''Deiphon'' is a distinctive
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...
phacopid trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...
s of the family
Cheiruridae
Cheiruridae is a family of phacopid trilobites of the suborder Cheirurina. Its members, as with other members of the suborder, had distinctive pygidia modified into finger-like spines. They first appeared in the uppermost Cambrian (upper Furongi ...
found in Western and Central
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
, and in Central and Eastern
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. The type
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, ''D. forbesi'', from
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
,
Bohemia
Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region of the Czech Republic. Bohemia can also refer to a wider area consisting of the historical Lands of the Bohemian Crown ruled by the Bohem ...
, and
Sweden
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
, was discovered and described by the
French paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
,
Joachim Barrande
Joachim Barrande (11 August 1799 – 5 October 1883) was a French geologist and palaeontologist.
Career
Barrande was born at Saugues, Haute Loire, and educated in the École Polytechnique and École Nationale des Ponts et Chaussées at Paris. Al ...
in 1850.
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 free 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
The pygidium (plural pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compo ...
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
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
predators, such as the Silurian
acanthodian
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes), typically considered a paraphyletic group. They are currently considered to represent a grade of various fish lineages leading up to the extant Chondrichthyes, which ...
''
Nostolepis''.
Each species differed from each other in the sizes of their glabella, as well as the size and curves of the pygidium and free cheek spines.
Cheirurids had the ability to enroll to protect their softer ventral area, and the spines would have thrust upward and outward. In all adult specimens of the genus, the body has up to nine segments, not including the cephalon or pygidium (which is formed from at least two fused and reduced segments).
Ecology
Because some of the other highly derived
cheirurid trilobites, such as the Devonian ''
Crotalocephalus
''Crotalocephalus'' is a genus of trilobites that lived from the Late Silurian to the Early Devonian. Its remains have been found in Asia, Australia, Africa, and Europe.
References
External links
''Crotalocephalus''in the Paleobiology Data ...
'' and ''
Cybelloides'' of the Ordovician, 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
The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels.
The sternum, together known as the thoracic cage, is a semi- ...
-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 ''Deiphons questionable hydrodynamics, and relatively tiny eyes (as opposed to the tremendous eyes normally found on other swimming or planktonic trilobites), 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.
References
*Burns, Jasper. Trilobites: Common Trilobites of North America (A NatureGuide book). Wilmington: Jasper Burns and Miller's Fossils, Inc., 1999.
*Fenton, Carroll L., et al. The Fossil Book New York: Dover, 1996 (first edition 1958).
External links
*Reconstruction of ''D. forbesi'' in comparison to ''Eurypterus remipedes'
{{Taxonbar, from=Q5252495
Fossils of the Czech Republic
Cheiruridae
Silurian trilobites of Europe
Silurian trilobites of North America
Paleozoic life of the Northwest Territories
Paleozoic life of Nunavut
Taxa named by Joachim Barrande