Private Collection Publications and Figured Specimens
Below is an illustrated list of primarily Douglass Collection specimens studied and figured in publications. Beginning with the family's relationship to Dr. Richardson and the Field Museum in the 1960s, numerous species have been described with the Douglass name - others figured - and many of these fossils are presently housed and on display in their Prehistoric Life Museum (711 Main St., Evanston, Illinois). Since I started to work as the museum's collection manager in 2023, new collaborations have begun with researchers interested in rare and exquisite examples from the Carboniferous Period (Mississippian and Pennsylvanian), and a partnership formed with the Lauer Foundation for Paleontology, Science and Education with a focus on Illinois Mazon Creek fossils. Many more projects are underway and will get posted here as the resulting papers are published. (Note: scale bars = 1cm.)
2026 - Direct Development in Early Tetrapods
Pardo, J.D., and Mann, A. 2026. Direct development of stem tetrapods across the fin-to-limb transition. Science, June 18, vol. 392, issue 6084, pp. 1292-1296. Supplementary text; Figs. S1 to S6; references (41-52).
https://www.science.org/doi/10.1126/science.aeb7635​
Two exceptionally preserved juvenile embolomeres in the study show that a transient larval state was absent in tetrapods both before and after the fin-to-limb transition. Amphibian-like tadpole features that scientists assumed early tetrapod hatchlings would have were missing. While these tetrapods did indeed grow limbs over the course of their development, they were lacking key amphibian tadpole traits such as frilly external gills. The same held true for other related stem tetrapod species. Even when the larval stages did undergo big changes on their way to adulthood, they did not show signs of true amphibian metamorphosis.
From the Richard Rock Collection, #701 - now FMNH PR5106 - donated to the Field Museum in 2023. It was found in the Pit 11 area near Braidwood, IL, over two decades ago and thought to be a baby lamprey. I was photographing Richard's Mazon Creek fossils in 2023 and came across this amazing little (2cm) animal.
Gilpichthys greenei, found by Loraine Rockwell in 1970 - cat # 5211 - and figured by Bardack and Richardson in 1977 (see below). It was later acquired by Dave Douglass and donated for research.
2026 - Loss of Complexity in Fossil Hagfish Eyes
McCoy, V.E., Pardo, J.D., Mann, A., Young, A., Lauer, R., Lauer, B., Miyashita, T. 2026. Stepwise loss of complexity in hagfish eyes prior to deep sea colonization. Biology Letters, vol. 22, pp. 1-7.
https://doi.org/10.1098/rsbl.2026.0127 ​​
A total of five Gilpichthys greenei specimens and one Squirmarious testai from the David and Sandra Douglass Collection, along with examples from the Field Museum, were used in the study. Three G. greenei fossils were figured as SEM secondary electron images showing only spherical melanosomes in the eyes. Two specimens photographed in super-high resolution were figured showing detailed eye lenses. All six fossils are now housed in the Lauer Foundation.
'Dasyleptus' sp. ​(DLD 4082-Prehistoric Life Museum), found in the 1980s from the Mazon River, Morris, IL.
2026 - Well-preserved Setae Found on 'Dasyleptus' sp.
Carr, T., Young, A., McCoy, V.E., 2026, Micro-scale preservation of setae on Mazon Creek’s ‘Dasyleptus’ sp.: Geological Society of America Abstracts with Programs, v. 58, no. 1.
https://doi.org/10.1130/abs/2026SE-12834
In the specimen to the left, from the David and Sandra Douglass Collection, ethanol-enhanced light microscopy has revealed well-preserved setae sockets on the abdomen as well as clearly defined setae present on both the abdomen and caudal filament. 
