Liu, Y., Q. Ji, X. Wang, J. Yang, J.K. O’Connor, B. Guo, T. Ren, T. Yin, and Y. Wang (2024)
Micro-XRF mapping elucidates the taphonomy of two Early Cretaceous paravian fossils from western Liaoning, China
Atomic Spectroscopy 45: 123–131
doi: 10.46770/AS.2024.033
https://www.at-spectrosc.com/as/article/abstract/2024033Free pdf:
https://www.at-spectrosc.com/as/article/pdf/2024033Paraves is the taxonomic group that includes Dromaeosauridae, Troodontidae and Avialae, and thus records the origin of birds, the evolution of pennaceous feathers, and their exaptation for flight. Non-destructive micro-X-ray fluorescence (micro-XRF) imaging technology was utilized to analyze two paravian fossil specimens, one referrable to the Microraptorinae (Dromaeosauridae) and the other to the Yanornithidae (Avialae). Both fossils are from the Lower Cretaceous Aptian Jiufotang Formation, a Lagerstätte that records the youngest stage of the famous Jehol Biota in western Liaoning, China. The analyses show that the bones preserve high amounts of Calcium (Ca), Phosphorus (P), and Sulfur (S), with significant amounts of heavy elements such as Strontium (Sr) and Yttrium (Y) which may be related to biological apatite. The preserved feathers show high amounts of Cuprum (Cu), Nickel (Ni) and Titanium (Ti). The claw sheaths exhibit high levels of P and Ca, which suggests they were preserved through phosphatization. Notably, large amounts of Ferrum (Fe) occur at the intraskeletal joints in both specimens and in the trunk of the microraptorine. Further analyses indicate that the enrichment of Fe may be related to the presence of pyrite. The distribution of Fe indicates precipitation of this element was a postburial taphonomic process. This micro-XRF data reveals the distribution of elements in different tissue types in these two paravian fossils and provides information for reconstructing the taphonomic processes responsible for exceptional preservation in paravian fossils in the Jiufotang Formation.