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Is It A Damper inside the Dinosaur Tooth?

Thursday, November 5, 2015

Elsa Ming-tzu Shih | User Administration & Promotion Office, National Synchrotron Radiation Research Center | | +886-3-5780281 ext. 8207

Do you know how a carnivorous dinosaur could snap at an elephant of 6000 kilograms without breaking its teeth first? An international research team of Chun-Chieh Wang (NSRRC), Yen-Fang Song (NSRRC), Cheng-Cheng Chiang (NSRRC), Sheng-Rong Song (National Taiwan University), Qiang Ji (Chinese Academy of Geological Sciences, China), Robert Reisz (Toronto University, Canada) and Timothy D. Huang (National Chung Hsing University) discovered that the unique internal structure of mantle dentin between the enamel and dentine of the carnivorous dinosaur functions like a damper. This tender layer could protect the teeth from fracture when tearing large animals with teeth. The research results have overthrown the conventional perceptions of the organization of a dinosaur tooth and were published in the latest issue of the prestigious journal Scientific Reports.

Dinosaur tooth fossils and crocodile teeth.

Resources from prestigious museums and a Taiwan night market

In the beginning of the research, 15 types of teeth samples were collected, including the ones from Tyrannosaurus, Tarbosaurus, Carcharatodonsaurus, Spinosaurus and Dilophosaurus. Most of the teeth samples were provided by National Taiwan Museum, Paleowonders Mineral and Fossil Museum, Beijing Museum of Natural History (China), Royal Ontario Museum (Canada) and Chinese Academy of Geological Sciences (China). In particular, the tooth of a Caiman crocodilus is offered by a night market vendor in Taiwan. “They said that a vendor is cooking crocodile meat at Sing Ren Garden Night Market in Taoyuan, so I drove there to have a look,” Wang said, “When I tried to pull out a tooth from the crocodile’s mouth, the cutting plier I used crashed. This tooth is exceptionally tough. I must find a tougher pincer plier to try again. It took me a while to get this tooth.”

Tyrannosaurus VS crocodile, which could win?

The research team discovered that the unique porous structure of mantle dentin between the enamel and dentine of the carnivorous dinosaur functions like a damper. The tender layer could protect the teeth from fracturing all of a sudden. Inherent with the deadly weapon in the mouth, Tyrannosaurus was able to prevail as the top predator for 165 million years. The team also noticed that such structure has vanished in the herbivorous dinosaurs during evolution. However, it has been kept in the crocodile lineage so far.

The crocodile meat stall at the night market. Right: The crashed cutting plier that Wang used to pull the crocodile’s tooth out.

“Tyrannosaurus had a maximum bite force of 6000 kilograms, which is equal to the weight of the African elephant, the largest mammals on land. This amazing but tiny shock absorber structure helps to bear such heavy weight. Compared with contemporary animals, the bite force is 2000 kilograms for saltwater crocodiles, 1000 kilograms for spectacled caimans, and only 40 kilograms for human beings,” Wang pointed out.

TXM at the NSRRC sees through the world 65 million years ago

A few months ago, researchers have proved the saw-like structure of carnivorous dinosaur teeth inherent using infrared microscopy. This time, researchers have discovered the exceptional mantle dentin in carnivorous dinosaur teeth using Transmission X-ray Microscopy (TXM) at the NSRRC.

“Synchrotron-based TXM reveals the internal structure of samples with highly transmitting hard X-ray, and it could construct 3D structures,” Yen-Fang Song explained, “It functions like CT scans for diagnostic medical use, but the resolution of TXM images is 2000 times higher than traditional CT scans.”

Sheng-Rong Song commented that this synchrotron-based analytic technique of high resolution could help us see through the subtle differences in ancient fossil structures. This will revolutionize the methods of categorizing the prehistoric creatures.

Other than examining the ancient fossils, synchrotron-based TXM can also be used to study material at the nanoscale and develop efficient and effective Lithium-ion battery.

The NSRRC is a non-profit and research institute, funded by the Ministry of Science and Technology (MOST) in Taiwan, to provide two synchrotron light sources (1st: 1.5 GeV - Taiwan Light Source (TLS) and 2nd: 3 GeV – Taiwan Photon Source (TPS) ) for researchers in Taiwan and overseas to conduct frontier scientific experiments. The TLS consists of 25 beamlines and over 50 experimental stations. The TPS will accommodate ~40 beamlines (partly available for sponsor, co-sponsor, or customization per request). Currently, the NSRRC has over 2000 users annually, the largest number of users among all large scaled scientific research facilities administrated under the MOST in Taiwan.