Abstract: Background, aim, and scope Oviparous animals accounted for more than 90% of the total animal species, and therefore oviparity is the most common reproductive type. Egg hatching is sensitive to seasonal abrupt climate change occurring during breeding seasons, and hatching success or failure is closely related to population dynamics and community succession. Therefore, eggs are a promising multi-discipline research record in paleoclimatology, paleoecology and paleontology. With the diversity of eggs and numerous research advancement, it is necessary to review the advancement of research in fossil eggs. Materials and methodsPrevious research on fossil eggs are summarized and reviewed. The advantages and potential value of fossil snail eggs are highlighted. Results The researches on fossil eggs mainly focus on vertebrate groups, which provides important evidence for the evolution of vertebrates. However, fossil eggs of vertebrates rarely form long and continuous sequences in the strata. Therefore, it is almost impossible through studies of vertebrate eggs to decipher the influence of climate change on the evolution of oviparous animals and on the succession of oviparous animal communities through time during geological past. Different from oviparous vertebrate, oviparous invertebrates generally can lay abundant eggs and so their eggs can continuously distribute in stratigraphy. Discussion This provides a great potential for reconstructing long sequences of eggs. Among oviparous invertebrates, snails and their eggs are the most abundant fossil in the Quaternary Chinese loess deposits. Therefore, snail eggs can be used to establish long and continuous egg sequences spanning numerous glacial-interglacial cycles, with the potential to provide novel understandings.Conclusionsinvertebrate eggs are likely used to decipher the impact of climate change on organism through time on long timescales, among which eggs of snail are most abundant. In order to fully explore the paleoclimatological and paleoecological significances of fossil snail eggs, it is urgent to clarify the implication of snail eggs to seasonal abrupt climate events, and to establish the long sequence of Quaternary fossil snail eggs, so as to reveal the change processes and characteristics of seasonal abrupt climate events during glacial-interglacial cycles. Most fossil snails are extant, which provides the opportunities to understand the climatic implications of their eggs through field observations and culturing experiment. Hopefully, the combination of studies on modern and geological processes will provide accurate interpretation of the Quaternary fossil egg changes. Recommendations and perspectivesFossil eggs are particularly useful in paleontology, paleoclimatology and paleoecology. Long time-series of eggs are rare. Systematic study of fossil eggs from one of the most abundant oviparous invertebrates, snails, based on both experimental and field investigations, is expected to establish long sequence of fossil eggs and yield new findings.
Keywords: fossil eggs; vertebrate; invertebrate; snail; paleoclimatology; paleoecology; paleontology