2025 - Syn-vivo Infestations in Fossil Horseshoe Crabs
Bicknell, R.D.C., Dunlop, J., Young, A., Lauer, B., Lauer, R., McCoy, V.E. 2025. Unique, dimple-like exoskeletal structures suggest syn-vivo infestations in Late Carboniferous horseshoe crabs. Biology Letters, vol. 21, pp. 1-7.
https://doi.org/10.1098/rsbl.2025.0565
Syn-vivo is a scientific and paleontological term meaning "during the life of the host". A syn-vivo infestation describes a parasitic, boring, or fouling organism actively colonizing a living host, proven by the host's biological defense mechanisms or shell regeneration. The specimen in the study is housed in the Lauer Foundation for Paleontology, Science and Education (LF 5499). 
      Tullimonstrum gregarium, LF 7165, showing         exceptional detail in the eyes.
2025 - Cartilage found in in Tullimonstrum gregarium
Potter, J. J., Mayer, P. S., Owen, H. A., Young, A., Coorough Burke, P., Lauer, R., Lauer, B., and McCoy, V. E., 2025, Microscale cartilage preservation in exceptional Tully Monster specimens: Geological Society of America Abstracts with Programs, v. 57, no. 6.
https://doi.org/10.1130/abs/2025AM-9973​ 
The specimen to the left is from the Douglass Collection (DLD 847) and I  found it to contain unusual features (such as a rarely seen, light-brown- colored eye cup) almost two years prior to my officially coming on as collection manager. Dark pigment in the Tully's eyes, as well as the nearly white lenses, are not uncommon. After its donation to the Lauer Foundation (now LF 7165), research at the University of Wisconsin-Milwaukee uncovered cartilaginous aspects in multiple parts of the animal's body which supports a chordate affinity.
2025 - New Exhibit at The Field Museum, Chicago
After the Age of Dinosaurs is a new exhibition at the Field Museum of Chicago opening August 29, 2025 (and closing January 3, 2027). The show explores what happened after the dinosaurs went extinct, when life on Earth dramatically changed, diversified, and evolved in surprising ways. The fossil skull to the right will be on display.
​Grande, L. 1980. Paleontology of the Green River Formation, with a Review of the Fish Fauna, The Geological Survey of Wyoming, Bulletin 63, page 202, Figure III.11b.
https://www.wsgs.wyo.gov/products/wsgs-1984-b-63
Crocodylomorpha - Tsoabichi greenriverensis 
​Green River Formation caiman skull, donated by the Douglass Collection to the Field Museum in 2024.
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ecologically diverse than modern crocodilians.
Installation views from After the Age of Dinosaurs, Field Museum of Natural History, Chicago, Illinois.
In the wake of dinosaurs, plants and animals reshaped Earth into a lush, tropical world teeming with new giants, tiny survivors, and life both familiar and strange. Discover how a colossal asteroid ended the dinosaurs’ reign and paved the way for life’s astonishing comeback, shaping the world we know today. 
Caiman Skull: Tsoabichi greenriverensis
52 million years old (Early Eocene), Wyoming – FMNH PR 5108
Donated by David and Sandra Douglass, James and Susanne Ali
Dave’s Down to Earth Rock Shop, Evanston, Illinois
Tsoabichi means “monster” in the Shoshoni language. It's related to caimans and alligators and lives like its relatives today,
eating fish and other aquatic animals. This caiman has two kinds of teeth: pointy ones in the front for grabbing prey and round ones in the back for crunching and crushing.
Euproops danae horseshoe crab parts in a lungfish bromalite (likely a regurgitalite) - Pit 9, Dresden Lakes, IL
2025 - Mazon Creek horseshoe crabs in bromalites
Bicknell, R.D.C., Kimmig, J., Young, A., Lauer, B., Lauer, R., McCoy, V.E. 2025. Mazon Creek bromalites evidence a specialized, xiphosaurid-rich diet for Pennsylvanian predators. PALAIOS, vol. 40, pp. 215-221.
https://doi.org/10.2110/palo.2025.013​
Four specimens (originally thought to be coprolites) containing crushed Euproops danae horseshoe crab exoskeletons were donated to the Lauer Foundation for the purpose of this study. Three were from the Douglass Collection - DLD 2496, 2502, and 3930 - and one came from the Andrew Young Collection (AY 2771). These are now LF 7282 (left), 7283, 7284, and 7285, respectively. 
