Skip to main content
SpringerLink
Log in

The Complex Structure of the Cuticle of Pseudagnostus (Agnostina, Trilobita?)

  • Published:
Paleontological Journal Aims and scope Submit manuscript

Abstract

The cuticle of Pseudagnostus ex gr. cyclopyge, a member of Agnostina, which is currently conditionally considered as an arthropod stem lineage, was studied using SEM. It has been believed so far that the agnostoid cuticle is simple and single-layered, differing in its primitive structure from other arthropods, both modern and extinct. However, our results showed that at least in this species, the cuticle has a very complex structure. Their carapace consisted of three layers, and each layer was characterized by its own features. The outer layer, which was a combination of a thin upper prismatic unit and a thick principal unit composed of relatively loosely packed lamellae, overlies the transitional layer. The transitional layer consists of stacks of thin lamellae, directed differently in each stack. On the thin inner layer there were numerous pits with a central element (peg). The peg pits create a specific profile of the inner layer, although the functions of these peg pits are not clear. The inner layer is underlain by a basal matrix of rhomboid fibrillar mesh possibly of chitin-protein nature. Specific cuticular sensilla were found both on the outer and inner layers. On the glabellar culmination there is a V-shaped groove with two rows of digitiform sensilla in the V-branches; campaniform sensilla were located along the symmetry axis between the branches. This sensory field apparently performed a mechanosensory function responding to currents outside an enrolled animal. Given the complexity of the integument of this species, further comparison with other agnostoid species, as well as with the cuticle of other arthropods, is needed. Such a comparison would be promising for understanding the phylogenetic position of Agnostina, as well as the evolution of the arthropod exoskeleton.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1.

Similar content being viewed by others

REFERENCES

  1. Dalingwater, J.E., Hutchinson, S.J., Mutvei, H., and Siveter, D.J., Cuticular ultrastructure of the trilobite Ellipsocephalus polytomus from the Middle Cambrian of Oland, Sweden, Palaeontology, 1991, vol. 34, pp. 205–217.

    Google Scholar 

  2. Dalingwater, J.E., Siveter, D.J., Mutvei, H., Cuticular micro-structure of some Silurian homalonotid trilobites from Sweden, J. Paleontol., 1999, vol. 73 (2), pp. 256–262.

    Article  Google Scholar 

  3. Dupont, S.T.K., Chambered cuticle, pellicles, strange sensilla, and extraordinary muscle arrangements: A study of the micropterigid larval trunk (Lepidoptera: Micropterigidae), J. Morphol., 2014, vol. 275 (7), pp. 797–821.

    Article  Google Scholar 

  4. Hackman, R.H., Expanding abdominal cuticle in the bug Rhodnius and the tick Boophilus, J. Insect Physiol., 1975, vol. 21, pp. 1613–1623.

    Article  Google Scholar 

  5. Hong, P.S., Lee, J.G., and Choi, D.K., Trilobites from the Lejopyge armata Zone (Upper Middle Cambrian) of the Machari Formation, Yongwol Group, Korea, J. Paleontol., 2003, vol. 77(5), pp. 895–907.

    Article  Google Scholar 

  6. Korovnikov, I.V. and Novozhilova, N.V., New data on the biostratigraphy of the Lower and Lower Middle Cambrian of the Kharaulakh Mountains (northeast of the Siberian Platform, Chekurovskaya Anticline), Geol. Geophys., 2012, vol. 53, no. 8, pp. 1014–1026.

    Google Scholar 

  7. Lazarenko, N.P. and Nikiforov, N.I., Middle and Upper Cambrian of the north of the Siberian Platform and adjacent folded areas, in Stratigrafiya, paleogeografiya i poleznyye iskopayemyye severnoy Arktiki (Stratigraphy, Paleogeography, and Minerals of the Northern Arctic), Leningrad: Nauchno-Issled. Inst. Geol. Arktiki, 1972, pp. 4–10.

  8. Lazarenko, N.P., Pegel, T.V., Sukhov, S.S., Abaimova, G.P., and Gogin I.Ya., The type section of the Upper Cambrian of the Siberian Platform is a candidate for the stratotype of stages of the international stratigraphic scale (Khos-Nelege River, western Yakutia, Russia), in Mater. 13-y Mezhd. konf. rabochey gruppy po yarusnomu deleniyu kembriya (Proc. 13th Int. Conf. of the Working Group on Stage Division of the Cambrian), Novosibirsk: Sib. Otd. Ross. Akad. Nauk, 2008, pp. 3–58.

  9. Leopold, R.A., Newman, S.M., and Helgeson. G., A comparison of cuticle deposition during the pre- and posteclosion stages of the adult weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), Int. J. Insect Morphol. Embryol., 1992, vol. 21, pp. 37–62.

    Article  Google Scholar 

  10. Li, G., Steiner, M., Zhu, M., and Zhao, X., Early Cambrian eodiscoid trilobite Hupeidiscus orientails from South China: Ontogeny and implications for affinities of Mongolitubulus-like sclerites, Bull. Geosci., 2012, vol. 87 (1), pp. 159–169.

    Article  Google Scholar 

  11. Locke, M., The Wigglesworth Lecture: Insects for studying fundamental problems in biology, J. Insect Physiol., 2001, vol. 47, pp. 495–507.

