A new species of trigonotarbid arachnid from the Pilsen Basin of the Czech Republic

Abstract A new specimen of the arachnid order Trigonotarbida is described from the Middle Pennsylvanian (lower Desmoinesian) Shelburn Formation of Indiana, which has previously yielded the remains of a phalangiotarbid. Two new trigonotarbid arachnid specimens are also described from the Middle Pennsylvanian (Desmoinesian) Senora Formation of Oklahoma. These are the first trigonotarbid specimens reported from Indiana and Oklahoma. The Indiana trigonotarbid belongs to the Eophrynidae, as indicated by distinct features such as the large tubercles on the dorsal surface of the opisthosoma and two pairs of terminal opisthosomal spines. This specimen is the first arachnid fossil to be imaged using a Multistripe Laser Triangulation scanner. The heavy dorsal tuberculation, lobed and subtriangular carapace, rounded clypeus, lack of terminal opisthosomal spines, and rounded opisthosoma on Oklahoma specimen FMNH PE 56932 indicate it belongs to the genusAphantomartus, in Aphantomartidae. The other Oklahoma specimen, FMNH PE 56955, possesses opisthosomal tergites that are divided into five plates longitudinally as well as a subquadrate carapace, which identify it as a member of Anthracomartidae; its rounded opisthosomal margin shows it to belong to the genusAnthracomartus.

ABSTRACT Molecular clock calculations suggest a late Cambrian (~ 500 Ma) divergence of myriapod classes. Yet, the earliest myriapods only appear in the latest Silurian (~425 Ma). 75 million years later; though correlation with the standard marine-based geological time scale is difficult. We radiometrically dated (U/Pb method) zircons in sediments at 3 sites in the UK associated with the supposed earliest millipedes. Kerrera, with only extinct kampecarid myriapods from temporary playa lake deposits in a semi-arid intermontane basin is 425 Ma old. Ludlow, with kampecarid myriapods and the first trigonotarbid arachnids (with book lungs), from transported material in ripple troughs at the base of a semi-arid delta complex, is 420 Ma. Cowie, with the supposed earliest air-breathing millipede (with spiracles), from a temporary playa lake in an intermontane basin complex, is 414 Ma old. The more diverse land arthropod fauna of the Rhynie Chert hot spring deposit, also in an intermontane basin, is 407 Ma old. A rapid radiative evolution from simple intermontane lake margin communities through more evolved lowland communities took only about 20 Ma to reach complex forest grade communities by the Middle Devonian Givetian (about 385 million years).

ABSTRACT Molecular clock calculations suggest a late Cambrian (~ 500 Ma) divergence of myriapod classes. Yet, the earliest myriapods only appear in the latest Silurian (~425 Ma). 75 million years later; though correlation with the standard marine-based geological time scale is difficult. We radiometrically dated (U/Pb method) zircons in sediments at 3 sites in the UK associated with the supposed earliest millipedes. Kerrera, with only extinct kampecarid myriapods from temporary playa lake deposits in a semi-arid intermontane basin is 425 Ma old. Ludlow, with kampecarid myriapods and the first trigonotarbid arachnids (with book lungs), from transported material in ripple troughs at the base of a semi-arid delta complex, is 420 Ma. Cowie, with the supposed earliest air-breathing millipede (with spiracles), from a temporary playa lake in an intermontane basin complex, is 414 Ma old. The more diverse land arthropod fauna of the Rhynie Chert hot spring deposit, also in an intermontane basin, is 407 Ma old. A rapid radiative evolution from simple intermontane lake margin communities through more evolved lowland communities took only about 40 Ma to reach complex forest grade communities by the Middle Devonian Givetian (about 385 million years).

