The Dinosaur Institute's 2008 field season began in April with a weeklong trip to the Mojave Desert (Matt Dinosaur Expedition) in southeastern California to collect diverse 170-million-year-old trackways contained in the Jurassic Aztec Sandstone. The crew included staff, students, and volunteers of the Dinosaur Institute as well staff from the San Bernardino County Museum. This expedition was very successful, resulting in the collection of trackways from theropod dinosaurs as well as other animals that lived with them.
The next excursion (Thornbury Dinosaur Expedition) revisited the area of San Juan County, Utah that was prospected in the summer of 2007. From mid May to mid June an international team including Dinosaur Institute personnel, members of the NHMLA's education department, and a colleague from the University of Copenhagen in Denmark surveyed the Late Jurassic exposures (150 million year old) of the Morrison Formation. Most of the work focused on collecting the large bones of a sauropod, but the team also discovered and collected a large quantity of dinosaur footprints contained in the approximately 100-million-year-old Cedar Mountain Formation. These fossils included the prints of sauropods, theropods, ornithopods, and stegosaurs. The team also collected a humerus of a brachiosaur that was larger than several members of the excavation team!
The summer season closed with an expedition (Holland Dinosaur Expedition) to the late Cretaceous of Carter County, southwestern Montana. The team surveyed 75-million-year-old rocks deposited in a shallow sea that flooded this portion of the world at that time and collected fossils of ancient seabirds and another marine animals. Additionally, the team collected fossils of small vertebrates from the somewhat younger, Latest Cretaceous, Hell Creek Formation, also within Carter County. On their way back to Los Angeles the expedition members collected footprints of flying reptiles (pterosaurs) from Late Jurassic rock exposures of the Sundance Formation near Casper, central Wyoming.
Overall this field season was a huge success! The fossils discovered are great additions to our growing collection, and some of them may go on display in our upcoming new dinosaur galleries. We are very excited to continue these field projects next year!
The newly discovered primitive bird Zhongornis haoae, from the early Cretaceous of China, was collected from rocks dating to approximately 125 million years old. As the most primitive short tailed bird known to date, Zhongornis helps to clarify the evolutionary transition between more primitive long tailed birds and short tailed birds like those living today.
Short tailed and long tailed birds have distinct anatomical, skeletal differences, such as the number of tail vertebrae and other specific skeletal structures. Long tailed birds have a greater number of tail vertebrae than short tailed birds, and short tailed birds have a bony structure of fused tail vertebrae called a “pygostyle” which is lacking in long tailed birds.
Zhongornis is the first bird discovered that has a short tail and a corresponding reduced number of tail vertebrae, yet lacks the pygostyle that is present in all other short tailed birds. Therefore, Zhongornis represents an evolutionary stage between the primitive long tailed birds and the short tailed, “pygostylian” birds. Additionally, Zhongornis suggests that a short tail with a reduced number of vertebrae evolved earlier in birds than did the pygostyle.
A paper published in the British Jjournal Palaeontology (Vol. 51, Part 4, pp. 775-791) details the research on Zhongornis. This investigation was part of the ongoing collaborative research project between the Dinosaur Institute and the Dalian Natural History Museum in China. It was supported by the National Science Foundation and individuals such as Carl and Lynn Cooper, Ron and Judy Perlstein, and Richard and Eileen Garson.
The new Center for Chinese Fossil Discoveries is a joint initiative between the University of Southern California (USC) and The Natural History Museum of Los Angeles County (NHMLA). This center will share resources and develop joint projects related to Chinese paleontology under the leadership of Dr. David Bottjer, Chair of the Department of Earth Sciences at USC, and Dr. Luis Chiappe, Director of the Dinosaur Institute (NHMLA).
Over the past decade China has been found to have extensive and exquisite fossil deposits that have the possibility of providing answers to many of the most important questions on evolution and the history of life. These Chinese fossils have been so spectacular that collaborative research on them has resulted in many publications in the journals Science and Nature, the most prestigious outlets for scientific publishing, and attracted media attention worldwide. The Chinese government has recognized that investments in fossil research bring scientific results acclaimed at the international level, so there has been a significant amount of funding in China directed towards paleobiological research and education. Both Dr. Bottjer and Dr. Chiappe have conducted years of research in China and have established collaborative projects with some of the most prestigious research and education centers in China. As part of its educational mission the Center will sponsor symposia and speaker series open to the public that will foster an awareness of spectacular Chinese fossils and their importance for answering fundamental biological problems. The Center will also sponsor and promote exhibits at the NHMLAC and maintain a webpage of research, educational programs, and discoveries, which will expose large portions of the public to science, paleobiology, and the magnificent fossil treasures of China.
Pterosaurs were a diverse group of flying reptiles that lived during the Mesozoic, when large terrestrial dinosaurs roamed. Like the large dinosaurs they also became extinct at the end of the Cretaceous. The fossil record yields a large number of different species of pterosaurs, yet many questions remain unanswered about their biology such as: How long did it take for a hatchling to grow to adult size? What kind of growth patterns did they have? Answers to some of these questions have been addressed for the bizarre filter feeding pterosaur - Pterodaustro - that lived about 100 million years ago in what is now Argentina. Dr Luis Chiappe, director of the Dinosaur Institute, led many of the expeditions to collect these creatures as well as contributing significantly to this current research.
This unusual pterosaur is represented by hundreds of individuals - from an embryo within its egg to tiny hatchlings with wing spans of only about 30cm to adults with wingspans of up to 2.5m. This incredible range of different-sized individuals has provided the unique opportunity for an international team of scientists to study its growth and development. The microscopic structure of Pterodaustro’s bones showed that juveniles grew rapidly for about 2 years until they reached approximately 53% of their adult body size. They appear to have attained sexual maturity at this stage, but continued to grow for at least another 3-4 years at comparatively slower rates until larger adult body sizes were attained. The histological analysis provides further definitive evidence that Pterodaustro had a determinate growth strategy i.e. like mammals and birds; they stopped growing at a certain size, unlike modern reptiles that typically grow for as long as they live.
Chinsamy A., Codorniú L., and Chiappe L.M. (2008). Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guiñazui. Royal Society's Biology letters.
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