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The Condylopygidae Raymond (2013) RAYMOND, P. E., 1913: Some changes in the names of genera
of trilobites. ''The Ottawa Naturalist'', 26: 137−142. are a family of small trilobites that lived during the Middle Cambrian, and found in Canada (Newfoundland and Nova Scotia), the Czech Republic, Germany, France, Spain, England, Wales, Sweden, and the Russian Federation (Siberia). They uniquely differ from all other Agnostina in having the frontal glabellar lobe wider than the rear lobe. The Condylopygidae are the only family assigned to the Condylopygoidea superfamily.
Like all Agnostida, members of the Condylopygidae are relatively small and isopygous with the cephalon and pygidium of approximately similar size and outline. The characteristic expansion of the glabellar frontal lobe, occipital structures instead of basal lobes, and pygidial axis with three pairs of side lobes and a posterior axial lobe differentiate Condylopygoidea from Agnostoidea. WHITTINGTON, H. B. ''et al''. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997
Taxonomy
The Condylopygoidea are an isolated branch in the Agnostina suborder that occur approximately contemporaneously with thePeronopsidae
The Peronopsidae (which may also be called peronopsids) comprise the earliest family of the Agnostina suborder. Species of this family occurred on all paleocontinents. The earliest representatives of this family first occur just before the start ...
, the earliest representatives of the main branch of the Agnostina. One species, ''Peronopsis palmadon'', appears intermediate between Peronopsidae and Condylopygidae, but it is not clear whether ''P. palmadon'' is ancestral to the Condylopygidae - a regression towards ancestral characters or an example of parallel evolution
Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and paral ...
.
Description
Like all Agnostida, members of the Condylopygidae are relatively small and isopygous with the cephalon and pygidium of approximately similar size and outline. The characteristic expansion of the glabellar frontal lobe, occipital structures instead of basal lobes, and pygidial axis with three pairs of side lobes and a posterior axial lobe differentiate Condylopygoidea from Agnostoidea. WHITTINGTON, H. B. ''et al''. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997
Key to the genera
References
{{Taxonbar, from=Q868710 Condylopygoidea Trilobite families Cambrian trilobites Cambrian first appearances Miaolingian extinctions