Late Paleozoic Trilobites from Kansas and Nebraska
A Thesis
Presented in Partial fulfillment of the requirements for the degree Bachelor of Science in Geological Sciences
by
Robert E. Swisher
The Ohio State University 2007 Table of Contents
Abstract...... 2
Acknowledgments ...... 3
Introduction ...... 4
Geologic Setting ...... 5
Geographic Locations ...... 11
Systematic Paleontology ...... 11
Graphs ...... 24
References ...... 27 Abstract
Species of late Paleozoic trilobites reported from Nebraska and Kansas include
Ameura missouriensis, Ditomopyge decurtata, Ditomopyge scitula, and Anisopyge whitei.
Restudy indicates that A. whitei is a subjective junior synonym of D. decurtata. Species of Ditomopyge seem to represent end members in a gradational evolutionary series. The earlier species, D. scitula (Carboniferous: Pennsylvanian) may have given rise to D. decurtata (Permian: Cisurialian) through evolutionary processes.
2 Acknowledgments
My sincerest appreciation and thanks go to Dr. Loren Babcock for his guidance, assistance, and understanding for the completion of this thesis. I would also like to thank all those who collected the specimens used in this study, including Dr. Babcock. For assistance with preparations of the specimen figures used I thank Dr. Babcock for help with the set up and use of equipment, and Brad Walls for assistance on presentation and formatting of the pictures.
3 Introduction
The goal of this study is to evaluate and systematically review four species of trilobites from Carboniferous and Permian strata of Kansas and Nebraska. The species of late Paleozoic trilobites examined in this study are: Ameura missouriensis, Ditomopyge decurtata, Ditomopyge scitula, and Anisopyge whitei.
Ameura missouriensis, has the mostly clearly defined and distinguishable features making it the easiest of the four species to identify. Distinguishing D. decurtata, D. scitula, and A. whitei is more complicated. Ditomopyge scitula and D. decurtata can often be difficult to separate based on morphological characteristics, with variations present often being gradational (Brezinski, 1988), leaving few examples of clearly identifiable specimens. Often the stratigraphic position of specimens has factored into the' identification with D. scitula occurring in the Carboniferous (Pennsylvanian Series) and
D. decurtata occurring in the Permian (Cisuralian Series). Temporal end members are distinct enough to recognize separate species (Brezinski, 1988) but it is also possible that the two forms represent a single gradational series. Ditomopyge scitula represents the earlier form. Ditomopyge decurtata may have evolved from D. scitula during the early part of the Permian through phyletic gradualism. The presence of forms transitional between the temporal end members supports this assumption. As described below, A. whitei seems to represent a synonym of D. decurtata.
4 Geologic Setting
Member Formation Holdenville Shale ldenbro limestone Mbr Lenapah Perry Farm Shale Mbr Ditompyge scitula- Norfleet ls. Mbr. Limestone Walter Johnson Ss. Mbr Nowata Shale Worland Limestone Mbr ...,_,...,...... _,,.~--··-·-·""". Altamont Cl.. Lake Neosho Sh. Mbr. limestone e:::i CJ Bandera Shale c: 0 Laberdie Ls. Mbr. ~ Mine Creek Shale Mbr. - Pawnee E \..., -· -:::;.--\: Myrick Station ls. Mbr. limestone ro C::::i::=I::> ·-- \ Anna Shale Member ~
(nglevale Ss. Mbr. Labette Shale
Higginsville ls. Mbr. Fort Scott Summit little Osage Sh Mbr. coal bed Limestone Blackjack Cr. ls. Mbr.
Figures 1. Generalized Marmaton Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
5 Member Formation ~-.. :·- .. ~ .. ~:-;.A A Bonner Sprin~s Sh . ,., y v- y y Ditompyge scitula- l Farley limestone Mbr
Ameura missouriensis- Island Creek Sh. Mb1 Wyandotte limes lone
____ .. -..., _..,- Frisbie limestone Mbr __ ,....- --- -
_,, -- '. •' ,. lane Shale _,. -·-_..---:.:.·: - -- - I _,.-- - Ameura missouriensis- Raytown Limestone Mbr. _ Muncie Creek Sh Mbr. Iola limestone -~/._:._:.·:::···-~ ., Paola Limestone Mbr.