Summary The distribution of lateral eyes in arachnids and their relatives (Chelicerata) is reviewed, including novel data for selected taxa. Particular focus was given to camel spiders (Solifugae) and whip scorpions (Thelyphonida), for which there are conflicting reports about their eye morphology in the literature, and to the condition in some fossil scorpions (Scorpiones) and some extinct trigonotarbid arachnids (Trigonotarbida), which have lateral eyes with c. 30 or up to 15 individual lenses, respectively. Arachnid outgroups like horseshoe crabs (Xiphosura) and sea scorpions (Eurypterida) have compound lateral eyes, but the hypothesis that reduction of these eyes to five lenses or fewer is a synapomorphy of Arachnida can be rejected. Fossil data indicate, instead, that the arachnid lateral eyes were also originally (semi-) compound, and that reduction to only a handful of lenses must be a homoplastic character state. Note that camel spiders retain vestigial lateral eyes, while fossil ricinuleids had a...

<italic>Trigonotarbus johnsoni</italic> Pocock, 1911, revealed by X-ray computed tomography, with a cladistic analysis of the extinct trigonotarbid arachnids

<i>Trigonotarbus johnsoni</i> Pocock, 1911, revealed by X-ray computed tomography, with a cladistic analysis of the extinct trigonotarbid arachnids

A new eophrynid trigonotarbid (Arachnida: Trigonotarbida: Eophrynidae) from the Pennsylvanian (Kasimovian) Astrasado Formation of the Kinney Brick Quarry, New Mexico is described. This fossil – the first arachnid to be recorded from the Astrasado Formation – is preserved primarily as a dorsal opisthosoma. Pleophrynus hawesi sp. nov. diagnostically preserves evidence for three pairs of posterior opisthosomal spines rather than the two usually seen in other eophrynids. A comparison of opisthosomal tuberculation patterns among the best known eophrynid species is included. At ca. 304.0–306.5 Ma, our new taxon represents one of the youngest records of Eophrynidae, while the Kinney Brick Quarry is only the twelfth site in North America to yield trigonotarbid arachnids; compared to more than 60 such localities in Europe.

This paper serves two roles. First, it acts as an introduction to Blender, an open-source computer graphics program, which can be of utility to paleontologists. To lessen the software's otherwise steep learning curve, a step-by-step guide to create an idealized reconstruction of a fossil in the form of a three-dimensional model in Blender, or to use the software to render results from ‘virtual paleontology' techniques, is provided as an online supplemental data file. Second, here we demonstrate the use of Blender with a case study on the extinct trigonotarbid arachnids. We report the limb articulations of members of the Devonian genusPalaeocharinuson the basis of exceptionally preserved fossils from the Rhynie Cherts of Scotland. We use these newly reported articulations to create a Blender model, and draw comparisons with the gait of extant arachnids to produce as accurate a representation of the trigonotarbid flexing its limbs and walking as possible, presented in additional online supplemental data files. Knowledge of the limb articulations of trigonotarbid arachnids also allows us to discuss their functional morphology: trigonotarbids' limbs and gait were likely comparable to extant cursorial spiders, but lacked some innovations seen in more derived arachnids.

Abstract New records of the extinct arachnid order Trigonotarbida are described from Upper Pennsylvanian (Moscovian: Bolsovian [ = Westphalian C]) spoil heaps associated with the Týnec mine near the village of Týnec in West Bohemia, Czech Republic. Three specimens are recorded, two of which are incomplete opisthosomas assigned to Trigonotarbida incertae sedis. A third fossil is more complete and is described here as Tynecotarbus tichaveki gen. et sp. nov. Its familial position is uncertain, but the presence of a weakly lobed carapace and finely tuberculate body ornament suggests affinities with the ‘eophrynid assemblage’ sensu Dunlop & Brauckmann (2006) and particularly the family Lissomartidae from Mazon Creek, USA. In order to be comprehensive in our study, we include a complete list of Czech trigonotarbids.

A trigonotarbid arachnid referable to Anthracomartus voelkelianus Karsch, 1882 is described from the Late Carboniferous (Moscovian) (= Westphalian C) of Jerusalemsberg near Dobšiná in eastern Slovakia. This record is significant as both the first fossil arachnid formally described from Slovakia and, whilst it does not come from a classic Coal Measures locality with a terrestrial palaeoenvironment, the sediments were deposited in a marine—deltaic environment typical for arachnid fossils. An overview of the distribution of the 17 currently recognized species of Anthracomartidae is presented.

