing half of a different large, partial turtle limb housed in the collections at the Academy of Natural Sciences of Drexel University. That bone also had a broken shaft, but only its proximal end, nearest to the shoulder, remained. The coincidence was striking.
“I didn’t think there was any chance in the world they would actually fit,” Schein said.
That’s because the Academy’s piece of the puzzle was much too old, according to the conventional wisdom of paleontology. Paleontologists expect that fossils found in exposed strata of rock will break down from exposure to the elements if they aren’t collected and preserved, at least within a few years– decades at the most. There was no reason to think a lost half of the same old bone would survive, intact and exposed, in a New Jersey streambed from at least the time of the old bone’s first scientific description in 1849, until Harpel found it in 2012.
The Academy’s older bone was also without a match of any kind, making a perfect match seem even more farfetched: It was originally named and described by famed 19th-century naturalist Louis Agassiz as the first, or type specimen, of its genus and species, Atlantochelys mortoni. In the intervening years, it remained the only known fossil specimen from that genus and species.
It remained so until that fateful day when Schein carried the “new” New Jersey fossil to the Academy in Philadelphia, connecting the two halves. The perfect fit between the fossils left little space for doubt. Stunned by the implications, Schein and Academy paleontology staffers Jason Poole and Ned Gilmore, who had assembled the puzzle together, called Daeschler into the room.
“Sure enough, you have two halves of the same bone, the same individual of this giant sea turtle,” said Daeschler. “One half was collected at least 162 years before the other half.”
Now, the scientists are revising their conventional wisdom to say that, sometimes, exposed fossils can survive longer than previously thought. They report their remarkable discovery in the forthcoming 2014 issue of the Proceedings of the Academy of Natural Sciences of Philadelphia. The find is also featured in the April 2014 issue of National Geographic magazine, on newsstands now.
“The astounding confluence of events that had to have happened for this to be true is just unbelievable, and probably completely unprecedented in paleontology,” said Schein.
The fully assembled A. mortoni humerus now gives the scientists more information about the massive sea turtle it came from as well. With a complete limb, they have calculated the animal’s overall size – about 10 feet from tip to tail, making it one of the largest sea turtles ever known. The species may have resembled modern loggerhead turtles, but was much larger than any sea turtle species alive today.
The scientists believe that the entire unbroken bone was originally embedded in sediment during the Cretaceous Period, 70 to 75 million years ago, when the turtle lived and died. Then those sediments eroded and the bone fractured millions of years later during the Pleistocene or Holocene, before the bone pieces became embedded in sediments and protected from further deterioration for perhaps a few thousand more years until their discovery.
Drexel News Blog There are fossils in New York’s Grand Central Station. It’s not a traveling museum exhibit. It’s not an exhibit at all. Hundreds of millions of years in the past, the limestone used to construct the station’s floors was formed through the accumulation … Continue reading Fossils in the Big Apple and Other Urban Paleontology Adventures
Drexel News Blog Scientists dig for fossils at Ellesmere Island in the Canadian Arctic. “Ice. Rock. Water. That’s what’s there,” Ted Daeschler said, discussing his upcoming field research expedition to Ellesmere Island in the Canadian Arctic. And that’s about all that’s there. No trees to … Continue reading How do you pack for a summer trip to the end of the Earth (for science)?
Drexel News Blog Dorsal view of the dermal armor of the newly identified fossil fish species, Phyllolepis thomsoni. Credit: Academy of Natural Sciences of Drexel University. In 370 million-year-old red sandstone deposits in a highway roadcut, scientists have discovered a new species of armored fish … Continue reading Dusting for Prints from a Fossil Fish to Understand Evolutionary Change
Originally posted on DrexelNow.
“We call it a ‘fish-eat-fish world,’ an ecosystem where you really needed to escape predation,” said Dr. Ted Daeschler, describing life in the Devonian period in what is now far-northern Canada.
