Eurypterids from the Viséan of East Kirkton, West Lothian, Scotland

Abstract

The hibbertopteroid eurypterid genera Hibbertopterus, Dunsopterus, and Cyrtoctenus occur in the East Kirkton Limestone of Bathgate, West Lothian. Most specimens are fragmentary and appear to have been washed into the depositional area with plant debris and tuffaceous sediment. Nearly all of the identifiable material can be attributed to Hibbertopterus scouleri (Hibbert), but two isolated Cyrtoctenus combs, and a femur comparable with Dunsopterus have also been recognised.New material of Hibbertopterus scouleri (Hibbert) reveals that the posterior legs and telson resemble those of the cyrtoctenids more closely than was previously thought. It is possible that Hibbertopterus, Dunsopterus, and Cyrtoctenus are indistinguishable except by relatively minor characteristics, and that all of the material from East Kirkton Quarry might be derived from a single eurypterid species. However, associations of the diagnostic sclerites which would demonstrate that these taxa are either cogeneric or distinct have not yet been found.

Redescription of Drepanopterus abonensis (Chelicerata: Eurypterida: Stylonurina) from the late Devonian of Portishead, UK

“…1985). The term ‘blade’ is used to describe the broad, flattened spines on the anterior prosomal appendages, as in Hibbertopterus and Cyrtoctenus (Jeram and Selden 1994), although the term was not introduced until similar structures were identified in Woodwardopterus and Megarachne (Selden et al. 2005).…”

“…Drepanopterus abonensis resembles the Carboniferous sweep‐feeders in having blades on its anterior appendages. The blades possessed large sensory setae, pits of which are seen on the blades in Hibbertopterus (Jeram and Selden 1994). Drepanopterus ’ mode of life was similar to the mycteropids and Hibbertopterus ; however, the primitive nature of the blades and the lack of coxal laden indicate Drepanopterus to be a proto‐sweep‐feeder, less specialised than its Carboniferous relatives.…”

“…The intrarelationships of the hibbertopterids are contentious, with various genera considered by Jeram and Selden (1994) and Selden et al. (2005) to be ontogenetic gradients of others.…”

A new Early Carboniferous tetrapod with a mélange of crown-group characters

“…Here we examine directly the role of ecological opportunity and competition in driving genetic diversification. We use the common aerobic bacterium Pseudomonas fluorescens 10 , which evolves rapidly under novel environmental conditions to generate a large repertoire of mutants [11][12][13] . When provided with ecological opportunity (afforded by spatial structure), identical populations diversify morphologically, but when ecological opportunity is restricted there is no such divergence.…”

Arthropod cuticles from the upper Viséan (Mississippian) of eastern Germany

“…Several myriapods (Shear 1994) are known as well as one harvestman (Dunlop & Anderson 2005). Eurypterids are represented by the up to 1.5 m long supposedly amphibious-terrestrial Hibbertopterus scouleri (Jeram & Selden, 1994) (Whyte 2005). The fish fauna of the lake consisted of different actinopterygians, acanthodians and a rhizodontid sarcopterygian as well as hybodont and xenacanth sharks (Coates 1994, Paton 1994) -the latter fishes are the producers of the shark egg capsules known from the Hainichen Subgroup .…”