We report the discovery of concentrated invertebrate inchnofossils in close association with a dinosaur nest from the Hekou Formation in Jiangxi Province, China. The seven dinosaurian eggs reported clearly belong to the Elongatoolithidae and burrow traces were most likely made by small crustaceans. This association prompts the question as to whether invertebrate activity had relations with the buried eggs. This may be just an occasional case or the eggs may have organically increased the content of organic matter in soil which attracted the crustaceans.

For social insects such as ants, the internal organs are likely important in understanding their eusocial behavior and evolution. Such organs, however, are rarely preserved on fossils. In each of the few cases reporting exceptionally fossilized soft tissues in arthropods, the nervous, muscular and cardiovascular systems have been described individually, but never in combination. Here, we report a female specimen (gyne) of the extinct ant group—†Zigrasimecia—included in a Cretaceous amber piece from Kachin, Myanmar, with an almost complete system formed by various internal organs. These include the brain, the main exocrine system, part of the digestive tract, and several muscle clusters. This research expands our knowledge of internal anatomy in stem group ants. As the gyne bears a morphologically unique labrum, our specimen’s internal and external features support the notion that the early ant may have special ecological habits during the Cretaceous period.

For social insects such as ants, the internal organs are important in understanding their eusocial behaviour and evolution. Such organs, however, are rarely preserved on fossils. In each of the few cases reporting exceptionally fossilized soft tissues in arthropods, only one of the nervous, muscular or cardiovascular systems was described. Here, we report a female specimen (gyne) of the extinct ant group – †Zigrasimecia – included in a Cretaceous amber piece from Kachin, Myanmar, with an almost complete system formed by various internal organs. These include the brain, the main exocrine system, part of the digestive tract, and several muscle clusters. Our findings expand the knowledge of fossil ants to their internal anatomy. As the gyne bears a morphologically unique labrum, the internal and external features of our specimen suggest that the early ant may have special ecological habits during the Cretaceous period.

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