Th mi · ::.:. ::.; '::·~:..__=--==_ Cottage Grove Ss. Mbr. 0. :::I coat bed ]_.:-_ _ -:~ Q. 0 Chanute Shale :I ... 0... <.:> bO .....>- 1 .0 :I u Cl) V) ('() Ameura missouriensis- Orum Limestone c: V) ~~l:/~\~_\·:~L~\~t~·?·~L~t§:~~::::~:~;:~:~;,~::~;~;;~:;~;:~M~~~:j· c: c: 0 :.J ('() _f,j, ,,,___~ " Quivira Shale Member ::s::: Westemlle ls. Mbr Wea Shale Member Cherryvale Shale Block Limestone Mb1. f ontana Shale Member ... " " Winterset ls. Mbr. Ameura missouriensis- 1 _:1~~~~ , .. ~-1~<~=--Tff,g-fff~ff~~~Slark Shale Member Dennis limestone - ~-;::;_ -:::._-· ______Canvill_e ls. Mb--+-r. ~ g. ) --:....---· _.:-- 0 Yt<·~=~:\:--0-od-ds-C-re-ek_S_s_.M-b-1-1 Galesburg Shale ~
Bethany falls Ls. Mbr. Hushpuckney Shale Mbr. Swope limestone § 'J---~- .. :-:.~: ~ Middle Creek Ls. Mbr. g F=:-iif., ___ _ Sniahar limestone Mbr. Ladore Shale cXl Mound City Shale Mbr. Hertha limestone 1. ) l Critzer limestone Mbr
Figures 2. Generalized Kansas City Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
6 Member Formation South Bend Ls. Mbr. Ameura missouriensis- Rock lake Shale Mbr. a. Stoner limestone Mbr. ::::> Ditompyge scitula- Stanton Limestone Eud0r1 Shale Member 0... (.!) Captain Creek Ls. Mbr. 0.0 c: Vilas Shale 'iii c: Ameura missouriensis- (\! S rin Hill ls. Mbr. ...J H1ckor Creek Sh. Mbr Plattsburg Limestone Ditompyge scitula- Mernam limestone Mbr.
Figures 3. Generalized Lansing Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
7 Member Formation i Coal Creek ls. Mb1. // Holt Shale Member /'!! Du Bois Limestone Mbr. ' Turner Creek Sh. Mbr. ,, Sheldon limestone Mbr. Topeka limestone CT~~~~~~~ Jones Point Shale Mbr. Ameura missouriensis- <:; , Curzon limestone Mbr. :::·. -c. .:::::\"\ Iowa. Point Shalt Mbr. · :__--:_~ \' Hartford Ls. Mbr. ··-.--· ------Calhoun Shale \ ·-·- • E1Vtne Creek Ls. Mbr. L " Larsh & Burroak Sh. Mbrs. Ditomopyge scitula _ _ / Rock Bluff Ls. Mbr. Deer Creek Limestone Ameura missouriensis Oskaloosa Shalt Mbr. Ozawkie limestone Mbr. .. ··. (.-. ~~. .. -·; Tecumseh Shale -··- - _,,.,.--· --- ·-- --~ . -~=-- =~.~-~;~'-:::-.- Avoca Limestone Mbr. ------·-~- I Kina Hill Shale Mbr. Ameura missouriensis- ~;; §--;~~-~--~-~~/ Beil limestone Member C 2 ,.. / Queen Hill Shale Mbr. Lecompton Limestone Big Springs Ls. Mbr. ( = Doniphan Shale Member Spring Branch Ls. Mbr. Stull Shale Member Ditomopyge decurtata ' . Clay Creek Ls Mbr. Kanwaka Shale Ameura missouriensis 13:§~~-~·:~JtE··~~-J_a_ck_s_on_Pa_r_k _S_h._M_b_' ______--1
( l Keretord Ls. Mbr. Heumader Shale Member Ditompyge decurtata- Plattsmouth Ls. Ml>r. Heebner Shale Member Oread Limestone Leavenworth ls. Mbr. Snyderville Shale Mbr. Toronto limestone Mbr.
