[dinosaur] Dinosaur bone bioerosion + eggshell evolution + Monjurosuchus + more

Ben Creisler

Some recent items notÂyet mentioned...

A fair number of Mesozoic tetrapod topics...

The 170th Regular Meeting
The Palaeontological Society of Japan
Abstracts with Programs (in Japanese)
(February 5â7, 2021, Online, Yokohama)

http://www.palaeo-soc-japan.jp/events/PSJ_Yokohama_Abstracts_2021_WebVersion.pdf

Note that the English title is given at the end of an abstract and the Japanese text can be copied into translation tools. A news story about a regurgitated pellet found with a plesiosaur was posted earlier on the DML.

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Felix J. Augustin, Andreas T. Matzke, Michael W. Maisch &Hans-Ulrich Pfretzschner (2021)
Dinosaur taphonomy of the Jurassic Shishugou Formation (Northern Junggar Basin, NW China) -- insights from bioerosional trace fossils on bone.
Ichnos (advance online publication)
doi: https://doi.org/10.1080/10420940.2021.1890590
https://www.tandfonline.com/doi/full/10.1080/10420940.2021.1890590

Bioerosional trace fossils can offer invaluable insights into taphonomic processes, ecosystem dynamics and environmental conditions that are not obtainable by other lines of evidence. Here, we describe the first invertebrate trace fossils on dinosaur bone from the Upper Jurassic Shishugou Formation of the northeastern Junggar Basin. The traces occur as spherical holes in the bone, closely resembling boreholes attributed to either indeterminate insects or dermestid beetles and thus they are here likewise ascribed to feeding and/or pupation by necrophagous insects. Such bioerosional trace fossils have several taphonomical and palaeoecological implications for they are only inflicted on subaerially exposed tissues and preferentially when carcasses are desiccated. We, therefore, conclude that the dinosaur carcass was exposed for at least several weeks under a semi-arid and seasonal climate before it was buried by sediment. This supports the general palaeoclimatological and paleoenvironmental reconstructions for the Shishugou Formation from sedimentological data. Moreover, this is the first evidence for invertebrateâvertebrate interactions from the Late Jurassic of Asia, offering a novel glimpse into the diverse biotic relationships of this ancient Jurassic ecosystem.

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Liliana D' Alba, Jonathan Goldenberg, Asritha Nallapaneni, Dilworth Parkinson, Zhu Chenhui, Bram Vanthournout & Matthew D. Shawkey (2021)
Evolution of Eggshell Structure in Relation to Nesting Ecology in NonâAvian Reptiles.
Journal of Morphology (advance online publication)
doi: https://doi.org/10.1002/jmor.21347
https://onlinelibrary.wiley.com/doi/10.1002/jmor.21347

Amniotic eggs are multifunctional structures that enabled early tetrapods to colonize the land millions of years ago, and are now the reproductive mode of over 70% of all terrestrial amniotes. Eggshell morphology is at the core of animal survival, mediating the interactions between embryos and their environment, and has evolved into a massive diversity of forms and functions in modern reptiles. These functions are critical to embryonic survival and may serve as models for new antimicrobial and/or breathable membranes. However, we still lack critical data on the basic structural and functional properties of eggs, particularly of reptiles. Here, we first characterized egg shape, shell thickness, porosity, and mineralization of eggs from 91 reptile species using optical images, SEM, and ÎCT, and collected data on nesting ecology from the literature. We then used comparative analyses to test hypotheses on the selective pressures driving their evolution. We hypothesized that eggshell morphology has evolved to protect shells from physical damage and desiccation, and, in support, found a positive relationship between thickness and precipitation, and a negative relationship between porosity and temperature. Although mineralization varied extensively, it was not correlated with nesting ecology variables. Ancestral state reconstructions show thinning and increased porosity over evolutionary time in squamates, but the opposite in turtles and crocodilians. Egg shape, size, porosity and calcification were correlated, suggesting potential structural or developmental tradeoffs. This study provides new data and insights into the morphology and evolution of reptile eggs, and raises numerous questions for additional research.

