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Dakota Paleontology and Geology

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Invertebrate Paleontology and Faunal Summary

In the descriptions which follow, a total of seventy-eight species and varieties is described. These embrace species described by Meek, Cragin, White and others, and new species described by the writer. An effort was made to see the material on which Cragin worked, but it could not be found. He listed many species which are doubtfully present, and he listed species by one name which he subsequently described under another. As he was far removed from large libraries and collections, it is obvious that he labored under extreme difficulties. It has been extremely difficult at times to decide what forms Cragin had in mind; but so far as the writer has been able, he has retained all names given by Cragin. Some of the names have been omitted as obviously in error. The fauna described by Meek from the "Dakota" sandstone has been included.

All the types of the species described in this article for the first time are in the museum of the University of Kansas. The writer has cotypes of all species of which material is abundant.

In their distribution the species are intimately related to the type of sediment in which they occur. Not a great many species are common to both the limy shales and limestones of the Kiowa shales and the sandstones of the Mentor beds. A few forms like Trigonia emoryi, Protocardia texana, Cardium kansasensis and Turritella occur in both the sandstone and the limy beds. On the other hand, no Gryphaeas have been collected from the sandstones and no Mactra siouxensis smolanensis have been found in the shales. The sandstones have thirty species, of which five occur in the calcareous strata, while there are forty-seven species in the latter which do not occur in the sandstones. In the Mentor beds there is much variation with respect to species distribution.

In addition to the species which have been described by name, there are others of which the material is not sufficiently well preserved to warrant generic or specific designation. The number of such approximates about a dozen.

The character of the fauna is dominantly molluscan. There is a total of forty-eight species and varieties of pelecypods in the Mentor and other marine strata of central and northern Kansas. There are an additional six species of pelecypods which were described by Meek from the "Dakota" of southeastern South Dakota. There are fourteen species of gastropods in the Kiowa and Mentor strata. All other groups are represented by but few species. The cephalopoda have four species; the annelids have two species; there is a single echinoid and a single coral. Brachiopods are exceedingly rare, only a few fragments of a Lingula having been collected. Several fragments of a Dentalium have been found.

The fauna of the Kiowa shale is essentially the same at all localities, but differs somewhat in different beds. The organisms in the Mentor beds vary in number and components with every locality, as is to be expected. The organisms found in most of the beds of the Kiowa shale probably did not live a great distance from where the shells now occur, but the shells in the Mentor bed in most instances appear to have undergone considerable transportation.


Astrocoenia nidiformis Cragin
(Plate X, figure 4.)

1866. Astrocoenia nidiformis Cragin. Colorado Coll. Studies, 6th Ann. Publication, p. 60.

Cragin's description (in part). Stock massive, broad and low, its breadth increasing more or less from the base upward; its summit excavated, the prominent, narrowly rounded border region of the summit being irregularly lobed; cells united by rather thick walls, calyces small, irregularly polygonal or slightly rounded-polygonal; columella short; septa rather stout, their free margins apparently a little uneven, their summits moderately depressed below the level of the calyx borders, the primary and secondary septa six each, short septa of the third order also appearing.

The above description was based on two specimens. The writer has collected an additional one (a colony), upon which the statements which follow are based.

The colony began its growth on fragments of shells and ultimately overgrew a portion of the surrounding sands. It is not over a centimeter thick. Each calyx is about 3/4 mm. in diameter and the intercalicular substance, is about 1/2 mm. wide. The calyces are about 1/4 mm. deep. The septa in the writer's specimen are in two sets, the larger reaching the center, the shorter consisting of well-defined ridges. There are twelve septa in each set. Cragin noted a columella which has not-been observed by the writer. Neither tabula nor dissepiments appear to have been preserved.

Horizon and locality. Cragin's two specimens came from the Champion shell bed in Champion Draw. The writer's specimen came from the same horizon and locality.


Neries? incognita Cragin
(Plate VII, figure 4.)