An exceptionally preserved specimen of the extinct trigonotarbid arachnid Eophrynus prestvicii (Arachnida: Trigonotarbida) from the Late Carboniferous (Duckmantian) British Middle Coal Measures of the UK is redescribed with the help of X-ray micro-tomography (XMT). Previous work is summarised and the correct spelling of the species name confirmed. Reconstruction of the void left by the original specimen within a siderite (ironstone) nodule reveals its three-dimensional structure as well as novel details which are difficult to resolve using traditional methods of study. The pedipalps and legs can now be reconstructed almost in their entirety and we can confirm that the chelicerae hung beneath the prosoma with a backwards-directed fang. Opisthosomal segmentation is clarified: a narrow tergite 1 is followed by eight further tergites (2–9), clearly demarked by their ornamentation. In general, a much more accurate picture of the spines and tuberculation ornamenting the dorsal surface of the body was resolved. ...

Two new specimens of a trigonotarbid arachnid are described from Upper Pennsylvanian (Virgilian) rocks of Kansas, U.S.A., from a horizon which elsewhere has yielded scorpion and mite remains. They are the first representatives of the arachnid order Trigonotarbida to be found in Kansas. The specimens are referred to the genus Anthracomartus but are not identified to species pending revision of the American anthracomartids.

An association of trigonotarbid arachnids from Siegenian strata of Burdenbach in the Westerwald is described. The Burdenbach trigonotarbids are numerically dominated by a new genus and species, Spinocharinus steinmeyeri n. gen. n. sp., which is characterized by a rounded carapace with a unique pattern of thorn-like tubercles. A comparison with previously described Devonian trigonotarbids suggests that the new taxon is most probably assignable to the family Palaeocharinidae, which is well represented by the genus Palaeocharinus from the Scottish Rhynie cherts. This would constitute the first record of Palaeocharinidae from the Rhenish Devonian and contrasts sharply with previously described Emsian associations from the Rhenish Slate Mountains, which are dominated by archaeomartids. A rare archaeomartid, Archaeomartus cf. levis, occurs in association with the putative palaeocharinids.

New material of the trigonotarbids Alkenia and Archaeomartus from the Lower Devonian type locality Alken an der Mosel/Germany is described. Stormer’s original description of Alkenia is essentially confirmed and supplemented. The genus is placed in Aphantomartidae. In contrast to earlier accounts, we show that Archaeomartus has an anterior diplotergite and a longitudinally three-divided posteriormost (ninth) tergite. The new family Archaeomartidae is proposed. Whether a marginal row of larger tubercles on the opisthosoma can be recognized is strongly influenced by the taphonomic history of the fossil, and sexual dimorphism may also be involved. Thus, we propose that Archaeomartus levis and A. tuberculatus, which can be discriminated solely by the presence or absence of this feature, are synonyms. Furthermore, morphological similarity suggests the possibility that archaeomartids, with their opisthosomal tergites divided into three plates, gave rise to the later (Carboniferous) anthracomartids, specifically through the division of the lateral plates and the ninth tergite. Finally, our reassessment of Archaeomartus shows that ‘A.’ roessleri Dunlop and Brauckmann, 2006 can no longer be adequately maintained in this genus. This younger species from the early Upper Carboniferous of Hagen-Vorhalle, Germany, is reassigned to Namurotarbus n. gen. as Namurotarbus roessleri n. comb.

A fossil trigonotarbid (Arachnida: Trigonotarbida) assigned to Palaeocharinus sp. from the Early Devonian (c. 410 Ma) Rhynie cherts of Aberdeenshire, Scotland, UK is described, specifically for a previously unrecognised feature of the distal end of the pedipalp. This exhibits a small chela formed from a movable, unpaired apotele articulating against a slightly shorter, fixed projection from the inferior surface of the tarsus. Among other arachnids, this morphology has only previously been observed in the rare and enigmatic Carboniferous—Recent taxon Ricinulei. This character offers explicit support for a monophylum (Trigonotarbida + Ricinulei); a hypothesis previously based on opisthosomal characters which (if correct) would draw Ricinulei within the so-called Pantetrapulmonata clade (i.e. spiders and their closest relatives). Our data is not consistent with Ricinulei’s traditional position as sister-group of mites (Acari) and is an example of how considering extinct taxa may help to resolve the position of a ‘difficult’ living group.

