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''Phacops'' is a genus of
at
The central raised area (or glabella) of the headshield (or cephalon) is moderately to strongly inflated near to its front, more or less flattened on the top, falling vertically to or slightly overhanging the border furrow. Up to three lateral furrows may be discernable on the glabella behind the utterly dominating frontal lobe. From the back there is a very distinct occipital ring, and in front of that a distinct preoccipital ring which is weakly divided into a strongly convex central lobe and weakly convex lateral lobes. The large to medium size eyes have a crescent shaped outline, and are elevated high above the cheeks. The steep visual surface is kidney shaped. The back corners of the cephalon (or genal angles) are acutely to bluntly rounded, but a genal spine is lacking in adults. In the ventral surface of the seam (or doublure) is in the frontal half of the cephalon a continuous furrow, delineated by ridges, and with notches laterally. This so-called vindicular furrow serves to lock the rim of the tailshield to the headshield when the trilobite is enrolled.
The axial rings of the thorax do not have convex lateral axial nodes on its outer surface. The tailshield (or pygidium) is well segmented. The pygidial axis has 9 to 11 rings, and the pleural areas to the sides have 5 to 8 pairs of recognizable ribs. Furrows between the ribs are deep, those that divide each rib in frontal and rear bands are very shallow, and the frontal bands are widest. The surface of the
There are specimens known of ''Phacops rana'' with many irregular black spots. Because similar spots in a specimen of '' Greenops boothi'' from the same site are arranged in rows, it may be assumed that they are original and not caused by the fossilisation process. The spots are irregular and have spurs branching outwardly, similar to the melanophores in many extant animals. In one specimen, the black spots are much larger than in another one. It is quite conceivable that changing the size of the melanophores enabled ''Phacops rana'' to camouflage itself in different environments.
at
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 ...
s in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North and South America and China from the Late Ordovician until the very end of the Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...
, with a broader time range described from the Late Ordovician.''Phacops''at
Fossilworks
Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world.
History
Fossilworks was cre ...
.org It was a rounded animal, with a globose head and large eyes, and probably fed on detritus
In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commu ...
. ''Phacops'' is often found rolled up (" volvation"), a biological defense mechanism that is widespread among smaller trilobites but further perfected in this genus.
Description
Like in all sighted Phacopina, the eyes of ''Phacops'' are compounded of very large, separately set lenses without a common cornea (so called schizochroal eyes), and like almost all other Phacopina, the articulate mid-length part of the body (orthorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the ...
) in ''Phacops'' has 11 segments.
The central raised area (or glabella) of the headshield (or cephalon) is moderately to strongly inflated near to its front, more or less flattened on the top, falling vertically to or slightly overhanging the border furrow. Up to three lateral furrows may be discernable on the glabella behind the utterly dominating frontal lobe. From the back there is a very distinct occipital ring, and in front of that a distinct preoccipital ring which is weakly divided into a strongly convex central lobe and weakly convex lateral lobes. The large to medium size eyes have a crescent shaped outline, and are elevated high above the cheeks. The steep visual surface is kidney shaped. The back corners of the cephalon (or genal angles) are acutely to bluntly rounded, but a genal spine is lacking in adults. In the ventral surface of the seam (or doublure) is in the frontal half of the cephalon a continuous furrow, delineated by ridges, and with notches laterally. This so-called vindicular furrow serves to lock the rim of the tailshield to the headshield when the trilobite is enrolled.
The axial rings of the thorax do not have convex lateral axial nodes on its outer surface. The tailshield (or pygidium) is well segmented. The pygidial axis has 9 to 11 rings, and the pleural areas to the sides have 5 to 8 pairs of recognizable ribs. Furrows between the ribs are deep, those that divide each rib in frontal and rear bands are very shallow, and the frontal bands are widest. The surface of the exoskeleton
An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...
is covered in tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projection ...
s.
Camouflage
There are specimens known of ''Phacops rana'' with many irregular black spots. Because similar spots in a specimen of '' Greenops boothi'' from the same site are arranged in rows, it may be assumed that they are original and not caused by the fossilisation process. The spots are irregular and have spurs branching outwardly, similar to the melanophores in many extant animals. In one specimen, the black spots are much larger than in another one. It is quite conceivable that changing the size of the melanophores enabled ''Phacops rana'' to camouflage itself in different environments.
Taxonomy
The concept of many fossil taxa has been tightened over time, including ''Phacops''. As a result, ''Boeckops'', ''Chotecops'', ''Paciphacops'', ''Prokops'' and ''Viaphacops'' have been erected as subgenera of ''Phacops'', and are now widely regarded as genera in their own right. Most recent, it was considered that some North-American and North-African species on the one hand and European species on the other hand differ sufficiently from each other to be assigned to separate genera. As thetype species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
is the European ''P. latifrons'', the North-American species are now called '' Eldredgeops''. However, the previous assigned species, like ''Phacops rana
''Eldredgeops rana'' (formerly ''Phacops rana'') is a species of trilobite from the middle Devonian period. Their fossils are found chiefly in the northeastern United States, and southwestern Ontario.
