Topic
Crozonaspis
About: Crozonaspis is a research topic. Over the lifetime, 2 publications have been published within this topic receiving 20 citations.
Papers
TL;DR: Many Ordovician trilobites possess morphological structures on the cephalon, the pygidium and sometimes also on the thoracic segments, which interlock during enrolment, and these coaptative devices are functional, inherited, and seem to remain stable at the species level.
Abstract: Many Ordovician trilobites possess morphological structures on the cephalon, the pygidium and sometimes also on the thoracic segments, which interlock during enrolment. These coaptative devices, also known in living arthropods, are functional, inherited, and seem to remain stable at the species level. Significant evolutionary changes in coaptative devices occur throughout time within the genera Placoparia (Pliomeridae) and Crozonaspis (Dalmanitidae). New data are presented which have relevance for the details of the coaptative structures in Placoparia ( Coplacoparia ), and for the classification of the dalmanitid species morenensis and dujardini . In some species of Crozonaspis and in Placoparia ( Coplacoparia ), interlocking structures prevent the possibility of shearing between cephalon and post-cephalic exoskeleton.
15 citations
TL;DR: On the basis of precise trilobite examples, the difficulties and interest in cladistic analysis are emphasized and cladograms by themselves do not clarify the distinction of primitive versus derived features; the stratigraphical distribution of species, although not conclusive, is helpful in clarifying relationships.
Abstract: On the basis of precise trilobite examples, the difficulties and interest in cladistic analysis are emphasized. The problem of distinguishing plesiomorphic and apomorphic characters is exemplified in Morgatia with reference to auxiliary impressions of the glabella and vincular furrows. In Crozonaspis, cladograms by themselves do not clarify the distinction of primitive versus derived features; the stratigraphical distribution of species, although not conclusive, is helpful in clarifying relationships. Although stratigraphical data are essential for reconstructing species lineages, they may be misleading when dealing with taxa above the species level. For all phylogenetical reconstructions, the completeness of the palaeontological and biogeographical record must be taken into consideration. D Trilobita, Phacopida, cladistics, Ordovician.
7 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 1985 | 1 |
| 1984 | 1 |