[dinosaur] Early Cretaceous dinosaur tracks from Ningxia + avian forelimbs + Jehol Biota date + preserving dinosaur bones

Ben Creisler

Some recent papers:

Free pdf:

YANG Qing, LÃ Jun-Chang, WANG Jin-Min, YANG Ke-Cheng, ZHAO Ming, ZHAO Ya, WAN Yang, WEI Li-Xin, ZONG Li-Yi, LIU Xiao-Li, ZHU Jian-Zhong & ÂHAN Jia-Yin (2019)
A Study of Early Cretaceous Dinosaur Tracks in Liupanshan Area, Ningxia. (in Chinese)
Acta Geoscientica Sinica 40(3): 483-491
http://www.cagsbulletin.com/dqxben/ch/reader/view_abstract.aspx?file_no=20190310&flag=1

Free pdf:
http://www.cagsbulletin.com/dqxben/ch/reader/create_pdf.aspx?file_no=20190310&flag=1&journal_id=dqxben&year_id=2019

This paper is based on the investigation of the dinosaur footprints found in Liupanshan area of Ningxia. The footprints were discovered from 5 fossil localities which belong to the Lower Cretaceous Heshangpu Formation, Liwaxia Formation and Madongshan Formation in Longde County and Jingyuan County, Guyuan City, Liupanshan area, Ningxia. These fossils consist of the sauropod and the ornithopod footprints, dominated by sauropod ones, including four trackways. Among them, the dinosaur individuals from the Xiangshui Town in Longde County are smaller, whose hip height are only 1.44 m long, the rest of the other trackways represent larger dinosaurs, and their hip heights are between 2.79 and 3.27 m. The hip height of ornithopod dinosaur is about 0.48 m, suggesting small ornithopod dinosaurs. On the basis of the Alexander's speed calculation method, the speeds of dinosaurs are estimated. The results show that the speed of sauropods was 0.34~1.41 m/s, and the ratio of stride length to hip height was less than 2, both indicating normal walking states. The footprints are mainly preserved in silty mudstone and fine-grained sandstone, with horizontal bedding, ripple marks, mud cracks, hail marks and other sedimentary structures, bearing plant fragment fossils as well as a lot of invertebrate burrows. Judging from the lithological and sedimentary study, the dinosaur tracks were preserved in lake-shore.

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Ron A. Meyers (2019)
Comparative anatomy of the postural mechanisms of the forelimbs of birds and mammals.
Journal of Ornithology (advance online publication)
DOI: https://doi.org/10.1007/s10336-019-01678-3
https://link.springer.com/article/10.1007/s10336-019-01678-3

One of the many differences between quadrupedal mammals and birds is that during standing, the forelimbs in mammals are involved in locomotion and support of the body, whereas the forelimbs of birds are involved in locomotion but not in body support. This dichotomy is reflected in the morphology and fiber types of the forelimb muscles. In mammals, the forelimb musculature forms a "pectoral sling" that suspends the trunk. Since mammals use the same muscles for postural and dynamic movements, their muscles possess a combination of slow and fast-contracting muscle fiber types that function in postural and dynamic activities. In a specific muscle, slow muscle fibers can perform postural actions via isometric contraction with minimal fatigue, whereas fast fibers can elicit dynamic, rapid, and forceful actions for locomotion. In contrast, the forelimb muscles of birds need only hold the wing folded while not in use. The muscles specialized for avian forelimb posture are comparatively small and consist entirely of slow fibers, and likely do not function in locomotion. In soaring birds, muscles with slow fibers also function isometrically and maintain the outstretched wing for extended lengths of time. Thus birds and mammals have evolved different strategies to deal with their forelimb postures and have different muscles specialized for posture.