   Bromalites containing Euproops danae pieces are found throughout the Braidwood Assemblage (brackish and freshwater)
​  in the Mazon Creek area. Left to right: localities include Pit 1, Coal City; Morocco Mine, Morris; and Pit 2, Wilmington, Illinois. 
'Dasyleptus' sp. (described by Kukalová-Peck 1987) from the David and Sandra Douglass Collection - DLD 5188 - found in the Mazon River, Morris, Illinois.
2025 - Possible preserved setation in 'Dasyleptus' sp.
Carr, T., Young, A., McCoy, V.E., 2025, Potential microscale preservation in Mazon Creek’s 'Dasyleptus' sp.: Geological Society of America Abstracts with Programs, v. 57, no. 3.
https://doi.org/10.1130/abs/2025NE-408112
Scanning electron microscopy (SEM) was used to investigate the microscale preservation of three specimens of Mazon Creek 'Dasyleptus' sp. from The David and Sandra Douglass Collection. Preliminary results of these investigations provide evidence of fine-scale preservation of various features. The ovipositors of each show both internal and external preservation of segmentation, and regularly spaced holes on the surface of one specimen are interpreted as the attachment points of scales. 
2025 - Bear Gulch cyclid aggregations
Bicknell, R.D.C., Klompmaker, A.A., Edgecombe, G.D., McCoy, V.E., Young, A., Lauer, B., Lauer, R., and Cuomo, C. 2025. Gregarious behaviour in Carboniferous cyclidan crustaceans. Biology Letters, vol. 21, pp. 1-7.
https://doi.org/10.1098/rsbl.2024.0734​
Crustacean aggregations in the fossil record are very rare,
and before this specimen was discovered and examined, the only known example of multiple Bear Gulch (Carboniferous) individuals on a plate counted four. This extraordinary example contains 50, and probably represents a mass
​molting or sheltering event preserved by rapid burial.  
Schramine montanaensis cyclids from the Bear Gulch limestone: Late Mississippian in age (325 to 318 mya). 
This exceptional Douglass Collection specimen - DLD 5474 - was acquired by the Lauer Foundation for the purpose of this study and is now LF 7078.
        Douglassarachne acanthopoda holotype
2024 - New Mazon Creek spider-like arachnid
Selden, P.A. and Dunlop, J.A. 2024. A remarkable spiny arachnid from the Pennsylvanian Mazon Creek Lagerstätte, Illinois. Journal of Paleontology, Cambridge University Press. Figs. 2-3, pp. 1-7.
https://doi.org/10.1017/jpa.2024.13​
Douglass Collection DLD 4137. One half of this specimen was donated to the Field Museum of Natural History and is now FMNH PE91366. The other half is on display in the Douglass Prehistoric Life Museum at Dave's Rock Shop, Evanston, Illinois, USA. This Mazon Creek spiny arachnid is so unusual that assignment to a proper Taxonomic Order remains elusive. At this point, it remains incertae sedis (or "of uncertain placement") until more examples are found and studied.
  The Douglass Collection Prehistoric Life Museum
2024 - New Undescribed, Salamander-like Tetrapod
​So, C., Mann, A., Pardo, J., Sues, H.D. A new slender and long-bodied amphibamiform temnospondyl from the Late Carboniferous Mazon Creek Lagerstätte reveals the earliest occurrence of body elongation in Dissorophoidea: Journal of Vertebrate Paleontology Program and Abstracts Book (2024), 84th Annual Meeting of the Society of Vertebrate Paleontology, October 30, technical session 5, pp. 509-510.
ISSN 0272-4634 / E-ISSN 1937-2809:    https://vertpaleo.org/wp-content/uploads/2024/10/2024_SVP_Program_Final3.pdf
Dave Douglass acquired this tetrapod specimen around 1990 to display in his family's museum and "protect for science." As seen in the photo, the fossil was mislabeled as Amphibamus grandiceps and even published in 2012 as such. (I took the photo to the left in 2017.) In 2021, it was loaned to Arjan Mann at the Smithsonian and later donated to the Field Museum for the purpose of research and, eventually, a full description. 
