Invertebrate Paleontology Earth Sciences Division Natural History Museum

Size: px

Start display at page:

Download "Invertebrate Paleontology Earth Sciences Division Natural History Museum"

Magnus Martin
5 years ago
Views:

Invertebrate Palentlgy Earth Sciences Divisin Natural Histry Museum UCLA Type Cllectin REPRINT D Nt Raniva Frbrn This Rm Reprinted frm JURNAL F PALENTLGY Vl. 38, N.

1 Invertebrate Palentlgy Earth Sciences Divisin Natural Histry Museum UCLA Type Cllectin REPRINT D Nt Raniva Frbrn This Rm Reprinted frm JURNAL F PALENTLGY Vl. 38, N. 4, July, 964 CSTATIN PATTERNS IN EARLY PENNSYLVANIAN SPIRIFERIDS N. GARY LANE University f Califrnia, Ls Angeles Species discriminatin f Early and Middle Pennsylvanian spiriferids in the United States has been based n mrphlgic characters that cmmnly are defined prly and are difficult t assess n many specimens. The frequency distributin f number and pattern f lateral cstae as discussed belw is judged t affrd anther useful character fr species discriminatin. These spiriferids, lng assigned t Spirifer Swerby but recently described (Lane, 963) as a separate genus, Anthracspirifer Lane, include Anthracspirifer cciduus (Sadlick), A. pimus (Hall), and A. birdspringensis Lane, which hereafter are referred t by their trivial names. ne sample each f these three species was btained frm three separate beds in the lwer part f the Bird Spring Frmatin in Clark Cunty, Nevada, and the samples were studied in detail as t the number and arrangement f lateral cstatins. Each sample had a frequency distributin f numbers f specimens with a specific number r pattern f lateral cstae that allwed the samples t be discriminated statistically with respect t these variables. The sample f 25 specimens frm the stratigraphically lwest f the three beds (UCLA Lc. 4622) is identified as Anthracspirifer cciduus (Sadlick), based n the specimens' large size, extended hinge line, and large number f lateral cstae, the inner nes f which cmmnly bifurcate (Sadlick, 96; Eastn, 962). Frty-eight spiriferids frm a thin bed f shale abut 5 feet stratigraphically abve the ccurrence f cciduus (UCLA Lc. 462), are identified as pimus (Hall). These spiriferids are smewhat smaller than cciduus, have a shrter hinge and mre runded lateral extremities, and fewer lateral cstae that cmmnly d nt split (bifurcate). The third and stratigraphically highest sample (UCLA Lc. 444) cnsists f 45 tptypes f birdspringensis. Because the arrangement f cstae n the flank f a pedicle valve is a cunterpart mirrr image f the cstatin arrangement n the same brachial valve flank f the same specimen, all cstatin patterns are recrded as if they were develped n the right flank f a pedicle valve. Right and left as used here are the same fr the specimen and bserver, with the specimen riented with the psterir tward the bserver and the brachial valve up. Each lateral flank n which the arrangement f cstae culd be tabulated accurately is recrded as a separate bservatin n Table and in subsequent calculatins based n that table. Lateral cstae in this grup f spiriferids cnsist f tw types: thse riginating clse t the beak r alng the edge f the interarea and here called primary lateral cstae; and thse riginating by splitting r bifurcatin frm primary lateral cstae sme distance frm the beak, acrss the

782 PALENTLGICAL NTES TABLE PATTERNS F LATERAL CSTAE IN THREE SAMPLES F Anthracspirifer LANE Number f lateral cstae Pattern 6 S--5 S-l-al-3 7 S--6 S-l-al-4 Number f bserved flanks cciduus pimus

