Dionide hectori Reed, 1926, is shown on the basis of new collections from the type area in New Zealand to be a Tremadocian ceratopygide close to Hysterolenus. The species was placed in Taihungshania by Kobayashi (1941). It was provisionally retained in the Taihungshaniidae by Lu (1975) who made hectori type species of a new genus Hectoria (non Hectoria Trechmann, 1918). Ruapyge nom.nov. is prop...

In this work we report on a unique and ancient type of eye, in which the lower surface of the upper calcite lens units possessed an enigmatic central bulge making the dioptric apparatus similar to a bifocal lens. This eye belonged to the trilobite Dalmanitina socialis, which became extinct several hundred million years ago. As far as we know, image formation by bifocal lenses of this kind did/d...

Abstract Walcottaspis vanhornei (Walcott, 1914) is a large, late Cambrian trilobite with unique pygidial morphology known only from narrow outcrop belt of the St. Lawrence Formation in Upper Mississippi Valley. Found carbonate-rich layers within heterolithic facies that represent toesets prograding shoreface, it restricted to single or small number parasequences. Only four specimens any its scl...

Ordovician trilobites are reviewed based on a new species-level relational database. The stratigraphical ranges of all 56 families with occurrences in the Ordovician are documented and the content, phylogenetic status, diversity and Ordovician distribution by major palaeocontinent/terrane are discussed. Aspects of higher classification are also dealt with. Global sampling is heavily biased towa...

Sparse material of an agnostid trilobite, previously referred to as Tomagnostus cf. corrugatus (Illing 1916), is recognized as a new species, T. brantevikensis n. sp. It occurs in the middle Cambrian (≈ Cambrian provisional Series 3) Triplagnostus gibbus and Acidusus atavus zones (Almbackenian regional Stage) in Scania, southernmost Sweden, but is very rare. The new species resembles T. corruga...