Some Unique Niagaran Cephalopods

Proceedings of the Iowa Academy of Science

Volume 22 Annual Issue Article 38

1915

A. O. Thomas State University of Iowa

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Recommended Citation Thomas, A. O. (1915) "Some Unique Niagaran Cephalopods," Proceedings of the Iowa Academy of Science, 22(1), 292-300. Available at: https://scholarworks.uni.edu/pias/vol22/iss1/38

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occupying the large sipli a fair more important : does the slender remna SOME UNIQUE NIAGARAN CEPHALOPODS. whose siphon is not knc A. 0. THOMAS. Fragments of these li Among the paleontological collections at the State University of the record left by i of Iowa are some unique cephalopod remains. It is the purpose the Niagaran seas of ea of this paper to call attention to a few of them and it is hoped the shell and a few of that at some later time the rich Niagaran fauna of which these siphuncle; more commrn are a part shall receive more extensive treatment. Such specimens show tl The specimens at hand consist chiefly of the siphuncles of and septa but several 01 several orthoceracone species. They are of the :immmuloidal type segments of the siphm and are usually strongly silicified. They occur at nearly all mains in Iowa has bee horizons in the Niagaran but most frequently in the Hopkinton in the Delaware county or Delaware stage. Specimens are never abundant. son county report. So The beautiful and rare pearly nautilus of our modern seas is article were doubtless 1 the nearest living relative of these extinct species. From our field work in the counti1 study of zoology it will be recalled that the coiled shell of the A paleogeographic m, nautilus is divided by transverse partitions (the septa) into garan epoch shows tha~ chambers. The septa are concave, their concave surfaces facing a part of a series 0£ di the opening· or aperture of the shell. The· animal lives in the Illinois then north alon1 body chamber, a cuplike cavity above the last-septum. An ex east again in the uppei tension of the body, known as the siphon, passes backward from north end of Lake Hur. the body chamber through perforations in the septa. In the The Niagaran outcroj modern nautilus the .perforation in the last sep,tum is but a species of these interei millimeter or two in diameter and becomes gradually smaller as known to scientists for it is traced back through earlier and earlier septa. On the con Dr.. John J. Bigsby read vex or posterior surface of each septum the shell substance is a paper entitled "Notes built out into a short tube around the siphonal perforation. Huron.''"· This paper, : T~is series of disconnected tubes is called the siphuncle. In the contains a description a modern nautilus each segment of it extends only about one shelled cephalopods fro1 third the distance across the air chamber into which it projects. the north end of the la] The Niagaran cephalopods which are here considered were siphuncles and it is not 1 straight-shelled tapering forms much as our coiled pearly nau led him to ,\iescribe the1 tilus would make were it possible to uncoil it into the form of general appearance a c a straight ·cone. Curved, loosely coiled, and even closely coiled Mr. Charles Stokes, a fel species were contemporaries of the straight-shelled ones but a to name the supposed

few of the straight species only will be discussed in this paper. 1Iowa Geo!. Surv.; Vol. X, · 2Iowa Geo!. Slirv., Vol. X\ The slender discontinuous siphuncle of the pearly nautilus •see Chamberlin and Salis Charles Schuchert, "Paleogeo1 is but a vestige of the large continuous siphuncle of its extinct Plate 67. •Trans. Geo!. Soc. London, Niagaran ancestors. Moreover, it is quite likely that the siphon xxv, xxvi, xxviii, xxx.

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Proceedings of the Iowa Academy of Science, Vol. 22 [1915], No. 1, Art. 38 SCIENCE NIAGARAN CEPHALOPODS 293

