| Acutiramus Temporal range: Late Silurian–Early Devonian | |
|---|---|
| |
| Life-size restoration of A. macrophthalmus at the National Museum of Nature and Science, Tokyo | |
| Scientific classification | |
| Domain: | Eukarya |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Clade: | Dekatriata |
| Order: | Eurypterida |
| Superfamily: | Pterygotioidea |
| Family: | Pterygotidae |
| Genus: | †Acutiramus Ruedemann, 1935 |
| Type species | |
| †Acutiramus cummingsi Grote & Pitt, 1875 | |
| Species | |
|
†A. bohemicus Barrande, 1872 | |
| Synonyms | |
|
Bunodella horrida Matthew, 1889 A. bohemicus A. cummingsi A. macrophthalmus | |
Acutiramus (/ækˈju:tˈiˈræmˌʌs/)(meaning "acute branch") is a genus of pterygotid sea scorpion (eurypterid) from the Late Silurian to Early Devonian period. Fossils attributed to the animal have been reported from the eastern United States and Canada, Czechia, Spain, Algeria, China, and Australia.[1]
Seven species have been described for Acutiramus. The smallest, such as A. floweri, grew to just 20 centimeters in length. The largest, A. bohemicus were around 2.1 meters long and, among arthropods, are rivalled in size only by a few species such as Jaekelopterus rhenaniae.
Studies of the appendages and visual power of Acutiramus indicate that it was a not-so-active, open water predator that targeted soft bodied organism such as fish.
Discovery & Naming[]
Misidentification as Pterygotus[]
Rocks of the Upper Silurian Bertie Formation, where the first known Acutiramus species are known
Historically, several species now attributed to genera such as Erettopterus and Acutiramus were lumped into the related genus Pterygotus. The first described material of Acutiramus was a carapace from Litchfield, New York, named Pterygotus macrophthalmus by James Hall in 1859. P. osborni was named in the same paper, from the same locality.[2] Later, P. cummingsi was described in 1875 based on a coxa. Pohlman named the taxa P. buffaloensis, P. acuticaudatus, and P. quadraticaudatus from New York. Oversea, Bohemian species including P. bohemicus and P. comes were being reported.
Separation of the Genus[]
Left is holotype coxa of A. cummingsi, while right is partial coxa and ramus of "Pterygotus buffaloensis"
Paleontologist Rudolf Ruedemann established subgenera of Pterygotus in 1935. Pterygotus (Acutiramus) united bohemicus, buffaloensis (the type), and macrophthalmus. Acutiramus means "acute" or "sharp" (acutus) "branch" (ramus) in Latin.[3]
Erik Kjellesvig-Waering established Pterygotus cummingsi, then considered a junior synonym of P. buffaloensis, as the type species of the subgenus. Acutiramus was recognized as a separate genus by Leif Størmer in 1974.[4]
Historical depiction of a pterygotid eurypterid, in dorsal (left) and ventral (right) views
Victor Tollerton Jr noticed that the status of P. (A.) buffaloensis as type species violated Article 68 of the 3rd edition of the ICZN (International Code of Zoological Nomenclature). Rueddeman had synonymized P. cummingsi with buffaloensis, despite the former being named earlier. This gave cummingsi the priority, making it a senior synonym and type of Acutiramus.[5]
Other Discoveries[]
A synziphosuran crustacean species, Bunodella horrida, was reported from New Brunswick by G. F. Matthew in 1889. It was later, in 2007, considered a nomen dobium. The holotype specimen, NBMG 3000, was identified as a coxa of a swimming leg belonging to Acutiramus sp.[6][7]
A. bohemicus, A. macrophthalmus, and A. cummingsi were the valid species of Acutiramus initially recognized. In 1955, the small species A. floweri was named by Erik Kjellesvig-Waering and Kenneth Caster, based on material from the Vernon Formation in New York (Ludfordian stage). In the same year, the former author also descibed A. suwanneensis. Its material was recovered from a borehole, Kie Vining, owned by the Gulf Oil Corporation in Florida, being Přídolí in age.[8][9]