Figures 4. Generalized pre-Wabau.nsee Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
8 Member Formation Brownville Ls. Mbr Pony Creek Shalt Mbr. Grayhorse ls. Mbr Wood Siding Plumb Shale Member Formation c. ::::i Nebmka City Ls. Mbt. 0.... Creek Sh Mbr. t:>D French ..0 Jim Creek Ls. Mbr. :::I Root Shale (/) Friedrich Shale Mbr. c: Grandhaven Ls. Mbr. 0 VI Ory Shale Member Stotler Limestone -e Dover Limestorni Mbr. .c: "'u Pillsbury Shale 0::: Stormont Maple Hill Ls. Mbr Zeandale Is. bed Wamego Shale Member Tarkio limestone Mbr. Limestone
Willard Shale a. c. :::I :::I Elmont limestone Mbr. 0 0... Emporia ire <.!) Harveyville Shale Mbr. ..0 Limestone ::J QJ Reading limestone Mbr (/) .,,QJ <'O c: .s::. ::::i Auburn Shale ro E ..0"' Wakarusa ls. Mbr. QJ <'O Soldier Cleek Sh. Mbr. Bern limestone z !: Burlingame Ls. Mbr.
Silver lake Shale Mbr.
Rulo Limestone Member Cedar Vale Shale Mbr Scranton Shale 0. ::::J Happy Hollow Ls Mbr. 0 ire :---:_:_--:--_:_-:--...:_-:- . ..0 --:-:--. ::-~ .-:-- :"'""-: - White Cloud Shale Mbr. :::I (/) >< Utopia limestone Mbr. 0 :::Lli~~(5:~ <:; Winzeler Shale Member <'O Ditompyge decurtata- Church limestorni Mbr. Howard limestone (/) l\aide Shale Mtmber -'~ ------=--~' Bachelor C1. Ls. Mbr. fl{~1 Severy Shale
Figures 5. Generalized Wabaundsee Group (Carboniferous: Pennsylvanian Series) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
9 Member Formation Speiser Shale Funston Limestone Blue Rapids Shale Crouse limestone Easly Creek Shale Middleburg Ls. Mbr Hooser Shale Member Bader limestone £iss limestone Member
Ditomopyge decurtata- Stearns Shale Morrill limestone Mbr. 0. Ditomopyge decurtata (revised)- ::s Fk>rena Shale Member Beattie Limestone ...0 Cottonwood Ls 11br. (.!> CV > Eskridge Shale ...0 (.!> Neva limes lone Mbr. ·u r: Salem Point Shale Mbr. ::s 0 Burr Limestone Mbr Grenola Limestone u Legion Shale Member Sallyards Ls. Mbr. Roca Shale Howe Limestone Member Red Eagle limestone Bennett Shale Member Glenrock Ls. Mbr. ------Johnson Shale long Creek Ls. Mbr. Ameura missouriensis- Hughes Creek Sh. Mbr. Foraker Limestone Americus Ls. Mbr
Figure 6. Generalized Permian (Cisuralian) stratigraphy of eastern Kansas showing lithologic units bearing trilobites. From Zeller 1968.
Ameura missouriensis ranges from the Carboniferious (Pennsylvanian Series) to the Permian (Cisuralian Series) It usually occurs in limestone. Specimens referable to D. decurtata from the Carboniferious (Pennsylvanian Series) through the Permian
(Cisuralian Series). They are mostly in shale units. Ditomopyge scitula occurs only in the
Carboniferous (Pennsylvanian Series) and is found in shale and limestone units.
IO Geographic Locations
Trilobite Species Geographic Localities of Specimens
Ameura missouriensis: Coffey Co. KS, Greenwood Co. KS, Lawrence Co. KS, Lecompton KS, Riley Co. Ks, Sunpy Co NE.
Ditomopyge decurtata: Elk Co. KS, Eudora KS, Greenwood Co. KS, Lecompton KS, Osage Co. KS, Wabaunsa Co. KS, Richardson Co. NE.
Ditomopyge scitula: DeSota KS, Montgomery Co. KS, Cass Co. NE.
Systematic Paleontology
Genus AMEURA Weller, 1936
AMEURA MISSOURIENSIS (Shumard, 1858)
Figure 7
Phillipsia missouriensis Shumard, 1858, p. 225.
Ameura missouriensis Shumard. Chamberlain, 1969, p. 60-62; Pabian and Fagerstrom,
1972, p. 811-813; Brezinski 1988, p. 941 (see for further synonymy).
Material. - 3 3 pygidia, 3 cephalons, 5 free cheeks.
Description. - Chamberlain ( 1969, p. 60-62).