2023 - New Mazon Creek hagfish
McCoy, V.E., Wittry, J., Sadabadi, H., and Mayer, P. 2023. A reappraisal of Nemavermes mackeei from
​the Mazon Creek fossil site expands Carboniferous cyclostome diversity. Journal of Paleontology, Cambridge University Press, Figs. 1,6, pp. 1-17.
https://doi.org/10.1017/jpa.2023.72​
Found by Dave Douglass in two parts in different years,
​the fossil was photographed and studied by Dr. Eugene Richardson in the late 1960s who originally called the fossil
​a "nudibranch." It was acquired by the Lauer Foundation for this study and is now LF 5664.
Squirmarius testai cyclostome: for years on display at
​the Douglass Prehistoric Life Museum (DLD 204) and mislabeled Gilpichthys greenei, a known species of jawless fish. 
Gilpichthys greenei, found at Pit 11 in the Mazon Creek area in the 1970s and originally housed in the David and Sandra Douglass Collection (DLD 3768). 
2023 - Hagfish Eye Evolution through Vestigialization
​McCoy, V.E., Young, A., Pardo, J., Sadabadi, H., Mann, A., Miyashita, T., 2023, Eyes or Eyespots: Investigation into the Visual Organs of Gilpichthys greenei, a Stem Hagfish from the Late Carboniferous Mazon Creek Fossil Assemblage: Geological Society of America Abstracts with Programs, v. 55, no. 6. https://doi.org/10.1130/abs/2023AM-392515  
The specimen to the left and four others were donated to the Lauer Foundation for Paleontology, Science and Education for the purpose of this study. Scanning electron microscopy (SEM) of the eyes revealed small, spherical microbodies resembling fossil melanosomes. ​
2020 - Mazon Creek Fossil Flora Book
Wittry, J. 2020. A Comprehensive Guide to the Fossil Flora of Mazon Creek. Bledig, J.M., Young, A. (eds.) Earth Science Club
​of Northern Illinois (ESCONI). Fig. 10, p. 100.
https://www.researchgate.net/publication/339386593_A_Comprehensive_Guide_to_the_Fossil_Flora_of_Mazon_Creek​
 Douglass Crenulopteris subcrenulata fern: 1/2 donated to FMNH (PP51104)
       The above is a unique specimen of Rhacophyllum cornutum from the Andrew Young Collection. It was donated to the                   Field Museum (FMNH PP55101) because of its attachment to a stem with a bulb-like feature. For the purpose of the book
       it is pictured on page 137, Fig. 5, and is currently being researched and analyzed using micro-CT scanning techniques.
2014 - 5 Figured Specimens in New Trilobite Book
Levi-Setti, R. 2014. The Trilobite Book: A Visual Journey, The University of Chicago Press, Chicago. 273 - Figures:
​p. 133, plate 124; p. 137, plate 128; p. 196, plate 180;
​p. 203, plate 187; p. 211, plate 196. 
https://press.uchicago.edu/ucp/books/book/chicago/T/bo17616349.html  
In addition to a comprehensive Mazon Creek fossil collection containing many rare and even unique (holotype) specimens, the Douglass Collection has on display in their Prehistoric Life Museum exquisite examples from all time periods. These include trilobites from around the world. In his two most recent volumes published by U. of Chicago Press, author Riccardo Levi-Setti figured at least eight Douglass trilobite specimens.
2012 - Mazon Creek Fossil Fauna Book
Wittry, J. 2012. The Mazon Creek Fossil Fauna. Bledig, J.M., Young, A. (eds.) Earth Science Club of Northern Illinois (ESCONI),
Downer's Grove, Illinois 202 p. - front cover image, Figs. xx.1, 47.1, 49.1, 117.3, 118.3-4, 130.2-3, 131.3-4, 136.2, 145.2-3, 146.3, 169.1.
https://www.researchgate.net/publication/270823603_The_Mazon_Creek_Fossil_Fauna​
Douglass Collection catalog numbers in order of the figures below (left to right, top to bottom): DLD 189, 4135, 226, 188, 1744, 516, 4133, 4140, 264, FMNH PR5055, 515, and 221.
