57 research outputs found

    The generalized Robinson-Foulds metric

    Get PDF
    The Robinson-Foulds (RF) metric is arguably the most widely used measure of phylogenetic tree similarity, despite its well-known shortcomings: For example, moving a single taxon in a tree can result in a tree that has maximum distance to the original one; but the two trees are identical if we remove the single taxon. To this end, we propose a natural extension of the RF metric that does not simply count identical clades but instead, also takes similar clades into consideration. In contrast to previous approaches, our model requires the matching between clades to respect the structure of the two trees, a property that the classical RF metric exhibits, too. We show that computing this generalized RF metric is, unfortunately, NP-hard. We then present a simple Integer Linear Program for its computation, and evaluate it by an all-against-all comparison of 100 trees from a benchmark data set. We find that matchings that respect the tree structure differ significantly from those that do not, underlining the importance of this natural condition.Comment: Peer-reviewed and presented as part of the 13th Workshop on Algorithms in Bioinformatics (WABI2013

    A New Troodontid Theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America

    Get PDF
    Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains.Here we report a gracile new troodontid theropod--Talos sampsoni gen. et sp. nov.--from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes.Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing

    Mount Edgcumbe

    No full text
    'MOUNT EDGCUMBE. DEVON. Drawn by J. D. Harding, from a sketch by Jendle. Engraved by E. Finden. London, Published for the Proprietors, by Geo. Virtue, 26, Ivy Lane.' Immediately below centre of image is '29'

    View from the beach at Sidmouth

    No full text
    'VIEW FROM THE BEACH AT SIDMOUTH. LOOKING TOWARDS THE SOUTH-WEST. Drawn by J. D. Harding, from a sketch by Jendle. Engraved by E. Finden. London; Published for the Proprietors by Geo. Virtue, 26, Ivy Lane.

    Budleigh Salterton

    No full text
    'BUDLEIGH SALTERTON. Drawn by J. D. Harding from a sketch by - Jendle. Engraved by W. Finden. London; Published for the Proprietors, by Geo. Virtue, 26, Ivy Lane'

    Plymouth, Devon

    No full text
    'PLYMOUTH, DEVON. Drawn by J. D. Harding from a sketch by - Jendle. Engraved by W. Finden. London, Published 1837, by Charles Tilt, 86, Fleet Street

    Nazareth [Material gráfico]

    No full text
    Resumen: Descripción: vista de Nazareth. En primer término, rebaño de ovejas y personajes; al fondo, el poblado
    • …
    corecore