''Dalmanites'' is a genus of

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 ...

in the order

Phacopida Phacopida ("lens-face") is an order of trilobites that lived from the Late Cambrian to the Late Devonian. It is made up of a morphologically diverse assemblage of taxa in three related suborders. Characteristics Phacopida had 8 to 19 thorac ...

. They lived from the

Late Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The ...

Middle 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, wher ...

. The trilobites of this genus have slightly convex

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 ...

s with an average length of . The

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino s ...

is semicircular or parabolic. The

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...

(center portion of the head) is often pear-shaped, and tapers outward toward the front. The glabella also always contains three pairs of obvious glabellar furrows. Also prominent are the large mosaic (schizochroal) eyes. The thorax is composed of eleven segments, with the relatively large

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 ...

with a slender axis of 11 to 16 rings and 6 or 7 pleural ribs. The pygidium ends in a striking tail spike.

Taxonomy

Species previously assigned to ''Dalmanites''

Some species formerly included in ''Dalmanites'' have now been reassigned to other genera. * ''D. lapeyrei'' = '' Zeliszkella torrubiae'' * ''D. maecurua'' = ''Amazonaspis maecurua'' * ''D. micheli'' = '' Phacopidina micheli'' * ''D. pleione'' = '' Bellacartwrightia pleione'' * ''D. torrubiae'' = '' Zeliszkella torrubiae'' * ''D. weaveri var. tenuimucronata'' = '' Bessazoon tenuimucronata''

Description

''Dalmanites'' is genus of

s with an average (about long), moderately vaulted

with an inverted egg-shaped outline (about 1.5× longer than wide). Its headshield (or

) is semicircular, with robust (genal) spines extending from the side of the cephalon back to approximately the 8th

thorax 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 cre ...

segment. The frontal margin of the cephalon is semicircular to parabolic, and it may have a simple and short anterior extension. The facial suture lies inside or touches the preglabellar furrow. The frontal lobe of the central raised area of the cephalon (or

) is much wider than the other lobes. The frontal lobe is vaulted. The eye is moderate to large, about half as long as the cheek. The "seem" that is visible from the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

side (or doublure) is wide and flat, and has a deep and wide antennal furrow. The "palate" (or

hypostome In zoology, the hypostome can refer to structures in distinct animal groups: *Hypostome (trilobite), the ventral mouthpart plate in trilobites *Hypostome (tick) The hypostome (also called the maxilla, radula, or labium) is a calcified harpoo ...

), also only visible from the ventral side, is subtriangular (about as long as wide) and adorned with three weak denticles at its back rim. To the front the hypostome has weak wings extending sideways. The thorax consists of 11 segments. The tips of the segments are pointed and angle back increasingly from about 30° for the anterior segment to slightly pointing inwards for the posterior segment. The tailshield (or

) is large, subtriangular, and about ⅔-¾× as long as wide. The axis is vaulted and ±35% of the width of the pygidium and consists of 12-15 rings. 9–10 deep and wide pleural furrows have flat or only slightly concave bottoms. The furrows within each pleural rib (or interpleural furrows) are very narrow. The frontal band of each pleural rib is more vaulted and broader than the rear band. The pleural furrows almost reach the margin. The pygidial termination (or mucro) is vaulted and more or less pointed into a spine, which may differ between species. The entire exoskeleton is covered in fine and coarse granules.

References

{{Taxonbar, from=Q3701172 Dalmanitidae Ordovician trilobites Silurian trilobites Devonian trilobites Trilobites of North America Devonian trilobites of South America Devonian Colombia Fossils of Colombia Late Ordovician first appearances Middle Devonian genus extinctions Fossil taxa described in 1852 Jeffersonville Limestone Paleozoic life of Ontario Floresta Formation Paleozoic life of New Brunswick Paleozoic life of Nova Scotia Paleozoic life of Quebec Taxa named by Joachim Barrande