occupying the large siphuncle of the Niagaran cephalopod played a_ fair more important function in -the life of the animal than OEPH.ALOPODS. does the slender remnant in the nautilus, the real function of whose siphon is not known with certainty. Fragments of these large siphuncles constitute the chief part 1s at the State University of the record left by the straight nautiloids which_ thrived in 3mains. It is the purpose the Niagaran seas of east-central Iowa. In rare cases a part of r of them and it is hoped the shell and a few of the septa have been preserved with the ran fauna of which these siphuncle; more commonly it is a cast of the shell that is found. Greatment. Such specimens show the relation of the siphuncle to the shell 1fly of the siphuncles of and septa but several of the species are known only from a few of the _nummuloidal type segments of _the siphuncle alone. The occurrence of such re 'hey occur at nearly all mains in Iowa has been noted! by Oalvin1 in the' Dubuque and 1uently in the Hopkinton in the Delaware county reports and also by Savage2 in the Jack er abundant. son county report: Some of the specimens described in this .us of our modern seas is _article were doubtless collected during the prosecution, of the tinct species. From our field work in the counties named. 1.t the coiled shell of the A paleogeographic map3 of North .America during the Nia titions (the septa) into garan epoch shows that the rocks of this age in Iowa are but ' concave surfaces facing a part of a series 0£ disconnected outcrops extending east into The animal lives: in the Illinois then north along the west shore of Lake Michigan then the last-septum. An ex east again in the upper peninsula of Michigan and across the n, passes backward from north end of Lake Huron into Ontario and on into New York. ts in the septa. In the The Niagaran outcrops just pointed out have yielded several te last sep.tum is but a species of these interesting cephalopods and they have been nes gradually smaller as known to scientists for nearly a century. .As early as 1823, rlier septa. On the con Dr._ John J. Bigsby read before the Geolo~cal Society of London Ill the shell substance is a paper entitled ''Notes on the Geography and Geology of Lake ie siphonal perforation. Huron.' '4 This paper, puhlished the following year at London, )d the siphuncle. In the contains a description and :figures of several species of straight xtends only about one shelled cephalopods from prummond and Thessalon islands in r into which it projects. the north end of the lake. Of one genus Bigsby had only the e here considered were siphuncles and it is not surprising that their actiniform lamellae 1 our coiled pearly nau- led him to •\iescribe them as sp.ecies of corals having ''in their 1coil it into the form of general appearance a considerable resemblance to vertehrae' '. and even closely coiled Mr. Charles Stokes, a fellow of the Geological Society, undertook light-shelled ones but a to name the supposed corals for Bigsby. He gave then the discussed in this paper. 1Iowa Geo!. Surv.,- Vol. X, p. 454, also Vol. VIII, pp. 152 and 158. of the pearly nautilus 2Iowa Geo!. Surv., Vol. XVI, p. 616. _ •see Chamberlin and Salisbury, "Introductory Geology," 1914, p. 390 or siphuncle of its, extinct Charles Schuchert, "Paleogeography of North America," Bull. G. S. A., 1910, Plate 67. ' ' e likely that the siphon •Trans. Geo!. Soc. London, second series, Vol. i, pt. ii, pp. 175-209, Plates xxv, xxvi, xxviii, xxx.

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generic name, Huronia, and assigned specific names to the five Shell straight, gradu~ species which Bigsby had separated on "variations of external verse section. Surface form''. Stokes recognized the otl).er cephalopods in Bigsby 's not preserved in the ma paper as "Orthocerae", but no names were suggested. Siphuncle smooth, c1 It may be of interest at this point to recall that Drummond position, and round in 1 Island was formerly the site of a British garrison and fossil re down a short distance i mains were first collected there by a Mr. White of the Army the one next older; the Medical Staff. By the treaty of Ghent the island was ceded to tween this expanded to the United States and the British garrison was withdrawn. Dr. ab(:>Ve; the groove for it: Bigsby, an ardent Englishman, laments in· his paper, page 202, inward for a distance < that "as it will not be held as a military post by its present ment 's base. Fragme~ owners, it will be long, probably, ere its fossils again become the grooves are very thin. object of research.'' Fourteen years,· however, after the reading ments is more or less o: of Bigsby's paper, Stokes read an article before the same society phuncle ; the. amount of ''On some Species of Orthocerata' '5 in which he corrected his the siphuncle,-in the s former view as to the coral nature of Huronia and interpreted fragments show the gre: the fossils as the siphuncles of orthoceracones. Endosiphuncle centra It would extend this paper to an unwarranted length were the smaller end of the segm writer to mention, even briefiy, the work of later geologists and and in others filled wii paleontologists who have contributed to our knowledge of the phuncle and the inner Niagaran cephalopods. Reference will be made to a few of them lamellae which in cross-~ in the descriptions which follow but no attempt will be made to phylloid coral. At the give a complete bibliography of each species. lamellae seem to be rep] For the sake of taxonom1c clearness it inay be stated here that concentrically between Hyatt6 makes Huronia a sub-genus of Actinoceras while East sep.tal groove. man in the second edition of Zittel 's T~xtbook of Paleontology, Measurements: speci 1913, page 609, treats it as a genus of equal rank with Actiiloceras least, 26 mm. ; length, 3 in the family Actinoceratidae. The latter will be followed in Specimen (b) three this paper. 30.2, 29.9, 27.0 mm.; lei DESCRIPTION OF SPECIES. each; obliquity 92°. Huronia vertebralis Stokes. Specimen (c), four Plate XXXIII, figure 1; Plate XXXIV, figure 5. 20.1, 20.1, 19.0, 18.5 mm 1824. Huronia vertebralis Stokes. Trans. Geol. Soc. London, second 16.0, 16.0, 15.5, 15.2 m:r series, Vol. i, pt. ii, p. 202, Pl. xxviii, fig. 2. One very fine specimen 1851. Huronia vertebralis Hall. Rept. on the Geol, of the Lake Super cherty dolomite; only a ca ior Land Dist., by Foster and Whitney, part ii, p. 221, Pl. xxxiv, fig. 1. has entirely effaced all tra1 quarry the slab was broke, 1857. Orthoceras canaaense Billings. Rept. of progr. Geol. · Surv., its relation to the origim Canada, p. 321. present. The specimen is 'Trans. Geol. Soc. London, second series, Vol. v, pt. iii, pp. 705-714,Pls. end and fifty at the sm: !ix, Ix. · •Proc. Boston Soc. Nat. Hist., Vol. xxii, .1884. The rate of tapering . in di,