Two other species, A. perryensis and A. perneri, entered the scientific literature in 1958 and 1994, respectively. A. perryensis was described by Willard Leutze, with a chelicera (pincer appendage) found in the Tymochtee dolomite in Fayette County, Ohio. Ivo Chlupáč named A. perneri based on a different chelicera from Cerna Rokle at Kosor, Czechia.[10][11]
A. cf. bohemicus from Wilson Creek Shale, Australia
More recently, eurypterid fossils attributed to Acutiramus cf. bohemicus have been identified in new locations. In Victoria, Australia, a claw was discovered in the Wilson Creek Shale. The Idjerane Sandstone in Algeria also yielded referred material. Both of these localities date to the Pragian stage of the Devonian period, about 413 - 410.8 MBC.[12][13][14]
In the Nagaoling Formation in Guangxi, China, specimens of Acutiramus sp. were reported in 2025. Estimated lengths for indeterminate species are about 1.6 to 1.8 meters. The Nagaoling rocks are Lochkovian in age.[15]
Timeline[]
Telson assigned to Pterygotus quadraticaudatus
Material originally described as the crustacean Bunodella
A. macrophthalmus fossil from Williamsville Member in Ontario, Canada
| Year | Details |
|---|---|
| 1859 | Pterygotus macrophthalmus and P. osborni are named based on fossils from New York. |
| 1872 | Behemian species Pterygotus bohemicus, P. nobilis, P. mediocris, and P. comes named.[16] |
| 1875 | Grote and Pitt described Pterygotus cummingsi from New York. |
| 1881-1882 | Pohlman described Pterygotus buffaloensis and, a year later, P. acuticaudatus and P. quadraticaudatus. |
| 1889 | Bunodella horrida is described as a crustacean.[6] |
| 1912 | Clarke and Ruedemann erect the family Pterygotidae. Pterygotus osborni is synonymized with P. macrophthalmus.[2] |
| 1935 | Ruedemann names Pterygotus (Acutiramus) as a subgenus, with P. (A.) buffaloensis as the type species. P. cummingsi, P. acuticaudatus, and P. quadraticaudatus are assigned to buffaloensis.[3] |
| 1955 | Pterygotus (Acutiramus) floweri named from New York and P. (A.) suwanneensis from Florida.[8][9] |
| 1958 | Pterygotus (Acutiramus) perryensis named from Ohio.[10] |
| 1974 | Størmer moves Pterygotus (Acutiramus) to a seperate genus, Acutiramus.[4] |
| 1994 | Acutiramus perneri named from Czechia. Additionally, Pteryogotus comes and P. mediocris (Barrande, 1872), P. blahai (Semper, 1898), and P. fissus (Seemann 1906) are synonymized with A. bohemicus. A. nobilis is found to be nomen dubium.[11] |
| 1997 | Type species of Acutiramus, A. buffaloensis, found to be junior synonym of A. cummingsi by ICZN law.[5] |
| 2002 | Acutiramus cf. bohemicus reported from Victoria, Australia.[12] |
| 2006 | Pterygotus cobbi var. juvenis is synonymized with Acutiramus macrophthalmus.[17] |
| 2007 | Bunodella horrida considered nomen dubium and belongs to Acutiramus sp.[7] |
Paleobiology[]
Size[]
Acutiramus cummingsi claw at the Yale Peabody Museum
Acutiramus species vary significantly in size. The largest species, A. bohemicus and A. macrophthalmus, are among the largest arthropods to have ever existed. The closely related Jaekelopterus rhenaniae was the only species known to have been longer, at 2.5 m (8.2 ft).[18]
Smaller species, meanwhile, obtained lengths of just 20 cm (7.9 in).
| Species | Measurement |
|---|---|
| floweri | 20 cm (7.9 in) |
| perryensis | 20 cm (7.9 in) |
| cummingsi | 25 cm (9.8 in) |
| suwanneensis | 45.7 cm (18 in) |
| perneri | 110 cm (43.3 in) |
| macrophthalmus | 200 cm (78.7 in) |
| bohemicus | 210 cm (82.7 in) |
Appendages[]
Chelicerae of four different Acutiramus species
A FEA (finite element analysis) model was used to test stress patterns in the chelicerae (pincers) various species of eurypterid and modern scorpion. In Acutiramus bohemicus it was found that stress was concentrated on the tips of the serrated, forward pointing denticles and the proximal part of the free ramus (the moving finger). In contrast, the FEA model showed significantly lower stress across the chelicera in Jaekelopterus rhenaniae.
