Middle Ordovician – Late Ordovician
Ceraurus is an extinct genus of fast-moving low-level epifaunal carnivores
Identification in Hand Sample:
- Cephalon short, wide, rather semicircular in outline, and is covered with tubercles of various sizes.
- Glabella is convex and slightly expanding forward
- Eyes small, holochroal, slightly elevated, situated well away from the glabella
- Thorax has 11 segments
- Pygidium is small, semicircular in outline, and has a long, convex, slightly bowed pair of marginal spines extending posteriorly from the anterior segment
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- Ceraurus Green, has an exoskeleton up to 5 cm in length. The cephalon is short, wide, rather semicircular in outline, and is covered with tubercles of various sizes; pleural areas are somewhat wider than the axis. The glabella is convex and slightly expanding forward; it slightly overhangs the anterior margin of the cephalon and has three pairs of deep lateral glabellar furrows. Eyes are small, holochroal, slightly elevated, and situated well away from the glabella. Facial sutures are proparian; librigenae are narrow; genal spines are moderately long, narrow, and directed posterolaterally. The thorax has 11 segments; pleural areas are wider than the axis; each pleura is nearly straight and terminates in a moderately long, stout, posteriorly curved marginal spine. The pygidium is small, semicircular in outline, and has a long, convex, slightly bowed pair of marginal spines extending posteriorly from the anterior segment. The axis has four axial rings and a short terminal piece.
Treatise on Invertebrate Paleontology, Part O (1959):
- Glabella expanding forward, with 3 pairs of short lateral furrows; eyes set well away from glabella, opposite 3p ; fixigenae with long genal spines. Thoracic segments generally 11. Pygidium with long pair of axially recurved pleural spines from anterior segment. Surface tuberculation coarse.
- Entire body subovate in outline. Cephalon subsemicircular or subsemielliptical in outline, genal angles produced in spines; glabella strongly convex, broadest in front, with three pairs of deep lateral furrows; posterior limbs of the facial sutures cutting the lateral margins well in front of the genal angles; eyes small. Thorax usually with eleven segments, rarely nine to thirteen; axis prominent, narrower than the pleura, bounded by strong axial furrows. Pygidium small, pleural segments produced into points or spines.