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The initial inversion model is typically established in a transient electromagnetic nonlinear inversion, assuming the accurate capture of the number of layers in the geoelectric model; however, this assumption leads to significantly poorer inversion results for complex models when obtaining the exact number of layers from available a priori information, which is challenging. This study proposes a segmented regularized inversion method to enhance inversion accuracy and stability under varying conditions. The process involves two key steps: Firstly, a segmented initial model is established based on preliminary information. The layering criteria and layer thickness threshold for each segment are set during inversion to reduce dependence on the accuracy of the preliminary information. Secondly, a segmented regularization constraint is added to the objective function to improve the efficiency and stability of the inversion, as numerous parameters can exacerbate the problem of inversion ambiguity. Subsequently, an improved sparrow search algorithm (ISSA) is utilized to optimize the inversion objective function. This enhances the efficiency of searching for the objective function and the algorithm's ability to escape local optimal solutions. The proposed method is evaluated using one-dimensional and two-dimensional models with different initial models and inversion algorithms and applied to the inversion of on-site exploration data in a coal mining area in Chongqing. Comparative results demonstrate that the proposed segmented regularization method, based on the improved sparrow search algorithm, exhibits superior practicality and a higher fitting accuracy. [ABSTRACT FROM AUTHOR]

Palaeopathological analyses have great potential to provide insights into dinosaurs' palaeobiology and life histories, but few cases have been reported in China. In this study, we report on four pathological sauropod ribs excavated in the same quarry of the Middle Jurassic in Yunyang County, Chongqing, southwest China. Based on morphological observation, computerised tomography (CT)-based energy spectrum data, and image analyses, three types of pathology were identified: traumatic fracture, fracture after bone infection, and osteosclerosis. This study increases the knowledge of dinosaur pathology, especially of Jurassic sauropods, and highlights the use of energy spectrum CT in palaeopathological studies. [ABSTRACT FROM AUTHOR]

Shunosaurus is a small eusauropod from China. It is characterised by solid cervical and dorsal vertebral centra without complicated pneumatic structures, platycoelous or amphicoelous middle and posterior vertebrae and a lack of pubic foramen in adult individuals. Although many Shunosaurus individuals have been discovered, the ontogenetic characteristics of its long bones and bone tissues are not very clear and the existing description of the postcranial skeleton is relatively rudimentary. The new well-preserved and the smallest Shunosaurus specimen discovered in Yunyang, Chongqing, China, provides good material for solving these problems. The radial distal breadth is more than twice the minimum midshaft breadth, and the fibular distal end is twice as wide as the midshaft, while these ratios are all smaller in adult specimens. The lateral trochanter is undeveloped. This individual does show a pubic foramen. The degree of vascularisation of the bone tissue in the juvenile bone tissue is higher for adults. There are no arrested growth lines and peripheral rest lines in the compact bone, indicating that body size still increases slowly after maturity. The discovery of this new material expands the distribution range of Shunosaurus in China. [ABSTRACT FROM AUTHOR]

A new species of Omeisaurus, O. puxiani sp. nov., from the Middle Jurassic of Southwest China is reported. The holotype consists of partial articulated vertebrae, forelimb, hind limb and other materials of an individual. Comparative study and cladistic analysis show that this new taxon belongs to Omeisaurus, and bears a unique combination of character states, such as all presacral vertebrae opisthocoelous, complex pneumatic fossa system in middle cervical centra, lateral fossae of dorsal centra divided by secondary septa, end of anterior caudal neural spines expanding posteriorly, edge of humerus deltopectoral crest turning posterolaterally and ratio of length of ulna to humerus of 0.69. The previously reported single middle cervical (S66) from the same locality and horizon can be referred to this new species. The discovery of Omeisaurus puxiani enriches the diversity of the genus of Omeisaurus and provides additional information to help understanding the evolutionary history of this genus in Eastern China. Abbreviations No. 208 HEGT: Chongqing Laboratory of Geological Heritage Protection and Research, No. 208 Hydrogeological and Engineering Geological Team, Chongqing Bureau of Geological and Mineral Resource Exploration and Development Chongqing, Chongqing, China; GSC: Chongqing Institute of Geological Survey, Chongqing, China; IVPP: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; ZDM: Zigong Dinosaur Museum, Zigong, Sichuan, China [ABSTRACT FROM AUTHOR]

A new neornithischian dinosaur, Sanxiasaurus modaoxiensis gen. et sp. nov., is described based on a partial postcranial skeleton from the Middle Jurassic Xintiangou Formation of Yunyang, Chongqing Municipality, China. It is the first neornithischian dinosaur from the Middle Jurassic Xintiangou Formation of Sichuan Basin, and also the earliest record of a neornithischian dinosaur in Asia. It differs from other neornithischians in possessing the following unique combination of characters: at least four sacrals; humerus strongly bowed laterally along its length; obturator process located at mid-length of ischial shaft; lesser trochanter of femur broadened, wing shaped and subequal in anteroposterior width to greater trochanter; distal tibia with elongate posterolateral process. Phylogenetic analysis shows that Sanxiasaurus modaoxiensis is positioned near the base of neornithischia. This find extends the Asia neornithischian stratigraphic horizon to the lower Middle Jurassic. [ABSTRACT FROM AUTHOR]

The article offers information on the 2019 Annual Symposium on Yunyang Dinosaur Fossil Protection and Research which was held in Chongqing, China, on December 16, 2019. It Further discusses the dinosaurs discovered from the early Middle Jurassic Xintiangou Formation in Yunyang, Chongqing; role of Xintiangou dinosaurs in studying the evolutionary sequence of dinosaurs; and also mentions typical Jurassic dinosaur faunas in China such as Early Jurassic Lufengosaurus Fauna.

A new sauropod-dominanted dinosaur fauna, including several new species of sauropods and stegosaurs, was recently excavated from the Lower Shaximiao Formation in Yunyang, northeastern Chongqing, southwestern China. Although this dinosaur fauna could possibly provide significant clues for a better understanding of the basal sauropod's evolution and diversification of basal sauropods in the Jurassic, many aspects of this fauna are not well defined constrained in terms of detailed stratigraphy, geochronology, and comparison with similar faunas in other regions of the Sichuan Basin. This paper reports on the petrological features of this locality, using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS), with laser ablation-multi-collector-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb geochronology for a tuffaceous siltstone layer beneath the dinosaur fossil-bearing layers from the fossil site. The SEM and XRD results show a typical tuffaceous mineral composition of this layer. Zircon U-Pb data yielded a weighted average age of 166.0 ± 1.5 Ma, indicating a maximum burial age for this dinosaur fauna. This fauna is chronologically comparable with the Shunosaurus-Omeisaurus Fauna, which is primarily found in the central Sichuan Basin. • 166.0 ± 1.5 Ma as the maximum burial age for dinosaur fauna in Chongqing, SW China. • Precise age constraints on newly discovered dinosaur in Lower Shaximiao Formation. • Basal sauropods in Sichuan Basin are younger than biostratigraphic ages. • Providing age constraints on the radiation of basal sauropods in Jurassic. [ABSTRACT FROM AUTHOR]