A tooth challenges beliefs about how ancient reptiles lived
At the beginning of the age of dinosaurs, gigantic reptiles—distant relatives of modern crocodiles—ruled the earth. Some lived on land and others in water and it was thought they didn't much interact. But a tooth found by a University of Tennessee, Knoxville, researcher in the thigh of one of these ancient animals is challenging this belief.
This image shows teeth from phytosaurs, a reptile from the Triassic Period, that lived about 210 million years ago in the western United States, in the hand of Virginia Tech research scientist Michelle Stocker. The gray tooth was 3-D printed from CT scans after being digitally extracted from the thigh bone of a large predatory reptile called a rauisuchid.
Credit: Michelle Stocker
Stephanie Drumheller, an earth and planetary sciences lecturer, and her Virginia Tech colleagues Michelle Stocker and Sterling Nesbitt examined 220-million-year-old bite marks in the thigh bones of an old reptile and found evidence that two predators at the top of their respective food chains interacted—with the smaller potentially having eaten the larger animal.
The evidence? A tooth of a semi-aquatic phytosaur lodged in the thigh bone of a terrestrial rauisuchid. The tooth lay broken off and buried about two inches deep in bone and then healed over, indicating that the rauisuchid, a creature about 25 feet long and 4 feet high at the hip, survived the initial attack.
"To find a phytosaur tooth in the bone of a rauisuchid is very surprising. These rauisuchids were the largest predators in their environments. You might expect them to be the top predators as well, but here we have evidence of phytosaurs, who were smaller, semi-aquatic animals, potentially targeting and eating these big carnivores," said Drumheller.
To study the tooth without destroying the bone, the team partnered computed tomographic (CT) data with a 3D printer and printed copies of the tooth. This, along with an examination of the bite marks, revealed a story of multiple struggles. The team found tissue surrounding bite marks illustrating that the rauisuchid was attacked twice and survived. Evidence of crushing, impact and flesh-stripping but no healing showed the team that the animal later died in another attack.
The tooth that was left behind revealed who was guilty of the attacks.
"Finding teeth embedded directly in fossil bone is very, very rare," said Drumheller of the bone obtained from the University of California Museum of Paleontology in Berkeley. "This is the first time it's been identified among phytosaurs, and it gives us a smoking gun for interpreting this set of bite marks."
The findings also suggest previous distinctions between water- and land-based food chains of this time, the Late Triassic Period, might be built upon mistaken assumptions made from fossil remains.
"This research will call for us to go back and look at some of the assumptions we've had in regard to the Late Triassic ecosystems," Stocker said. "The aquatic and terrestrial distinctions made were oversimplified, and I think we've made a case that the two spheres were intimately connected."
The research also calls into question the importance of size in a fight.
"Both of the femora we examined came from some of the physically largest carnivorous species present at both locations. Yet they were targeted by other members of the region—specifically phytosaurs," said Drumheller. "Thus, size cannot be the only factor in determining who is at the top of the food chain."
The research is published online in the German scientific journal Naturwissenschaften, The Science of Nature.
Whitney Heins | Eurek Alert!
The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University
Earth's magnetic field measured using artificial stars at 90 kilometers altitude
14.11.2018 | Johannes Gutenberg-Universität Mainz
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly
The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
15.11.2018 | Life Sciences
15.11.2018 | Materials Sciences
14.11.2018 | Materials Sciences