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Robert Spicer, Paul Valdes, Alice Hughes, Jian Yang, Teresa Spicer, Alexei Herman and Alexander Farnsworth (2019)
New insights into the thermal regime and hydrodynamics of the early Late Cretaceous Arctic.
Geological Magazine (advance online publication)
doi: https://doi.org/10.1017/S0016756819000463
https://www.cambridge.org/core/journals/geological-magazine/article/new-insights-into-the-thermal-regime-and-hydrodynamics-of-the-early-late-cretaceous-arctic/D561B4623B27F69E65727D98E682CFDB

The Arctic is warming faster than anywhere else of comparable size on Earth, impacting global climate feedbacks and the Arctic biota. However, a warm Arctic is not novel. The Late Cretaceous fossil record of the region enables a detailed reconstruction of polar environmental conditions, and a thriving extinct ecosystem, during a previous 'hothouse' global climate. Using leaf form (physiognomy) and tree ring characteristics we reconstruct Cenomanian to Coniacian polar thermal and hydrological regimes over an average annual cycle at eight locations in NE Russia and northern Alaska. A new high spatial resolution (~1 km) WorldClim2 calibration of the Climate Leaf Analysis Multivariate Program (CLAMP) yields results similar to, but often slightly warmer than, previous analyses, but also provides more detailed insights into the hydrological regime through the return of annual and seasonal vapour pressure deficit (VPD), potential evapotranspiration (PET) estimates and soil moisture, as well as new thermal overviews through measures of thermicity and growing degree days. The new results confirm the overall warmth of the region, particularly close to the Arctic Ocean, but reveal strong local differences that may be related to palaeoelevation in the Okhotsk-Chukotka Volcanogenic Belt in NE Russia. While rainfall estimates have large uncertainties due to year-round wet soils in most locations, new measures of VPD and PET show persistent high humidity, but with notably drier summers at all the Arctic sites.

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Free pdf:

PEI Jun-Ling,YANG Zhen-Yu,SUN Zhi-Ming,TONG Ya-Bo,CAI Yu-Hang,WANG Xu-Ri & ZHAO Yue (2019)
Magnetostratigraphic Dating of the Early Jehol Biota. (in Chinese)
Acta Geoscientica Sinica 40(3): 393-404.
http://www.cagsbulletin.com/dqxben/ch/reader/view_abstract.aspx?file_no=20190302&flag=1

Free pdf:
http://www.cagsbulletin.com/dqxben/ch/reader/create_pdf.aspx?

file_no=20190302&flag=1&journal_id=dqxben&year_id=2019

The early record of the Jehol Biota has been well preserved in the Mesozoic Dabeigou Formation and Dadianzi Formation. The magnetostratigraphic study can provide age control for the evolution of the Jehol Biota, the origin of birds, and the evolution of angiosperm. Meanwhile, it will offer chronological evidence for the terrestrial JurassicâCretaceous boundary in China, the Early Cretaceous division and global stratigraphic correlation. Additionally, it can also afford "deep-time" age control for the timing of destruction of the North China Craton. Based on magnetostratigraphic results from more than 1 100 oriented samples of the Luanping Basin, northern Hebei Province, the authors established a high-resolution magnetic polarity sequence of Dabeigou and Dadianzi Formations. By magnetostratigraphic correlation, the magnetic polarity sequence of the Dabeigou, Dadianzi and Xiguayuan Formations is correlated to M12âM9 in standard magnetic polarity time scale. The DabeigouâDadianzi Formation belongs to Mid-ValanginianâMid-Hauterivian. The authors hold that the early age of the Jehol Biota is younger than the Early Cretaceous Valanginian Age. The studies conducted by the authors refute the stratigraphic subdivision that the terrestrial JurassicâCretaceous boundary in China would be set between the Dabeigou and the Dadianzi Formations.

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Also, a new issue ofÂShandong Land and Resources 2019(5)Âin Chinese, devoted to preservation and protection of dinosaur bone fossils:

YU Xuefeng, DU Shengxian, CHEN Jun, JIA Chao, ZHANG Shangkun, TIAN Jingxiang & YANG Bin (2019)

Study on Protection Effect of Nnew Protective Materials on Dinosaur Fossils.

