Four Mile Dam Formation | |
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Stratigraphic range: Middle Devonian (Givetian) PreꞒ Ꞓ O S D C P T J K Pg N | |
Vertebrate remains from the Four Mile Dam Formation. | |
Type | Geological formation |
Unit of | Traverse Group |
Lithology | |
Primary | Limestone |
Location | |
Region | Michigan |
Country | United States |
Type section | |
Named by | Cooper & Warthin |
Year defined | 1941 |
The Four Mile Dam Formation, also called the Four Mile Dam Limestone, is a geologic formation in Michigan. It preserves fossils dating back to the middle Devonian period.
Fossil content
Vertebrates
Acanthodians
Acanthodians reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
'Acanthodii' | Unidentified | "Two partial fin spines (JS 120, JS 121)". | "Distinct from named acanthodians (Gyracanthus, Machaeracanthus, and Oracanthus) and chondrichthyans (Tamiobatis and Acondylacanthus) reported from Michigan". |
Conodonts
Conodonts reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Acodina | A. formosa | Also found in the Detroit River, Traverse, Dundee, Bell, Alpena and Norway Point formations. | |||
Belodella | B. devonicus | Also found in the Detroit River, Traverse, Antrim, Alpena and Norway Point formations. | |||
Icriodus | I. latericrescens latericrescens | Also found in the Traverse, Bell, Ferron Point, Genshaw, Newton Creek, Alpena, Norway Point, Potter Farm and Thunder Bay formations. | |||
Ozarkodina | O. willsi | Also found in the Detroit River, Traverse, Antrim, Dundee, Alpena and Norway Point formations. | |||
Polygnathus | P. varcus | Also found in the Traverse, Antrim, Alpena, Norway Point and Thunder Bay formations. |
Placoderms
Placoderms reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
?Macropetalichthys | ?M. sp. | "A partial head shield (32M)". | A petalichthyid. | ||
?Mylostoma | ?M. sp. | 39 specimens, including potential juveniles. | |||
'Placodermi' | Unidentified | "One specimen of an armour plate (JS 4)". | |||
Protitanichthys | P. rockportensis | "One specimen of an armor fragment (JS 101)". | A coccosteid. |
Invertebrates
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Brachiopods
Brachiopods reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Douvillina | D. distans | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | Also found in the Hungry Hollow Formation and Logansport Formation. | ||
Leptalosia | L. radicans | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | Also found in the Norway Point, Gravel Point, Alpena and Genshaw formations. | ||
Longispina | L. emmetensis | Dock Street clay member. | Also found in the Alpena Limestone and Gravel Point Formation. | ||
Megastrophia | M. gibbosa | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | Also found in the Hungry Hollow Formation and Logansport Formation. | ||
Oligorhachis | O. oligorhachis | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | Also found in the Gravel Point Formation. | ||
Pentamerella | P. alpenensis | Dock Street clay member. | Also found in the Alpena Limestone and Gravel Point Formation. | ||
P. sp. C | Dock Street clay. | A complete specimen. | |||
Protoleptostrophia | P. lirella | Dock Street clay member. | Also found in the Norway Point Formation and Alpena Limestone. | ||
Schuchertella | S. anomala | Possibly the Dock Street clay member. | Also found in the Gravel Point Formation. | ||
S. sp. | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | ||||
Spinulicosta | S. mutocosta | Four Mile Dam, Thunder Bay River, Alpena County, Michigan. | Also found in the Bell, Rockport Quarry, Ferron Point, Beebe School, Thunder Bay and Potter Farm formations. | ||
Strophodonta | S. erratica | Dock Street clay member. | Also found in the Alpena Limestone and Gravel Point Formation. | ||
S. fissicosta | Dock Street clay member. | Also found in the upper Gravel Point Formation. | |||
S. nanus | Dock Street clay member. | Also found in the Alpena Limestone and Gravel Point Formation. | |||
S. paula | Dock Street clay member. | Also found in the Alpena Limestone. | |||
S. sp. B | Dock Street clay member and overlying crystalline limestone beds. | Several specimens. | |||
Rhipidomella | R. penelope traversensis | Thunder Bay River, Alpena County, Michigan. |
Corals
Corals reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Aulocystis | A. cooperi | Also found in the Plum Brook shale, Silica shale and Potter Farm Formation. | |||
A. jacksoni | Dock Street clay member. | Also found in the Silica Shale, Ferron Point Formation, Petoskey Formation, Hungry Hollow Formation, Widder Shale, Wanakah shale and Centerfield Limestone. | |||