Published by UNI ScholarWorks, 1915 3 Proceedings of the Iowa Academy of Science, Vol. 22 [1915], No. 1, Art. 38

CIENCE NIA

pecific names to the five Shell straight, gradually· tapering; slightly elliptical in trans "variations of external verse secti-0n. Surface -0f the shell and character of the septa cephalopods in Bigsby 's not preserved in the material at hand. . were suggested. Siphuncle smooth, conspicuously segmented, sub-central · in o recall that Drummond position, and round in cross-section. Each joint or segment fits ih garrison and fossil re down a short distance into the swollen and deflected summit of Mr. White of the ·Army the one next older; the proximal edge of the septum passed be t the island was ceded to tween this expanded top and the contracted base of the joint ;on was withdrawn. Dr. a.b0ve; the groove for its recepti-On is very narro:w and it extends ~ in· his paper, page 202, inwfil.d for a distance of about one-fifth the radius of the seg-: tary post by its present ment 's base. Fragments of the septa still remaining in the I fossils again become the grooves are very thin. The plane of contact between two seg ~wever, after the reading ments is more or less oblique to the longitudinal. axis of the si e before the same society phuncle; the amount of obliquity depends on the eccentricity of L which he corrected his the siphuncle,-in the specimens at hand the large siphuncular Huronia and interpreted fragments show the greatest obliquity. •aeon es. End-0siphuncle central, its diameter about one-sixth that of the arranted length were the smaller end of the segment; in some of the specimens it is open ~k of later geologists and and in others filled with foreign matter. Between the endosi :o our knowledge of the phuncle and the inner surface of the segments radiate vertical )e made to a few of them lamellae which in cross-section resemble the septa of some cyatho attempt will be made to phylloid coral. .At· the constrictions between the segments the pecies. lamellae seem to be replaced by short cylindrical rings arranged Ginay be stated here that concentrically between the endosiphuncle and the base of the Actinoceras while East sep.tal groove. extb-0ok of Pale-0ntology, Measurements: specimen (a) diameter, greatest, 33 mm., ial rank with Actiiloceras least, 26 mm.; length, 31 mm.; obliquity, 97°. >tter will be followed in Specimen (b) three successive segments; diameter, greatest, 30.2, 29.9, 27.0 mm.; least, 26.0, 25.2, 25.0 mm.; length, 25 mm. ~CIES. each; obliquity 92°. Stokes. Specimen ( c), four successive segments; diameter, greatest, KXXIV, figure 5. 20.1, 20.1, 19.0, 18.5 mm.; least, 17.3, 16.5, 16.0, 15.2 mm.; length, Geol. Soc. London, second 16.0, 16.0, 15.5, 15.2 mm.; obliquity, 92°. !. One very fine specimen in the university museum lies in a slab of P.e Geol, of the Lake Super cherty dolomite; only a cast of the shell remains, while dolomitization rt ii, p. 221, Pl. xxxiv, fig. 1. has entirely effaced all traces of the septa. On being removed from the pt. of frogr. Geol. Surv., quarry the slab was broken in such a way as to show the siphuncle in its relation to the original shell or conch. Seventeen· segments are present. The specimen is ninety millimeters in diameter at the larger ol. v, pt, iii, pp. 705-714,Pls. end and fifty at the smaller, and is approximately 420 mm. long. The rate of tapering . indicates that it was at least twice this, length

