Maternal care is shared by three of the five living orders of centipedes and is generally thought... more Maternal care is shared by three of the five living orders of centipedes and is generally thought to have a single evolutionary origin in this group. Literature on brooding behaviour in the order Scolopendromorpha is scattered, with observations available for six genera. Brooding in the diverse genus Otostigmus Porat, 1876, with ca 120 species mostly distributed in the tropics, has been documented in only two species from Brazil. Six broods of O. spinosus representing different embryonic and adolescent (post-embryonic) stages are documented from southern Thailand. Size of the brood is similar to other species of Otostigmus, and this species exhibits filial cannibalism also documented in the Neotropical O. scabricauda. O. spinosus is redescribed with emphasis on a large sample of Thai material and is reported from Laos for the first time. Sexual dimorphism is apparently exhibited by a distal projection on tarsus 1 of legs 20 and 21 in males. Considerable variability in taxonomic char...
Increasing evidence, in particular from gene expression data, indicates that mandibles throughout... more Increasing evidence, in particular from gene expression data, indicates that mandibles throughout the Mandibulata are gnathobasic and that myriapod and hexapod mandibles do not represent 'whole limbs'. These observations do not necessarily imply that the gnathal edges of the mandibles are also homologous, though this homology finds some support from gene expression. The gnathal edges of mandibles commonly consist of three parts: an incisor process (pars incisivus), a molar process (pars molaris) and a lacinia mobilis (or similar structures with different names), situated between the two processes. A comparative SEM study shows that, in contrast to the lacinia mobilis, a broad homology of the pars incisivus and the pars molaris in Myriapoda, Crustacea and Hexapoda can potentially be defended. In Chilopoda, the proximal part of the gnathal edge is represented by a bristled pad, the 'Haarpolster', that has been identified as equivalent to a pars molaris. By comparison t...
Proceedings of the Royal Society B: Biological Sciences
Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosyste... more Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (scle...
Cambrian lobopodians have attracted much attention in that they are considered to have close affi... more Cambrian lobopodians have attracted much attention in that they are considered to have close affinities with the origin of arthropods, and recent studies agree that they sample the stem-groups of both Arthropoda and Onychophora. A new lobopodian species, Diania cactiformis Liu et al., 2011, was recently reported from the Chengjiang Lagerstätte (southwest China; Cambrian Series 2). This animal was interpreted as bearing arthropod-like articulated appendages and was resolved as sister-taxon to Arthropoda in a cladistic analysis. A reanalysis of the published dataset did not reproduce the phylogenetic placement of D. cactiformis, and the interpretation of its appendage morphology is controversial. New observations on D. cactiformis are made using newly collected material, rejecting the evidence for sclerotized, segmented and articulated appendages; instead the appendages compare more closely to lobopods. The criteria for defining arthropodized appendages are further discussed through c...
The relationships of major arthropod clades have long been contentious, but refinements in molecu... more The relationships of major arthropod clades have long been contentious, but refinements in molecular phylogenetics underpin an emerging consensus. Nevertheless, molecular phylogenies have recovered topologies that morphological phylogenies have not, including the placement of hexapods within a paraphyletic Crustacea, and an alliance between myriapods and chelicerates. Here we show enhanced congruence between molecular and morphological phylogenies based on 753 morphological characters for 309 fossil and Recent panarthropods. We resolve hexapods within Crustacea, with remipedes as their closest extant relatives, and show that the traditionally close relationship between myriapods and hexapods is an artefact of convergent character acquisition during terrestrialisation. The inclusion of fossil morphology mitigates long-branch artefacts as exemplified by pycnogonids: when fossils are included, they resolve with euchelicerates rather than as a sister taxon to all other euarthropods.
Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known... more Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known only from Borneo and the Philippines. It is unique within the order Scolopendromorpha for its slow gait, robust tergites, and highly modified gizzard and mandible morphology. Not much is known about the biology of the species but it has been speculated to be arboreal with a possibly vegetarian diet. Until now its phylogenetic position within the subfamily Otostigminae has been based only on morphological characters, being variably ranked as a monotypic tribe (Arrhabdotini) or classified with the Southeast Asian genus Sterropristes Attems, 1934. The first molecular data for E. octosulcatum sourced from a newly collected specimen from Sarawak were analysed with and without morphology. Parsimony analysis of 122 morphological characters together with two nuclear and two mitochondrial loci resolves Edentistoma as sister group to three Indo-Australian species of Rhysida, this clade in turn gr...