Note: the undescribed tetrapod on the bottom left was donated to the Field Museum in 2021 for study and description. It has the new number of FMNH PE5055 and will eventually be named after the Douglass family.
Mischoptera douglassi holotype, Fig. xx.1
Amphicentrum orbiculare fish, book cover 
Kottixerxes gloriosus arthropod, Fig. 47.1
Jeletzkya douglassae holotype, Fig. 118.4
Euphoberia sp. millipede, Fig. 49.1
Wiedeyoceras sp. cephalopod, Fig. 117.3
Bandringa herdinae, Fig. 131.3
(now accommodated by B. rayi) 
Conchopoma edesi ​lungfish, Fig. 136.2
Bandringa rayi shark, Fig. 130.3
Undescribed tetrapod, Fig. 145.3
​(mis-ID'd as Amphibamus grandiceps)
Phlegethontia longissima, Fig. 146.3
Illilepas damrowi barnacle attached to a myalinid bivalve, Fig. 169.1
2006 - Mazon Creek Fossil Flora Book
Wittry, J. 2006. The Mazon Creek Fossil Flora, Earth Science
Club ​of Northern Illinois (ESCONI), Downer's Grove, Illinois 154 p. 
https://www.researchgate.net/publication/270823596_The_Mazon_
​Creek_Fossil_Flora  
Crenulopteris subcrenulata, p. 22, Fig. 11 and Pecopteris strongii, p. 28, Fig. 6.
Note: one half of each specimen above resides in the Douglass Collection and is on display in their museum. (Field Museum donations: PP51104 and PP53157.)
2004 - Mazon Creek newspaper article 
​Sula, M. 2004. The Vanishing Mother Lode of Mazon Creek. Chicago Reader, Friday, July 2, Vol. 33, no. 40, pp. 1, 14-15. 18-20, 22-23.
https://chicagoreader.com/news/the-vanishing-mother-lode-of-mazon-creek  
  David Douglass at Dave's Down to Earth Rock Shop, page 22.
This 2004 article in the Chicago Reader is what made me aware of the world-famous site (in paleontology, a Konservat-Lagerstätte, or deposit with exceptional fossil preser­vation). The following year was my first collecting at the celebrated Pit 11. 
       Holmacanthus keithi shark holotype, p. 254, Fig. 18.15
1997 - New Mazon Creek Shark
Bardack, D. in Zangerl, R. 1997. Cartilaginous Fishes (Chondrichthyes), Richardson’s Guide to the Fossil Fauna of Mazon Creek. C. W. Shabica and A. A. Hay (eds.), Northeastern Illinois University, Chicago.
​Figs. 18.15, 18.16. pp. 253–255.
https://archive.org/details/richardsonsguide0000unse
Douglass Collection DLD 581. Note: one half of this specimen is housed in the Field Museum (FMNH PF14309) and the other half is on display in the Douglass Prehistoric Life Museum.
1997 - 3 Additional Figured Specimens in the Richardson's Guide 
                 Left to right: Jeletzkya douglassae, p. 128, Fig. 8D.10 and
                    Pipiscius zangerli, p. 229, Fig. 17.3
               Conchopoma edesi, figured as a latex cast, p. 240, Fig. 17.22
Note: the three fossils pictured above are housed in the David and Sandra Douglass Collection and displayed in their Prehistoric Life Museum (711 Main St., Evanston, Illinois). Clockwise from top left: they are numbered DLD 188, DLD 177,
​and DLD 4140 respectively. One half of the latter is in the Field Museum of Natural History with number FMNH PF9907.
1993 - 3 Figured Specimens in Trilobite Book
Levi-Setti, R. 1993. Trilobites, The University of Chicago Press, Chicago, 342 p. - Figures: p. 73, plate 45; p. 233, plate 149; p. 295, plate 204. 
