title: Tiny individuals attached to a new Silurian arthropod suggest a unique mode of brood care.
abstract: The ∼430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities-that the tethered individuals represent a different epizoic or parasitic arthropod-appear less likely.
authors.affiliation: Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109; Yale Peabody Museum of Natural History, Yale University, New Haven, CT 06520-8109; derek.briggs@yale.edu.
authors.forename: Derek E G
authors.initials: DE
authors.lastname: Briggs
authors.affiliation: Oxford University Museum of Natural History, Oxford OX1 3PW, United Kingdom; Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom;
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Siveter
authors.affiliation: Department of Geology, University of Leicester, Leicester LE1 7RH, United Kingdom;
authors.forename: David J
authors.initials: DJ
authors.lastname: Siveter
authors.affiliation: Department of Earth Sciences and Engineering, Imperial College London, London SW7 2BP, United Kingdom.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Sutton
authors.affiliation: Oxford University Museum of Natural History, Oxford OX1 3PW, United Kingdom;
authors.forename: David
authors.initials: D
authors.lastname: Legg
mesh_terms: D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology* / Q000502:physiology*; D004739:England; D005580:Fossils
keywords: Herefordshire Lagerstätte; Silurian; arthropod; brood care; juvenile