Remarks. - Specimen proportions are slightly smaller than usual. Free checks and genal spines are slightly shorter, while pygidia are also slightly smaller compared to other described A. missouriensis specimens. However these variations fall within the range
11 described (Chamberlain, 1969). Some specimens show a reduction in the posterior pygidal boarder.
Occurrence. - Clay Creek Limestone Member of the Kanwaka Shale; Curzon Limestone
Member of the Topeka Limestone; Drum Limestone; Farley Limestone Member of the
Wyandotte Limestone; Raytown Limestone Member of the Iola Limestone; Winterset
Limestone Member of the Dennis Limestone; Stoner Limestone Member of the Stanton
Limestone; Spring Hill Limestone Member of the Plattsburg Limestone; Deer Creek
Limestone; Beil Limestone Member of the Lecompton Limestone.
12 : ~ .. L
Figure 7.
13 Figure 7. Ameura missouriensis, from the Carboniferous of Kansas. Specimens are reposited in the University of Kansas Museum of Invertebrate Paleontology (KUMIP).
1. Cephalon and anterior thorax; x2. Curzon Limestone Member of the Topeka
Limestone, Coffey County, Kansas; KUMIP _.
2. Complete pygidium x2. Drum Limestone, SW of Coffeyville, Kansas; KUMIP _.
3. Complete pygidium; x2. Clay Creek Limestone Member of the Kanwaka Shale,
Greenwood County, Kansas; KUMIP _.
14 Genus D1TOMOPYGE Newell, 1931
DITOMOPYGE DECURTATA (Gheyselinck, 1937)
Figure 8
Phillipsia (Neophillipsia) decurtata Gheyselinck, 1937, p. 56.
Ditomopyge decurtata (Gheyselinck) Weller, 1944, p. 320-321; Shimer and Shrock,
1944, p. 645; Mudge and Y ochelson, 1962, p. 96-97; Hahn and Hahn, '1970, p.
175; Owens, 1983, p. 26; Brenzinski, 1988, p. 941-942.
Material.- 122 enrolled specimens, 5 cephalons, 33 pygidia, and 4 free cheeks
Description.- See Brezinksi (1988, p. 941-942).
Remarks. - The studied Ditomopyge decurtata specimens cited above are from the following localities; the Kanwaka shale of the Carboniferous Pennsylvannian Series and the Florena Shale Member of the Beattie Limestone (Permian: Cisuralian Series).
Specimens from the Kanwaka Shale are slightly smaller than average. Cephalic proportions in the glabella, preoccipital lobes, and other measurable features are almost identical to those of Ditomopyge scitula. The main deviations are a decrease in genal spine length; shorter with a more triangular appearance with the spine reaching the second through third thoracic segments. While being less consistent with D. scitula, these lengths are similar to those seen in Anisopyge whitei, with genal spines reaching the second through third thoracic segments and showing a triangular appearance. Pygidia are semicircular in appearance, they resemble those of D. scitula. Pleural regions show a lack of geniculation seen more predominantly in D. scitula, and also have a more uniform
15 width throughout the length of the pygidium and occur in a ratio of 6 pleural lobes to 10-
11 axial lobes. Along the axial profile a subrounded appearance is present.
Specimens from the Florena Shale Member of the Beattie Limestone (Permian:
Cisuralian Series) have a relatively large variance in size and measurable features. Many of the specimens are enrolled, accounting for some of the variation. Cephalic proportions in the gaballer region, preoccipital lobes, and other measurable features are almost identical to those of D. scitula. Differences are in the length of genal spines, with a relatively shorter length resulting in a more triangular appearance than that of the longer
D. scitula specimens. Lengths of genal spines range from the second through fourth thoracic segments. While being less consistent with D. scitula, these lengths are similar to those seen in the Anisopyge whitei, with genal spines reaching the second through third thoracic segments and showing a triangular appearance. A large degree of variation is seen the anterior glabeller borders of the specimens. Narrow to wide anterior borders are not present in D. scitula, and are similar to the borders in A. whitei.
Pygidia also show a large degree of variation in the D. decurtata specimens. The axial profile ranges from subrounded to a slightly longer and less rounded form than those of D. scitula (see Brezinski, 1982). Pleural lobes in the pygidium range from seven to eight, and axial rings range from fifteen to sixteen. Pleural regions lack the geniculations of the pleural lobes seen more predominantly in D. scitula, and also have a more uniform width along the length of the pygidium. Granules on top of the axial lobes run the length of the pygidium in some specimens. Pygidial shape outline tends to be subrounded to triangular.