Because of its abundance and popularity wit ...
'', are still widely used among fossil collectors. ''Eldredgeops'' has a raised ridge along the ventral margin of the cephalon, the glabella is more inflated, the lateral parts of the preoccipital ring are not round but rectangular, the palpebral area and palpebral lobe are larger than in ''P. latifrons'', and there is no fold right behind the posterior vertical row of lenses, nor an isolated raised area just below the lenses. Not all of these characters may differentiate between ''Eldredgeops'' and other ''Phacops'' species however.
During the Eifelian in the present-day Belgian Ardennes
The Ardennes (french: Ardenne ; nl, Ardennen ; german: Ardennen; wa, Årdene ; lb, Ardennen ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Be ...
, several ''Phacops'' species developed from each other, the oldest being ''P. imitator'', followed by ''P. fragosus'', then ''P. latifrons'' and finally ''P. sartenaeri''. These species show a decrease in the number of lenses, which is a more widespread and recurring trend in many Phacopinae.
Fossils of ''Phacops salteri'' have been found in the trilobite-rich Late Emsian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...
to Early Givetian Floresta Formation of the Altiplano Cundiboyacense, Colombia.Floresta Faunaat
Fossilworks
Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world.
History
Fossilworks was cre ...
.org
Species
''Phacops'' currently contains the following species: * ''P. accipitrinus'' (Phillips, 1841) * ''P. algericus'' Alberti, 1983 * ''P. breviceps'' Barrande, 1846 * ''P. chlupaci'' Alberti, 1983 * ''P. circumspectans'' Paeckelmann, 1913 * ''P. degener'' Barrande, 1852 * '' P. fecundus'' * ''P. fragosus'' Struve, 1970 * ''P. granulatus'' (Munster, 1840) synonyms ''Calymene granulata'', ''P. posidoniae'' * ''P. hoseri'' Hawle & Corda, 1847 * ''P. iowensis'' Delo, 1935 * ''P. imitator'' Struve, 1970 * ''P. kockeli'' Alberti, 1968 * ''P. latifrons'' (Bronn, 1825) * ''P. maurulus'' * ''P. modestus'' Barrande * ''P. ouarouroutensis'' Crônier, 2018 * ''P. platilegnotor'' * ''P. salteri'' Kozlowski, 1923 * ''P. sartenaeri'' Struve, 1985 * ''P. sobolevi'' Kielan, 1954 * ''P. sternbergi'' * ''P. turco'' Richter & Richter * ''P. wedekindi'' Richter & Richter, 1926 * ''P. zinkeni'' F.A. Roemer, 1843Species previously assigned to ''Phacops''
A number of species previously assigned to the genus ''Phacops'' have since been transferred to other genera: * ''P. acuticeps'' = '' Acuticryphops acuticeps'' * ''P. arcticus'' = '' Acernaspis arctica'' * ''P. asper'' = '' Ananaspis aspera'' * ''P. birdsongensis'' = '' Paciphacops birdsongensis'' * ''P. boecki'' = '' Boeckops boecki'' * ''P. braziliensis'' = '' Phacopidina braziliensis'' * ''P. bronni'' = '' Reedops bronni'' * ''P. bulliceps'' = '' Eophacops bulliceps'' * ''P. caecus'' = '' Trimerocephalus caecus'' * ''P. caffer'' = ''Metacryphaeus caffer
''Metacryphaeus'' is an extinct genus of trilobites from the family Calmoniidae. ''Metacryphaeus'' fossils have been found in Bolivia, Brazil, South Africa and Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, Repúbl ...