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when whole. The thirteen posterior segments average twenty-two Measurements: Grea millimeters in length. It was obtained at the Farley Quarry, North (aver.) 38.1 mm. ; lengt1 Farley, Dubuque county. 95°. Occurrence and Locality: In Niagaran dolomite at Hopkin · Occurrence and Locali ton, Delaware county, and at Farley, Dubuque county, Iowa. In sity collection and is lal collection of the State University. Huronfa Huronia obliqua Stokes. Plat Plate XXXIII, figure 2. Siphuncle large, stra 1824. Huronia obUqua Stokes. Trans. Geol. Soc. London, second series, Vol. i, pt. ii, p. 203, Pl. .xxviii, fig. 4. · specimen consists of fo ment of a fifth segment.' Siphuncle straight, smooth, tapering at the rate of a little over The segments. are str one millimeter for each segment length. Transverse section cir two-fifths as long as wi cular. Segments short in proportion to their lengths--seven upper one-third of eac~ having . a total length of one hundred millimeters while their turns abruptly inward t average greatest diameter is 37.4 mm. The obliquity of the plane ment above. The obliq· passing through the line of contact of any two joints is. 97°. This A fragment of the se exceeds 'the obliquity of any other species of this genus with the double ; this is an actir exception of some of the gerontic siphuncles of H. vertebralis. observed, in any other ~ Endosiphuncle central and proportionately smaller than in the The endosiphuncle is preceding; the actiniform lamellae well developed. · meter. The actiniform Occurrence and Locality: The only specimen in the Univer crowded than in any of sity collection is labelled Niagaran, northeastern Iowa. . This species differs f Huronia subcylindrica. sp. nov. the proportions of the anterior ring. Plate XXXIV, figure 4. ,l\foasurements: Gire Siphuncle straight, round in cross section, sides parallel, or (a~er.) 46 mm.; length nearly so; the specimen consists of seven segments, four of them Occurrence and Local whole. It shows no appreciable tapering. sity collection and is la1 The segments are about one-half as long as their average dia meter and their nearly parallel sides give them a cylindrical ap Hurc pearance. The anterior endi of each segment is partly set off Pla1 from its main body by a sort of uneven contact which somewhat 1824. Huro'/'l,ia · turbinata resembles the epiph.yseal surface in the limb bones of young series, Vol. i, pt. ii, p. 20 mammals. The contact between two segments is slightly oblique. Siph.uncle straight, The endosiphuncle is six to eight millimeters in diameter, is specimen consists of fo1 out of the center by about one-half this amount, and its wall is feet, the two middle on wrinkled and irregular. The lamellae are strong, more or less The segments are not ,convoluted, a:rid are irregularly arranged. of each is prominent : periphery is quite well Fragments of the thin proximal edges of the septa are present half of each segment i~ between all the joints; they enter between them at an angle of concave and smoother tl nearly 45 ° from the vertical.

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~CIENCE NIAGARAN CEPHALOPODS 297

~ments average twenty-two t the Farley Quarry, North Measurements: Greatest diameter (aver.) 40 mm., least (aver.) 38.1 mm.; length of segments (aver.) 21 mm.; obliquity, 'ran dolomite at Hopkin- 95°. . 11buque county, Iowa. In Occurrence and Locality: The type specimen is in the Univer sity collection and is labelled Niagaran, Delaware county, Iowa.