[20]
The denticle size and shape changes through ontogeny in Acutiramus.[21]
A. cummingsi fossil showing head shield and telson on right
In 2023, Russell Bicknell, Katrina Kenny, and Roy Plotnick analyzed numerous Acutiramus fossils of various species to produce an up-to-date 3D visualization of the genus. Eurypterid fossils are often taphonomically compressed into a 2D shape, thus superimposing the anatomical structures. This makes reconstructing eurypterids by traditional means difficult.[22]
Compared with now outdated pterygotid reconstructions, based on Clark and Ruedemann, 1912, the 3D model had several corrections to the limb placement and morphology. The chelicerae (appendage I) are anteriorly directed and slightly overlain by the epistoma (not to be confused with epistome), rather than the lateral projection at medial eye margin in older depictions. Appendage II was actually quite smaller than III-V, being a palp beside the mouth. The "walking legs", III-V, attached in front of the compound eyes, on the first third of the prosoma.[22]
Appendage VI is often called the "swimming leg". They were large and oar-shaped, used to propel the body through the water.
3D model of Acutiramus, with chelicerae in different orientations, from Bicknell et al. 2023
Kjellsvig-Waering suggested in 1964 that the chelicerae had a fourth joint. Questions were raised about the range of motion in the three-joined appendages, and how they could bring food to the gnathobasic (mouth) region for processing. The proposed fourth joint was not present, though.
Harvestman species Leiobunum ventricosum
Two different rotations for the chelicerae were proposed by Bicknell et al.:
- Perhaps, they rotated ventrally (downwards) when the animal travelled, akin to the prosomal appendages on harvestmen (arachnids originating in the Devonian; Opiliones).[23]
- Like extant scorpions, they could have rotated sagittally (upwards) in a defensive posture.
Ventral prosomal appendage in Bertie FormationAcutiramus
The ventral genital appendages of eurypterids are divided in A and B types, considered female and male, respectively. Genital appendages of A. macrophthalmus are known from the Bertie Formation (Late Silurian).[24]
Ecdysis[]
Arthropods (bugs) go through the process of ecdysis - shedding of the exoskeleton - when growing. Danita Brandt reviewed the sizes and presence of spines and sizes in eurypterids. A possible trend in that taxa with long spines and higher appendage widths tend to have shorter temporal ranges was noted. Acutiramus macrophthalmus and A. cummingsi both have 2 long spines.[19]
Eyes[]
Head of A. macrophthalmus from Herkimer County, New York (Bertie Group)
The eyes of eurypterids are large and compound, composed of many lenses. By measuring the quantity of lenses and their IOA (interommatidial angle; angle between optical axes of two touching lenses), visual acuity can be inferred. Compared with modern predatory bugs and other pterygotids such as Jaekelopterus, Acutiramus cummingsi had few lenses and a high IOA. Notably, younger (ontogenetically) individuals were less extreme in those measurements.[25]
Classification[]
Telson of A. cummingsi (YPM 210099, top) and A. macrophthalmus (YPM 212388, bottom)
Acutiramus belongs the Pterygotidae family of eurypterids. the majority of giant eurypterids known belong to this family.
James Lamsdell published a revised taxonomy of 152 eurypterid species in 2025. In total, 238 morphological characters were used. The maximum parsimony analysis produced the following tree for the Pterygotoidea clade.[21]
| Pterygotoidea |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Species[]
Seven Acutiramus species are currently valid.