''
* ''P. cambelli'' = '' Paciphacops cambelli''
* ''P. claviger'' = '' Paciphacops claviger''
* ''P. caudatus'' = '' Dalmanites caudatus''
* ''P. constrictus'' = '' Acastoides constrictus''
* ''P. coronatus'' = '' Heliocephalus coronatus''
* ''P. cristatus bombifrons'' = '' Viaphacops bombifrons''
* ''P. cristatus cristatus'' = '' Viaphacops cristatus''
* ''P. crossleii'' = '' Paciphacops crossleii''
* ''P. cryptophthalmoides'' = '' Trimerocephalus cryptophthalmoides''
* ''P. cryptophthalmus'' = '' Cryphops cryptophthalmus''
* ''P. cultifrons'' = '' Eophacops trapeziceps''
* ''P. dagincourti'' = '' Bouleia dagincourti''
* ''P. deshayesi'' = '' Zeliszkella deshayesi''
* ''P. downingiae'' var. ''α. vulgaris'' = '' Acaste downingiae''
* ''P. downingiae'' var. ''β. macrops'' = '' Acastocephala macrops''
* ''P. downingiae'' var. ''γ. inflatus'' = '' Acaste inflata''
* ''P. ensae'' = '' Weyerites ensae''
* ''P. fecundus'' = '' Ananaspis fecunda''
* ''P. fecundus minor'' = '' Lochkovella minor''
* ''P. ferdinandi'' = '' Chotecops ferdinandi''
* ''P. glaber'' = '' Eophacops glaber''
* ''P. glockeri'' = '' Phacopidella glockeri''
* ''P. grimbergi'' = '' Lochkovella grimbergi''
* ''P. handwerki'' = '' Eophacops handwerki''
* ''P. hanusi'' = '' Lochkovella hanusi''
* ''P. hoeninghausi'' = '' Prokops hoeninghausi''
* ''P. hudsonicus'' = '' Paciphacops hudsonicus''
* ''P. incisus'' = '' Nephranops incisus''
* ''P. khatangensis'' = '' Acernaspis khatangensis''
* ''P. kayseri'' = '' Eocryphops kayseri''
* ''P. lacunosus'' = '' Trimerocephalus lacunosus''
* ''P. latigenalis'' = '' Paciphacops latigenalis''
* ''P. latilimbatus'' = '' Cryphops latilimbatus''
* ''P. lentiginosus'' = '' Trimerocephalus lentiginosus''
* ''P. limbatus'' = '' Dianops limbatus''
* ''P. logani'' = '' Paciphacops logani''
* ''P. lopatini'' = '' Monorakos lopatini''
* ''P. mancus'' = '' Eophacops mancus''
* ''P. marklandensis'' = '' Acernaspis marklandensis''
* ''P. mastophthalmus'' = '' Trimerocephalus mastophthalmus''
* ''P. metacernaspis'' = generic assignment uncertain
* ''P. michelini'' = '' Pseudocryphaeus michelini''
* ''P. microps'' = '' Kainops microps''
* ''P. milleri'' = '' Eldredgeops milleri''
* ''P. miser'' = '' Lochkovella miser''
* ''P. musheni'' = '' Eophacops musheni''
* ''P. nudus'' = generic assignment uncertain
* ''P. ocellus'' = '' Hadrorachus ocellus''
* ''P. opitzi'' = '' Chotecops opitzi''
* ''P. orestes'' = '' Acernaspis orestes''
* ''P. orientalis'' = '' Ananaspis orientalis''
* ''P. parabolus'' = '' Phillipsinella parabola''
* ''P. phillipsi'' = '' Kloucekia phillipsi''
* ''P. primaevus'' = '' Acernaspis primaeva''
* ''P. prokopi'' = '' Prokops prokopi''
* ''P. pulcellus'' = '' Acernaspis pulcella''
* ''P. quadrilineatus'' = '' Acernaspis quadrilineata''
* ''P. rana'' = ''Eldredgeops rana
''Eldredgeops rana'' (formerly ''Phacops rana'') is a species of trilobite from the middle Devonian period. Their fossils are found chiefly in the northeastern United States, and southwestern Ontario.
Because of its abundance and popularity wit ...
''
* ''P. raymondi'' = '' Kainops raymondi''
* ''P. schlosseri'' = '' Struveops schlosseri''
* ''P. serratus'' = '' Paciphacops serratus''
* ''P. schlotheimi'' = '' Geesops schlotheimi''
* ''P. socialis'' = '' Dalmanitina socialis''
* ''P. speculator'' = '' Austerops speculator''
* ''P. sphaericeps'' = '' Dereimsia sphaericeps''
* ''P. steinachensis'' = '' Trimerocephalus steinachensis''
* ''P. stellifer'' = '' Greenops (Neometacanthus) stellifer''
* ''P. stokesii'' = generic assignment uncertain
* ''P. straitonensis'' = '' Podowrinella straitonensis''
* ''P. trapeziceps'' = '' Eophacops trapeziceps''
* ''P. veles'' = '' Kainops veles''
* ''P. vodorezovi'' = '' Trimerocephalus vodorezovi''
* ''P. volborthi'' = '' Denckmannites volborthi''
* ''P. wocklumeriae'' = '' Weyerites wocklumeriae''
References
External links
* {{Taxonbar, from=Q44129 Phacopidae Ordovician trilobites of Europe Silurian trilobites of Europe Devonian trilobites of Europe Ordovician United Kingdom Trilobites of North America Silurian United States Devonian United States Fossils of Georgia (U.S. state) Trilobites of South America Devonian Bolivia Devonian Brazil Devonian Colombia Fossils of Colombia Devonian Venezuela Ordovician first appearances Late Devonian animals Late Devonian genus extinctions Fossil taxa described in 1839 Paleozoic life of Ontario Floresta Formation Paleozoic life of New Brunswick Paleozoic life of the Northwest Territories Paleozoic life of Quebec