​https://archive.org/details/trilobites00levi 
Riccardo Levi-Setti was a professor of physics and director of the Enrico Fermi Institute at the University of Chicago. He was also a research associate at the Field Museum of Natural History. Although trained as a physicist, he studied trilobites
​as a passion.
Type, Figured, and Referred Specimens from Private Collections
Carman, Mary R. 1990. Catalog of Type, Figured, and Referred Mazon Creek Fossils in Private Collections. Fieldiana Geology, February 28,
​Field Museum of Natural History Publication1407, No. 19, pp. 7-8.
https://www.biodiversitylibrary.org/bibliography/3448 ​
At the time of this publication, there were eight Douglass Collection specimens listed; most of them are indicated on this web page. The only missing fossil is a Douglass Titanoscorpio douglassi paratype that was part of the species description in Kjelleswig-Waering's 1986 catalog, A Re-study of the Fossil Scorpionida of the World
​(p. 240, text-figs. 108A-E). I'm still searching for the fossil.
             Buthiscorpius lemayi scorpion holotype
1986 - New Mazon Creek Scorpion
Kjellesvig-Waering, E.N. 1986. A Restudy of the Fossil Scorpionida of the World. Palaeontographica Americana, March 18, No. 55, Buthiscorpius lemayi, pp. 102-105.
https://www.biodiversitylibrary.org/page/28877537#page/107/mode/1up​
Douglass Collection DLD 180. Note: the above catalog was published in 1986, seven years after Kjellesvig-Waering's passing. The specimen was found in 1971 at coal strip mine Pit 6 in Coal City, Illinois, and acquired by Dave Douglass for the Prehistoric Life Museum. ​
1986 - Another New Mazon Creek Scorpion
Kjellesvig-Waering, E.N. 1986. A Restudy of the Fossil Scorpionida of the World. Palaeontographica Americana, March 18, No. 55, Titanoscorpio douglassi, pp. 240-242.
https://www.biodiversitylibrary.org/page/28877537#page/245/mode/1up​
Douglass Collection DLD 182 -found by and named for David L. Douglass. Locality: Greer Earth Moving School, Northern Illinois Coal Company Pit 1, Coal City, IL.
     Titanoscorpio douglassi scorpion claw holotype,
        on display at the Prehistoric Life Museum.
   Gerarus vetus - Mazon Creek insect, Scudder 1885
1983 - Cataloging Carboniferous Insects
Burnham, L. 1983. Studies on Upper Carboniferous Insects: 1. The Geraridae (Order Protorthoptera) Psyche: A Journal of Entomology, January 1, Vol. 90, No. 14, Issues 1-2, pp. 1-57.
https://onlinelibrary.wiley.com/doi/epdf/10.1155/1983/42898​
Douglass Collection DLD 4150 (178) ​is currently on display at the Prehistoric Life Museum along with associated drawings. The order Protorthoptera is considered a “wastebasket taxon” and a temporary category used to classify early, primitive winged insects that could not be placed in any modern lineage. Most were described from isolated fossilized wings that definitely need revision.
          Riodinella nympha Raydome butterfly 3 holotype
1978 - New Eocene Butterfly
​Durden, C.J., Rose, H. 1978. Butterflies from the Middle Eocene: The Earliest Occurrence of Fossil Papilionoidea (Lepidoptera). Pearce-Sellards Series No. 29, Texas Memorial Museum, University of Texas at Austin,
​Figs. 4, 5, 6E, 6F, pp. 17-21.
https://repositories.lib.utexas.edu/items/eba1f3e1-71b8-41ca-bdbc-e4d057d9350e
Fig. 4. Riodinella nympha n.g., n.sp., HOLOTYPE, Raydome butterfly No. 3a (David Douglass, Prehistoric Life Museum Collection); Fig. 5: No. 3b (Black Hills Minerals Collection).