2 782 PALENTLGICAL NTES TABLE PATTERNS F LATERAL CSTAE IN THREE SAMPLES F Anthracspirifer LANE Number f lateral cstae Pattern 6 S--5 S-l-al-3 7 S--6 S-l-al-4 Number f bserved flanks cciduus pimus birdspringensis S-l S-l-al-5 6 S-l-al-al-3 6 S-l-ala-4 9 S-l-8 2 S-l-al S-l-al-al-4 2 S-l-ala-5 2 S-l-ala-al-3 2 S-l-l-l-l-al-3 S-l-l-al-5 S-l-9 2 S-l-al S-l-al-al S-l-ala-6 2 S-l-al-ala-4 S-l-ala-al-4 S-al-8 S-al-al-ala-3 S-l- S-l-al-8 4 S-l-al-al-6 4 S-l-al-l-l-al-4 2 S-l-al-9 S-l-ala-8 S-l-al-al-7 2 S-l-al-ala-6 3 S-l-al- 4 S-l-al-al-9 6 S-al-al-al-al-al-6 Ttals visceral regin f the flank. These latter cstae are called secndary laterals; they are initially lwer and narrwer than the primary csta frm which each riginates, but they gradually increase in prminence anterirly until each equals a primary csta in size. Amng the ttal 8 flanks recrded, nne had secndary cstae arising by implantatin r intercalatin between primary cstae nr bifurcating secndary cstae. At the place where a secndary csta riginates frm a primary csta ne can bserve n which side f the primary csta the bifurcatin ccurs. Develpment f a secndary csta n the admedial side f a primary csta is mre cmmn in pedicle valves and is cncurrent with a similar develpment n the abmedial side f a brachial valve primary csta. In rder t describe the variatin in patterns f primary and secndary cstae. after cnversin f cstatin patterns f brachial valves and left flanks f pedicle valves t the standard recrding scheme as if nly right flanks f pedicle valves were bserved the fllwing shrthand ntatin is used n Table. The csta bunding the right edge f the sulcus is dented "S." This csta riginates at the beak, extends the full length f the shell, and is the mst admedial lateral csta. Frm this csta tw bifurcatins generally ccur; ne results in an abmedial sulcal csta, and the ther is the secnd lateral csta. The furrw bunding the edge f the fld in the brachial valve is the cunterpart f the csta here called "S." This admedial lateral csta (S), and its bifurcatins are nt included in tabulatin f number f splits r number f lateral cstae n Table because they are the same n all speci-

3 783 PALENTLGICAL NTES mens. Primary lateral cstae are designated by the numeral "," and secndary cstae as lwer case "a" placed t the right r left f "," depending n whether the secndary lateral riginates n the abmedial r admedial side respectively f the primary. The number f simple, nnbifurcating cstae n the distal parts f the flank is indicated at the right f the ntatin. Fr example the pattern "S-l-al-ala-3" means that the first primary csta des nt split; that the secnd primary csta has a secndary csta develped n its admedial side; that the third primary csta has secndary nes n bth sides; and that the three uter primary laterals are simple, resulting in a ttal f nine lateral cstae. The three samples were tested fr significance f difference in frequency distributin f ttal number f lateral cstae per flank (Table 2) and f ttal number f bifurcatins (splits) per flank (Table 3) using a Chi-square test (Text-fig. ). In cmparisn f any tw samples the frequency distributin f bth variables was significantly different at the 5 percent level f cnfidence, except fr the number f splits in cciduus and birdspringensis. In additin, the mean number f lateral cstae and f splits per flank in each sample was cmpared using the parametric t test (Dixn & Massey, 957), and each sample had a significantly different mean number f lateral cstae and f splits per flank at the 5 percent level f cnfidence, except fr the mean number f splits in cciduus and birdspringensis. Therefre, statistical analysis f number and arrangement f lateral cstae in samples f Anthracspirifer is a useful means f discriminating different ppulatins and is a usable criterin fr distinguishing between species in cnjunctin with ther mrphlgic criteria. Cnsideratin f bth the pattern and TABLE 2 NUMBER F CSTAE PER FLANK IN THREE SAMPLES F Anthracspirifer LANE N. f cstae per flank cciduus pimus Ttal Mean TABLE 3 NUMBER F SPLITS (BIFURCATINS) PER FLANK IN THREE SAMPLES F Anthracspirifer LANE N. f splits per flank cciduus 3 9 pimus birdspringensis birdspringensis Ttal Mean number f lateral cstae in these three samples shws that 55 percent f the bserved flanks f cciduus and pimus are distinct with respect t specific pattern and number f cstae; that 6 percent f the flanks f pimus and birdspringensis are distinct; and that n flanks f cciduus and birdspringensis have bth the same pattern and number f lateral cstae. Althugh detailed studies f lateral cstae in ther Late Palezic genera f spiriferids have nt been reprted, analyses f patterns f cstae as described abve mst prbably wuld serve t distinguish Anthracspirifer frm Nespirifer Fredericks r ther genera f Late Palezic spiriferids. In summary, this study f lateral cstatin indicates that Anthracspirifer birdspringensis has a significantly small ttal number f lateral cstae and a large number f bifurcatins per flank; that pimus has a small number and few bifurcatins f lateral cstae; and that cciduus has a larger mean number f lateral cstae and cmmn bifurcatins f the cstae. Lcalities. UCLA Lc feet due west f the sutheast crner f sec. 8, T. 9 S., R. 59 E., Crn Creek Springs quadrangle, Clark Cunty, Nevada. Five-ft shale expsed in suth side f suthern branch f main wash, cntaining A. pimus, rthtetes Fischer, prductid brachipds, Reticulariina Fredericks sp., Millerella Thmpsn, Endthyra Phillips, Tetrataxis Ehrenberg, slitary rugse crals, bryzans, and trilbites. UCLA Lc feet nrtheast f Lc. 462, 2-inch thick blue-gray shaly limestne expsed n upper bedding surface f the 3-ft thick limestne with abundant rthtetes, n suth side f wash; shaly limestne cntains large Linprductus Cha, Antiquatnia Milradvich, A. cciduus and bryzans. UCLA Lc See Lane (963).

