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| Genus: | Diplorrhina Hawle & Corda, 1847 [1] |
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Mesospheniscus | |
Diplorrhina Hawle and Corda (1847) [2] is a genus of trilobite belonging to Order Agnostida. It lived during the early Middle Cambrian (Amgan and Mayan stages) in what are now the Czech Republic and the North Siberian plateau. as in members of the family Peronopsidae it lacks a preglabellar furrow. Both cephalon and pygidium lack spines. It is difficult to distinguish Diplorrhina from many other peronopsids. [3]
The ancestor of Diplorrhina is most likely one of the Siberian species of the genus Archaeagnostus .D. recta is the most primitive species and it gave rise to D. cuneifera, which was in turn ancestral to Diplorrhina triplicata. [3]
Both border and border furrow of the cephalon are relatively narrow. The transglabellar furrow is straight or curved slightly towards posterior. The posterior glabellar lobe is parallel sided, has two pairs of lateral furrows and small basal lobes; there is no median node. The pygidial border is flattened and wide with posterolateral angles, but no spines. The pygidal lobes reach the median node but do not cross the axis. The distance between the pygidial axis and border furrow is short or sometimes touching. [3]
Diplorrhina differs from members of the subgenus Peronopsis (Peronopsis) in the better developed transaxial furrows, better developed lateral furrows of the glabella, larger basal lobes, and in the trend towards the formation of a transverse depression of the axis. [3]
Agnostus is a genus of agnostid trilobites, belonging to the family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian. It is the type genus of the family Agnostidae and is subdivided into two subgenera, Agnostus and Homagnostus.
Agraulos is a genus of Solenopleuridae trilobites that lived during the Middle Cambrian in North America and Europe, particularly the Czech Republic. The genus was named by Hawle & Corda in 1847.
The Paradoxididae are a family of trilobites, a group of extinct marine arthropods. They occurred during the late Lower Cambrian (Toyonian) and disappeared at the end of the Middle Cambrian. Representatives of this family have been found in the paleocontinents of Avalonia, Baltica, and Gondwana, now Canada, USA, England, Wales, Morocco, Spain, Czech Republic, Poland, Russia, Mongolia, and Turkey. Species in this family can typically grow large to very large, are relatively flat, have an inverted egg-shaped outline, opisthoparian sutures, a glabella that in early genera has parallel sides and expands forward in later representatives, and approaches or reaches the frontal border. All species have an almost semicircular headshield with long backward-directed genal spines. The articulate middle part of the body consists of 15 to 21 segments ending in sickle-shaped spines that to the back curve increasingly further backwards. The tailshield is small.
Eoagnostus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the terminal Lower Cambrian (Toyonian), until the earliest Middle Cambrian.
Acadagnostus is a genus of trilobite from the Middle Cambrian, with 7 species currently recognized. The type species A. acadicus has the widest distribution known from any peronopsid and has been found in North America, Greenland, England, Western Europe, Eastern Europe, Central Asia, the Altai Mountains, the Siberian shield, China, and Australia.
Peronopsis is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America.
Lotagnostus is a genus of very small trilobites in the order Agnostida, which lived on the outer continental shelves worldwide, during the late Upper Cambrian. It was described by Whitehouse in 1936, and the type species is Lotagnostus trisectus, which was originally described as a species of Agnostus by Salter in 1864.
Phalagnostus is a genus of small trilobites, in the order Agnostida. It lived during the Middle Cambrian, in what are now Canada, China, the Czech Republic, Denmark, England, France, the Russian Federation, Wales, Sweden, and possibly the United States (Vermont). The headshield is almost entirely effaced and wider than the tailshield. The pygidium is also very effaced, but the ovate pygidial axis is well defined and a border furrow is also present.
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.
Lejopyge laevigata is a species of agnostid trilobite belonging to the genus Lejopyge. It existed during the Guzhangian to the Paibian Age of the Cambrian. It has a cosmopolitan distribution and is an important index fossil in biostratigraphy.
Eodiscina is trilobite suborder. The Eodiscina first developed near the end of the Lower Cambrian period and became extinct at the end of the Middle Cambrian. Species are tiny to small, and have a thorax of two or three segments. Eodiscina includes six families classified under one superfamily, Eodiscoidea.
Glyptagnostus reticulatus is a species of agnostid trilobite belonging to the genus Glyptagnostus. It existed during the Paibian Age of the Cambrian. It has a cosmopolitan distribution and is an important index fossil in biostratigraphy. It was characterized by an unusual net-like pattern of furrows on both the cephalon and the pygidium.
The Peronopsidae 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 of the Middle Cambrian, and the last disappeared just after the start of the Upper Cambrian.
Thoracocare is a minute to very small trilobite, that lived during part of the Middle Cambrian in what are today the states of Idaho, Nevada and Utah. It is the only trilobite known with just two thorax segments outside most members of the Agnostida order. It can be distinguished from Agnostida by the very wide subquadrate glabella, parallel-side or widening forward in the largest specimen, with the full front side touching the border. Two species are known, one, T. idahoensis, only from pygidia.
Itagnostus is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America.
The Condylopygidae Raymond (2013) are a family of small trilobites that lived during the Middle Cambrian, and found in Canada, 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.
Pleuroctenium Hawle & Corda (1847) is an agnostid trilobite belonging to the family Condylopygidae Raymond (1913). The genus occurs in Middle Cambrian (Drumian) strata of Canada, the Czech Republic, England and Wales, France, and Sweden.
Condylopyge Hawle and Corda (1847) is a genus of agnostid trilobite that lived during the late Lower and early Middle Cambrian, in what are today Canada, the Czech Republic, England and Wales, France, Germany, Italy, Morocco, the Russian Federation, Spain, Turkey and Sweden. It can easily be distinguished from all other Agnostida because the frontal glabellar lobe is notably wider than the rear lobe. It belongs to the same family as Pleuroctenium but the frontal glabellar lobe does not fold around the rear lobe, as it does in that genus. Condylopyge is long ranging, possibly spanning the early Cambrian Terreneuvian Series in Nuneaton, central England into at least Drumian strata at various locations elsewhere.
Toragnostus is a genus of trilobites restricted to the late Middle Cambrian. Its remains have been found in the United States, Greenland, Denmark, China, Sweden, the Russian Federation, and Kazakhstan. Its headshield and tailshield are almost completely effaced and it has two thorax segments.
The Paradoxidoidea Hawle & Corda 1847, are a superfamily of trilobites, a group of extinct marine arthropods. They occurred during the late Lower Cambrian (Toyonian) and disappeared at the end of the Middle Cambrian.