This was the environment where the famous fossil fish species Tiktaalik roseae lived 375 million years ago. This lobe-finned fish, co-discovered by Daeschler, an associate professor at Drexel University in the Department of Biodiversity, Earth and Environmental Science, and associate curator and vice president of the Academy of Natural Sciences of Drexel University, and his colleagues Dr. Neil Shubin and Dr. Farish A. Jenkins, Jr., was first described in Nature in 2006.This species received scientific and popular acclaim for providing some of the clearest evidence of the evolutionary transition from lobe-finned fish to limbed animals, or tetrapods.
Daeschler and his colleagues from the Tiktaalik research, including Academy research associate Dr. Jason Downs, have now described another new lobe-finned fish species from the same time and place in the Canadian Arctic. They describe the new species, Holoptychius bergmanni, in the latest issue of the Proceedings of the Academy of Natural Sciences of Philadelphia.
“We’re fleshing out our knowledge of the community of vertebrates that lived at this important location,” said Downs, who was lead author of the paper. He said describing species from this important time and place will help the scientific community understand the transition from finned vertebrates to limbed vertebrates that occurred in this ecosystem.
“It was a tough world back there in the Devonian. There were a lot of big predatory fish with big teeth and heavy armor of interlocking scales on their bodies,” said Daeschler.
Daeschler said Holoptychius and Tiktaalik were both large predatory fishes adapted to life in stream environments. The two species may have competed with one another for similar prey, although it is possible they specialized in slightly different niches; Tiktaalik’s tetrapod-like skeletal features made it especially well suited to living in the shallowest waters.
The fossil specimens of Holoptychis bergmanni that researchers used to characterize this new species come from multiple individuals and include lower jaws with teeth, skull pieces including the skull roof and braincase, and parts of the shoulder girdles. The complete fish would have been 2 to 3 feet long when it was alive.
“The three-dimensional preservation of this material is spectacular,” Daeschler said. “For something as old as this, we’ll really be able to collect some good information about the anatomy of these animals.”
The research on Holoptychius bergmanni was led by Downs, a former post-doctoral fellow working with Daeschler who also teaches at Swarthmore College. Other co-authors of the paper with Downs and Daeschler are Dr. Neil Shubin of the University of Chicago, and the late Dr. Farish Jenkins, Jr. of Harvard University, who passed away in 2012.
Honoring a Modern Arctic Explorer and Supporter of Science
The researchers named the new fossil fish species Holoptychius bergmanni in honor of the late Martin Bergmann, former director of the Polar Continental Shelf Program (PCSP), Natural Resources Canada, the organization that provided logistical support during the team’s Arctic research expeditions spanning more than a decade. Bergmann was killed in a plane crash in 2011 shortly after the team’s most recent field season in Nunavut.
“We decided to choose Martin Bergmann to honor him, not ever having met him, but with the understanding that his work with PCSP made great strides in opening the Arctic to researchers,” said Downs. “It’s an invaluable project happening in the Canadian Arctic that’s enabling this type of work to happen.”
Bergmann’s organization assisted the research team with many aspects of expedition logistics including difficult flight operations to carry supplies and research personnel to remote research sites on Ellesemere Island. Daeschler described the pilots as capable of landing a Twin Otter aircraft almost anywhere, as long as the ground was solid – a condition they tested by briefly touching down the airplane and circling back to see if the tires left a deep mark in the mud.
Daeschler and colleagues intend to return to Ellesemere Island for another field expedition in the summer of 2013 to search for fossils in older rocks at a more northerly field site than the one where they discovered T. roseae and H. bergmanni.
A Deeper Look at the Devonian
Daeschler and a different co-author described another new species of Devonian fish in addition to H. bergmanni, in the same issue of the Proceedings of the Academy of Natural Sciences. More information about this new placoderm from Pennsylvania is available at the Drexel News Blog.
Drexel News Blog Could a pit of sand in southern New Jersey be one of the most important sites for paleontology in the world? Dr. Ken Lacovara isn’t sure about that yet, but he’s working to figure it out. Lacovara, an associate professor in the … Continue reading Moment of Impact?
Originally posted on DrexelNow.
Researchers at Drexel University are bringing the latest technological advancements in 3-D printing to the study of ancient life. Using scale models of real fossils, for the first time, they will be able to test hypotheses about how dinosaurs and other prehistoric animals moved and lived in their environments.
