Scientists Reveal "Guangzhou is a City on the Back of Dinosaurs", First Discovery of Crocodile Egg Fossil Dinosaurs in China | Guangzhou | Scientists
On the evening of July 1st, researchers and visiting researchers from Guangzhou Zhengjia Natural Science Museum, as well as Xing Lida's research team from China University of Geosciences, announced at the museum that dinosaur egg fossils discovered in Guangzhou indicate that dinosaurs were active in the late Cretaceous period, approximately 90 to 70 million years ago, and Guangzhou is a city on the back of dinosaurs.
A middle school student discovers fragments of dinosaur eggshell fossils
Dinosaur egg fossils are important materials for studying dinosaur reproduction. In 1923, a research team from the American Museum of Natural History discovered dinosaur eggs for the first time on the Mongolian Plateau, and since then, there have been reports of dinosaur eggs around the world. Guangdong Province in China is one of the provinces that produces the most dinosaur egg fossils, with fossils mostly concentrated in the Heyuan and Nanxiong regions. In 1976 and 1998, dinosaur egg fossils were discovered in both Baihe Cave and Zhongshan Wulu in Guangzhou, but detailed research has not yet been conducted. Between 2020 and 2021, fossil enthusiast and high school student Ni Zijie discovered a batch of dinosaur eggshell fossil fragments at several construction sites in Guangzhou. These fossils were subsequently donated to the Guangzhou Zhengjia Natural Science Museum and handed over to the Xing Lida research group of China University of Geosciences for systematic research.
A total of 6 fragments of eggshell fossils were discovered this time. Among them, specimens 468 and 469 were discovered in June 2020 at Guangzhou South Station in Panyu District; Specimens 470 and 471 were discovered at the construction site of the Financial City in Tianhe District in March 2021; Specimens 472 and 473 were discovered on Xique Road in Liwan District in February 2020. Through stratigraphic comparison, the fossil sites in the Financial City of Tianhe District belong to the Upper Cretaceous Dalangshan Formation, while other fossil sites belong to the Upper Cretaceous Sanshui Formation. The Dalangshan Formation is later in age than the Sanshui Formation.
The classification of dinosaur eggs used to be a difficult problem, and scientists hoped to correspond dinosaur eggs to specific dinosaur genera that laid eggs, but this could only be determined by specimens preserved with both eggs and bones. In 1975, Chinese paleontologist Mr. Zhao Zikui proposed a classification scheme based on the characteristics of eggs themselves, established a classification system for dinosaur eggs, and applied it.
Researchers take a small portion of each eggshell and use professional machines to cut and grind them. They observe their structure under different resolution microscopes and classify them. By observing and comparing the microstructure of eggshells, scholars have classified 468 as the genus Prismatic Eggs in the family Prismatic Eggs, and 469, 471, 472, and 473 as the genus Giant Eggs in the family Long Eggs. The prismatic egg family is generally believed to be produced by the Theropoda. Scientists speculate that the discovered prismatic egg has a complete length of about five to six centimeters. The elongated egg family is generally believed to be produced by egg stealing dinosaurs. Scientists speculate that the discovered prismatic eggs have a complete length of about 16 to 21 centimeters, with a nest of more than ten or more.
Restoration of Egg Stealing Dragons
Restoration image of the injured toothed dragon
Giant Egg Skin and Microscopic Structure
First discovery of crocodile egg fossils in China
The main author of the paper, Guo Zisheng, pointed out that what is exciting is that the microstructure of 470 is different from any type of dinosaur egg, and consistent with the microstructure of crocodile egg fossils. In particular, the eggshell of 470 has wedge-shaped shell units, with gaps between shell units, which is different from most dinosaur egg shells, which generally have two layers, and the conical layer at the bottom is obvious. So researchers classified it as a crocodile egg fossil. Scientists speculate that the complete length of the crocodile egg discovered this time is about six or seven centimeters. This is the first discovery of crocodile egg fossils in China. Previously discovered crocodile egg fossils were mainly distributed in Europe, South America, and North America, with only a small number found in Pakistan and India in Asia.
In geological history, Guangzhou belonged to the sedimentary area of the Sanshui Basin. Prior to this, in addition to the discovery of prismatic and elongated egg families, fossils of the circular egg family were also discovered in the Sanshui Basin. The circular egg family is generally believed to be produced by hadrosaurs. The discovery of this egg fossil indicates the existence of a quadrupedal combination of dinosaurs, such as the theropod dinosaur Oviraptor duck billed dinosaur and ancient crocodile, in the Sanshui Basin. This combination is the first to be discovered in Guangzhou and even the Sanshui Basin, filling the gap in the record of ancient vertebrates in the region.
Xu Xing, a famous dinosaur expert, a researcher of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and the academic dean of the Institute of Paleontology of Yunnan University, believes that the discovery is interesting because of its special discovery site. Thanks to the efforts of enthusiasts, people have found evidence of dinosaurs living in the "gap" of urban infrastructure, and scientists have thus been able to preliminarily reveal the face of the Cretaceous dinosaur world in Guangzhou.