784 PALENTLGICAL NTES CHI-SQUARE TESTS UJ C P HI C BI UJ P BI 2 II R </> R LL. z X z = 2. I, df = I * =.5 5 4 iq 5 44 25 48 54 9 R z R MRE 2 6 27 2 J^ 4 39 LL 73 25 45 X z = 39.7 df = I a- =.

4 784 PALENTLGICAL NTES CHI-SQUARE TESTS UJ C P HI C BI UJ P BI 2 II R </> R LL. z X z = 2. I, df = I * = iq R z R MRE J^ 4 39 LL X z = 39.7 df = I a- =.5 9 R 8 R " LL_ X z = 4.6 ; df = I * =.5 C BI UJ < h- t R UJ < I- U) R 9 R P BI (f) P BI " TI ^J 2 R CL W R z 7 R X z = 7. 4 ; df = 3 ; * = X z = 6.8 ; df = I a =.5 LL X z = 2.4 df = I, a =.5 in J t i _i Q. C 2 R R C P C BI m P BI t i _L R Q. (f) R R Q. ~ cn F F X Z = 3. ; df = I ; * =.5 Z =.28 ; df = I ; a =.5 X z = 6.5 j df = I ; a- =.5 C - P CSTAE Nc = 25 NP = 48 NP = 48 NBI = 45 =.9 XQP = 9.2 XP = 9.2 ^BI = 8.2 s 2 =.83 S 2 =.38 s 2 =.38 P s2 = BI SP =.97 Q2 = > P.8 / =5.74 / 5 (df = 7) ~ 2. / TESTS P -BI C-BI CSTAE SPLITS / = 2.96 '.5 < df=9l > I ft ft N c =25 N BI.= 45 X c =.56 X BI =.29 S 2 c 8 S^ =.89 Sp =.96 t = I. 3 'cs Wf-68)».67 P - BI S P LITS N P = 48 N BI =45 X p =.58 X BI =.29 S 2 p =.42 S I =.89 Sp =.65 / = 5.26 / 5 (df = 9) S.66

5 785 PALENTLGICAL NTES REFERENCES DIXN, W. J., & MASSEY, F. J., JR., 957, Intrductin t statistical analysis: McGraw-Hill Bk C., Inc., v-xiii, 488 p. EASTN, W. H., 962, Carbniferus frmatins and faunas f central Mntana: U. S. Gel. Survey, Prf. Paper 348, iv+26 p., 3 pis. LANE, N. G., 963, A silicified Mrrwan brachipd faunule frm the Bird Spring Frmatin, suthern Nevada: Jur. Palentlgy, v. 37, p , pis SADLICK, WALTER, 96, New name fr Spirifer ccidentalis (Girty) and its gelgic histry: Jur. Palentlgy, v. 34, p SIEGEL, SIDNEY, 956, Nnparametric statistics fr the behaviral sciences: McGraw-Hill Bk C., Inc., vii-xviii, 32 p. A j ///// M TEXT-FIG. I Chi-square and t tests f three samples f Anthracspirifer. C, P, and BI stand fr A. cciduus, pimus, and birdspringensis respectively. Statistical prcedure fr the chi-square test is in accrd with Siegel, 956, p. 24-2; prcedure and symbls fr the t test are the same as in Dixn & Massey, 957, p. 2.

Bootstrap Method > # Purpose: understand how bootstrap method works > obs=c(11.96, 5.03, 67.40, 16.07, 31.50, 7.73, 11.10, 22.38) > n=length(obs) >

Bootstrap Method > # Purpose: understand how bootstrap method works > obs=c(11.96, 5.03, 67.40, 16.07, 31.50, 7.73, 11.10, 22.38) > n=length(obs) > Btstrap Methd > # Purpse: understand hw btstrap methd wrks > bs=c(11.96, 5.03, 67.40, 16.07, 31.50, 7.73, 11.10, 22.38) > n=length(bs) > mean(bs) [1] 21.64625 > # estimate f lambda > lambda = 1/mean(bs);