Gokes. Huronia hopkintonensis sp. nov. Lre 2. Plate XXXIII, figure 3. . Soc. London, second serie8, Siphuncle large, straight, tap.ers very gradually. T4e. type specimen consists of four pa:rily broken segments and a frag i.t the rate of a little over· ment of a fifth segment. Transverse section apparently circular. :Transverse· section cir- The segments ar.e strikingly short and broad and are about to their lengths-seven two-fifths. as long as wide; their sides slope gradually and the . millimeters while their upper one-third of ~ach is moderately swollen; the top of each rhe obliquity of the plane turns abruptly inward then obliquely downward beneath the seg LY two joints is 97°. This ment above. The obliquity of the segmental contact is small. es of this genus with the A fragment of the sepitum between the two lower segments is 11nCles of H. vertebralis. double ; this is an actinoceran character not present, as far as ately smaller than in the observed, in any other specimen of H uronia at hand. . developed. · The endos.iphuncle is central and is two millimeters in dia specimen in the Univer meter. The actiniform lamellae are very numerous and more ~heas.tern Iowa. crowded than in any of the other sp.ecies here described. This species differs from H. vertebralis in its larger size, in sp. nov. the proportions of the se·gments, and! in the much less swollen r·e 4. anterior ring. sction, sides parallel, or Measurements: GTeatest diameter, (aver.) 55 mm., least (aver.) 46 mm.; length of segments (aver.) 20.6; obliquity, 93°. l segments, four of them lg. Occurrence and Locality: The type specimen is in the Univer ing as their average dia sity collection and is labelled Niagaran, Hopkinton, Iowa. ·e them a cylindrical ap Huronia turbinata Stokes. ~gment is partly set off Plate XXXIII, figure 4. contact which somewhat 1824. Huronia · tu.rbinata Stokes. Trans. Geol. Soc. London, second :e limb bones of young series, Vol. i, pt. ii, p. 203, Pl. xxviii, fig. 3. ments is slightly o1Jlique. Siphuncle straight, round, and tapering gradually. Our .limeters in diameter, is specimen consists of four segments, the upper and lower imper amount, and its wall is fect, the two middle ones nearly whole. are strong, more or less The segments are notably turbinate in shape; the swollen part l. of each is prominent and a circle passing along its greatest of the septa are present periphery is quite well back from the anterior end. The upper 1en them at an angle of half of each segment is convex while the lower half is slightly concave and smoother than the upper. The maximum and mini-

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300 IOWA ACADEMY OF SCIENCE

The high ol;Jliquity of the segments of this fragmentary specimen makes its reference to Stokes' species rather doubtful, while the highly silicified condition of the interior makes even generic determination uncertain. Occurrence and Locality: The specimen is in the University collection and was found in the Niagaran, Hopkinton, Iowa. GEOLOGICAL LABORATORY, STATE UNIVERSITY OF loWA.

EXPLANATION OF PLATE XXXIII. (All Figures Natural Size.) HURONIA VERT'.EBRALIS Stokes. Fig. 1. Two large segments showing unusual obliquity for. this species. HURONIA OBLiQUA Stokes. Fig. 2. A series of nine segments, the terminal ones imperfect. The greatest obliquity is at right angles to the side shown. Note that the concave surface of each segment is smoother than the convex. HURONIA HOPKINTONENSIS sp. nov. Fig. 3. The type specimen. Greatest obliquity riot shown .. HURONIA TURBINATA Stokes. Fig. 4. Portion of the siphuncle showing the obliquity of the segments, also a· fragment of the turned up part of the septum adhering to the concave surface of the upper segment. The smoothness

Published by UNI ScholarWorks, 1915 9 Proceedings of the Iowa Academy of Science, Vol. 22 [1915], No. 1, Art. 38

CENCE PLATE XXXIII. tis fragmentary specimen :1oubtful, while the highly en generic determination len is in the University t, Hopkinton, Iowa.

XXXIII. ize.) obliquity for. this· species.

:nal ones imperfect. ·The ie side shown. Note that moother than tlie convex.

.y not shown. obliquity of the segments, f the septum adhering to t: The .smoothness of the the photograph. XXXIV. ize.)

· siphuncle , sh-owing the of their separation,, and

.Iler indi'vidual, the holo-

tiowing . its ·nummuloidal b.ed to the posterior. sur bliquity of the segments.

r cylindrical chara ct ~r of ;he narrow septa! groove. st obliquity. amount of tapering, seg i evenly-inflated anterior

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