Cambrian trilobite Ovatoryctocara granulata Tchernysheva, 1962 and its biostratigraphic significance

The missisquoiid trilobite Parakoldinioidia Endo 1937 in the uppermost Cambrian of Oklahoma and Texas, and its biostratigraphic significance

TRILOBITES of the family Missisquoiidae Hupé 1955 occur throughout Laurentian North America in a relatively narrow interval of what is now the latest Cambrian succession (e.g., Shaw 1951; Winston & Nicholls 1967; Stitt 1971, 1977; Taylor & Halley 1974; Ludvigsen 1982; Fortey 1983; Westrop 1986; Dean 1989). Although widely distributed, both geographically and environmentally, missisquoiid trilob...

Modularity of a Cambrian ptychoparioid trilobite cranidium.

Modularity of the cranidium of Crassifimbra? metalaspis, a Cambrian ptychoparioid trilobite, is investigated using landmark-based geometric morphometric methods to gain insight into the integration among morphogenetic processes responsible for shaping the head of an ancient arthropod. Of particular interest is the extent to which the structure of phenotypic integration was governed by direct in...

A Cambrian peak in morphological variation within trilobite species.

Morphological variation within species is a raw material subject to natural selection. However, temporal change in morphological diversity has usually been studied in terms of variation among rather than within species. The distribution of polymorphic traits in cladistic character-taxon matrices reveals that the frequency and extent of morphological variation in 982 trilobite species are greate...

Biostratigraphic and Geological Significance of Planktonic Foraminifera

Jurassic Favusellidae 1 2 3 a b 1 2 a b 3 a 1 b 2 3 1 2 1 1 1 2 3 2 2 3 2 4 1 3 4 a b 1 2 3 1 2 1 2 a b b a a b b a b a Praehedbergellidae Hedbergellidae a b 3 b a a b

The 1962 Highway Act: Its Long Term Significance