Abstract A length–frequency sample ( n = 295) from a fossil population of the Ordovician trilobite Triarthrus eatoni Hall, 1838, assembled and analyzed by J. L. Cisne in 1973 is here reexamined using methods analysis commonly used fishery science marine biology. Theoretical considerations empirical data at hand suggest that growth T. was not “linear,” but asymptotic, as most Recent invertebrate...

This paper presents a phylogenetic analysis of the ‘‘Fallotaspidoidea,’’ a determination of the biogeographic origins of the eutrilobites, and an evaluation of the timing of the Cambrian radiation based on biogeographic evidence. Phylogenetic analysis incorporated 29 exoskeletal characters and 16 ingroup taxa. In the single most parsimonious tree the genus Fallotaspidella Repina, 1961, is the s...

Abstract Records of abnormal fossil arthropods present important insight into how extinct forms responded to traumatic damage and developmental complications. Trilobites, bearing biomineralized dorsal exoskeletons, have arguably the most well-documented record abnormalities spanning Cambrian through end-Permian. As such, new records malformed, often injured, trilobites are occasionally identifi...

The Cambrian time scale is in a state of flux due to lack reliable geochronological dates which can be tied biostratigraphic scales. Most recent Australian relevant the geochronologic have been determined from Early successions South Australia and Middle Late sedimentary volcanic rocks western Tasmania. This work has based on SHRIMP using zircon standard SL13. reliability these questionable dou...