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Lophphllid Corals

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The fossiliferous formations of Upper Carboniferous strata of the midcontinent region contain considerable numbers of rugose corals. Especially abundant are the small solitary column-bearing types that may be designated collectively as lophophyllids. These lophophyllid corals have been grouped under a very few wide ranging "species" of little stratigraphic value.

Previous studies

Upper Carboniferous corals from many parts of the world have been described, but most are included as a minor part of work on large faunas. Upper Carboniferous lophophyllid corals are described by Douglas (1920), Smith (1934), and Dobrolyubova (1936). Permian species are described by Yakovlev (1903), Grabau (1922, 1928), Soschkina (1925, 1928, in Licharew and others, 1939), Huang (1932), Yoh and Huang (1932), Heritsch (1933, 1936a, 1938), Chi (1935, 1938), and Felser (1937).

Many of the important faunal zones of the Lower Carboniferous, such as the Dibunophyllum and Caninia zones of Europe and the Yuanophyllum and Pseudouralinia zones of Asia, are based on corals (Vaughan, 1905, 1915; Yu, 1931). Gorsky (1937, p. 95) and Fomitchev (1938, p. 219-222) have outlined a broad zonation of the Russian Middle and Upper Carboniferous by means of corals, but elsewhere Upper Carboniferous corals seem to have been little used in stratigraphic studies. Heritsch (1936, 1936a, 1936b, 1936c, 1937, 1937a) and Huang (1932) have set up a general zonation of the Permian system by means of the rugose corals. Extensive investigations of Late Paleozoic coral faunas have established the general lines of coral development, and detailed studies in the future should fill many of the gaps in the knowledge of Upper Carboniferous corals.

In North America, Upper Carboniferous corals have been described in many separate papers, but no detailed study has been published. Only two species of rugose corals (Newell, 1935) from these rocks have been described since 1915, but previously described species have been widely reported in faunal studies and lists that do not give evidence of careful study of the details of the types. [Note: The papers on Late Paleozoic corals by W. A. Kelley and C. W. Merriam in the Jour. Paleontology, vol. 16, no. 3 were published after proof of this paper had been received.]

The first mention of an American Upper Carboniferous lophophyllid coral is the description by Edwards and Haime (1851, p. 323) of an external mold of a calyx from Flint Ridge, Ohio, which was named Cyathaxonia profunda, n. sp. In 1850, McChesney (p. 75) described some similar lophophyllid corals from Springfield, Illinois, and western states as Cyathaxonia prolifera, n. sp. Both of these species were subsequently referred to Lophophyllum Edwards and Haime (Meek, 1872, p. 144; Foerste, 1888, p. 136), and American students of Late Paleozoic faunas have come to regard them as synonymous. A more cylindrical and irregular coral from Illinois, first described as Cyathaxonia distorta, n. sp., by Meek and Worthen (1875, p. 526), was placed in Lophophyllum by Girty, (1915a, p. 318). White (1877, p. 101) described a coral from New Mexico and Colorado, that is larger and more robust than typical examples of L. proliferum, and designated it as a new variety, Lophophyllum profundum var. sauridens. In a general study of the Kansas Upper Carboniferous fauna, Beede (1898, p. 17) described a subcylindrical coral that bears an interrupted solid column, naming it Amplexus westi, n. sp. Subsequently, this species was referred to Lophophyllum (Beede, 1900, p. 17). A short, broadly conical coral described by Rowley (1901, p. 349) as Axophyllum? alleni, n. sp., has been assigned to Lophophyllum by Girty (1915a, p. 318). In his extensive study of the fauna of the Wewoka formation, Girty (1911, p. 122; 1915, p. 23-27) described specimens that he referred to Lophophyllum profundum and a new variety of lophophyllid coral called L. profundum var. radicosum. He also discussed the generic assignment of these corals.

Scope of the present paper

Seeming lack of interest in Upper Carboniferous corals is in rather striking contrast to their abundant general occurrence. This paper reports on part of a general study of American Upper Carboniferous coral faunas. The wide distribution of lophophyllid corals throughout the midcontinent area and the extensive collections now available suggested the study of these forms as a first division of my work on corals.

An attempt is made to clarify taxonomic problems involved in the description of lophophyllid corals and to describe new species that may be of stratigraphic value. The internal characters of the genotype of Lophophyllidium Grabau, which is Cyathaxonia prolifera McChesney, have not previously been described. They are described and illustrated here from authentic material for the first time. This paper has been limited to the rather closely allied Lower Pennsylvanian corals, but stratigraphically higher forms have been studied in a preliminary manner to determine relationships and trends in development.

Material studied

The large numbers of lophophyllid corals from exactly determined stratigraphic horizons and precisely described localities that are contained in the collections of the Kansas Geological Survey have furnished the basic material for this study. A few lots of corals have been collected subsequent to the start of my work, and several other small collections have been made available to me. Specimens of lophophyllid corals from Springfield, Illinois, and Muskingum County, Ohio, were borrowed in order that characters of the type of Lophophyllidium might be determined.