A. bohemicus[]
A. bohemicus reconstruction at the Indiana State Museum
This was the largest species in the genus, reaching 2.1 meters in length. Only Jaekelopterus rhenaniae surpasses it in size. A coxa, L23505, from the Přídolí Formation is its holotype. This and another formation in which A. bohemicus lived, the Požáry, date to the Přídolí epoch, 422.7-419.6 MBC.[11]
In Bohemia, this species persisted into the Lochkovian stage (419.6-413 MBC). Specimens referred to A. bohemicus have been found in Pragian (413-410.8 MBC) rocks from Gondwana, specifically Algeria and Australia.[12][14]
Four species from Přídolí localities in Czechia have been named and later synonymized with A. bohemicus.[11][26]
A. cummingsi[]
A. cummingsi fossil
The type specimen of Acutiramus was historically synonymized subjectively (incorrectly) with Pterygotus buffaloensis". According to ICZN protocol, its name warrants priority, as it was named first; in 1875 while buffaloensis was named in 1881. Two other species, P. acuticaudatus and P. quadraticaudatus have also been synonymized with A. cummingsi, the former being a juvenile and the latter having a matching telson.[5][4][21][26]
A. cummingsi is known from the Williamsville and Fiddlers Green Members of the Bertie Formation, mainly in New York and Ontario. These rocks date to the Přídolí epoch at the end of the Silurian, 422.7-419.6 MBC.[27]
A. floweri[]
A. floweri is the oldest and one of smallest Acutiramus species known. It measured about 20 cm in length.[19]
The holotype specimen is NYSM 10712, a chelicera. It was found in the Vernon Formation south of Kenwood, New York. The Vernon was deposited in the Ludfordian stage, 425-422.7 MBC.[8]
A. macrophthalmus[]
A. macrophthalmus artwork by Jun
The second largest species, A. macrophthalmus is also the first one named. James Hall described it in 1859, writing that it was a new species of Pterygotus. At the same time, he also named P. osborni, now considered a synonym of the former. A variety of "Pterygotus cobbi", var. juvenis, was proposed by Clarke and Ruedemann in 1912 and is now a junior synonym of A. macrophthalmus.[2][21][26]
This species coexisted with A. cummingsi. Both are known from the Bertie Formation of New York and Ontario, dating to the Pridoli epoch, 422.7-419.6 MBC.[27]
A. perneri[]
This mid-sized species alongside A. bohemicus in Lochkovian Bohemia (Radotin Limestone Formation). Its holotype is L30739, reported in 1994. Specimens referred to both Czechian taxa have also been found in Barcelona, Spain, in the Olorda Formation.[28][11]
A. perryensis[]
As small as A. floweri, this species was discovered in the Tymochtee Dolomite Formation in Fayette County, Ohio. Willard Leutze named it in 1958. It lived during the Late Silurian period.[10]
A. suwanneensis[]
A fixed ramus and chelicera hand are known of this species, measuring 3.1 cm together. In life, it measured roughly 45.7 cm long - among the smaller Acutiramus species. A. suwanneensis was found in the Kie Vining Borehole, occupied by the Gulf Oil Corporation. The layer it was preserved in dates to the Přídolí epoch.
As a juvenile, A. suwanneensis lacked serrations on the pincer denticles.[9]
Paleoecology[]
A. cummingsi alongside smaller Eurypterus, by Mary Parrish
Acutiramus lived from the Ludfordian of the Late Silurian to the Pragian stage of the Early Devonian period, 425 to 410.8 million years BC. Species are found in Canada, the eastern United States, Czechia, Spain, Australia, and Algeria.[1]
Map of Late Silurian North America, showing the Fort Erie, Ontario, where A. macrophthalmus and A. cummingsi are reported
The Bertie Formation or Group is the source of A. cummingsi and A. macrophthalmus. Their fossils are found specifically in the Williamsville and Green Fiddlers Members. the formation now spreads across northeastern states (Pennsylvania, New York, Ohio) and Ontario. These rocks date to the Přídolí epoch of the Late Silurian, 422.9 - 416 MBC. The Bertie Formation was formed by the transgressive-regressive of the ancient Cayugan Sea. Fossiliferous limestone here preserved bioturbation; activity in the sediments by small invertebrates. Several other eurypterids lived here, including Pterygotus and four species of Eurypterus. The acanthodian fish Nerepisacanthus denisoni was also present here, as was the early scorpion Proscorpius osborni.[29][30][27]
Crinoid fragments from Požáry Formation, by David Bressan
In the Late Silurian of Bohemia (region in southern Germany and Czechia), A. bohemicus and A. perneri are found in the Požáry and Přídolí Formations. This time in Bohemian prehistory saw several different paleoenvironmental conditions, separated into over a dozen trilobite assembalges. Shale and volcanic deposits are known. These shallow marine environments are attributed to the Rheic Ocean, which once separated Gondwana and Laurussia. Numnerous trilobites are known here, including Ceratocephala and Radiaspis.[31]
Discoveries of Acutiramus in Gondwana increase the diversity and distribution of these eurypterids. The Pragian Idjerane Sandstone Formation (Algeria) and Wilson Creek Shale Formation (Australia) yield the youngest accepted fossils of A. cf. bohemicus known.[14][12]
Hunting[]
Visual acuity was potentially poorer in Acutiramus than in other pterygotids or modern arthropod predators. This, along with the stress patterns observed in their chelicerae, has led some individuals to infer a less-active predatory lifestyle than relatives like Jaekelopterus. Additionally, their chelicerae seem designed for handling softer organisms such as fish, while other pterygotids targeted hard-shelled invertebrates such as other eurypterids and trilobites. Some authors have suggested that Acutiramus represents a form intermediate between generalistic and actively predatory lifestyles.[32][25][20]
The spread of the "walking legs" (III-V) in Acutiramus suggest it more pelagic or nektobenthic than previously assumed; it performed behaviors higher in the water column, rather than regularly stabilizing itself on the sea floor.[22]
In Popular Culture[]
Acutiramus in Carnivores: Cordelia
- Acutiramus is featured in the Cordelia Tour for Carnivores 2. It is found in the oceans of the 'Dinosaur Planet' FMM UV-32. Their colour scheme in the game is grayish cyan.[33]
References[]
- ↑ 1.0 1.1 Acutiramus - PBDB Taxon
- ↑ 2.0 2.1 2.2 Clarke, J. K., Ruedemann R. (1912) "The Eurypterida of New York"
- ↑ 3.0 3.1 Ruedemann, R. (1935). A review of the genus Pterygotus with descriptions of two new species. Proceedings of the American Philosophical Society, Vol. 75, No. 2, pp. 109-119.
