of Drepanopterus abonensis (Chelicerata : Eurypterida
: Stylonurina) from the Late Devonian of Portishead, UK
James C. Lamsdell1,
Simon J. Braddy1, and O.
1 Department of Earth Sciences, University
of Bristol, Wills Memorial Building, Queen's Road, BRISTOL
2 Sandmoen Østre, N-7863 Overhalla,
Stylonurid eurypterids (Arthropoda : Chelicerata) include
some of the largest known arthropods; bizarre sweep-feeding
hibbertopterids from the Carboniferous to end-Permian. New
material of Drepanopterus abonensis, a
stylonurid from the Late Devonian (Famennian) of Portishead,
south-west England, offers key insights into this genus
and its affinities. A redescription utilising the new material
enables D. abonensis to be assigned as basal member
of the Superfamily Hibbertopteroidea, the large-sweep feeding
forms, possessing a cleft metastoma and blades (modified
blunt spines) on their anterior prosomal appendages. D.
abonensis also shares characters such as a clavate
telson and median ridge on the carapace with the proposed
hibbertopteroid sister-group, the Kokomopteroidea. Hibbertopteroid
eurypterids are the most long-ranging stylonurids, surviving
the decline and extinction of the other eurypterid families
in the Late Devonian, their survival probably due to their
sweep-feeding mode of life, which was not in direct competition
with their eurypterine relatives and other predators.
words: Palaeozoic, Famennian, Drepanopteridae,
Sweep-feeding, Old Red Sandstone, Hibbertopteroidea, Palaeoecology.