16 The variations seen between the two sets of D. decurtata specimens are consistent
with findings on other specimens described. The Kanwaka Shale specimens show 10 through 11 to six pygidial lobes and ribs ratio and smaller pygidal sizes similar to those in
Appalachian D. decurtata specimens (Brezinski. 1988); while the Florena specimen are similar to the Wolfcampian Series specimens of mid continental North America with a ratio of 15 through 16 to eight for lobes to ribs. Explanations of variation include phyletic size increase of holaspid individuals, or ecophenotypic responses (Brezinski, 1988).
Anisopyge whitei and D. scitula have been associated together in the past, with D. scitula being considered a probable ancestor of Permian A. whitei (Pabian and
Fagerstrom, 1972). While many morphological characteristics and biometric measurements have been taken to show the similarities between the two, variances where present provide distinction, between the species. D. scitula lacks or has a very narrow anterior gabellar lobe, while A. whitei has a relatively wide anterior border. Genal spines of D. scitula extend to the fourth to fifth thoracic segments, while those of A. whitei extend to the second to the third segment. Also D. scitula has a larger range of pygidial lobes ranging from 11 to 14 axial and seven to eleven pleural ribs, A. whitei shows a similar but more stable count fourteen to fifteen axial and seven to eight pleural ribs, with the pleural ribs showing a more uniform width (Pabian and Fagerstrom, 1972). While these differences are minor they do offer some distinction.
The range of variation in A. whitei is entirely consistent with D. decurtata.
Ditomopyge decurtata specimens do have variation in the anterior gabellar lobe. Some specimens have a narrow border, other specimens have anterior borders of comparable in thickness to that of A. whitei specimens. Genal spines are also reduced in D. decurtata
17 extending to the second to the fourth thoracic segments, comparable to the second to the third seen in A. whitei. Ditomopyge decurtata and A. whitei 's pygidia are comparable both in a subrounded to triangular outline and in counts of axial and pleural lobes and ribs. Based on these similarities and near indistinguishablity it seems likely that the two are actually the same species. Anisopyge whitei has been noted to share more characteristics with the genus Ditomopyge than Anisopyge (Pabian and Fagerstrom, 1972) and upon comparison with D. decurtata it seems the two are actually one in the same.
Occurrence. - Clay Creek Limestone Member of the Kanwaka Shale; Florena Shale
Member of the Beattie Limestone; Plattsmouth Limestone Member of the Dread
Limestone; Church Limestone Member of the Howard Limestone.
18 Figure 8.
19 Figure 8. Ditomopyge decurtata from the Permian of Kansas and Nebraska. Specimens in figures 8.2, 8.3, 8.7, and 8.8 were previously referred to as Anisopyge whitei; specimen in figure 8.2is the holotype of A whitei. Specimens are reposited in the University of Kansas
Museum of Invertebrate Paleontology (KUMIP) and the University of Nebraska State
Museum (UNSM).
1,4. Dorsal (1), Ventral (4) portion of broken cephlon from an enrolled trilobite; x3. In
( 4) hypostome is visible with rostral plate. Florena Shale Member of the Beattie
Limestone, Grand Summit, Cowley County, Kansas, KUMIP _.
2. Cephalon ofrevised D. decurtata; x3. Damage to upper left of anterior border, slight distortion from burial. Cottonwood Limestone Member of the Beattie Limestone,
Richardson Co., Nebraska, UNSM 8092.
3. Gabella of revised D. decurtata; x3. Cottonwood Limestone Member of the Beattie
Limestone, Richardson Co., Nebraska, UNSM 8094.
5. Pygidium of enrolled specimen; x3. Florena Shale Member of the Beattie Limestone,
Grand Summit, Cowley Co. Kansas, KUMIP _.
6. Pygidium of enrolled specimen; x3. Florena Shale Member of the Beattie Limestone,
Grand Summit, Cowley Co. Kansas, KUMIP _.
7. Pygidium ofrevised D. decurtata; x3. Cottonwood Limestone Member of the Beattie
Limestone, Richardson Co., Nebraska, UNSM 8121.
8. Pygidium ofrevised D. decurtata,- x3. Cottonwood Limestone Member of the Beattie
Limestone, Richardson Co., Nebraska, UNSM 8113.
