The Paper's reporter Lu Xinwen
On August 12, 2021, Scientific Reports, an international academic journal owned by Nature, published online the research paper "The first dinosaurs from the Early Cretaceous Hami Pterosaur Fauna, China", led by a Chinese-Brazilian collaborative team led by Wang Xiaolin of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences. The latest research results of dinosaur fossils in the early Cretaceous pterosaur fauna in Xinjiang are reported. The 3 dinosaur fossils reported this time all belong to the sauropod class Somphospondylan, and the fossils are incomplete, preserving an associated cervical vertebra, an associated tail vertebra and a recommended vertebrae, as well as a theropod dinosaur tooth preserved with the tail vertebrae. According to the characteristics of the cervical spine, a new genus of Euhelopodidae was established: The Chinese Silk Road Dragon (Silutitan sinensis); according to the characteristics of the tail vertebrae, a new genus of Titanosauria was established: Hamititan xinjiangensis. This is the first report of a porous vertebrate dinosaur in the Lower Cretaceous strata of Xinjiang and the first report of dinosaur fossils in the Hami Pterodactyl fauna. The study of the Chinese Silk Road Dragon and the Xinjiang Hami Dragon has increased the diversity of the Hami pterosaur fauna, and also increased the diversity of the early Cretaceous sauropod dinosaurs in China. The emergence of two species of porous vertebrate dinosaurs provides new information for the evolution of this dinosaur taxa, further demonstrating the broad diversity of Asian Early Cretaceous porous vertebrate dinosaurs.
Three newly studied dinosaur fossil skeleton preservation schematics (Maurilio Oliveira painting) Red (cervical vertebrae): Chinese Silk Road Dragon; Yellow (tail vertebrae): Xinjiang Hami Dragon; Green (Recommended Vertebrae): Unnamed Fossils
Porous vertebrates, an oversized family of sauropods
Porous vertebrates are a group of sauropod dinosaurs , Titanosauriformes , that lived from the Late Jurassic to the Late Cretaceous period , and are rich in diversity , with fossils found on all continents of the world. Most of the porous vertebrates were large , such as Argentine dragons and Yellow River dragons , both of which were over 30 meters long. The main features of the porous vertebrates include a longer neck and forelimbs, with at least 15 cervical vertebrae, unlike lepidosaurs with extremely long tails and shorter forelimbs; the teeth are rod-shaped, unlike spoon-like teeth like brachiosaurus. The phylogenetic relationship between the species of the porous vertebrate dinosaurs is controversial, with some researchers suggesting that the porous vertebrates consisted of macrosaurus and several basal species, including discoptidosaurs, while others believed that the porous vertebrates consisted of only megalosplens and several basal species, and that discoposclatophytes were not part of the porous vertebrate species. In recent years, the fossils of porous vertebrates have been found and reported in the Cretaceous strata of some places in China, which are mainly distributed in Gansu, Henan, Shandong, Liaoning, Guangxi and other regions, of which the fossils of panpods in the 1920s were first found in Mengyin, Shandong. Previously, no fossils of peoporous vertebrates have been found in the Cretaceous strata of Xinjiang, and the only sauropod dinosaur is a similar Asian dragon found in the Cretaceous Tugulu group under the Junggar Basin, and its taxonomic location and naming validity are still controversial due to fragmentation of specimens.
Fossils were found in the early Cretaceous Hami pterosaur fauna in Xinjiang
The newly studied dinosaur fossils were discovered by a Hami expedition team led by Wang Xiaolin, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, in the Tuha basin underground Cretaceous Tugulu Qunsheng Jinkou Group, and were symbiotically preserved with hami pterosaur fossils. Due to the long-term exposure of fossils to the Extremely Arid and Strong Winds and Sands Gobi Region, which was severely weathered and broken on the surface, the scientific expedition team carried out rescue collection in 2008, 2013 and 2016 respectively. Since 2006, the Hami expedition team of the Institute of Paleovertebrates of the Chinese Academy of Sciences has been conducting scientific research in the Hami Gobi for more than ten consecutive years and has discovered a rare group of Hami pterosaur fauna, which has become the world's largest and most abundant pterosaur fossil production area, hundreds of millions of pterosaurs once flourished here, is a veritable pterosaur Eden. Through more than ten years of scientific investigation and rescue collection, several remarkable achievements have been made in the study of pterosaurs, not only the first three-dimensional preservation of male and female pterosaurs, but also the discovery of a large number of 3D preserved pterosaur eggs and pterosaur embryos symbiosis. In 2014, in a cover article in Current Biology, a large number of juvenile to adult male and female pterosaurs were reported, naming the first species in the Hami pterosaur fauna, the Tianshan Hami pterosaur, and reporting the world's first three-dimensional preserved pterosaur egg, revealing that Hami pterosaur had a leather eggshell structure similar to that of the living reptile snake, showing that pterosaurs lived in groups. In 2017, Science reported an important specimen of more than 200 pterosaur eggs, embryos and fossilized bones, of which 16 pterosaur eggs contained three-dimensional preserved embryos, which is also the first time in the world that 3D pterosaur embryos have been found. Through the study of bone histology and ontogenesis, including embryos and other bones, it is believed that Hami Pterodactyl has a rapidly growing skeletal structure, belongs to the development mode of relatively precocious type, can not fly after birth, and still needs parental care, these findings and studies reveal the life history of this special flying reptile. Through years of fieldwork and evidence from burial, sedimentology and stratigraphy, it is believed that these massive pterosaurs experienced multiple Cretaceous lake storm events, resulting in the death of their herds and rapid burial. The sauropods studied this time are the first non-pterosaur vertebrates found in the Hami pterosaur fauna, all produced in the equivalent layers of hami pterosaur fossils, and the three specimens were produced at about 2-5 km apart.
