Deiphon

From Palaeos.org

<==Deiphoninae
   |--Ovalocephalus Koroleva 1959
   `--+--Deiphon Barrande 1850
      |    |--*D. forbesi Barrande 1850
      |    |--D. americanum Weller 1907
      |    |--D. angelini Warburg 1925
      |    |--D. barrandei Whittard 1934
      |    |--D. braybrooki Perry & Chatterton 1979
      |    |    |--D. b. braybrooki
      |    |    `--D. b. bainsi Chatterton & Perry 1984
      |    |--D. brevispina Ramsköld 1983
      |    |--D. dikellum Whittard 1934
      |    |--D. ellipticum Ramsköld 1983
      |    |--D. fleur Šnajdr 1980
      |    |--D. globifrons Angelin 1854
      |    |--D. grovesi Chatterton & Perry 1984
      |    |--D. longifrons Whittard 1934
      |    |--D. pisum Foerste 1894
      |    |--D. pospisili Přibyl & Vaněk 1984
      |    |--D. salmoni Chatterton & Perry 1984
      |    |--D. snodensis Ramsköld 1983
      |    `--D. sphaericum Ramsköld 1983
      |--Onycopyge Woodward 1880
      `--Sphaerocoryphe

Deiphon was a distinctive genus of Silurian phacopid trilobites of the family Cheiruridae found in Western and Central Europe, and in Central and Eastern United States. The type species, D. forbesi, from Bohemia, in what is now the Czech Republic, was discovered and described by the French paleontologist, Joachim Barrande in 1850.

[edit] Description

The glabella was inflated, and globular-shaped, and covered in small wart-like bumps. If it was filled with fat, or oil, the glabellum would have helped to have made the creature positively buoyant. On the other hand, trilobites with large glabellae are often suspected of being predatory, as the volume of glabella would be filled with digestive organs, or used to store captured/swallowed prey. The cheeks of the cephalon formed a pair of long, curved spines, and the segments of the pleural lobes were separated and elongated to form rib-like struts. These modifications, along with the "V" shaped pygidium give these trilobites a cartoon "fish-skeleton" appearance. The defensive value of these highly elongate spines is also apparent, as they would have stuck in the throats of vertebrate predators, such as the Silurian acanthodian Nostolepis. In all adult specimens, the body has up to nine segments, not including the cephalon or pygidium (which is formed from at least two fused and reduced segments).

[edit] Planktonic or Benthic?

Because some of the other highly-derived cheirurid trilobites, such as the Devonian Crotalocephalus, have been interpreted as being swimmers or plankters, the species of Deiphon have been popularly thought of as being planktonic, as well. Mostly, it is due to the idea that its globular glabellum was filled with fat or oil, thus, serving as a balloon to keep it in the water column, and its elongated pleural lobes serving to keep it from sinking. If it were a nektonic or planktonic trilobite, the spherical glabellum, coupled with its rib cage-like pleural lobes and spine-like cephalon cheeks would have presented serious impediments to its hydrodynamic ability, and would have been either a drifter, or a very leisurely swimmer, feeding on phytoplankton, or slow-moving zooplankton.

On the other hand, because of Deiphon's questionable hydrodynamics, some think of it as being a benthic predator that scurried on top of the substrate in search of prey, only swimming when necessary (such as evading larger predators). It may have even used its enormous glabellum to store subdued prey for later digestion.