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Free text:

Roger Benson, Pedro Godoy, Mario Bronzati, Richard Butler & William Gearty (2021)
Reconstructed evolutionary patterns for crocodile-line archosaurs demonstrate impact of failure to log-transform body size data.
PaleorXiv preprint
doi:10.31233/osf.io/k3dwf.
https://paleorxiv.org/k3dwf/

Pseudosuchia includes crocodylians, plus all extinct species more closely related to them than to birds. They appeared around 250 million years ago and have a rich fossil history, showing extinct diversity that exceeds that of their living members1-4. Recently, Stockdale & Benton5 presented analyses of a new dataset of body size estimates spanning the entire evolutionary history of this group. They quantified patterns of average body size, body size disparity through time, and rates of evolution along phylogenetic lineages. Their results suggest that pseudosuchians exhibited considerable variation in rates of body size evolution, for which they provided various group-specific explanations and asserted the importance of climatic drivers. This differs from two recent studies that analysed a substantial portion of pseudosuchian body size evolution and proposed that adaptation to aquatic life, a biological innovation of some subgroups, was the main driver of body size evolution, with patterns of disparity also being influenced by size-dependent extinction risk6,7. Here we show that the analytical results of Stockdale & Benton5 are strongly influenced by a methodological error in their body size index. Specifically, that they chose not to log-transform measurement data prior to analyses.

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Posted earlier but now with free pdf:

ZHANG Li-Jun (2020)
Analysis on fossil community of tetrapods in Lujiatun bed of Lower Cretaceous Yixian Formation in Beipiao, Liaoning.
Global Geology 39(4): 737-745 (Chinese edition)
DOI: 10.3969/j.issn.1004-5589.2020.04.001

http://sjdz.jlu.edu.cn/EN/abstract/abstract9668.shtml

Free pdf:
http://sjdz.jlu.edu.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=9668

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LIANG Qingqing & XING Lida (2021)
Dinosaur-related Database Development and Examples of Data-driven Discovery.
Geological Journal of China Universities 27(1): 32-44. (in Chinese)
DOI: 10.16108/j.issn1006-7493.2020105
https://geology.nju.edu.cn/EN/10.16108/j.issn1006-7493.2020105

Dinosaurs are one of high profile symbols in paleontology. They dominated the Mesozoic terrestrial and marine ecosystems and therefore are of great significance to study the Earth evolution. In recent years, along with the rapid increase dinosaurology data and the quick fusion of data science and paleontology, various types of dinosaur-related databases have been constructed worldwide. Those databases serve for different purposes. Some mainly contain introductions for the aim of popular science, some are built for specific research targets and others are comprehensive paleontological database containing dinosaur data. Because none of them is a professional dinosaur database, common defects such as incomplete data coverage and poor data structure, could be found and none has long-term sustainability. With the help of the Deep-time Digital Earth (DDE) big science project, to construct a professional dinosaur database combining the purposes of scientific research and popular science, can promote both the dinosaur evolution study and the public understanding for paleontology.

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JI Shuâan (2021)
The Chinese translated name of the fossil reptile Monjurosuchus splendens from Jehol Biota and the brief research history on its systematic position.
Geological Review 67(1):67020011 (in Chinese)
http://www.geojournals.cn/georeven/ch/reader/view_abstract.aspx?file_no=20216701038&flag=1

Free pdf:
http://www.geojournals.cn/georeven/ch/reader/create_pdf.aspx?file_no=20216701038&flag=1&journal_id=georeven&year_id=2021

Monjurosuchus splendens is the first formally named fossil reptile taxon from the Lower Cretaceous in western Liaoning Province. The definite meaning of the name Monjurosuchus splendens was not explained by the original author, which caused several different Chinese translated names of this taxon. Its systematic position had also been in dispute for more than a half century, until it was correctly assigned to the Order Choristodera in 2000. In the present paper, a new Chinese translated name of this taxon is suggested, and the research history on the systematic position of this fossil reptile is briefly reviewed and discussed.

Methods: About the revised Chinese name of Monjurosuchus splendens, the writer checks the original meaning about the generic name in the Japanese abstract attached with the first research paper published in English, and the literal sense of the specific name. On the systematic position of this reptile, the writer reviews the research history and confirms the main characters of both Monjurosuchus splendens and another reptile taxon "Rhynchosaurus orientalis".
Results: In the generic name "Monjuro"refers to "Manchoukuo" according to the Japanese abstract of the original paper published in English in 1940.The species name "splendens" in Latin is just one word, meaning "splendid"; on the contrary, it does not consist of two words "splen-"(different from "sphen-" or "sphaen-") and "dens". Since 2000, Monjurosuchus splendens has been correctly regarded as a choristodere. And it has been accepted that "Rhynchosaurus orientalis" is the same animal as Monjurosuchus splendens.
Conclusions: A new Chinese nameâåäææéâ for Monjurosuchus splendens is proposed here instead ofâæéææéâ. The viewpoint is strengthened that this taxon should be classified within Family Monjurosuchidae, Order Choristodera, and that "Rhynchosaurus orientalis" is a synonym of Monjurosuchus splendens.

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