BEIJING, June 8 (Xinhua) -- In the early Cretaceous Urhoptera fauna in the Junggar Basin of Xinjiang, China (about 135 million years ago), the discovery and research of pterosaur footprint fossils has attracted much attention, and its newly discovered fossils of as many as 114 pterosaur footprints have aroused concern.
The Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (Institute of Paleovertebrates of the Chinese Academy of Sciences) released a message on the 8th that the research team of Wang Xiaolin of the Institute has made the latest progress in this regard: after research and identification, the rich footprint fossils in this place are classified into the pterosaur footprint genus of the pterosaur footprint family, and a new species is established and named "Urhe pterosaur footprint".
All members of the Pterodactyl Footprint Family and Urhopteratops pterosaur footprint new species d, me histogram. Wang Xiaolin team Courtesy photo
The research team also made the first reliable inference from the footprint fossil tracers, believing that the tracers were most likely compound tooth lake pterosaurs, which also provided direct evidence for the gregarious lifestyle of pterosaurs hundreds of millions of years ago. The latest progress paper of this important paleontological research by Chinese scientists was recently published online by the international academic journal Peerj.
Naming the new species "Urho Pterodactyl Footprint"
Li Yang, the first author of the paper and a doctoral candidate at the Institute of Paleovertebrates of the Chinese Academy of Sciences, said that the fossil footprints of pterosaurs found in this study were preserved on the gray-green fine-grained sandstone surface of about 125 centimeters long, about 25 centimeters wide and with an area of about 0.3 square meters, with a total of 114 footprints, including 57 forefoot footprints and 57 hindfoot footprints.
Comparison of the footprints of Urho pterosaurs (new species) with the skeleton of the hindpods of Pterodactylosaurus. Wang Xiaolin team Courtesy photo
The 114 footprint fossils are relatively chaotic, and in order to find the traces as much as possible, the research team counted all the footprints in the direction of travel and found some possible tracks (that is, footprints of the same direction and equivalent size).
Fossil pterosaur footprints are four-legged walking footprints with no trails. Three-fingered forefoot, strongly asymmetrical, smaller in size, average length about 3.40 cm, width about 1.59 cm, I. finger shortest (about 1.31 cm), usually pointing laterally or laterally posterior, the second finger medium length (about 1.90 cm), pointing posteriorly, crescent shape III. finger longest (approx. 3.15 cm), pointing posteriorly, pointing posteriorly, the interphalangeal angle between the ii and III fingers is 1.74 times the angle between the I and II fingers; the hind foot is in a row, approximately triangular, with four toes, and smaller in size ( It is about 4.02 cm long), the I. toe is the shortest, the remaining three toes are approximately equal, the tip is narrow and long, approximately equal to the toe, and the lateral angle between the toes is small.
Li Yang said that from the analysis of the size and morphological characteristics of the footprints, the newly discovered footprint fossils are different from the existing beaked-billed dinosaur footprint family and the Agadir footprint family, and are consistent with the characteristics of the pterosaur footprint genus Pterodactyl in the pterosaur footprint family.
Further, through comparative analysis with the existing 9 effective species of the genus Pterosaur footprint, it is distinguished from the existing members of the genus Pterosaur footprint based on the small interphalangeal angle between the I and ii fingers of the forefoot, the length-to-width ratio of the hind feet, the relative length of the four toes (the I. toes are the shortest, and the remaining three toes are approximately equal), and the approximately equal toes and lame imprints.
Therefore, the research team established a new species of the genus Pterosaur in the family Pterosaur footprint family and named it "Urhe Pterosaur Footprint" for discovery, which is the third effective pterosaur footprint species in China.
Line diagram of all pterosaur footprint species and major undetermined species. Wang Xiaolin team Courtesy photo
The Creator is most likely a Pterodactyl
Jiang Shunxing, a co-author of the paper and an associate researcher at the Institute of Paleovertebrates of the Chinese Academy of Sciences, said that in the latest study, the research team extracted anatomical features (the relative length of the four toes, the length of the toes and the length of the footprints of the toes) from the hind feet of the "Urhe Pterodactyl Footprints" and compared them for the first time with the solid fossils of pterosaurs found locally.
The results show that two pterosaur footprints of different sizes and morphologies have been found in the Urho region: the smaller one is the new species "Urho Pterosaur Footprint" in this study, and the larger size also belongs to the members of the genus Pterodactyl Footprint, indicating that these two types of footprints are left by two different types of pterosaurs.
At present, there are only two kinds of pterosaur skeleton fossils in the Urho Pterodactyl fauna, namely the smaller Compound Tooth Lake Pterodactyl and the larger Wei's Junggar Pterodactyl, of which the Compound Tooth Lake Pterodactyl has well preserved hindfoot skeleton fossils.