The phylogenetic interrelationships of animals (Metazoa) have been elucidated by refined systemat... more The phylogenetic interrelationships of animals (Metazoa) have been elucidated by refined systematic methods and by new techniques, notably from molecular biology. In parallel with the strong molecular focus of contemporary metazoan phylogenetics, morphology has advanced with the introduction of new approaches, such as confocal laser scanning microscopy and cell-labelling in the study of embryology. The discovery of new animal diversity
The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstätte, which is by far the mo... more The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstätte, which is by far the most important Burgess Shale-type (BST) deposit in Australia, occurs mainly in the bottom 10 m of the Emu Bay Shale at Big Gully on the north coast of Kangaroo Island, South Australia. In this area, the exposed Cambrian succession commences with the White Point
Maternal care is shared by three of the five living orders of centipedes and is generally thought... more Maternal care is shared by three of the five living orders of centipedes and is generally thought to have a single evolutionary origin in this group. Literature on brooding behaviour in the order Scolopendromorpha is scattered, with observations available for six genera. Brooding in the diverse genus Otostigmus Porat, 1876, with ca 120 species mostly distributed in the tropics, has been documented in only two species from Brazil. Six broods of O. spinosus representing different embryonic and adolescent (post-embryonic) stages are documented from southern Thailand. Size of the brood is similar to other species of Otostigmus, and this species exhibits filial cannibalism also documented in the Neotropical O. scabricauda. O. spinosus is redescribed with emphasis on a large sample of Thai material and is reported from Laos for the first time. Sexual dimorphism is apparently exhibited by a distal projection on tarsus 1 of legs 20 and 21 in males. Considerable variability in taxonomic char...
Increasing evidence, in particular from gene expression data, indicates that mandibles throughout... more Increasing evidence, in particular from gene expression data, indicates that mandibles throughout the Mandibulata are gnathobasic and that myriapod and hexapod mandibles do not represent 'whole limbs'. These observations do not necessarily imply that the gnathal edges of the mandibles are also homologous, though this homology finds some support from gene expression. The gnathal edges of mandibles commonly consist of three parts: an incisor process (pars incisivus), a molar process (pars molaris) and a lacinia mobilis (or similar structures with different names), situated between the two processes. A comparative SEM study shows that, in contrast to the lacinia mobilis, a broad homology of the pars incisivus and the pars molaris in Myriapoda, Crustacea and Hexapoda can potentially be defended. In Chilopoda, the proximal part of the gnathal edge is represented by a bristled pad, the 'Haarpolster', that has been identified as equivalent to a pars molaris. By comparison t...
Proceedings of the Royal Society B: Biological Sciences
Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosyste... more Extant arthropods are diverse and ubiquitous, forming a major constituent of most modern ecosystems. Evidence from early Palaeozoic Konservat Lagerstätten indicates that this has been the case since the Cambrian. Despite this, the details of arthropod origins remain obscure, although most hypotheses regard the first arthropods as benthic predators or scavengers such as the fuxianhuiids or megacheirans ('great-appendage' arthropods). Here, we describe a new arthropod from the Tulip Beds locality of the Burgess Shale Formation (Cambrian, series 3, stage 5) that possesses a weakly sclerotized thorax with filamentous appendages, encased in a bivalved carapace, and a strongly sclerotized, elongate abdomen and telson. A cladistic analysis resolved this taxon as the basal-most member of a paraphyletic grade of nekto-benthic forms with bivalved carapaces. This grade occurs at the base of Arthropoda (panarthropods with arthropodized trunk limbs) and suggests that arthrodization (scle...
Cambrian lobopodians have attracted much attention in that they are considered to have close affi... more Cambrian lobopodians have attracted much attention in that they are considered to have close affinities with the origin of arthropods, and recent studies agree that they sample the stem-groups of both Arthropoda and Onychophora. A new lobopodian species, Diania cactiformis Liu et al., 2011, was recently reported from the Chengjiang Lagerstätte (southwest China; Cambrian Series 2). This animal was interpreted as bearing arthropod-like articulated appendages and was resolved as sister-taxon to Arthropoda in a cladistic analysis. A reanalysis of the published dataset did not reproduce the phylogenetic placement of D. cactiformis, and the interpretation of its appendage morphology is controversial. New observations on D. cactiformis are made using newly collected material, rejecting the evidence for sclerotized, segmented and articulated appendages; instead the appendages compare more closely to lobopods. The criteria for defining arthropodized appendages are further discussed through c...
The relationships of major arthropod clades have long been contentious, but refinements in molecu... more The relationships of major arthropod clades have long been contentious, but refinements in molecular phylogenetics underpin an emerging consensus. Nevertheless, molecular phylogenies have recovered topologies that morphological phylogenies have not, including the placement of hexapods within a paraphyletic Crustacea, and an alliance between myriapods and chelicerates. Here we show enhanced congruence between molecular and morphological phylogenies based on 753 morphological characters for 309 fossil and Recent panarthropods. We resolve hexapods within Crustacea, with remipedes as their closest extant relatives, and show that the traditionally close relationship between myriapods and hexapods is an artefact of convergent character acquisition during terrestrialisation. The inclusion of fossil morphology mitigates long-branch artefacts as exemplified by pycnogonids: when fossils are included, they resolve with euchelicerates rather than as a sister taxon to all other euarthropods.
Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known... more Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known only from Borneo and the Philippines. It is unique within the order Scolopendromorpha for its slow gait, robust tergites, and highly modified gizzard and mandible morphology. Not much is known about the biology of the species but it has been speculated to be arboreal with a possibly vegetarian diet. Until now its phylogenetic position within the subfamily Otostigminae has been based only on morphological characters, being variably ranked as a monotypic tribe (Arrhabdotini) or classified with the Southeast Asian genus Sterropristes Attems, 1934. The first molecular data for E. octosulcatum sourced from a newly collected specimen from Sarawak were analysed with and without morphology. Parsimony analysis of 122 morphological characters together with two nuclear and two mitochondrial loci resolves Edentistoma as sister group to three Indo-Australian species of Rhysida, this clade in turn gr...
The phylogenetic interrelationships of animals (Metazoa) have been elucidated by refined systemat... more The phylogenetic interrelationships of animals (Metazoa) have been elucidated by refined systematic methods and by new techniques, notably from molecular biology. In parallel with the strong molecular focus of contemporary metazoan phylogenetics, morphology has advanced with the introduction of new approaches, such as confocal laser scanning microscopy and cell-labelling in the study of embryology. The discovery of new animal diversity
The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstätte, which is by far the mo... more The lower Cambrian (Cambrian Series 2, Stage 4) Emu Bay Shale Lagerstätte, which is by far the most important Burgess Shale-type (BST) deposit in Australia, occurs mainly in the bottom 10 m of the Emu Bay Shale at Big Gully on the north coast of Kangaroo Island, South Australia. In this area, the exposed Cambrian succession commences with the White Point
New interpretations are available from recently published appendages of Eoredlichia intermedia (E... more New interpretations are available from recently published appendages of Eoredlichia intermedia (Early Cambrian Chengjiang fauna), the most primitive trilobite for which appendages are known. The basis (formerly identified as the coxa) is preserved in one appendage. An allegedly long proximal podomere in the endopod is actually subdivided into two and, at least in posterior appendages, each of these podomeres bears a strong, angular endite. The large, subquadrate basis, angular endite on the first podomere of the endopod, and attachment of the exopod along the whole length of the basis are features shared with naraoiids, for which Naraoia longicaudata Zhang & Hou is exemplar. The long line of attachment of the exopod to the basis works as a hinge joint in E. intermedia and is a feature shared by Olenoides serratus. This joint allows rotation of the basis and endopod around the hinge line, permitting extensive leg movement without forcing the large exopod fan out of position. The shape of the basis in O. serratus is reinterpreted here, and a new reconstruction of the exopod shows detailed similarity to E. intermedia. The limbs of Eoredlichia show that appendage structure in primitive trilobites is little altered from shared ancestry with naraoiids.
"Eine Gruppe von Encrinurinae (Trilobiten) aus dem späten Llandovery und ausnahmsweise frühesten ... more "Eine Gruppe von Encrinurinae (Trilobiten) aus dem späten Llandovery und ausnahmsweise frühesten Wenlock des Baltikums, der Britischen Inseln und Kanadas wird als monophyletisch erkannt und mit dem Gattungsnamen Wallacia Lamont 1978 belegt. Wallacia wird als Schwestergruppe von Encrinurus sensu stricto betrachtet. Eine Revision der Arten von Gotland führt zur Ausscheidung von W. laevis (Angelin 1851) aus den Oberen Visby-Schichten, sowie von W. jaanussoni n. sp. und W. masterleei n. sp. aus den Unteren Visby-Schichten. Auf siebzehn Merkmale beruhende Cladogramme der zehn benannten Arten von Wallacia zeigen W. masterleei und W. laevis als die nächsten Verwandten einer Gruppe aus dem Telychium Kanadas, zu der W. elegantula (Billings 1866), W. chattertoni n. sp. und W. hypolepra (Stearn 1956) gehören.
A group of late Llandovery and, exceptionally, earliest Wenlock encrinurine trilobites from the Baltic area, the British Isles, and Canada, is recognized as monophyletic. The generic name Wallacia Lamont 1978 is available for this group. Wallacia is regarded as sister taxon to Encrinurus sensu stricto. A systematic revision of species from Gotland recognizes W. laevis (Angelin 1851), from the Upper Visby Beds, and W. jaanussoni n. sp. and W. masterleei n. sp. from the Lower Visby Beds. Cladograms based on seventeen characters for the ten named species of Wallacia place W. masterleei and W. laevis as the closest relatives of a Canadian Telychian clade that includes W. elegantula (Billings 1866), W. chattertoni n. sp., and W. hypolepra (Stearn 1956)."
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A group of late Llandovery and, exceptionally, earliest Wenlock encrinurine trilobites from the Baltic area, the British Isles, and Canada, is recognized as monophyletic. The generic name Wallacia Lamont 1978 is available for this group. Wallacia is regarded as sister taxon to Encrinurus sensu stricto. A systematic revision of species from Gotland recognizes W. laevis (Angelin 1851), from the Upper Visby Beds, and W. jaanussoni n. sp. and W. masterleei n. sp. from the Lower Visby Beds. Cladograms based on seventeen characters for the ten named species of Wallacia place W. masterleei and W. laevis as the closest relatives of a Canadian Telychian clade that includes W. elegantula (Billings 1866), W. chattertoni n. sp., and W. hypolepra (Stearn 1956)."