A new trigonotarbid (Arachnida: Trigonotarbida) Arianrhoda bennetti gen. et sp. nov. is described from the Lower Devonian (Lochkovian) of a quarry near Tredomen, Powys, mid Wales, UK. This relatively complete specimen is the first record of a pre‐Carboniferous arachnid from Wales, one of only a handful of early Devonian arachnids, and the second oldest trigonotarbid recorded. Based on the rounded prosomal dorsal shield and the relatively narrow, elongate opisthosoma we refer this new fossil to the family Anthracosironidae. A distinct flange‐like ornament on the leg 4 tibia in the new fossil is unique among trigonotarbids and is the primary autapomorphy for the new genus.

ABSTRACTThe Windyfield chert site is located 700 m NE of the original Rhynie chert locality at Rhynie, Aberdeenshire, Scotland. Originally identified by concentrations of surface float material, a drilling and trenching programme of the area in 1997 revealed a chert ‘pod’ in situ interbedded with fluvial/lacustrine sandstones and hydrothermally altered shales. Chert morphologies identified from float blocks and trench material range from tabular beds to lenticular pods displaying massive, nodular, laminated and brecciated fabrics, and geyserite splash textures. A suite of floral and faunal associations, when combined with distinctive macro- and microscopic chert textures, has been used to interpret depositional conditions. Palaeoenvironments ranged from terrestrial laminated, brecciated and vegetated sinter sheets to low-temperature pools and marginal aquatic settings. The flora comprises six higher land plant species, nematophytes, charophytes, various fungi and probable cyanobacteria. Arthropods include branchiopod crustaceans, a euthycarcinoid, trigonotarbid arachnids, centipedes, eoarthropleurids and a possible hexapod. The biota of the Windyfield chert is closely comparable to that found in the Rhynie chert. Together, the Windyfield and Rhynie cherts contain the most diverse associated fossil arthropod fauna of terrestrial and freshwater origin from rocks of comparable age anywhere in the world.

Abstract New terrestrial and freshwater arthropods are described from the Windyfield cherts, a suite of silicified sinters deposited 700m north‐east of the Rhynie cherts and part of the same Early Devonian hot‐spring complex. The diverse assemblage consists of Heterocrania rhyniensis (Hirst and Maulik, 1926a), here recognized as a euthycarcinoid; scutigeromorph centipede material assigned to Crussolum sp.; the crustacean Lepidocaris; trigonotarbid arachnids; a new arthropod of myriapod affinities named Leverhulmia mariae gen. et sp. nov.; and the distinctively ornamented arthropod cuticle of Rhynimonstrum dunlopi gen. et sp. nov. The Leverhulmia animal preserves gut content identifying it as an early terrestrial detritivore. Abundant coprolites of similar composition and morphology to the gut contents of the euthycarcinoid crowd the matrix. Chert texture, faunal associations, and study of modern analogues strongly suggest that the terrestrial arthropods were ubiquitous Early Devonian forms with no particular special adaptation to localized conditions around the terrestrial hot‐spring vents. The aquatic arthropods represent biota from ephemeral cool‐water pools in the vicinity of the hot‐spring vents.

A new trigonotarbid arachnid,Gigantocharinus szatmaryinew genus and species, is described from Upper Devonian (Late Famennian) sediments in Pennsylvania. Devonian trigonotarbids were known before from only a single North American locality and several European ones. The new trigonotarbid occurs in what had previously been a significant time gap between the faunas of the Middle Devonian and the late Carboniferous.Gigantocharinus szatmaryiis assigned with some hesitation to the family Palaeocharinidae.