Conocoryphe

Conocoryphe is a genus of primarily eyeless trilobites belonging to the family Conocoryphidae. They lived during the Middle Cambrian period, about 505 million years ago. These arthropods lived on the sea bottom (epifaunal) and lived off dead particulate organic matter (a lifestyle called detritivorous).

Conocoryphe
Temporal range:
Conocoryphe sulzeri
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Trilobita
Order:
Ptychopariida
Family:
Conocoryphidae
Genus:
Conocoryphe

Hawle and Corda 1847
species
  • C. sulzeri (Schlotheim, 1823) (Type) = Trilobites sulzeri, Conocephalites sulzeri
  • C. cirina (Barrande, 1846) = C. sulzeri cirina, Conocephalites cirina
  • C. gerlinda Snajdr, 1982
  • C. punctata
  • C. caecigena Dean, 1982
Synonyms

Conocephalus Zenker, 1833, non Thunberg, 1815 (conehead bushcricket), Conocephalites, Couloumania

Distribution

Cambrian of the Czech Republic,[1][2] France, Spain, Turkey,[3] United States (Wisconsin).

Taxonomy

Conocephalites Barrande, 1852 was introduced as a replacement for Conocephalus Zenker, 1833, which was unavailable since Thunberg (1815 [4]) had previously used the name for a genus of conehead bushcricket. Barrande, however, was unaware that Conocoryphe had already been proposed by Hawle and Corda in 1847.[5]

Type species

Trilobites sulzeri (Schlotheim, 1823 [6] = Conocoryphe sulzeri sulzeri (Schlotheim, 1823); Conocoryphe latifrons Hawle & Corda, 1847 [7]

Reassigned species

Some species, that were describe as belonging to Conocoryphe have since been classified in other genera.[5]

  • C. kingii = Elrathia kingii
  • C. rouayrouxi = Solenopleuropsis rouayrouxi
  • C. salteri = Leptoplastides salteri

Description

Conocoryphe is a rather flat trilobite of average size with an elongate oval outline. Overall shape of the cephalon is semicircular. The glabella tapers forward, is defined by deep axial furrows, and has three pairs of lateral furrows that are directed backward and inward and which do not connect across the midline. The glabella is separated from the anterior margin by a very conspicuous narrow convex preglabellar field that is lower than and does not reach the adjacent fixigenae. Occipital ring is distinct. Without eyes but for one known exception. Eye ridges (when present) are threadlike, evenly curved, extending from anterior corners of the glabella to the genal angles. Anterior cephalic border furrow is deep, concave and wider than the narrow convex border itself. The lateral cephalic border is divided longitudinally by a suture and extends into slender, backward-directed genal spines. Genal spines extend to the 4th thorax segment, but are often broken off, even in well preserved specimens. The hypostome is natant (or floating) i.e. not attached to the doublure and aligned with front edge of the glabella . The cephalic doublure and ventral sutures are not known. Thorax consists of 14 segments, with a rather narrow axis (of about 20% of the total width) that tapers evenly backwards. Deeply furrowed pleurae extend outward perpendicular to the axis and have rounded tips. Pygidium has 6 to 8 segments that are arched backward and become less well-defined towards posterior. The pygidium is semicircular in outline, its outer margin evenly curved, and it has a narrow, well-defined border. It is about half as wide as the cephalon (micropygous), and about half as long as wide.[5]

Secondary sight

Conocoryphe provides a rare (but not unique) example of secondary eye development. Conocoryphids lack eyes except for Conocoryphe oculata. This species is otherwise very similar to its relatives from the Montagne Noir region in France. C. oculata has normal curving eye ridges, although the dorsal suture is marginal like in its blind family. Due to poor preservation, lenses have not been found. It seems that the expression of a gene for eye development was only suppressed and not lost, and the eye could develop when the suppression lifted.[8]

References
  1. SCHLOTHEIM, E. F. 1823. NachtraÈge zur Petrefactenkunde. Zw. Abteilung, Gotha, 114 pp.
  2. BARRANDE, J. 1846. Notice preÂliminaire sur le systeÁme silurien et les trilobites de BoheÃme. Leipzig, 97 pp
  3. DEAN, W. T. 1982. Middle Cambrian trilobites from the Sosink Formation, Derik-Mardin district, south-eastern Turkey. Bulletin of the British Museum (Natural History), Geology Series, 36, 1±41.
  4. THUNBERG (1815) Hemipterorum maxillosorum genera illustrata plurimisque novis speciebus ditata ac descripta, Mémoires de l'Académie Impériale des Sciences de St. Pétersbourg (Mem. Acad. Imp. Sci. St. Peterburg) 5:211-301).
  5. MOORE, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Vol. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O242. ISBN 0-8137-3015-5.
  6. SCHLOTHEIM, E. F. 1823. Nachträge zur Petrefactenkunde. Zw. Abteilung, Gotha, 114 pp.
  7. HAWLE, I. and CORDA, A. J. C. 1847. Podrom einer Monographie der bo Èhmischen Trilobiten. Abhandlungen der Ko Èniglichen No Èhmischen Gesellschaft der Wissenschaften, 5, 1-176.
  8. WHITTINGTON, H. B.; et al., eds. (1997). Part O, Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. Treatise on Invertebrate Paleontology.
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