20 9. Pygidium; x4. Clay Creek Limestone Member of the Kanwaka Shale, Greenwood Co.,
Kansas, KUMIP_.
21 DITOMOPYGE SCITULA (Meek and Worthen, 1865)
Figure 9
Phillipsia (Griffithides) scitula Meek and Worthen, 1865, p. 270, 271.
Ditomopyge scitula (Meek and Worthen). Brezinski and Stitt, 1982, p. 1242-1248 (see for additional synonymy).
Material.- 5 cephala, 25 pygidia, 9 free cheeks.
Description.- See Brezinski (1988, p. 941 ).
Remarks. - Genal spines on average are longer and more slender in appearance than in
D. decurtata, with lengths extending to the fourth and fifth thoracic segments. Other cephalic proportions are almost identical. Slight variation in maximum glabeller width, are present; the border is slightly wider in D. scitula.
Occurrence. - Haynies Limestone Member of the Deer Creek Limestone; Perry Farm
Shale Member of the Lenapah Limestone; Farley Limestone Member of the Wyandotte
Limestone; Stoner Limestone Member of the Starton Limestone; Merriam Limestone
Member of the Plattsburg Limestone.
22 Figure 9.
23 Figure 9. Ditomopyge scitula from the Carboniferous of Nebraska. Specimens are reposited in the University of Nebraska State Museum (UNSM).
1. Complete specimen, damage to left side of cephalon; x3. Haynies Li~estone Member of the Deer Creek Limestone, Cass County Nebraska, UNSM 7299.
2. Ventral view of cephalon and thoracic segments, pygidium missing; x3. Haynies
Limestone Member of the Deer Creek Limestone, Cass County Nebraska, UNSM 7300.
3. Cephalon and thoracic segments; x3. Haynies Limestone Member of the Deer Creek
Limestone, Cass County Nebraska, UNSM 7283.
24 Graphs
E 8 E_ 7 ra Cl) s... ra 6 : ra ... c: 5 -0 ,,.I•\. s... + D. decurtata 4 • • -0 t •.• - II A. OOif ej ..c: 3 •••• -"'O •~· 3: 2 • E :::s E 1 >< ~ 0 0 2 4 6 8 10 Palpebral cranidial width, mm
Figure 10. Comparison of cranidal measurements between D. decurtata and A. whitei.
25 6 Q) ~ Q) ~ E 5 • :!: E • • Q) a) 4 If • • O> 0 • • D. decurtata c: ~ 3 • <(- en 11 A. whitei ctl ·- c: c 2 Q) Q) (!) ..c >< 0 Q) _J 1 -.... ~ 0 +--~~~~~~~~~~--~~~~~~ 0 5 10 15 Total Length of Free Cheek, mm
Figure 11. Comparison of measurements of liberigenae between D. decurtata and A. whitei.
26 --·------
14 l
12 - E E 10 ..c:- 8 ~ "'C I • 0. decurtata - I 3:: ca 6· 11 A. ooi~~~_J ·-"'C C> 4 >- i::i.. • 2
0 - --~--···---- 0 2 4 6 8 10 12 Pygidia Length, mm
Figure 12. Scatter plot of pygidial length vs. width comparing D. decurtata to A. whitei.
27 References
Brezinski, D. K. 1988. Appalachian Carboniferous trilobites. Journal of Paleontology, 62:934-945.
Brezinski, D. K., Stitt, J. H. 1982. Ditomopyge scitula (Meek & Worthen) from the lower Pennsylvanian of Central Missouri and Central Texas. Journal of Paleontology, 56: 1242-1250.
Chamberlain, C. K. 1969. Carboniferous trilobites: Utah species and evolution in North America. Journal of Paleontology, 43 :41-68.
Meek, F. B., and Worthen, A.H. 1865. Contributions to the paleontology of Illinois and other western states. Academy of Natural Sciences of Philadelphia, Proceedings, p. 245-273.
Moore, R. C., Frye, J.C., Jewett, J.M., Lee, W. and O'Connor, H. G. 1951. The Kansas Rock Column. Geological Survey of Kansas Bulletin 89. p. 42-63
Pabian, R.K., and Fagerstrom, J. A. 1972. Late Paleozoic trilobites from southeastern Nebraska. Journal of Paleontology, 46:789-816.
Zeller, P. 1968. KU, Kansas Geological Survey, The University of Kansas. 18 June 2007.
28