1977 - New Mazon Creek Jawless Fish
Bardack D. and Richardson, Eugene S. 1977. New Agnathous Fishes from the Pennsylvanian of Illinois. Fieldiana Geology, June 23, Field Museum of Natural History, Publication 1261, Vol. 33, No. 26, pp. 497-508.
https://www.biodiversitylibrary.org/bibliography/5167
This Douglass Collection specimen (DLD 5196) was loaned to Dr. Richardson at the Field Museum in the mid-1970s. After 50 years, it was found in a the back of a cabinet and recently returned to Dave Douglass. With new interest and available technologies, this fossil is now out on loan again for further research on this hagfish species.
Gilpichthys greenei cyclostome; referred specimen in Bardack.
     Pipiscius zangerli cyclostome, figured on page 491.  
1977 - Another New Mazon Creek Jawless Fish
Bardack D. and Richardson, Eugene S. 1977. New Agnathous Fishes from the Pennsylvanian of Illinois. Fieldiana Geology, June 23, Field Museum of Natural History, Publication 1261, Vol. 33, No. 26, pp. 490-497, Fig 3.
https://www.biodiversitylibrary.org/bibliography/5167
Douglass Collection DLD 604 is on display at the Prehistoric Life Museum. The species, now in the superclass Cyclostomata, has a characteristic circular mouth and is considered a lamprey. 
1975 - Mazon Creek Conchopoma Lungfish 
Schultze, H.-P. 1975. Die Lungenfisch-Gattung Conchopoma (pisces, Dipnoi). Senkenbergiana lethaea, Vol. 56, pp. 191–231, referred p. 214
​Douglass Collection DLD 517 - referred specimen, on display
at the Prehistoric Life Museum, Evanston, Illinois. The species' long pectoral fins are thought to have been used for "walking" on the riverbed or other substrate, suggesting how the first tetrapods may have transitioned from water to land.
     Conchopoma edesi lungfish, described by Denison, 1969
     Mischoptera douglassi insect nymph holotype - DLD 189
1968 - New Mazon Creek Insect Nymph
Carpenter, F. M. and Richardson, Eugene S. 1968. Megasecopterous Nymphs in Pennsylvanian Concretions from Illinois. Psyche: A Journal of Entomology, December, Vol. 75, No. 4, pp. 295–309;
page 301, text-Fig. 2, plates, 24, 25, 27.
https://www.biodiversitylibrary.org/item/207022​
Found by Lincoln E. Douglass at Northern Illinois Coal Company Pit 6, near the Grundy-Will County line, Illinois.
At the time of its description, researchers called it “the most important fossil insect ever found.” Now on display at the Douglass Prehistoric Life Museum.
1968 - New Mazon Creek Cephalopod
Species Description
Johnson, R.G. and Richardson, Eugene S. 1968. Ten Armed Fossil Cephalopod from the Pennsylvanian of Illinois. Science, February 2, Vol. 159, Issue 3814, pp. 526-528.
https://doi.org/10.1126/science.159.3814.52​
1979 - Species Re-evaluation
Saunders, W.B. and Richardson, E.S. 1979. Middle Pennsylvlanian (Desmoinesean) Cephalopoda of the Mazon Creek fauna, northeastern Illinois. Mazon Creek Fossils, Nitecki M.H. (ed.), p. 351, text-fig. 8.
https://www.journals.uchicago.edu/doi/10.1086/411743
​The above describes a new find attributed to Jeletzkya, which, along with the holotype, provides more insight into its morphology, including a radula, arm hooks, mantle debris, and ink.
            Jeletzkya douglassae cephalopod holotype
​Douglass Collection DLD 188 - currently on display at the Prehistoric Life Museum - found by and named for June L. Douglass.  Locality: South Wilmington Sportsmen’s Club, Peabody Coal Company Pit 11, Essex, Illinois. 
Copyright © 2021 Andrew Young. All specimen images on this page and in the fossil galleries may be protected by copyright. They are presented here in ​accordance with fair use principles and are only being used for informational and educational purposes. They may not be republished electronically or in print without the written consent of the individuals and institutions who have lent them here.