Monti, Daniela S.Confalonieri, Viviana A.Tortello, M. Franco
15页
查看更多>>摘要：Hypermecaspidinae (Trilobita; Olenidae) constitutes a monophyletic clade but its internal relationships are unknown and its phylogenetic position with respect to the rest of Olenida has recently been questioned. In order to propose a phylogenetic hypothesis, and to resolve the status of the group, a cladistic analysis of the hypermecaspidinids was performed. One hundred characters (28 quantitative and 72 qualitative) of holaspid morphology were coded for 30 taxa (18 Hypermecaspidinae). Two groups of analyses were performed considering the percentage of missing data. For each group of analyses, discrete partition was treated as totally unordered or as with some characters (describing intensity, position or shape of certain structures) ordered. The analyses were performed with TNT using maximum parsimony and implied weighting as optimality criteria. Hypermecaspididae constitutes a monophyletic family within Olenida, and is the sister group of pterocephaliids. In light of the present analysis, an emended diagnosis of the family is provided. The results suggest that 'Tropidopyge' broeggeri should be reassigned to Hypermecaspis. Hypermecaspidids would have originated in the late Furongian and rapidly diversified across different parts of the world in the Early Ordovician. With the exception of H. armata and H. chamarrensis, the species of Hypermecaspis have a proportionately large pygidium with a wide doublure and a distinct postaxial field. An evolutionary trend toward an increase in the size of these characters is observed in the genus. The cranidium shows a tendency toward enlargement of the glabella and the palpebral lobes, together with a narrowing of the interocular genae.
查看更多>>摘要：Barklice are insects belonging to the order Psocodea. They are herbivorous or detritivorous, and inhabit a wide range of environments. Their oldest fossil record dates back to the late Carboniferous, but it was not until the Cretaceous that they became much more diverse. However, their fossil record could be affected by taphonomic processes due to their tiny size and soft bodies. Here, we present new psocid specimens from five amber-bearing outcrops in Spain that are Albian in age. One of the specimens, a well-preserved psocid nymph assigned to dagger Archaeatropidae, lacks evidence of debris-carrying behaviour. Some of the specimens belong to the previously known species Archaeatropos alavensis Baz & Ortuno and Preempheria antiqua Baz & Ortuno (Trogiomorpha: Atropetae), providing new anatomical and biogeographical information. Furthermore, we describe a new species, Libanoglaris hespericus sp. nov. (dagger Archaeatropidae). The diagnosis for the family dagger Archaeatropidae is emended. The abundance of psocids in Cretaceous amber and their virtual absence in compression outcrops could be due to taphonomic bias. Considerations on the phylogenetic placement of trogiomorphan families and the relationships between dagger Archaeatropidae and dagger Empheriidae are included. Today, the least diverse psocid suborder is Trogiomorpha, but this suborder comprises the majority of the Cretaceous psocodean species described to date, possibly due to palaeobiological or evolutionary constraints. Trogiomorphans could have been relegated to marginal habitats by niche competition with psocomorphans. Debris-carrying behaviour in response to predatory pressure might not have been widely distributed, geographically or phylogenetically, in the Cretaceous psocid nymphs.
查看更多>>摘要：Gekkota (geckos and pygopods) constitute a diverse and early diverging clade of squamates, but their highly fragmentary fossil record allows only limited insights into their evolutionary history. Even long-known classic Palaeogene Lagerstatten, such as the Eocene Messel and Geiseltal, remained uninformative for gecko evolution. Here we describe an articulated near-complete crown-gekkotan skull from the Eocene of Geiseltal. The skull represents one of the most complete and oldest fossil geckos from the Cenozoic and warrants the naming of a new taxon, Geiseleptes delfinoi gen. et sp. nov. Parsimony analysis of an expanded morphological dataset that comprehensively samples fossil geckos recovers at least two lineages in the Palaeogene of Europe: Gekkonidae and Sphaerodactylidae. Further clades may have been present but require further support. The new species, together with several other European extinct taxa, belongs to the extant clade Sphaerodactylidae. Published molecular phylogenies imply a European dispersal from Africa for the clade, and G. delfinoi constrains the timing of this event to no later than the middle Eocene. Within Sphaerodactylidae, several Eocene, Oligocene and Miocene species form the stem-lineage of the extant Mediterranean-endemic Euleptes europaea of which G. delfinoi is the oldest representative. We here define the new clade Euleptinae for this group. Euleptine geckos had an unusually long evolutionary history in Cenozoic Europe and may represent one of the very few vertebrate clades with a persistent presence since the early Palaeogene, indicating extreme adaptability. As the oldest known crown-sphaerodactylid, G. delfinoi represents an important fossil calibration for divergence dating analyses of geckos.
Ghirotto, Victor M.Crispino, Edgar B.Chiquetto-Machado, Pedro, INeves, Pedro A. B. A....
17页
查看更多>>摘要：Stick insects (Phasmatodea) are herbivorous, mostly nocturnal insects known for their camouflage specialization, constituting a moderately diverse group with around 3400 extant described species. The overall poor and often confusing fossil record of Phasmatodea, especially regarding older taxa, has muddled the knowledge of the early evolution of the lineage and hindered reliable calibration points for ordinal-level phylogenies. The phylogenetic relationships within the order remain unresolved, but recent research sheds more light on the subject. Here we report on the oldest known fossil of Euphasmatodea, by revising the taxonomic identity of one fossil species (Eoproscopia reliquum Mendes, Vasconcelos & Oliveira) previously described as a stick grasshopper (family Proscopiidae). Based on the finding of a more complete specimen the taxon is redescribed and a new genus, Araripephasma, is erected to accommodate this species in Euphasmatodea. Araripephasma reliquum comb. nov. is a remarkably modern-looking stick insect species that provides a new minimum age for Euphasmatodea and sets a good and reliable calibration point for phylogenetic and evolutionary studies. The implications of this rare finding for the evolutionary history of Phasmatodea are discussed.
查看更多>>摘要：Arthropods are ubiquitous in all modern habitats and yet their origin remains poorly documented. It is widely thought that their segmented and arthrodized body evolved from the annulated vermiform body of a lobopodian ancestor c. 540 Ma. This major transformation included the evolution of sclerotized and articulated appendages from annulated non-jointed limbs or lobopods. However, this scenario is complicated by the presence in many stem-group arthropods of body flaps of various origins, characteristics and functions. We describe the new lobopodian Utahnax vannieri gen. et sp. nov. from Drumian strata of the House Range in Utah. Known from an incomplete specimen, this taxon features a vermiform, annulated body flanked by pairs of swimming flaps, except in the caudal region, and a digestive system with putative glands. Extensions of the body cavity into the body flaps of Utahnax suggest that they are modified lobopods similar to the ventral body flaps of radiodonts; as such, they are not homologous to the dorsal body flaps of the stem-group arthropods Opabinia, Pambdelurion, and possibly Kerygmachela. We discuss the details of the limb anatomy of these three taxa and consider an alternative interpretation for Kerygmachela. Despite morphological similarities in radiodonts, Utahnax, and possibly Kerygmachela, our parsimony and Bayesian inference phylogenetic analyses suggest that ventral body flaps have evolved convergently in those taxa, probably accompanying a shift towards a predominantly swimming predatory lifestyle. Ecological competition with radiodonts is proposed as an explanation for the scarcity of non-radiodont swimming lobopodians in Cambrian Lagerstatten.
NSTL
Wiley