    Article  Google Scholar 

  12. McAllister, J.E. and Brand, U., Primary and diagenetic microstructures in trilobites, Lethaia, 1989, vol. 22, pp. 101–111.

    Article  Google Scholar 

  13. Miller, J., Structure and function of trilobite terrace lines, Fossil and Strata, 1975, vol. 4, pp. 155–178.

    Article  Google Scholar 

  14. Moysiuk, J. and Caron, J.-B., Burgess Shale fossils shed light on the agnostid problem, Proc. R. Soc. B, 2019, vol. 286, Paper 20182314. https://doi.org/10.1098/rspb.2018.2314

  15. Müller, K.J. and Walossek, D., Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden, Fossils and Strata, 1987, vol. 19, pp. 1–124.

    Article  Google Scholar 

  16. Mutvei, H., SEM studies on arthropod exoskeletons. 2. Horseshoe crab Limulus polyphemus (L.) in comparison with extinct eurypterids and recent scorpions, Zool. Scripta, 1977, vol. 6, pp. 203–213.

    Article  Google Scholar 

  17. Neville, A.C., Biology of the Arthropod Cuticle, Berlin: Springer-Verlag, 1975.

    Book  Google Scholar 

  18. Okada, J., Structure and cuticle formation on the reticulated carapace of the ostracode Bicornucythere bisanensis, Lethaia, 1982, vol. 15, pp. 85–101.

    Article  Google Scholar 

  19. Peng, S. and Robison, R.A., Agnostoid biostratigraphy across the Middle–Upper Cambrian boundary in Hunan, China, J. Paleontol., 2000, vol. 74, no. S53, pp. 1–104.

    Article  Google Scholar 

  20. Roer, R., Abehsera, S., and Sagi, A., Exoskeletons across the Pancrustacea: Comparative morphology, physiology, biochemistry and genetics, Integr. Comp. Biol., 2015, vol. 55, pp. 771–791.

    Article  Google Scholar 

  21. Roer, R. and Dillaman, R., The structure and calcification of the crustacean cuticle, Am. Zool., 1984, vol. 24, pp. 893–909.

    Article  Google Scholar 

  22. Shergold, J.H., Classification of the trilobite Pseudagnostus, Palaeontology, 1977, vol. 20, pp. 69–100.

    Google Scholar 

  23. Teigler, D. and Towe, K.M., Microstructure and composition of the trilobite exoskeleton, Fossils and Strata, 1975, vol. 4, pp. 137–149.

    Article  Google Scholar 

  24. Wang, L., Vannier, J., Yang, X.-g., Sun, Y.-f., Hao, W.-J., Tang, Q.-q., Lui, P., and Han, J., Cuticular reticulates replicates the pattern of epidermal cells in lowermost Cambrian scalidophoran worms, Proc. Biol. Sci., 2020, vol. 287 (1926), Paper 20200470.

  25. Whittington, H.B. and Wilmot, N.V., Microstructure and sculpture of the exoskeletal cuticle, in Treatise on Invertebrate Paleontology, Part O, Arthropoda 1. Trilobita, Revised. Vol. 1: Introduction, Order Agnostida, Order Redlichiida, Lawrence, Kansas: Univ. Kansas Press., 1997, pp. 74–83.

  26. Wilmot, N.V., Design and Function of Trilobite Exoskeletons. Unpublished Ph.D. Thesis, Aston University, UK, 1988.

  27. Wilmot, N.V., Cuticular structure of the agnostine trilobite Homagnostus obesus, Lethaia, 1990, vol. 23 (1), pp. 87–92.

    Article  Google Scholar 

  28. Yamada, S., Ultrastructure and cuticle formation of the carapace in the myodocopan ostracod exemplified by Euphilomedes japonica (Crustacea: Ostracoda), J. Morphol., 2019, vol. 280, pp. 809–826.

    Article  Google Scholar 

Download references

ACKNOWLEDGMENTS

The authors sincerely thank Roman Rakitov (Paleontological Institute, Russian Academy of Sciences), who contributed greatly, both inspirationally and technically, to the SEM study of the material. The authors are also grateful to the reviewers A.S. Alekseev and I.V. Korovnikov, whose recommendations undoubtedly helped to improve the original manuscript.

Funding

The work was carried out within the framework of the state task of the PIN RAS and the state task of Moscow State University.

Author information

Authors and Affiliations

  1. Paleontological Institute, Russian Academy of Sciences, 117647, Moscow, Russia

    E. B. Naimark

  2. Biology Faculty, Moscow State University, 119192, Moscow, Russia

    S. Yu. Chaika

Authors
  1. E. B. Naimark
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. S. Yu. Chaika
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding authors

Correspondence to E. B. Naimark or S. Yu. Chaika.

Ethics declarations

The authors declare that they have no conflict of interest.

Additional information

Translated by S. Nikolaeva

Publisher’s Note.

Pleiades Publishing remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Naimark, E.B., Chaika, S.Y. The Complex Structure of the Cuticle of Pseudagnostus (Agnostina, Trilobita?). Paleontol. J. 57, 762–774 (2023). https://doi.org/10.1134/S0031030123070080

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1134/S0031030123070080

Keywords:

Search

Navigation