Based on this, the research team extracted the length of the four toes, the length of the toes and the length of the lames from the hind feet of the smaller plesiosaurs, and fitted them to the parameters of the "Urhe Pterodactyl Footprint", and the two were consistent in the length of the four toes, the length of the toes and the length of the lames. "This suggests that the tracers of urhe pterosaur footprints are most likely pterosaurs, with an estimated wingspan of about 2 meters in adult individuals." Jiang Shunxing said.
Fossil photographs and line drawings of the footprints (new species) of Urhe pterosaurs. Wang Xiaolin team Courtesy photo
Provide direct evidence of pterosaur life
Researcher Wang Xiaolin, the corresponding author of the paper, pointed out that the study focused on a detailed morphological study of a fossil footprint of a smaller pterosaur footprint preserved in the Urho area, and analyzed the tracers and possible behavioral habits.
An analysis of the possible behavioral characteristics of the tracers of the "Urhe Pterodactyl Footprints" shows that the tracers are undoubtedly four-legged walking from the perspective of the simultaneous preservation of the forefoot and hind feet on the footprint rocks. In addition, 114 footprint fossils are preserved on a rocky level of about 0.3 square meters, with a density of up to 365 per square meter, and the footprint fossils vary in size: the size of the forefoot footprint is 1.9-5.15 cm, and the size of the posterior footprint is 2.68-5.71 cm.
"This means that urhopteratops footprints are left by pterosaurs of different ages, representing that pterosaurs of different ages lived on the shores of lakes in the Urho region, and this high density is often used as evidence of social habitation." Wang Xiaolin stressed.
He said the research team also counted the direction of pterosaur footprints and found that they mainly focused on two opposite main directions, "which reflects that these footprint fossils may have been left by tracers going back and forth in this area."
Ecological restoration map of Pterodactyl of The Dinosaur that most likely created the footprints of the Tracer. Zhao Chuang drawing
Urho pterosaur fauna "ins and outs"
The discovery and study of paleovertebrate fossils in the Junggar Basin of Xinjiang began in the 1960s. In 1964, paleontologist Yang Zhongjian named and studied the Wei's Dzungar pterosaur found in the Lower Cretaceous Tugulu group in the Urho region of Karamay, the first relatively complete fossil skeleton of pterosaur in China.
Yang Zhongjian also led the Xinjiang Paleontology Expedition team of the Institute of Paleontology of the Chinese Academy of Sciences that year, and found a large number of pterosaurs and other vertebrates such as turtles and turtles, crocodiles, plesiosaurs and a variety of dinosaur fossils in the Urhe area, and called the vertebrate fossil group urhe pterosaur fauna.
Since 2006, the scientific expedition team of the Institute of Paleovertebrates of the Chinese Academy of Sciences led by Wang Xiaolin has conducted continuous investigations of Mesozoic paleontology and strata in the turpan-Hami Basin and Junggar Basin in the north and south of the Tianshan Mountains in Xinjiang for more than 10 years, and found a rich fossil group of pterosaurs, dinosaurs and other skeleton fossils and a large number of footprints of pterosaurs, dinosaurs, birds and turtles preserved in multiple layers, which greatly enriched the fossil types and composition of urho fauna.
Urhe pterosaur footprint (new species) forward direction histogram and rose chart, red and blue represent the two main directions. Wang Xiaolin team Courtesy photo
Fossil pterosaur footprints have been found worldwide and in China
Wang Xiaolin said that so far, 77 pterosaur footprint sites have been found in 13 countries around the world, and a total of 15 effective species of pterosaur footprint fossils of 3 families and 5 genera have been reported, of which the distribution range of pterosaur footprints is the most extensive.
Pterosaur footprint genus was established in 1957 based on the fossil pterosaur footprint in the Upper Jurassic strata of Arizona, USA, the main feature is four-legged walking, the forefoot is asymmetrical three-fingered, finger-line, I. to III. finger length gradually increases; the hindfoot is approximately oblong-shaped, protruded, with four toes, ii-toes and III. toes slightly longer than the I. and IV. toes; in the ipsilateral anterior foot combination, the hindfoot footprint is in the front and the forefoot footprint is in the lateral posterior.
Urhe pterosaur footprints (new species) positive, secondary and overlapping footprints. Wang Xiaolin team Courtesy photo
China's pterosaur footprints were first found in 2004 in the Lower Cretaceous strata of Yongjing, Gansu, and then in Zhejiang, Shandong, Sichuan, Xinjiang, Chongqing, Guangdong also found pterosaur footprint fossils, but in general, the number and preservation of pterosaur footprints are relatively poor, in addition to the Urhe region of Xinjiang, a total of 79 pterosaur footprint fossils were reported in 6 other provinces, and this time in Xinjiang research newly discovered pterosaur footprint fossils are as many as 114.
The fossil pterosaur footprints found in China are classified as pterosaur footprints, except for the pterosaur footprint fossils in Zhejiang and Guangdong, which are dated to the Late Cretaceous, and the rest are Early Cretaceous. (End)