Aulopora | A. conferta | Also found in the Bell, Ferron Point, Gravel Point, Genshaw, Alpena, Potter Farm, Petoskey and Hungry Hollow formations. | |||
A. gregaria | Also found in the Genshaw Formation, Alpena Limestone and Petoskey Formation. | ||||
Pachyphragma | P. concentricum | Dock Street clay member. | Also found in the Ferron Point Formation, Gravel Point Formation and Alpena Limestone. |
Gastropods
Gastropods reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Anematina | A. conica | Upper limestone unit. | An elasmonematid. | ||
A. mellaria | Upper limestone unit. | An elasmonematid, very rare in the Four Mile Dam Limestone. | |||
Bembexia | B. (Genuspira) nodosa | Upper limestone unit. | About 35 specimens. | An eotomariid and the most abundant gastropod in the formation. | |
Dictyobembix | D. bella | Upper limestone unit. | 5 specimens. | An eotomariid. | |
Mourlonia | M. lirata | Upper limestone unit. | An eotomariid. | ||
Murchisonia | M. (Murchisonia) subulata | Upper limestone unit. | A murchisoniid, extremely rare in the formation. | ||
Naticopsis | N. sp. | Upper limestone unit. | A neritopsid, extremely rare in the formation. | ||
Palaeoscurria? | P.? sp. | Upper limestone unit. | 3 poorly preserved ventral molds. | A metoptomatid. | |
Platyceras | P. (Platyceras) bartlettense | Dock Street Clay Member. | A platyceratid. | ||
P. (Euthyrachis) indianense | Dock Street Clay Member. | A platyceratid. | |||
P. (Orthonychia) variabilis | Upper limestone unit. | A platyceratid. | |||
Pseudozygopleuridae? Genus A | Genus A sp. A | Upper limestone unit. | Relatively numerous steinkerns. | ||
Pseudozygopleuridae? Genus B | Genus B sp. B | Upper limestone unit. | One very poorly preserved steinkern with a few small shell patches (YPM 23684). | ||
Spiroscala | S. sp. | Upper limestone unit. | One specimen (UMMP 47377). | An eotomariid. | |
Straparollus | S. (Philoxene) sp. | Upper limestone unit. | 3 poorly preserved specimens. | An euomphalid. | |
Trepospira | T. (Angyomphalus) bella | Upper limestone unit. | A raphistomatid, very rare in the Four Mile Dam Limestone. | ||
Turbinilopsis | T. anacarina | Upper limestone unit. | Abundant specimens. | An anomphalid. |
Sponges
Sponges reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Anostylostroma | A. anacolumna | On Thunder Bay River. | A stromatoporoid. |
Trilobites
Trilobites reported from the Four Mile Dam Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Material | Notes | Images |
Cordania | C. rara | ||||
Dechenella | D. (Monodechenella) macrocephala | Also found in the Hamilton Group. | |||
D. (Basidechenella) rowi | Also known from the Hamilton Group. | ||||
Eldredgeops | E. rana | Originally reported as Phacops rana. Also found in the Hamilton, Hungry Hollow, Widder, Plum Brook, Prout, Ten Mile Creek, Alpena, Norway Point and Gravel Point formations. | |||
Greenops | G. aequituberculatus | Dock Street clay member. | Also found in the Norway Point and Gravel Point formations. | ||
G. traversensis | Dock Street clay member. | Also found in the Gravel Point Formation. | |||
Phacops | P. rana | Reassigned to the genus Eldredgeops. | |||
Proetus | P. (Crassiproetus) traversensis | Also known from the Gravel Point Formation. |
See also
References
- ^ Stack, Jack; Sallan, Lauren (2018-09-20). "An examination of the Devonian fishes of Michigan". PeerJ. 6 (2). doi:10.7717/peerj.5636. PMC 6151260.
- ^ Tyler, John H. (1965). "Gastropods from the Middle Devonian Four Mile Dam Limestone (Hamilton) of Michigan". Journal of Paleontology. 39 (3): 341–349. ISSN 0022-3360.
- ^ Orr, R. William (1971). "Conodonts from Middle Devonian Strata from the Michigan Basin".
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(help) - ^ Imbrie, John (1959). "Brachiopods of the Traverse group (Devonian) of Michigan. Part 1, Dalmanellacea, Pentameracea, Strophomenacea, Orthotetacea, Chonetacea, and Productacea. Bulletin of the AMNH ; v. 116, article 4".
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: Cite journal requires|journal=
(help) - ^ Watkins, J. Lloyd (1959). "Middle Devonian Auloporid Corals from the Traverse Group of Michigan". Journal of Paleontology. 33 (5): 793–808. ISSN 0022-3360.
- Tyler, John H. (1964). "Anostylostroma anacolumna n. sp. from the Four Mile Dam Limestone (Hamilton), Alpena County, Michigan". Journal of Paleontology. 38 (5): 885–886. ISSN 0022-3360.
- ^ Stumm, Erwin (1953). "Trilobites of the Devonian Traverse Group of Michigan" (PDF). University of Michigan Press - Museum of Paleontology.
- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 25 March 2022. Retrieved 17 December 2021.
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