CHICAGO - Two fossils of a newly discovered dinosaur - an early, distant cousin of the Triceratops - have been discovered in China, according to research that will be published in Nature March, 21, 2002.
But rather than weighing ten tons and being studded with massive horns and a wide frill, like its well-known cousin, the new dinosaur weighed only about seven pounds and shows signs of only rudimentary horns and a frill. About the size of a hare, Liaoceratops yanzigouensis is the smallest, oldest and most primitive neoceratops ever found.
"This small, primitive dinosaur is actually more interesting to science in many ways than its larger, more famous relatives because it teaches us more about evolution," says Peter Makovicky, PhD, assistant curator of dinosaurs at The Field Museum and co-author of the research. "Basal [primitive] dinosaurs are critical because they help us to tie different groups of dinosaurs together and map out evolutionary patterns."
Long ago, ceratopsians branched into two lines: neoceratopsians, the main line that includes Triceratops, and psittacosaurids, parrot-beaked dinosaurs.
"Liaoceratops establishes that this split occurred no later than the earliest part of the Cretaceous Period about 130 million years ago," Dr. Makovicky says. "Also, it indicates that ceratopsians acquired some of their distinctive features earlier and more rapidly than was previously recognized.
"In addition, Liaoceratops demonstrates that the large, spectacular species that grace many museum exhibits are descended from some very small ancestors," he adds. "We see this common pattern in many different groups of dinosaurs. "
The Nature paper will describe two fossils: a juvenile specimen and a holotype - the single specimen designated by the authors as the definitive example of this new species. The adult skull is 4.4 inches long (11.1 centimeters), and an adult Liaoceratops (lee-ow-cer-a-tops) stood about one foot tall and measured less than about three feet long.
What was the purpose of horns and frill?
Scientists have long debated whether the ceratopsians' horns and frill were structures for supporting large jaw muscles or display features for attracting mates and/or intimidating rivals and predators. Perhaps both theories are correct.
Liaoceratops has a small horn facing sideways under each of its eyes that seem to be display structures, according to Dr. Makovicky. The frill, which gets very large in advanced ceratopsians, is often considered a display structure. But there is evidence that powerful muscles were attached to the short frill in Liaoceratops.
"Pitted surface texture on the rim of the frill clearly indicates that the jaw muscles passed behind the cheek and were attached to the frill," he says. "Although short, the frill is thick to counteract the contraction of these large muscles." There appears to be little evidence that ceratopsians' horns evolved for defensive purposes, according to Dr. Makovicky. "Liaoceratops appears unable to protect itself against most predators, which would have included carnivorous dinosaurs and crocodiles. Instead, it probably relied on concealment or flight to defend itself."
Liaoceratops ate plants, possibly ginkgo, horsetails or conifers. Evidence of these plants is preserved in the same rock unit in which the dinosaur was found. Its teeth were built primarily for slicing and shearing rather than grinding. "Liaoceratops gives us a great window on the early evolution of horned dinosaurs and tells us that Triceratops and its relatives evolved from very small Asian ceratopsians," Dr. Makovicky concludes.
China site rich in fossils
The name of the new dinosaur refers to the province and village in China (Liaoning and Yanzigou, respectively) where the fossils were collected. Recently, scientists have discovered many groundbreaking fossils in western Liaoning, including feathered dinosaurs and Sinovenator changii, a dinosaur that is closely related to and almost the same age as Archaeopteryx, the oldest known bird.
The Field Museum, National Geographic Society, American Museum of Natural History, and the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences supported this research.
Looking ahead, Dr. Makovicky plans to conduct collaborative fieldwork in China to look for more fossils. "This area is yielding extremely important information on the evolution of dinosaurs, mammals, insects and flowering plants," he says. "I hope to find even more primitive specimens than Liaoceratops."
NOTE: Renowned dinosaur illustrator Michael Skrepnick has rendered a lifelike color image of the dinosaur, which can be downloaded from EurekAlert at http://www.eurekalert.org, March 18 to March 29. The jpg image will also be available from The Field Museum at http://www.fmnh.org/museum_info/press_room.htm, March 20 (after the embargo lifts) to March 29. Two resolutions are available: 200 dpi and 300 dpi, both at about 8x10 inches.
Journal
Nature