Shandong Land and Resources 2019(5): 1-7

https://caod.oriprobe.com/articles/55948508/Study_on_Protection_Effect_of_Nnew_Protective_Mate.htm

Zhucheng city is one of the important sites of dinosaur fossils in China. Fossils in this area are abundant and well preserved with great scientific value. In order to protect the important geological relic resource and enhance the feasibility and effectiveness of fossil conservation, from the aspect of protective materials of dinosaur fossil, on the basis of a large number of experiments, a new type of composite protective material has been prepared by blending methyl triethoxy silicone resin and fluorocarbon resin with nano-SiO2. As showed by the test results, the new protective material has good anti-ultraviolet aging resistance and thermal stability, and can be used as outdoor fossil protection material. From the protection effect of dinosaur fossils, the film has good transparency. It can truly reflect the original appearance of fossils, improve the waterproof of fossils, enhance heat resistance and acid and alkali resistance. This material has good prospects for popularization in fossil protection.

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ZHANG Shangkun, YU Xuefeng, JIA Chao, DU Shengxian, TIAN Jingxiang, SONG Xiangsuo & CHEN Wenfang (2019)

Experimental Simulation of Internal Fracture Expansion in Dinosaur Fossils during Weathering Destruction.

Shandong Land and Resources 2019(5): 8-14

https://caod.oriprobe.com/articles/55948514/Experimental_Simulation_of_Internal_Fracture_Expan.htm

On the basis of theoretical analysis, the fracture damage process of fractured dinosaur fossils under uniaxial pressure has been simulated and analyzed. The calculation program based on volume element analysis is compiled in FLAC3 D with FISH language. The crack initiation propagation penetration law and fracture damage mechanism of dinosaur fossils have been analyzed by using elastic-brittle constitutive model. Under uniaxial compression, the failure process of dinosaur fossil specimens with cracks can be divided into three stages, they are linear deformation stage, non-linear deformation stage and softening stage. When the load exceeds the peak strain strength, a large number of new induced cracks will be formed in the fossil, resulting in drastic changes in the internal structure of the fossil. It is noteworthy that the post-peak strength softening process of dinosaur fossils is very unstable, and the mechanical behavior of materials near the peak is very sensitive to the distribution of internal defects in fossil specimens. The experimental results show that the compressive strength of fractured dinosaur fossils is 30%, lower than that of non-fractured dinosaur fossils, and the ultimate residual compressive strength is also slightly smaller. Under loading stress, compared with dinosaur fossils without internal fissures, the internal fissures of fractured dinosaur fossils will expand rapidly and greatly, which aggravates the weathering degree and destruction speed of dinosaur fossils.

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JIA Chao, DU Shengxian, ZHANG Shangkun, YU Xuefeng, SONG Xiangsuo, CHENG Jun & ÂYANG Bin (2019)

Comparison of Protective Properties of Methyl Triethoxy Silicone Resin Modified by Nano-SiO2 and FEVE Fluorocarbon Resin.

Shandong Land and Resources 2019(5): 15-20

https://caod.oriprobe.com/articles/55948517/Comparison_of_Protective_Properties_of_Methyl_Trie.htm

Accompanying with the deepening of supply side reform, the need for innovation driven and new to old kinetic energy conversion for the development of new materials is becoming more and more urgent. Paleontological fossil conservation is of great significance. According to the particularity of fossil conservation, the latest protective material, nano-SiO2 modified methyl triethoxy organosilicon resin has been developed by our team through a large number of experiments. From the aspects of fossil protection effect, air permeability and anti-ultraviolet aging, cmparing nano-SiO2 modified methyl triethoxy organosilicon resin with FEVE fluorocarbon resinïfluoroolefin-vinyl ether copolymerï, It is considered that nano-SiO2 modified methyl triethoxy organosilicon resin has the advantages of strong permeability and good air permeability, while the candidate and corrosion resistance of FEVE fluorocarbon resin are good. It is slightly better than nano-SiO2 modified methyl triethoxy silicone resin. Therefore, using nano-SiO2 modified methyl triethoxy silicone resin as the underlying protective material and FEVE fluorocarbon resin as the surface protective material of fossils can play a good protective effect on dinosaur fossils.

