Diplorrhina
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Diplorrhina Temporal range: early Middle Cambrian earliest Amgan to latest Mayan |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Trilobita |
| Order: | Agnostida |
| Suborder: | Agnostina |
| Superfamily: | Agnostoidea |
| Family: | Peronopsidae |
| Genus: |
Diplorrhina Hawle & Corda, 1847 |
| species | |
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| Synonyms | |
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Mesospheniscus |
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Mesospheniscus
Diplorrhina is a genus of trilobites, a well known class of extinct marine arthropods. It lived during the early Middle Cambrian (Amgan and Mayan stages) in what are now the Czech Republic and the North Siberian plateau. Like all agnostina it has a headshield (or cephalon and tailshield (or pygidium of approximately the same shape and size (or isopygeous), and two thorax segments. Like other members of the Peronopsidae family, it lacks a furrow connecting the furrow surrounding the central raise area of the cephalon (or glabella) and the furrow that defines the border of the cephalon. Both the cephalon and the pygidium lack spines. It is difficult to distinguish from many other peronopsids.
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.
Both the border and the border furrow of the cephalon are relatively narrow. The furrow that divides the glabella in an anterior and posterior part (or transglabellar furrow) is straight or bent slightly rearwards. The posterior lobe is parallel sided, has two pairs of lateral furrows in shape of prominent grooves, or pits small basal lobes, and no median node. The pygidium has a border that is flattened and widened. The pygidium is not entirely subcircular, because posterolateral corners are somewhat developed, but without spines. The lobes of the rhachis are separated by narrow groves (or transaxial furrows) that reach the median node but do not cross the rhachis. The distance between the tip of the rhachis and the border furrow is short or these even touch, but there is no furrow midline that connects the furrows defining the rhachis and the pygidial border.
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.
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Wikipedia