- ↑ 4.0 4.1 4.2 Kjellesvig-Waering, E. N. (1961). The Silurian Eurypterida of the Welsh Borderland. Palaeontographica Americana, Vol. 4, No. 29, pp. 79-101.
- ↑ 5.0 5.1 5.2 Tollerton, V. P. Jr 1997 "The Type Species of the Eurypterid Genus Acutiramus Ruedemann, 1935" Journal of Paleontology 71(5):950-951
- ↑ 6.0 6.1 Matthew, G. F. (1889). "On some remarkable organisms of the Silurian and Devonian rocks in southern New Brunswick". Transactions of the Royal Society of Canada. 6 (4): 49–62.
- ↑ 7.0 7.1 Miller, Randall F.; Tetlie, O. Erik (2007). "The presumed Synziphosuran Bunodella horrida Matthew, 1889 (Silurian; Cunningham Creek Formation, New Brunswick, Canada) is a eurypterid". Journal of Paleontology. 81 (3): 588–590. Bibcode:2007JPal...81..588M. doi:10.1666/05127.1. S2CID 85708511.
- ↑ 8.0 8.1 8.2 E. N. Kjellesvig-Waering and K. E. Caster. 1955. The Pterygotidae of the Silurian Vernon Shales of New York. Journal of Paleontology 29:1041-1047
- ↑ 9.0 9.1 9.2 E.N. Kjellesvig-Waering. 1955. A new phyllocarid and eurypterid from the Silurian of Florida . Journal of Paleontology 29(2):295-297
- ↑ 10.0 10.1 10.2 Leutze, W. P. (1958). Eurypterids from the Silurian Tymochtee Dolomite of Ohio. Journal of Paleontology, 32:937–942. https://www.jstor.org/stable/i255721
- ↑ 11.0 11.1 11.2 11.3 11.4 I. Chlupac. 1994. Pterygotid eurypterids (Arthropoda, Chelicerata) in the Silurian and Devonian of Bohemia. Journal of the Czech Geological Society 39(2-3):147-162
- ↑ 12.0 12.1 12.2 12.3 Bicknell, Russell D. C.; Smith, Patrick M.; Poschmann, Markus (2020). "Re-evaluating evidence of Australian eurypterids". Gondwana Research. 86: 164–181. Bibcode:2020GondR..86..164B. doi:10.1016/j.gr.2020.06.002. S2CID 225748023.
- ↑ Smith, P., & Bicknell, R. (2020, July 14). Prehistoric sea scorpions once terrorised Australia. The Australian Museum Blog. Retrieved from https://australian.museum/blog/amri-news/prehistoric-sea-scorpions-once-terrorised-australia/
- ↑ 14.0 14.1 14.2 Legrand, P. (1965). Mémoires du Bureau de Recherches Géologiques et Minières, 33: 119–137.
- ↑ Wang, Han & Sun, Zhixin & Zhang, Haichun. (2025). New eurypterids from the Lower Devonian Nagaoling Formation of Guangxi, South China. Palaeoworld. 34. 200954. 10.1016/j.palwor.2025.200954.
