Abstract:

As the most important late Cretaceous dinosaur egg fossil producing area in China, Ganzhou’s fossil record has unique value in revealing dinosaur breeding behavior and paleoenvironmental evolution.In this study, multi-scale analysis (polarizing microscope, scanning electron microscope and sedimentology) was used to systematically study the newly discovered dinosaur egg fossils in the Lianhe Formation (K₂l) in Zhanggong area.The results showed that: (1) The egg body was elongated in appearance, with a long diameter of 165-184 mm (mean 174 mm) and an equatorial diameter of 65-79 mm (mean 73 mm).The egg body was ridged in shape, and the ratio of the thickness of the shell columnar layer to the pyramidal layer was about 6:1, which was confirmed as Elongatoolithus magnus.(2) Under the scanning electron microscope, the pyramidal layer was intact and neatly arranged, the interior was dense, and the mastoid space was small, indicating that the nest of dinosaur eggs should be in the early stage of embryo hatching.The columnar layer mainly develops vertical micro-pores, which is conducive to the exchange of gas and water.There is a loose layer with large pores on the columnar layer, which can protect the eggshell.The large eggshell thickness may be affected by the arid-semi-arid climatic conditions at the end of the Late Cretaceous.(3) According to the lithology and structure of the strata containing dinosaur eggs, the study area belongs to the sedimentary facies of the middle-distal braided channel of the alluvial fan, and from the preservation state of the egg nest, it can be seen that the egg fossils are buried in situ.

Key words: dinosaur egg, late Cretaceous, structure of eggshell, ultrastructural characteristics