The present collection of lophophyllid corals contains specimens from about 450 localities and more than 100 stratigraphic units throughout the Upper Carboniferous. All of the series and nearly all of the formations of the Kansas Pennsylvanian column are represented. The number of specimens from each locality varies from one to several hundred. Most of the material is from Kansas and Texas, but there are additional specimens from Oklahoma, Nebraska, Iowa, Missouri, Arkansas, and Colorado.

The Upper Carboniferous corals of the midcontinent area are nearly always well preserved as calcite, with little disruption of internal features or silicification. Most of the specimens have weathered completely from the surrounding limestone or shale so that external details are easily studied.

Method of study

The rugose corals of the North American Late Paleozoic strata were originally described largely on the basis of external form and such details of internal structure as were visible on broken or weathered specimens. This method usually served to distinguish specimens of corals having a prominent axial column, a wide dissepimental zone, prominent and complete tabulae, deep fossulae, and pecularities of external form. This sort of study later was supplemented by preparation and examination of a few thin sections and polished sections. In no case, excepting a study of a few lower Pennsylvanian corals by Morgan (1924), was a series of transverse sections made, insofar as reported, and rarely were longitudinal sections used to illustrate any Pennsylvanian rugose coral, either in original descriptions or in subsequent faunal studies. Duerden (1906), Gordon (1906), and Brown (1909) illustrated the early and subsequent growth stages of some Upper Carboniferous corals, but locality descriptions and other details were omitted. The studies by Grabau (1922, 1928), Lang (1923), Huang (1932), and Schindewolf (1940) have shown that knowledge of early as well as late stages in the development of a corallite are necessary for placement of the form in the proper phylogenetic line. The work of Grabau (1922), Huang (1932), Heritsch (1936a), and Moore and Jeffords (1941) on the genera of lophophyllid corals has indicated that transverse sections of the mature or upper part of the corallite of specimens of several genera may be identical, even though striking differences in ontogenic development are shown clearly in lower sections.

Study of Upper Carboniferous corals has been carried on by me at the same time as investigations of Permian corals have been made in collaboration with R. C. Moore. The methods used in this study are essentially those described by Moore and Jeffords (1941). An extensive illustrated card catalog of published species and generic descriptions of Late Paleozoic corals has been prepared to facilitate the coral studies.

The entire collection of the Kansas Geological Survey was examined in assembling corals for this study. Species found in beds of Morrow, Lampasas, Des Moines, and Missouri age are included in this paper. Work on younger Pennsylvanian species has not been completed.

Corals from each locality, representing each of the stratigraphic units, were examined and separated first on the basis of external features. Sections were prepared of one or more specimens of each group from each of the localities, except in cases where there were several very similar collections from the same stratigraphic horizon.

The specimens selected for study were mounted in plaster of Paris and cut transversely by means of a thin-bladed band saw, fed with a mixture of carborundum and water. This sawing removed a thickness of about 0.5 mm from the average calcareous corallites for each cut, and somewhat more than this thickness in the case of a few harder forms. One cut was made just above the apex of the coral, in order to show a very early growth stage, and another at or just below the floor of the calyx in order to observe the mature portion of the corallite. The remaining central part of the corallite was cut in one, or preferably two, places depending on the size of the specimen and the acceleration in development. These sections were covered with oil and photographed.

After determination of the counter-cardinal plane, the corals were assembled and cemented in original orientation by matching index marks and the pattern of the septal grooves. The specimens then were cut longitudinally in a plane normal to the counter-cardinal axis.

A few thin sections and nitrocellulose peels (Graham, 1933) were made to show structures not clearly indicated in the roughly cut sections. The peels were as satisfactory as the thin sections, if not enlarged over ten times, and they do not require the destruction of the specimen. In nearly all cases, however, the photographs were sufficiently clear for inking and study, and the longer procedure of preparing peels commonly was omitted.

Positive prints of the oiled transverse and longitudinal sections were made at a uniform enlargement of 5 times natural size. Inasmuch as the photographs of the sections commonly show many confusing features that are due to variations in the matrix, calcite cleavage, and replacement, it is desirable to eliminate such defects. Therefore the structural elements of the corals, as shown in the photographs, were compared with the original specimen studied under a binocular and inked with waterproof ink. The photographs were then bleached, leaving the drawing of the inked structures.

Throughout this study the illustrations of transverse sections are oriented with the counter septum uppermost. The position of the counter, cardinal, and two alar septa are indicated on the transverse sections. The arrangement of the septa, as given in following specific descriptions, is indicated uniformly in a clockwise direction, the counter septum being placed at the top. Measurements of the length of the corallites here described were taken in the vertical plane without regard to their slight curvature. Unless otherwise indicated diameters were determined at the calyx and are the maximum diameter.

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Kansas Geological Survey, Geology
Placed on web September 2005; originally published November 30, 1942.
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