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DU Shengxian, CHEN Jun, YU Xuefeng, JIA Chao, ZHANG Shangkun, SONG Xiangsuo & ÂLUO Wenqiang (2019)

Numerical Experiment on Axial Comression of Dinosaur Fossils Containing Fracture Angle and Study on Crack Growth Mechanism.

Shandong Land and Resources 2019(5): 21-27

https://caod.oriprobe.com/articles/55948511/Numerical_Experiment_on_Axial_Comression_of_Dinosa.htm

Dinosaur fossil conservation is a worldwide problem. The weathering causes of fossils are various, among which the internal fissures of fossils are the important factors leading to the weathering and destruction of dinosaur fossils. Based on the theory of rock fracture mechanics, the failure of dinosaur fossils with cracks under pressure has been simulated and analyzed. The numerical compression tests of dinosaur fossils with cracks have been carried out by means of numerical simulation, and the crack propagation mechanism of dinosaur fossils with cracks has been studied. It is showed that with the increase of the crack angle, the crack angle decreases gradually, and the stress concentration at the crack, especially at both ends, is low and evenly distributes in other parts. The crack propagation starts at the crack tip and eventually extends to the edge. This result will provide basic references for revealing the weathering mechanism of dinosaur fossils and developing conservation.

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ZHANG Shangkun, YU Xuefeng, JIA Chao, DU Shengxian, TIAN Jingxiang, SONG Xiangsuo & ÂCHEN Wenfang (2019)

Study on Weathering Damage of Dinosaur Fossils Caused by Stress Release in the Process of Dinosaur Fossil Excavation.

Shandong Land and Resources 2019(5): 28-32

https://caod.oriprobe.com/articles/55948511/Numerical_Experiment_on_Axial_Comression_of_Dinosa.htm

ÂIn the process of dinosaur fossil excavation, mechanical disturbance will directly lead to the fragmentation of fossils or surrounding rocks, and stress release will lead to the generation and expansion of surface cracks of fossils and surrounding rocks. These fractures will provide a channel for the movement of water and air, and make weathering damage more rapid. Based on the theory of layered excavation, a numerical model has been established to simulate the process of fossil excavation. Through computer simulation of the process of equivalent stress change and XZ direction stress change at the depths of 0 m, 11 m, 14 m and 19 m, the maximum equivalent stress difference on the suface of fossils before and after excavation is 0.34 MPa, and the maximum equivalent stress difference on the surface of surrounding rocks is 0.3 MPa. It is found that the more obvious the bullet phenomenon is, the more serious the stress release is. Although the shear stress on the surface of the fossils is small, its influence on the weathering of the fossil is much greater than that under the compressive stress condition, which is the main reason for the unloading cracks. Therefore, the excavation of dinosaur fossils should be slowly excavated layer by layer, so that the fossils gradually reach a new stress balance, so as to reduce the weathering damage caused by stress release to fossils, especially to do a good job of slope protection to prevent the generation of shear stress to the maximum extent.

SONG Xiangsuo, JIA Chao, ZHANG Shangkun, DU Shengxian, LUO Wenqiang & YANG Bin (2019)

Effects of Dry and Wet Cycle on the Mechanical Properties of Dinosaur Fossils.

Shandong Land and Resources 2019(5): 33-37

https://caod.oriprobe.com/articles/55948513/Effects_of_Dry_and_Wet_Cycle_on_the_Mechanical_Pro.htm

Dinosaurs are ancient vertebrates that have long been extinct. Dinosaur fossils are of great significance in geology, especially in the study of paleontology. It has important, scientific, theoretical and practical values on the stratigraphic division, the determination of the geological era, the study of paleogeography, paleoenvironment, paleoclimate and biological extinction events. In recent years, dinosaur fossils have been continuously excavated, and the protection of dinosaur fossils has become increasingly urgent and important. In this paper, the effects of water on the weathering ability of fossils have been studied through dry and wet cycles and expansion experiments. As showed by the experimental results, the influence of water on weathering of fossil surrounding rocks is much greater than that of dinosaur fossils.