“Technology in paleontology hasn’t changed in about 150 years,” said Drexel paleontologist Dr. Kenneth Lacovara, an associate professor in the College of Arts and Sciences. “We use shovels and pickaxes and burlap and plaster. It hasn’t changed — until right now.”
3-D Printing Technology in Paleontology
Lacovara has begun creating 3-D scans of giant dinosaur bones and other fossils in his lab. The 3-D scan puts a virtual image in a digital workspace that researchers can manipulate and analyze. To bring these scans to life, Lacovara is also teaming up with mechanical engineer Dr. James Tangorra, an assistant professor in Drexel’s College of Engineering, to use 3-D printing technology to create and test scale models of fossil bones.
A 3-D printer is a technology for rapid prototyping and manufacturing objects based on a digital design. Common models work by repeatedly extruding extremely thin layers of a resin or other material, building up strata to create a physical object.
“It’s kind of like Star Trek technology, where you can press a button and the object pops out,” Lacovara said. A six-inch model of a dinosaur bone can be printed in a few hours using current technology.
Using 3-D printing can aid paleontology in several ways:
- To create exact-size replicas for museum display, without the limitation on the number of copies made and materials and storage hassles of traditional casting methods.
- To create small-scale models for educational use.
- To create small-scale models for modeling and testing hypotheses about the mechanics of how long-extinct animals moved and behaved.
This biologically-derived modeling to test possible movements of extinct species is the major focus of Lacovara and Tangorra’s collaboration.
Robotic Models to Test Mechanics of Dinosaur Movement
“We don’t know a lot about the way dinosaurs move,” Lacovara said. “How did they stand? How did they ambulate? Did they run or trot? How did they reproduce? It’s all a bit mysterious,” especially when it comes to the largest dinosaurs. Paleontologists’ current methods of understanding such mechanics rely heavily on guesswork and common sense about what types of movements seem possible. With new technology, researchers can begin testing their predictions for the first time.
Lacovara has been part of scientific teams unearthing some of the largest known giant sauropod dinosaur specimens, including the new species Paralititan stromeri found in Egypt in 2000, which is the second-most-massive known dinosaur species and a new giant from Patagonia. Such giant sauropod dinosaurs could reach weights of 60 to 80 tons, which is 12 to 14 times heavier than a large modern elephant.
When working with enormous dinosaur fossils, Lacovara said, it’s simply physically impossible to manipulate the bones to test theories about mechanics and movement. That’s why scaled-down replicas that preserve the exact shape and proportion of the bones can help. Researchers can also digitally reshape the models to correct for changes that may have occurred over millions of years of fossilization and compression.
Lacovara and Tangorra will work together to create robotic models of giant sauropod dinosaurs, attaching artificial muscles and tendons to perform comprehensive tests of how the animal’s body could have handled physical stresses of the environment.
This work is similar to Tangorra’s ongoing work modeling and manufacturing robotic fish. “We extract features from biological species and create software-based or robotic testing systems. It’s easier to test a biorobotic system than a biological system,” Tangorra said. This work relies on studies of the fish’s movements, biomechanics and fluid mechanics to ensure that the robot reflects the biological system. Tangorra noted that because the dinosaur species they are modeling are extinct, any robotic reconstructions will be more speculative.
Lacovara predicts that they will have a working robotic dinosaur limb constructed by the end of 2012. A complete robotic dinosaur replica will take one to two years to create.
“A Virtual Zoo of Cretaceous New Jersey”
In addition to constructing models of giant dinosaurs, the researchers will make 3-D models of some fossils found closer to home. A fossil dig site in Gloucester County, N.J., has yielded a large number of marine animal fossils from the Cretaceous period, 65 million years ago. Lacovara and his students and collaborators from other institutions continue to excavate the site. Now they will begin producing 3-D models of the turtles, crocodilians, fish and other animals found at that site, for what Lacovara called “a virtual zoo of Cretaceous New Jersey.” A sample of their first reconstruction, of an ancient New Jersey crocodile, can be seen here: http://www.drexel.edu/now/features/archive/2011/November/Evan-Boucher-Dream-Job/