Ceraurus milleranus

Phylum: Arthropoda
Class: Trilobita
Order: Phacopida
Family: Cheiruridae
Genus: Ceraurus
Species: Ceraurus milleranus (Miller & Gurley, 1897)

Stratigraphic Occurrences

C. milleranus_strat

Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C5 Sequence (Waynesville)
  • C3 Sequence (Corryville)
  • C2 Sequence (Fairview: Fairmount)

Identification in Hand Sample

  • Cephalon short, wide, pustulose, semielliptical. Covered with irregularly placed tubercles within the marginal borders
  • Glabella prominent, convex, narrower than the cheeks at the occipital ring
  • Genal spines long,finely granulose
  • Eyes small,prominent, globular, placed near the center of the cheeks
  • Pygidimn short consisting of three segments, bears a pair of stout spines.

Ceraurus milleranus from the Arnheim formation of Hamilton, Ohio (left, OUIP 1229); from the Fairview formation of Batavia, Ohio (middle, OUIP 308; right, OUIP 316)

Published Description

Davis (1998):

  • Exceedingly spiny. Has a short, wide, pustulose cephalon with prominent glabella, long genal spines and small eyes. Fairmount and Corryville.

Walter (1927):

  • C. milleranuns is distinguished from C. pleurexanthemus by its proportionally shorter cephalon, its less flaring genal spines, and by its eyes being globular and situated about equidistant from the dorsal furrows and from the posterior margin of the cephalon. The eyes of C. pleurexanthemus are conical and nearer the dorsal furrows. Further, the spines of the pygidium in C. milleranuns converge at their points instead of diverging as in C. pleurexanthemus

Raymond & Barton (1913):

  • The other name, Ceraurus milleranus, is open to many of the same objections, but fortunately we have, through the kindness of Professor Weller, been able to study the type, which is No. 6,062 in the collection at the Walker Museum of the University of Chicago. This specimen agrees with the other specimens from Cincinnati in the length of the genal spines and the position of the eyes, but the pygidium is peculiar, in having the tips of the great spines very close together. We have before us twenty good pygidia from Cincinnati, and none of them show this feature, although there is some approximation toward it in one or two specimens. We believe that this feature, which Miller and Gurley considered the most important of their specific characters, is really due to a deformation of the specimen.
  • In the matter of the position of the eyes, C. milleranus is intermediate in position between C. pleurexanthemus and C. dentatus. In C. pleurexanthemus the eye is further from the posterior margin of the head than from the glabella. In C. milleranus it is equidistant from the posterior margin and the glabella, while in C. dentatus it is nearer the posterior margin than the glabella.
  • The part of the pygidium of C. milleranus which is between the great spines has a rather undulate marginal outline. The second segment sends off short spines which extend beyond the margin, but they are so short and blunt that they merely make an undulation on the margin. All the specimens seem to be of this type.
  • Ceraurus milleranus is of about the same size as C. pleurexanthemus and about the same general proportions. The type is 39 mm. long without the pygidial spines, or 45.5 mm. long with them. The width at the genal angles is 22 mm., the cephalon is 9 mm. long, the glabella 7 mm. wide at the front and 6 mm. wide at the neck-ring. A larger cephalon is 13 mm. long and 31 mm. wide.

Slocom (1904):

  • Cephalon semielliptical, width nearly three times the length; dorsal furrows well marked. Glabella convex, narrower than the cheeks at the occipital ring, gradually widening anteriorly until its width about equals its length, abruptly bent downward at the frontal margin; anterior lobe constituting about one-third the length of the glabella; the three pairs of lateral furrows are short and about equidistant, forming three pairs of small convex lateral lobes; the two anterior pairs of furrows extend slightly forward, but the posterior pair is transverse for a part of its course and then bends abruptly backward until it meets the occipital furrow isolating the posterior lateral lobes. Occipital segment arched upward, higher than the anterior portion of the glabella, greatest height at the posterior margin, sloping gradually into the occipital furrow. This furrow is narrow and deep behind the posterior lateral glabella lobes but wider and shallow in its median portion. Cheeks convex with well-defined rounded marginal borders, posterior angle produced into spines, which point backward; eyes prominent, globular, placed near the center of the cheeks; the palpebral lobes bear a pit near the base on the side nearest to the dorsal furrows; the facial sutures originate on the lateral margins about in line with the occipital furrow, curve forward and inward to the palpebral lobes, which they traverse, thence pass forward with a sigmoid curve to the anterior margin of the cephalon. Thorax composed of ten segments; axis convex, about the same width as the pleurre; pleurre flattened for one-third to one half their width from the dorsal furrows, then bent downward and backward, tapering to a point; each pleural segment is ornamented with a prominent tubercle situated near the point where the pleurre curve downward; an angular furrow originates on the anterior margin of each pleural segment at the dorsal furrow and crosses it obliquely, reaching the posterior margin behind the tubercle; dorsal furrows distinct, nearly parallel from the first to the eighth thoracic segment, then converging posteriorly. Pygidimn short, much narrower than the posterior segment of the thorax, consisting of three segments: the anterior segment bears a pair of stout spines, which extend posteriorly with the points somewhat converging; axis undefined. Surface of the cephalon, within the marginal borders, covered with irregularly placed tubercles; on the cheeks the tubercles are somewhat farther apart and the interspaces are pitted ; the marginal borders and genal spines are finely granulose; two or more conical tubercles are situated on the posterior borders of the cheeks; the entire thorax is finely granulose, as is also the pygidium, but the granulations are more conspicuous on the caudal spines.