A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41922763.
- Also identified by DOI 10.1038/s41586-026-10284-2.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Chelicerata is a megadiverse (over 120,000 species) arthropod clade that includes familiar taxa of profound ecological and economic importance, such as scorpions, spiders and mites<sup>1</sup>. Extant chelicerates share a unique anatomical character, the chelicerae-feeding first appendages terminated by a simple pincer-like chela<sup>2</sup>. The fossil record of these primarily predatory animals spans almost 500 million years<sup>3</sup>, suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods<sup>4-6</sup>, megacheirans<sup>4,7-9</sup>, habeliids<sup>10-13</sup> and mollisoniids<sup>14,15</sup> have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan's origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.