Jiangshan cover news reporter Liu Kesheng
On June 26, a team of Chinese and foreign paleontologists, including Jiang Shan Associate Research Librarian, Peng Guangzhao Research Librarian, Ye Yong Research Librarian, and Associate Professor Xing Lida of China University of Geosciences (Beijing), announced that they had discovered a number of well-preserved dinosaur footprints in Zigong Fushun, Sichuan Province, including a tiny dinosaur footprint of only 10.2 mm long, which may reveal the early or very early developmental strategies of theropod dinosaurs.
It is reported that the participating units include the Zigong Dinosaur Museum, China University of Geosciences (Beijing), Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, university of Colorado, German Museum of Paleontological and Amphibians, and Charleston College. The paper was published in this issue of the journal Historical Biology.
Villagers dig ponds to store water
The "chicken claw mark" on the stepping stone was found to be a dinosaur footprint
How were the footprints of the "Sparrow Dinosaur" discovered? In July 1998, Ding Yongfu and Ding Yongjian, villagers of Wuli Village, Yongnian Town, Fushun County, decided to use the open space next to their houses to dig a pond to store water in order to solve the problem of daily washing and laundry water at home.
Because the surface of the loose pile is all hard yellow-gray sandstone underneath, so the Ding brothers will mine long strips of stone around the pond as stepping stones to facilitate everyone to walk, although people sometimes notice that some rock surfaces are covered with "chicken feet" like shapes during walking, but everyone does not think much about it.
With the continuous discovery of dinosaur footprint fossils in recent years, the continuous deepening of dinosaur footprint research and the continuous strengthening of publicity reports, more and more people have known and understood dinosaur footprint fossils, and Ding Yongfu's daughter Ding Li is one of them. In April 2017, she posted several photos of the stepping stones next to the pond in her hometown online and asked whether the "chicken feet" on the photos were dinosaur footprints, and the Zigong Dinosaur Museum immediately contacted Ding Li after learning of this news, and asked in detail about the specific location of the rocks in the photos and the people who needed to be contacted to investigate.
At the beginning of May 2017, the Zigong Dinosaur Museum first went to the field to check and confirmed that it was a dinosaur footprint. In mid-May, after consulting with the other party, the Zigong Dinosaur Museum collected these dinosaur footprint fossils back to the Zigong Dinosaur Museum for collection and protection, and carried out research.
A footprint of about 10 mm on the footprint board
Confirmed as "China's Smallest Dinosaur Footprint"
After a survey of the outcrops of the surrounding rock formations, scholars believe that the fossil production layer of the footprint is the Lower Jurassic artesian well formation. The Sichuan Basin during the Jurassic period was much larger than it is now. The north is roughly bounded by the Daba Mountains, the northwest by the Longmen Mountains, the south to the Qianzhong area, the southwest to the Central Yunnan Basin, and the southeast to the western Hubei, forming a huge inland sedimentary basin.
In the early Jurassic period, the inland terrain of the basin was relatively flat, roughly bounded by Jiangyou-Ziqi-Peng'an-Liangping, and the northern region was a humid swamp and lakeside environment, depositing a set of lakeside sandstone, river alluvial conglomerates and coal systems, while the vast southern area, including Zigong, was a drier shallow lake environment, depositing a set of thinner purple-red mudstone and fine-grained sandstone. Around these lakes and shallow lakes, there is usually a more lush vegetation, providing a good place for dinosaurs and other animals to live and a rich food source, they live and breed here, have developed rapidly, and then opened the first flourishing period in the middle of the Jurassic.
Zigong Dinosaur Museum this collection of specimens have eight footprint boards, in order to accurately outline the outline of the footprints, the research team used three-dimensional picture reconstruction, data analysis visualization, and three-dimensional point cloud processing software to produce three-dimensional pictures, in this process, a very small footprint on the Fifth Rock Slab attracted the attention of scholars.
According to reports, the No. 5 rock slab is about 0.35 square meters, with at least 44 three-toed footprints on it, and the footprint density is about 120 footprints per square meter. One of the footprints is very small, it is 10.2 mm long and 9.6 mm wide, with three distinct toes, of which the III toe is the most prominent, without a clear toe pad, and a relatively blunt paw print on each toe. This footprint is currently the smallest dinosaur footprint recorded in China.
Compared with this small footprint, the other footprints on the rock slab are larger, and the length is between 2.2 and 6.2 centimeters. Morphologically, these footprints can be classified as stilt-footed dragon footprints, the common size of the stilt-footed dragon footprints is less than 15 cm, and some very small stilt-footed dragon footprints have been found around the world before, such as the footprints of Emei Stilt-footed dragons from the Emei Cretaceous in Sichuan, which was once considered to be one of the smallest dinosaur footprints from China, of which the best preserved footprints contain claw prints of 27 mm, and the Emei footprints have also found another micro-small theropod dinosaur dragon footprint, which is typically between 15-30 mm in length. The small dragon footprint from Changsan Island in South Korea is the shortest known, with a length of only 10.5 mm. South Korea has also found a tiny two-toed footprint, one of the smallest dinosaur footprints in the world, with an average length and width of 10.3 mm and 4.2 mm, respectively.
Scholar analysis
"Footprints are left by newborn dinosaurs"
Dinosaur footprints can determine the state of the dinosaur at that time
Like the footprints of most micro-small theropod dinosaurs, it remains inconclusive whether the Fushun specimen was left by a newborn baby dinosaur or by an adult small dinosaur. A series of footprints of varying sizes but relatively uniform morphology are preserved on the slabs, possibly representing a collection of footprints of small theropod dinosaurs at different stages of development. Therefore, scholars tend that the tiny footprints of Fushun were left by small dinosaurs that had just been born, and the size of their footprint makers is estimated to be about 12 centimeters long, roughly equivalent to modern sparrows.
If the Tiny Footprints of Fushun do record the footprints left by juvenile theropods very early in life, this most likely indicates a developmental strategy of early or ultra-early growth. Early or ultra-early adulthood is one of the ancient features of the main plesiosaurs, which have appeared in some dinosaurs (e.g., diplodonts, anti-birds) and other vertebrates (e.g., pterosaurs).
Among living animals, some early or ultra-early adult animals, such as most land birds, game birds chicks, when they hatch from the egg shell, the eyes have been open, the whole body has dense villi, the legs are strong, and they can follow the parent birds to feed in a day or even a few hours.
"As a typical fossil remains, the dinosaur footprint contains a wealth of information and is a microcosm of the dynamic behavior of dinosaurs at that time. An important function of dinosaur footprint science is that it can effectively determine the composition of the local fauna at that time, and this information can largely compensate for the limitations of skeletal fossils. Scholars introduced that at the same time, according to the footprints of dinosaurs, the movement status of dinosaurs at that time can be judged, such as walking, running and even swimming.
It is reported that the footprint combination found in Zigong Fushun expanded the dinosaur fossil record of the lower Jurassic strata in the region, which is also the first record of the footprints of micro-small theropod dinosaurs in the Zigong Jurassic period, revealing the early or very early adulthood of theropod dinosaurs, and the possibility of the existence of tiny adult tracers. A large number of footprints such as the footprints of the stilted dragon indicate the high abundance of the local theropod dinosaurs at that time. These theropod dinosaurs have been confirmed to be widely distributed in the Sichuan Basin in the early Jurassic Period, and this discovery is of great significance for the restoration of the paleo-ecology, paleogeography and paleoenvironment of the region.
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