Identification of chitin in 200-million-year-old gastropod egg capsules

Abstract

Chitin occurs in a variety of invertebrates, especially in arthropod cuticles, but is rarely reported in the fossil record. Although it has been detected in fossils as old as Middle Cambrian and Silurian, the majority of records come from much younger, Cenozoic deposits. In this paper, we report the preservation of chitin in Early Jurassic neritimorph gastropod egg capsules deposited in bivalve shells from prodelta-deltafront and nearshore paleoenvironments of the Holy Cross Mountains, Poland. We used a number of analytical methods to confirm the presence of chitin preserved in these ancient fossils. This is the first record of chitin preservation in Mesozoic deposits that, interestingly, do not follow the conventional Konservat-Lagerstätten manner of preserving soft-bodied and non-biomineralized organisms. We believe that deltaic settings characterized by episodic, high input of fluvial deposits, oligohaline conditions, and oxygen-poor microenvironment within the sediment—as well as early cementation of sediment infilling the shells—were crucial for chitin preservation. The preservation of chitin in such recalcitrant structures as egg capsules and deposits that formed outside conventional Konservat-Lagerstätten conditions renders it likely similar deposits may yield promise for discoveries of similar biological macromolecules.

Renewable chitin from marine sponge as a thermostable biological template for hydrothermal synthesis of hematite nanospheres using principles of extreme biomimetics

“…As a preliminary procedure for identifying the intactness of chitin structures in these composites we used a specific chitin stain Calcofluor White (CFW), the fluorescent brightener [26,27,[39][40][41][42][43][44][45][46]. CFW binds to the glucan chains and linear β-(1,4)-glucosidically linked units of N-acetyl-D-glucosamine.…”

Poriferan Chitin as a Versatile Template for Extreme Biomimetics

“…Recently, Ehrlich and co-workers reported that fragments of chitin fibers survived in the 505 million year old (Middle Cambrian) Burgess Shale Vauxia gracilenta sponge fossils [60]. The chitin found in these Vauxia sponge fossils is thus far the oldest known to show this exceptional chitin preservation, compared to previously reported chitin fossils [61,62].…”

Gastropod egg capsules preserved on an Early Cretaceous ammonite from Daghestan, Russia

“…2013). They are tough, leathery and, although composed of such organic compounds as conchiolin and chitin (Adegoke et al, 1969;Bandel 1982;Soliman 1987;Kano and Fukumori 2010;Fukumori et al, 2013;Wysokowski et al, 2014), they may additionally be strengthened by aragonitic or calcitic spherulites, as well as other different particles stored in the unique organ called the crystal sac (see Kano and Fukumori 2010;Fukumori et al, 2013). This feature gives the neritimorph egg capsules better fossilization potential than those produced by other gastropods.…”

“…Certainly, these egg capsules have not been reinforced by other particles as such were not detected. If the crystal sac and hence the calcium carbonatestrengthened egg capsules originated during the Late Cretaceous along with the divergence of the family Neritidae (see Fukumori et al, 2013), then the older neritimorphs could have produced "soft", unstrengthened egg capsules, composed of such organic compounds as chitin, which has been detected in the Early Jurassic egg capsules (Wysokowski et al, 2014).…”