- ↑ Barrande, J. 1872. Système Silurien du centre de la Bohême, I. Recherches Paléontologique, supplement au vol. 1 (Trilobites, Crustacés divers et Poissons). Prague: Barrande, 647 pp.
- ↑ Tollerton Jr., V.P. 2006. Strabismus and pseudofossils: a case study of Rudolf Ruedemann (1864–1956). Earth Sciences History 25: 239–250.
- ↑ Braddy, Simon J.; Poschmann, Markus; Tetlie, O. Erik (2007). "Giant claw reveals the largest ever arthropod". Biology Letters. 4 (1): 106–109. doi:10.1098/rsbl.2007.0491. PMC 2412931. PMID 18029297.
- ↑ 19.0 19.1 19.2 Brandt, Danita. (2021). Eurypterid morphology and implications for ecdysis and evolutionary longevity. Lethaia. 54. 10.1111/let.12434.
- ↑ 20.0 20.1 Bicknell et al. (2022). "Biomechanical analyses of pterygotid sea scorpion chelicerae uncover predatory specialisation within eurypterids." PeerJ, DOI 10.7717/peerj.14515
- ↑ 21.0 21.1 21.2 21.3 James C. Lamsdell "Codex Eurypterida: A Revised Taxonomy Based on Concordant Parsimony and Bayesian Phylogenetic Analyses," Bulletin of the American Museum of Natural History, 2025(473), 1-196, (11 June 2025)
- ↑ 22.0 22.1 22.2 Russell D.C. Bicknell, Katrina Kenny, Roy E. Plotnick "Ex Vivo Three-Dimensional Reconstruction of Acutiramus: A Giant Pterygotid Sea Scorpion," American Museum Novitates, 2023(4004), 1-20, (20 November 2023)
- ↑ Wolff, J.O., J. Martens, A.L. Schönhofer, and S.N. Gorb. 2016. Evolution of hyperflexible joints in sticky prey capture appendages of harvestmen (Arachnida, Opiliones). Organisms Diversity and Evolution 16: 549–557.
- ↑ Evan Cheng, Derek E. G. Briggs "Genital Appendages of the Giant Pterygotid Eurypterid Acutiramus from the Silurian (Pridoli) Bertie Group of North America," Bulletin of the Peabody Museum of Natural History, 65(2), 305-315, (25 October 2024)
- ↑ 25.0 25.1 McCoy VE, Lamsdell JC, Poschmann M, Anderson RP, Briggs DE. All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids. Biol Lett. 2015 Aug;11(8):20150564. doi: 10.1098/rsbl.2015.0564. PMID: 26289442; PMCID: PMC4571687.
- ↑ 26.0 26.1 26.2 Dunlop, J. A., Penney, D. & Jekel, D. 2020. A summary list of fossil spiders and their relatives. In World Spider Catalog. Natural History Museum Bern, online at http://wsc.nmbe.ch, version 20.5, accessed on 30 October 2025.
- ↑ 27.0 27.1 27.2 Moelling, Leah I. (2013). "Eurypterid Paleoecology: Characterization and Analysis of a Late Silurian Shallow Marine Fossil Assemblage from Southern Ontario, Canada" (PDF). Senior Honors Thesis, Faculty of the University of Utah. Archived from the original (PDF) on 2018-02-28. Retrieved 2018-02-27.
- ↑ Chlupáč, I. & Ferrer, E. & Mane, R. & Sanz-López, Javier. (1997). Early Devonian eurypterids with Bohemian affinities from Catalonia (NE Spain). Batalleria. 7. 9-21.
- ↑ Eurypterid-Associated Biota of the Williamsville Member, Buffalo, New York at Fossilworks.org
- ↑ Hamell, R. D., & Ciurca, S. J., Jr. (1986). Paleoenvironmental analysis of the Fiddlers Green Formation (Late Silurian) in New York State. New York State Geological Association.
- ↑ Chlupáč, I. (1987). Ecostratigraphy of Silurian trilobite assemblages of the Barrandian area, Czechoslovakia. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, Volume 17(3), 169–186. https://doi.org/10.1127/nos/17/1987/169
- ↑ Braddy, S.J., and K.C. Gass. 2023. A eurypterid trackway from the Middle Ordovician of New York State. Journal of Paleontology 97: 158–166
- ↑ Carnivores Cordelia mod - ModDB