(palaeontology, zoology) A stage in the development of a trilobite at which the creature has gained its adult segmentation, but continues to molt and grow.
2001, Jonathan M. Adrain, Gregory D. Edgecombe, Bruce S. Lieberman (editors), Fossils, Phylogeny, and Form: An Analytical Approach, page 46,A similar situation may also characterize S. wenlockiana, a species with six segments in holaspis, the smallest holaspids of which have similar glabellar lengths to those of the sixth degree meraspis of A. konincki.
2008, Xuejian Zhu, Shanchi Peng, Jingxun Zuo, Revision an Ventral Structure of Guangxiaspis guangxiensis Zhou, 1977 (Trilobita), Isabel Rábano, Rodolfo Gozalo, Diego GarcÃa-Bellido Capdevila (editors), Advances in Trilobite Research, page 444,The pygidial spines are stout and direct outward in the early holaspis (Fig. 2, A-B, F), but become slender and direct inward in the late holaspis (Fig. 2, D, E).
2009, Michael J. Benton, David A. T. Harper, Introduction to Paleobiology and the Fossil Record, page 366,The holaspis stage has a full complement of thoracic segments for the species but growth continues through further molts and maturity may not be reached until some time after the holaspis stage was reached.