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CHEN Cheng, JIA Chao, ZHANG Shangkun, DU Shengxian, LUO Wenqiang & TIAN Jingxiang (2019)

Study on the Effect of Burial Depth on Dinosaur Fossils.

Shandong Land and Resources 2019(5): 38-42

https://caod.oriprobe.com/articles/55948510/Study_on_the_Effect_of_Burial_Depth_on_Dinosaur_Fo.htm

At present, most of the dinosaur fossils have been found buried in the strata of different depths. In order to deeply study the weathering mechanism of dinosaur fossils and explore the protection measures and methods of dinosaur fossils, the influence of lateral pressure generated by burial depth on the strength and destruction characteristics of dinosaur fossils has been analyzed. Finite difference software FLAC3 D has been used for numerical simulation to reveal the impact of burial depth on dinosaur fossil preservation. It is showed that the lateral pressure exerted by the surrounding rock is an important factor affecting the deformation and strength of dinosaur fossils. In the elastic deformation stage, the initial strength and peak strength of dinosaur fossils increase with the increase of lateral pressure. When the stress exceeds the ultimate strength of dinosaur fossils, it enters the plastic deformation, and its initial strength and peak strength gradually decrease, and finally reach the residual strength.

LIU Fengchen, YU Xuefeng, JIA Chao, DU Shengxian, SONG Xiangsuo, YANG Bin & ZHANG Shangkun (2019)

Effect of Coupling of Temperature Field and Seepage Field on Weathering Damage of Dinosaur Fossils.

Shandong Land and Resources 2019(5): 43-49

https://caod.oriprobe.com/articles/55948516/Effect_of_Coupling_of_Temperature_Field_and_Seepag.htm

Temperature and water are two main factors affecting the weathering of dinosaur fossils. In order to study the mechanism of weathering and destruction of dinosaur fossilsand protect dinosaur fossils more effectively, scientifically and reasonably, taking dinosaur fossils and surrounding rocks as rock masses, by using the coupling relationship between temperature field and seepage field, the intrinsic mechanism of temperature and water in the process of weathering and destruction of dinosaur fossils has been studied. The interaction between temperature field and seepage field in the weathering process of dinosaur fossils has been simulated by establishing a numerical model of temperature field and seepage field. The destruction mechanism of the interaction between temperature and water on the weathering process of dinosaur fossils has been qualitatively analyzed.

CHEN Jun, DU Shengxian, ZHANG Shangkun, JIA Chao, LIU Fengchen & YANG Bin (2019)

Effect of Confining Pressure and Axial Pressure on Stress Field of Dinosaur Fossils.

Shandong Land and Resources 2019(5): 50-57

https://caod.oriprobe.com/articles/55948518/Effect_of_Confining_Pressure_and_Axial_Pressure_on.htm

Paleontological fossils including dinosaur fossils are not only important geological remains, but also the most important data on studying biological evolution. In this paper, from the aspect of physical mechanics, through numerical experiments, the effects of confining pressure and axial pressure on the strength and failure characteristics of dinosaur fossils have been analyzed. It is showed that the confining pressure has a great influence on the stress of the fractured fossils with different angles at different burial depths, and the stress of the fractured fossils increases greatly with the increase of burial depth. When confining pressure and axial pressure act together, the influence of burial depth on cracking angle is small, and the limit load increases with the increase of burial depth. At the same time, the crack angle at different depth has the same trend with the crack angle, and decreases with the increase of the crack angle. The ultimate load varies with the crack angle.

LIU Fengchen, ZHANG Shangkun, TIAN Jingxiang, JIA Chao, CHEN Jun & CHEN Wenfang (2019)

Simulated Study on the Effects of Direct Sunlight, Indoor Shading and Protective Layers on the Weathering of Dinosaur Fossils.

