Abstract
Ten distinct microstructures occur in fossil serpulids and serpulid tubes can contain several layers with different microstructures. Diversity and complexity of serpulid skeletal structures has greatly increased throughout their evolution. In general, Cenozoic serpulid skeletal structures are better preserved than Mesozoic ones. The first complex serpulid microstructures comparable to those of complex structures of molluscs appeared in the Eocene. The evolution of serpulid tube microstructures can be explained by the importance of calcareous tubes for serpulids as protection against predators and environmental disturbances. Both fossil cirratulids and sabellids are single layered and have only spherulitic prismatic tube microstructures. Microstructures of sabellids and cirratulids have not evolved since the appearance of calcareous species in the Jurassic and Oligocene, respectively. The lack of evolution in sabellids and cirratulids may result from the unimportance of biomineralization for these groups as only few species of sabellids and cirratulids have ever built calcareous tubes.
Highlights
IntroductionCalcareous tubes are known in serpulids, cirratulids and sabellids [1,2,3]
Among polychaete annelids, calcareous tubes are known in serpulids, cirratulids and sabellids [1,2,3].The earliest serpulids and sabellids are known from the Permian [4], and cirratulids from the Oligocene [5]
The aim of the present paper is to review known mineral microstructes and mineral compositions of fossil calcareous polychaetes and to hypothesize about the evolution of polychaete biomineralization
Summary
Calcareous tubes are known in serpulids, cirratulids and sabellids [1,2,3]. The earliest serpulids and sabellids are known from the Permian [4], and cirratulids from the Oligocene [5]. Polychaete annelids build their tubes from calcite, aragonite or a mixture of both polymorphs. Calcareous polychaete tubes possess a variety of ultrastructural fabrics, from simple to complex, some being unique to annelids [1]. Serpulid tubes are usually single layered or composed of two layers, but some species have multiple tube layers [1,6,7,8,9,10]. Modern calcareous sabellid tubes can have two layers with distinct microstructures [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
