Abstract Olenellid trilobites from the lower Cambrian of Iberian Peninsula are very scarce and poorly studied, making them difficult to compare with defined species include in biostratigraphic paleobiogeographic analyses. Based on newly collected specimens, we revise ‘ Callavia ? lotzei ’ Richter Richter, 1941 ‘Cumbres beds’ Cumbres de San Bartolomé ‘Herrerías shale’ Cañaveral León, Sierra del ...

En el presente trabajo se destaca interés que tiene género Odontochile para estudio del Devónico en momento actual. Se realiza un análisis de las especies este encontradas Inferior la Cordillera Cantábrica y Pirineo, dándose algunas precisiones sobre distribución estratigráfica primera región. O. spinifera, especie amplia repartición geográfica, es única forma común entre los Trilobi­tes devóni...

The Arachnomorpha or Arachnata concepts have resolved Trilobita as most closely related to Chelicerata amongst extant Arthropoda. An alternative position of trilobites in the stem lineage of Mandibulata is suggested by their pattern of head tagmosis. The antennae of trilobites and Mandibulata are considered non-homologous with the antennae of Onychophora and stem lineage Euarthropoda: they repr...

—Ontogenetic stages of trilobites have traditionally been recognized on the basis of the development of exoskeletal segmentation. The established protaspid, meraspid, and holaspid phases relate specifically to the development of articulated joints between exoskeletal elements. Transitions between these phases were marked by the first and last appearances of new trunk segment articulations. Here...