Hostname: page-component-8448b6f56d-gtxcr Total loading time: 0 Render date: 2024-04-23T22:45:35.869Z Has data issue: false hasContentIssue false
  • English
  • Français

Ontogeny of the Ptychaspidid Trilobite Quadraticephalus elongatus Kobayashi, 1935 from the Furongian (Late Cambrian) Hwajeol Formation, Korea

Published online by Cambridge University Press:  15 October 2015

Ji-Hoon Kihm ,
Tae-Yoon Park  and
Duck K. Choi
Ji-Hoon Kihm
Affiliation:
School of Earth and Environmental Sciences, Seoul National University, Seoul 151–747, Korea, ; Division of Polar-Earth System Sciences, Korea Polar Research Institute, Incheon 406–840, Korea,
Tae-Yoon Park
Affiliation:
Division of Polar-Earth System Sciences, Korea Polar Research Institute, Incheon 406–840, Korea,
Duck K. Choi
Affiliation:
School of Earth and Environmental Sciences, Seoul National University, Seoul 151–747, Korea, ;
Get access Rights & Permissions [Opens in a new window]

Abstract

The development of the trilobite pygidium involves both an articulation process at the frontal part and the formation of new segments at the rear end, and hence the development of the meraspid pygidium entails complicated morphological changes. This study deals with the ontogeny of the Furongian (late Cambrian) ptychaspidid trilobite, Quadraticephalus elongatus (Kobayashi, 1935), from the Hwajeol Formation of the Taebaek Group, Taebaeksan Basin, Korea, with a special focus on the segmentation process during the meraspid pygidial development. Compared to the ontogeny of a ptychaspidid trilobite, Asioptychaspis subglobosa (Sun, 1924), which is assumed to be an ancestral species of Q. elongatus, the convexity of the cranidium of Q. elongatus increased in a slower rate; the yoked free cheek of Q. elongatus splits to form a ventral median suture in a later developmental stage; and, a rim-like ridge, which disappeared in the early holaspid pygidium of A. subglobosa, was maintained in the late holaspid period of Q. elongatus. These morphological changes with growth imply that paedomorphosis was involved in the evolution of Q. elongatus. Eleven stages are recognized for the meraspid pygidial development, which began with an accumulation phase during which the number of segments increased from three to seven, followed by an equilibrium phase with seven segments, and ended up with a depletion phase during which the number of segments within the pygidium decreased to four. During the depletion phase, the pygidial length did not increase or even slightly decreased. The onset of the epimorphic phase, in which the total number of trunk segments does not increase anymore, precedes the onset of the holaspid period, demonstrating that the developmental mode of Q. elongatus is protomeric.

