Cladistic parsimony analysis of the subfamily Deiphoninae Raymond, 1913 was conducted to produce a hypothesis of relationship for the group. The genera Deiphon Barrande, 1850 and Onycopyge Woodward, 1880 are found to be monophyletic, while the genus Sphaerocoryphe Angelin, 1854, as it was previously defined, is paraphyletic. A modified Brooks Parsimony Analysis using the phylogenetic hypothesis...

Analysis of the degree of intraspecific morphological polymorphism during the evolutionary history of trilobites using an informatic approach(1) provides striking evidence of a long-suspected but previously unsubstantiated pattern: degrees of polymorphism are markedly higher in phylogenetically basal, stratigraphically early species. This unequivocal pattern prompts further exploration of the r...

The fossil record of the Cambrian Period has been known as a problem for evolutionary thegfory since Darwin’s Origin of Species in 1859. Darwin was aware of the sudden appearance of complex animal forms in the Cambrian from his own collecting in northeastern Wales. Complex animal forms such as trilobites seemed to appear with geological suddenness with no apparent ancestors in older rocks below...

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 Lower Paleozoic sediments of the Barrandian area are globally renowned as a classical example well-preserved skeletal marine fauna, including abundant remains trilobites. Several tens morphologically anomalous exoskeletons trilobites have been collected and documented from Cambrian to Devonian clastic carbonates. One them, an exceptionally well preserved, articulated partly enrolled exoskel...