Shandong Land and Resources 2019(5): 58-61

https://caod.oriprobe.com/articles/55948509/Simulated_Study_on_the_Effects_of_Direct_Sunlight_.htm

Dinosaur fossils are biological remains or relics preserved in the stratum during geological history. Once exposed to the surface due to natural reasons or artificial excavation, it will face serious weathering problems. The most serious damage factor is mainly from the sunlight. The fossils have been affected by sunshine for a long time, and they start again and again. Thermal stress causes cracks on the surface of the fossils, and finally the fossils are broken as a whole. Fossil heating includes direct sunlight, indoor shading and a protective coating on the surface of the fossil. From these three different situations, the sensitivity of fossils and surrounding rocks to temperature has been studied by numerical model. It is found that the temperature stress produced by temperature gradient in direct sunlight is much larger than that produced by indoor shading and protective coating; without protective coating, the temperature stress produced by temperature gradient in part of fossil is larger than that produced by temperature gradient and temperature stress in protective coating.

SONG Xiangsuo, ZHANG Shangkun, JIA Chao, DU Shengxian, CHEN Cheng & TIAN Jingxiang (2019)

Study on Weathering Damage Mechanism of Dinosaur Fossils by Freeze-thaw Cycle.

Shandong Land and Resources 2019(5): 62-65+72

https://caod.oriprobe.com/articles/55948515/Study_on_Weathering_Damage_Mechanism_of_Dinosaur_F.htm

The weathering process of dinosaur fossils is relatively complex, and there are many factors that cause the destruction of dinosaur fossils. The freeze-thaw cycle is one of the important factors. In this paper, the mechanism of weathering destruction of dinosaur fossils and surrounding rocks caused by freeze-thaw cycle has been studied through indoor experiments. It is proved that the freeze-thaw cycle will reduce the strength and elastic modulus of the surrounding rocks, and multiple freeze-thaw cycles will cause the surrounding rocks and fossils to suffer from mass loss, mudization, and block loss. The freeze-thaw cycle has a great effect on the physical destruction of fossils.

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CHEN Cheng, DU Shengxian, YU Xuefeng, JIA Chao, ZHANG Shangkun, LUO Wenqiang & TIAN Jingxiang (2019)

Study on the Effect of Thermal Stress on Dinosaur Fossils with Inner Crack.

Shandong Land and Resources 2019(5): 66-72

https://caod.oriprobe.com/articles/55948519/Study_on_the_Effect_of_Thermal_Stress_on_Dinosaur_.htm

In order to further study the effect of thermal stress for further research on dinosaur fossils with inner crack, six kinds of temperature difference in 10 â,20â,30â,40â,50â and 60â have been simulated. The mechanism of effect on dinosaur fossils between surface temperature and the inner temperature has been revealed by using ABAQUS numerical simulation software. As showed by the experimental results, under the action of different temperature difference, the distribution of thermal stress is mainly concentrated in the upper right corner of dinosaur fossils crack, while there is no obvious thermal stress in the lower right corner. The distribution of thermal stress is uneven, which is easy to induce the crack of dinosaur fossil and accelerate the weathering speed. The thermal stress increases approximately linearly with the increase of temperature difference. Under the condition of same temperature difference and different axial compression, the growth rate of thermal stress value has the trend of declining.The largest growth rate is 93.54%, which is formed in the temperature of 10 â and axial compression changing from 0.04 MPa to 0.12 MPa. The minimum growth rate is 17.46%, which is formed in the temperature of 60 â and axial compression changing from 0.12 MPa to 0.20 MPa. Accompanying with the increase of temperature difference, cracking angle will decrease. When the temperature difference is 40 â, the maximum cracking angle is 51.5. When the temperature difference continues to increase, the cracking angle shows a decreasing trend. When the temperature difference grows, the limit load of dinosaur fossil will decrease. Among them, when the temperature difference is 10 â, the maximum limit load is 2.5 MPa. When the temperature difference is 60 â, the minimum limit load is 1.5 MPa.

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