Type
Research Article
Information
Journal of Paleontology , Volume 87 , Issue 3 , May 2013 , pp. 379 - 390
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adrain, J. M. 2011. Class Trilobita Walch, 1771. InZhang, Z.-Q.(ed.), Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa, 3148:104–109.CrossRefGoogle Scholar
Adrain, J. M., Peters, S. E., and Westrop, S. R. 2009. The Marjuman trilobite Cedarina Lochman: thoracic morphology, systematics, and new species from western Utah and eastern Nevada, U.S.A. Zootaxa, 2218:35–58.CrossRefGoogle Scholar
Chatterton, B. D. E. and Speyer, S. E. 1997. Ontogeny, p. 173–247. InKaesler, R. L.(ed.), Treatise on Invertebrate Paleontology, Pt. O, Arthropoda 1, Trilobita 1 (Revised). Geological Society of America and University of Kansas Press, Lawrence, Kansas and Boulder, Colorado.Google Scholar
Choi, D. K. 1998. The Yongwol Group (Cambrian–Ordovician) redefined: a proposal for the stratigraphic nomenclature of the Choson Supergroup. Geoscience Journal, 2:220–234.CrossRefGoogle Scholar
Choi, D. K., Chough, S. K., Kwon, Y. K., Lee, S.-B., Woo, J., Kang, I., Lee, H. S., Lee, S. M., Sohn, J. W., Shinn, Y. J., and Lee, D.-J. 2004. Taebaek Group (Cambrian–Ordovician) in the Seokgaejae section, Taebaeksan Basin: a refined lower Paleozoic stratigraphy in Korea. Geoscience Journal, 8:125–151.CrossRefGoogle Scholar
Endo, R. and Resser, C. E. 1937. The Sinian and Cambrian formations and fossils of southern Manchoukuo. Manchurian Science Museum Bulletin, 1:1–474.Google Scholar
Fortey, R. A. 1990. Ontogeny, hypostome attachment and trilobite classification. Palaeontology, 33:529–576.Google Scholar
Fortey, R. A. 1997. Late Ordovician trilobites from southern Thailand. Palaeontology, 40:397–449.Google Scholar
Fortey, R. A. and Chatterton, B. 1988. Classification of the trilobite suborder Asaphina. Palaeontology, 31:165–222.Google Scholar
Hughes, N. C., Minelli, A., and Fusco, G. 2006. The ontogeny of trilobite segmentation: a comparative approach. Paleobiology, 32:602–627.CrossRefGoogle Scholar
Kobayashi, T. 1933. Upper Cambrian of the Wuhutsui basin, Liaotung, with special reference to the limit of Chaumitien (or Upper Cambrian) of eastern Asia and its subdivision. Japanese Journal of Geology and Geography, 11:55–155.Google Scholar
Kobayashi, T. 1935. The Cambro–Ordovician Formations and Faunas of south Chosen. Palaeontology, Part 3, Cambrian Faunas of south Chosen with a special study on the Cambrian trilobite genera and families. Journal of the Faculty of Science, 4 (2):49–344.Google Scholar
Kobayashi, T. 1942. Two new trilobite genera, Hamashania and Kirkella. Journal of the Geological Society of Japan, 59:37–40.Google Scholar
Lee, S. B. and Choi, D. K. 2011. Dikelocephalid trilobites from the Eosaukia fauna (upper Furongian) of the Taebaek Group, Korea. Journal of Paleontology, 85:279–297.CrossRefGoogle Scholar
Park, T.-Y. and Choi, D. K. 2009. Post-embryonic development of the Furongian (late Cambrian) trilobite Tsinania canens: implications for life mode and phylogeny. Evolution and Development, 11:441–455.CrossRefGoogle ScholarPubMed
Park, T.-Y. and Choi, D. K. 2010 a. Two middle Cambrian diceratocephalid trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, from Korea: development and functional morphology. Lethaia, 43:73–87.CrossRefGoogle Scholar
Park, T.-Y. and Choi, D. K. 2010 b. Ontogeny and ventral median suture of the ptychaspidid trilobite Asioptychaspis subglobosa (Sun, 1924) from the Furongian (upper Cambrian) Hwajeol Formation, Korea. Journal of Paleontology, 84:309–320.CrossRefGoogle Scholar
Park, T.-Y. and Choi, D. K. 2011 a. Ontogeny of the Furongian (late Cambrian) remopleuridioid trilobite Haniwa quadrata Kobayashi, 1933 from Korea: implications for trilobite taxonomy. Geological magazine, 148:288–303.CrossRefGoogle Scholar
Park, T.-Y. and Choi, D. K. 2011 b. Constraints on using ontogenetic data for trilobite phylogeny. Lethaia, 44:250–254.CrossRefGoogle Scholar
Salter, J. W. 1864. On some new fossils from the Lingula-flags of Wales. Quarterly Journal of the Geological Society, 20 (1−2):233–241.CrossRefGoogle Scholar
Simpson, A. G., Hughes, N. C., Kopaska-Merkel, D. C., and Ludvigsen, R. 2005. Development of the caudal exoskeleton of the pliomerid trilobite Hintzeia plicamarginis new species. Evolution and Development, 7:528–541.CrossRefGoogle ScholarPubMed
Sohn, J. W. and Choi, D. K. 2007. Furongian trilobites from the Asioptychaspis and Quadraticephalus zones of the Hwajeol Formation, Taebaeksan Basin, Korea. Geoscience Journal, 11:297–314.CrossRefGoogle Scholar
Sun, Y. C. 1924. Contributions to the Cambrian faunas of North China. Palaeontological Sinica Series B, 1:297–314.Google Scholar
Walcott, C. 1905. Cambrian faunas of China. Proceedings of U.S. National Museum, 29:1–106.CrossRefGoogle Scholar
Whittington, H. B. 2003. The upper Cambrian trilobites Plethopeltis and Leiocoryphe: morphology, paedomorphism, classification. Journal of Paleontology, 77:698–705.2.0.CO;2>CrossRefGoogle Scholar
Whittington, H. B. 2007. Reflections on the classification of the Trilobita. New York State Museum Bulletin, 507:225–230.Google Scholar
Whittington, H. B. and Kelly, S. R. A. 1997. Morphological terms applied to Trilobita, p. 313–329. InKaesler, R. L.(ed.), Treatise on Invertebrate Paleontology, Pt. O, Trilobita (Revised). Geological Society of America and University of Kansas Press, Lawrence, Kansas.Google Scholar
Zhang, W. T. and Jell, P. A. 1987. Cambrian trilobites of North China: Chinese trilobites housed in the Smithsonian Institution. Science Press, Beijing, 459p.Google Scholar