Protaspid larvae are unique to trilobites. (July 2021)

• Record Type: Journal Article
• Authors: Lerosey-Aubril, Rudy; Laibl, Lukáš
• Is Part Of: Arthropod structure & development. Volume 63(2021)
• Publication Date: 2021-07
• Subjects: Euarthropoda -- Aglaspidida -- Trilobita -- Protaspis -- Larval ecology -- Ordovician; Arthropoda -- Morphology -- Periodicals; Arthropoda -- Anatomy -- Periodicals; Arthropoda -- Cytology -- Periodicals; Arthropods -- growth & development -- Periodicals; 595
• DOI: 10.1016/j.asd.2021.101059
• Languages: English
• ISSNs: 1467-8039

Abstract

Abstract: Trilobites represent a model for 'evo-devo' studies in fossil euarthropods, owing to a rare developmental trait: the biomineralization of the dorsal exoskeleton soon after hatching. Many fossilized trilobite ontogenies thus feature early stages – the protaspides – characterized by non-articulated, calcified dorsal exoskeletons. The recent discovery of a protaspid-like fossil occurring with aglaspidid remains in Middle Ordovician strata of Siberia has been interpreted as evidence for the presence of protaspides in these distant relatives of trilobites. In this contribution, we demonstrate that this Siberian protaspis actually belongs to the asaphid trilobite Isotelus (or a related taxon), a genus likely present in the same bed. We conclude that protaspid larvae still represent a developmental trait unique to Trilobita. Highlights: Protaspid larvae uniquely feature a biomineralized non-articulated dorsal exoskeleton. 'Aglaspidid' larva from the Ordovician of Siberia belongs to an asaphid trilobite. Protaspides are unique to Trilobita within the phylum Euarthropoda. Planktonic protaspides might have evolved independently in several trilobite lineages.