The new dinosaurs were named the Chinese Silk Road Dragon and the Xinjiang Hami Dragon
Due to the extremely severe weathering of the exposed surface of the fossils, only part of the broken vertebral body on the surface of the three specimens remained, and after rescue collection, the technicians of the scientific expedition team carried out scientific repairs to the other side of the surface buried in the rock without exposure. After repair, it was revealed that the three specimens were 6 associated cervical vertebrae and cervical ribs, 7 associated tail vertebrae and a broken recommended vertebrae, of which the first two specimens were named Chinese Silk Road Dragon and Xinjiang Hami Dragon respectively. The new dinosaur name comes from the fossil origin and the huge size of this type of dinosaur, representing the discovery of such large dinosaurs in Hami, Xinjiang, China, which is also an important town in the "Belt and Road" Silk Road Economic Belt, to commemorate the great Silk Road that has connected China to the world since ancient times.
Ecological restoration map of the Chinese Silk Road Dragon (left) and Xinjiang Hami Dragon (right) and Hami Pterodactyl fauna (Creation/Zhao Chuang, Scientific Guidance/Wang Xiaolin)
The Chinese Silk Road Dragon preserves 6 more complete cervical vertebrae associated with 6 sections, namely the 10th-15th section, the length of a single cervical vertebra is between 455-540 mm, and the total length of the 6 cervical vertebrae is about 3 meters, which is nearly 2 times the average length of the cervical vertebrae corresponding to the early Cretaceous Shishi's Discoptera (body length of about 15 meters) found in Mengyin, Shandong, China, and the body length of the Chinese Silk Road Dragon is conservatively estimated to be more than 20 meters. Its identification features include the lateral ventral part of the posterior articular process-transverse septum of the middle posterior cervical spine, the anterior part of the vertebral body-transverse septum, the secondary synaptic-transverse septum with a developed ventral flange, and the anterior and posterior contractions of the transverse process of the middle and posterior cervical vertebrae at the contact surface of the ribs. Detailed morphological observations have found that the cervical vertebrae of the Chinese Silk Road Dragon have a thick superior-anterior articular process partition and a drooping neck rib, and compared with other discopardosaurs that preserve the cervical vertebrae, the orientation of the superior-anterior articular process septum of the cervical spine, the direction of the anterior articular process-transverse process diaphragm, and the degree of development of the lateral concave of the cervical vertebrae are significantly different from other known species. Also preserved with the Chinese Silk Road dragon is a broken jaw of Hami pterosaur, indicating that these largeosaur dinosaurs lived in the sky and land of the Cretaceous period with Hami pterosaur.
China's Silk Road Dragon (Silutitan sinensis gen. et sp. nov.) Positive specimen
Xinjiang Hami dragon preserves 7 associated tail vertebrae, namely 4-10 sections, the middle 5 segments are more complete, the length of a single tail vertebrae varies from 210-320 mm, which is about 1.5 times the average length of the tail vertebrae corresponding to the late Cretaceous post-cretaceous tail dragon found in Mongolia (body length is about 12 meters), and the body length of Xinjiang Hami dragon is conservatively estimated to be about 17 meters. Its identification features include the sum of the height of the crest and nerve arch of the caudal spine greater than the height of the vertebral body, the sagittal expansion of the vertebral arch of the anterior caudal vertebrae, the deep fossa of the posterior articular process septum and the diaphragm of the nerve spinous transverse, the transverse process of the anterior caudal spine pointing upwards, and the transverse process of the caudal vertebra sequence transitioning abruptly from pointing upwards to pointing downwards without transition. Xinjiang Hamiosaurus is one of the few sauropod dinosaurs found in Asia, and it exhibits unusual combinations of sauropods. The researchers compared the morphological characteristics of Hamiosaurus and other megalomaniacs in detail, and found that the length of the tail vertebral vertebrae, the anterior concave tail vertebral body, the lateral side of the caudal vertebral body near the abdomen, and the shape and direction of the transverse process were significantly different from other known macrosaurus in East Asia. Also preserved with the Xinjiang Hami giant dragon is a theropod dinosaur tooth, which is also the first reported theropod dinosaur fossil in the Hami pterosaur fauna. Since no tooth marks of the theropod dinosaurs were found on the skeleton of the Hami dragon in Xinjiang, it is not certain whether there was a phenomenon of theropod dinosaur eating the carcass of the dragon. Sauropods are all tetrapods, and the discovery and study of these large plant-eating dinosaurs and carnivorous theropods has greatly increased the species and ecological diversity of the Hami pterosaur fauna.