[Note: this should probably be Nereis, as is listed on plates]

1894. (?Neries) incognita Cragin. Am. Geol., vol. XIV, p. 2, pl. I, figs. 20, 21.

Cragin's description. The specific name, incognita, is proposed as a convenient designation for the large, apparently neried worm that inhabited the sandy beach of the Comanchean sea of southern Kansas, and the casts of whose burrows (part of one of which is shown natural size from above and in cross section in figures 21 and 22 of Plate I) occur commonly in Kiowa county in No. 5 of my Belvidere section, and occasionally at least in Clark County, in the earthy and saccharoidal sandstone which constitutes No. 4 of my Bluff Creek section.

The burrows form boldly sweeping, tortuous curves which lie in a slightly warped surface and occasionally cross themselves in a sigmoid or "figure 8" path. The transverse section of the cast is lenticular, averaging about 10 mm. and 6 mm. in major and minor diameters.

The writer has seen markings in the sandstones which were interpreted as seaweed impressions. It is possible that these are the forms described under the above name.

Serpula cragini, n. sp.
(Plate VII, figure 1.)

1889. Serpula intrica White, Cragin. Bull. Washburn College Lab. Nat. Hist., vol. II, No. 9, p. 35 (not described). Ibid., No, 11, 1890, p. 76 (not described).
1895. Serpula championi Cragin. Am. Geol., vol. XVI, p. 389 (not described).

The tubes are of varying diameters up to 2 mm. Slow increase in diameter, with the smallest less than 1 mm. Each tube very long and intricately tortuous. Surface without any observed ornamentation. Not certain that either end of a tube has been seen. The walls of some of the largest examples are about a third of a millimeter thick, and in some specimens each wall is composed of three layers. In other specimens only one layer has been observed.

The tubes were first identified by Cragin as S. intrica White, a species from the Upper Cretaceous of Utah. It differs from that species in greater diameter of the tubes.

Horizon and locality. Occurs in abundance in the Champion shell bed; not seen elsewhere.


Salenia kansasense, n. sp.
(Plate VII, figure 7.)

The test is small, 18 mm. in diameter (which may be a little too great, as there is some distortion), 8 mm. thick. The actinal surface appears to have been slightly concave in the vicinity of the mouth opening.

The ambulacral areas are narrow, about 2 3/4 mm. where widest, increasing from the abactinal end to the peripheral margin, and thence continuing to the mouth with parallel sides. Plates simple, arranged in alternation. Two rows of tubercles in alternating position are along the middle, at least 20 in each row (there may possibly be one or two more, as a small portion of the test is broken away around the peristome). The tubercles are mammillated and the surrounding areas apparently are granulated. Pores uniserial, the outer row situated on the ambulacral plates and two of this row to each plate. Every alternate pore of the inner row is in the central portion of the plate. Each intermediate pore of this row is divided into two parts by the planes separating the plates. Pore couplets slightly inclined.

Interambulacral areas 7 to 7 1/2 mm. wide at the widest portion, narrowing in both directions, formed of two rows of broad plates which are about 3 1/2 mm. in each direction, rectangular and not in alternation. Each with a large crenulated tubercle in the center; these increase rapidly in size from the peristome and are surrounded by mammillated granules of different sizes. An imperforate mamelon is situated within the crenulated margin of the large tubercle.

The apical disk is large, convex, nearly circular, 10 mm. in diameter. Small grooves extend from one plate to those adjacent. Each groove has a small pore in the middle which is shared by each plate. The subanal plate occupies the center of the disk. The anal opening appears to be nearly round, but may be flattened anteriorly-posteriorly. Oculars exsert.

Peristome apparently round; margin broken away so that the original width not determinable. The opening so made is 7 1/2 mm. in diameter.

The shell is about the size of that of S. texana Credner, but differs markedly in the sculpturing of the apical disk and the number of pores to one of the ambulacral plates.

Horizon and Locality. A single specimen from the Champion shell bed, Champion Draw, Belvidere, Kan.

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Kansas Geological Survey, Geology
Placed on web February 2006; originally published 1924.
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