Xinjiang Hami dragon (Hamititan xinjiangensis gen. et sp. nov.) Positive specimen
Phylogenetic analysis basically confirmed the taxonomic positions of the two new dinosaur classes
Due to the relatively large number of species of porous dinosaurs, the phylogenetic studies of predecessors have focused on different evolutionary clades. The researchers selected the latest two phylogenetic matrices in 2019 to analyze the phylogenetic location of the newly discovered porous vertebrates in Hami, among which Filippi and others focused on the phylogenetic relationship of the entire dragon-shaped class, including porous vertebrates, containing a total of 83 species and 405 features; Mannion et al. focused on the phylogenetic evolution of porous vertebrates, containing a total of 120 species and 548 features. Because the new specimens are relatively fragmented, there are fewer features that can be used for identification, and only it can be confirmed that they belong to the porous vertebrate vertebrate class, so they are basically not considered in phylogenetic development.
Phylogenetic diagram based on the Filippi et al. matrix (A) China Silk Road Dragon and Xinjiang Hami Dragon as a single taxon, and (B) China Silk Road Dragon and Xinjiang Hami Dragon as two independent taxa. 1. Titanosauria，2. Colososauria，3.Lithostrotia
A phylogenetic diagram based on the Mannion et al. matrix is based on the Chinese Silk Road Giant Dragon and the Xinjiang Hami Giant Dragon as two independent taxa: (A) equal weights and (B) extended implicit weights, with a k-value of 9. 1. Euhelopodidae, 2. Titanosauria, 3. Lithostrotia, 4. Colossosauria
In order to determine whether the cervical and caudal vertebrae belong to the same type, the characteristics of the cervical and caudal vertebrae are analyzed as a whole in two matrices, and this combination type forms a sister group with the genus Euhelopus, but the features that support this sister group are only the characteristics of the cervical vertebrae, while making the strict concord tree add many unsolved multi-branch structures to the original results. Then the characteristics of the cervical vertebrae and the tail vertebrae are separated and analyzed as two types, and the Chinese Silk Road dragon represented by the cervical vertebrae constitutes a sister group with the genus Pan-legged dragon in the analysis of the two matrices, and there are multiple features to support, indicating that it has a close relationship with Pan-legged Dragon, so the Chinese Silk Road Dragon belongs to the Pan-legged Dragon class. The Xinjiang Hami dragon represented by the tail vertebrae is located in the dragon class in the analysis of the two matrices, but the addition of the Xinjiang Hami dragon makes the entire dragon class increase the unresolved multi-branch structure, and its own system position is not the same in the analysis of the two matrices, so its further system position cannot be confirmed, and new fossil materials and further research are required.
The research was carried out in cooperation with the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences/University of Chinese Academy of Sciences, the National Museum of Brazil/Rio Federal University, Jilin University, the Beijing Museum of Natural History and the Hami Museum. Professor Wang Xiaolin of the Institute of Paleovertebrates of the Chinese Academy of Sciences/University of Chinese Academy of Sciences is the first author and co-corresponding author, Professor Alexander Kellner of the National Museum of Brazil/Rio Federal University is the co-corresponding author, and other authors include The National Museum of Brazil, Kamila Bandeira, Dr. Qiu Rui, Institute of Paleovertebrate Vertebrate of the Chinese Academy of Sciences/Beijing Museum of Natural History, Jiang Shunxing, Associate Researcher of the Institute of Paleovertebrates, Chinese Academy of Sciences, Jilin University/ Associate Professor Cheng Xin of the University of Caerili, Brazil, and Ma Yingxia Research Librarian of the Hami Museum.
The research has been supported by the National Natural Science Foundation of China, the Strategic Pilot Project B of the Chinese Academy of Sciences, the Youth Promotion Association of the Chinese Academy of Sciences, the Field Excavation Fund and Key Deployment Project of the Institute of Paleovertebrates of the Chinese Academy of Sciences, the Hami Local Government Cooperation Project and the Alpine Science Promotion Center.
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