Four Mile Dam Formation

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Four Mile Dam Formation
Stratigraphic range: Middle Devonian (Givetian)[1]
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File:An examination of the Devonian fishes of Michigan fig-5-full.png
Vertebrate remains from the Four Mile Dam Formation.
TypeGeological formation
Unit ofTraverse Group[1]
Lithology
PrimaryLimestone
Location
RegionFile:Flag of Michigan.svg Michigan
CountryFile:Flag of the United States.svg United States
Type section
Named byCooper & Warthin[2]
Year defined1941[2]

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.

File:An examination of the Devonian fishes of Michigan fig-1-full.png
Stratigraphy of the Devonian deposits of the northern part of the Lower Peninsula of Michigan, showing the Four Mile Dam Formation[1]

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)".[1] "Distinct from named acanthodians (Gyracanthus, Machaeracanthus, and Oracanthus) and chondrichthyans (Tamiobatis and Acondylacanthus) reported from Michigan".[1]
File:An examination of the Devonian fishes of Michigan fig-5-a.png

Conodonts

Conodonts reported from the Four Mile Dam Formation
Genus Species Presence Material Notes Images
Acodina A. formosa [3] Also found in the Detroit River, Traverse, Dundee, Bell, Alpena and Norway Point formations.
Belodella B. devonicus [3] Also found in the Detroit River, Traverse, Antrim, Alpena and Norway Point formations.
Icriodus I. latericrescens latericrescens [3] Also found in the Traverse, Bell, Ferron Point, Genshaw, Newton Creek, Alpena, Norway Point, Potter Farm and Thunder Bay formations.
Ozarkodina O. willsi [3] Also found in the Detroit River, Traverse, Antrim, Dundee, Alpena and Norway Point formations.
Polygnathus P. varcus [3] 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)".[1] A petalichthyid.
File:An examination of the Devonian fishes of Michigan fig-8-a.png
?Mylostoma ?M. sp. 39 specimens, including potential juveniles.[1]
File:An examination of the Devonian fishes of Michigan fig-5-b.png
'Placodermi' Unidentified "One specimen of an armour plate (JS 4)".[1]
File:An examination of the Devonian fishes of Michigan fig-5-c.png
Protitanichthys P. rockportensis "One specimen of an armor fragment (JS 101)".[1] A coccosteid.

Invertebrates

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

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.[4] Also found in the Hungry Hollow Formation and Logansport Formation.
Leptalosia L. radicans Four Mile Dam, Thunder Bay River, Alpena County, Michigan.[4] Also found in the Norway Point, Gravel Point, Alpena and Genshaw formations.
Longispina L. emmetensis Dock Street clay member.[4] Also found in the Alpena Limestone and Gravel Point Formation.
Megastrophia M. gibbosa Four Mile Dam, Thunder Bay River, Alpena County, Michigan.[4] Also found in the Hungry Hollow Formation and Logansport Formation.
Oligorhachis O. oligorhachis Four Mile Dam, Thunder Bay River, Alpena County, Michigan.[4] Also found in the Gravel Point Formation.
Pentamerella P. alpenensis Dock Street clay member.[4] Also found in the Alpena Limestone and Gravel Point Formation.
P. sp. C Dock Street clay.[4] A complete specimen.[4]
Protoleptostrophia P. lirella Dock Street clay member.[4] Also found in the Norway Point Formation and Alpena Limestone.
Schuchertella S. anomala Possibly the Dock Street clay member.[4] Also found in the Gravel Point Formation.
S. sp. Four Mile Dam, Thunder Bay River, Alpena County, Michigan.[4]
Spinulicosta S. mutocosta Four Mile Dam, Thunder Bay River, Alpena County, Michigan.[4] Also found in the Bell, Rockport Quarry, Ferron Point, Beebe School, Thunder Bay and Potter Farm formations.
Strophodonta S. erratica Dock Street clay member.[4] Also found in the Alpena Limestone and Gravel Point Formation.
S. fissicosta Dock Street clay member.[4] Also found in the upper Gravel Point Formation.
S. nanus Dock Street clay member.[4] Also found in the Alpena Limestone and Gravel Point Formation.
S. paula Dock Street clay member.[4] Also found in the Alpena Limestone.
S. sp. B Dock Street clay member and overlying crystalline limestone beds.[4] Several specimens.[4]
Rhipidomella R. penelope traversensis Thunder Bay River, Alpena County, Michigan.[4]

Corals

Corals reported from the Four Mile Dam Formation
Genus Species Presence Material Notes Images
Aulocystis A. cooperi [5] Also found in the Plum Brook shale, Silica shale and Potter Farm Formation.
A. jacksoni Dock Street clay member.[5] Also found in the Silica Shale, Ferron Point Formation, Petoskey Formation, Hungry Hollow Formation, Widder Shale, Wanakah shale and Centerfield Limestone.
Aulopora A. conferta [5] Also found in the Bell, Ferron Point, Gravel Point, Genshaw, Alpena, Potter Farm, Petoskey and Hungry Hollow formations.
A. gregaria [5] Also found in the Genshaw Formation, Alpena Limestone and Petoskey Formation.
Pachyphragma P. concentricum Dock Street clay member.[5] 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.[2] An elasmonematid.
A. mellaria Upper limestone unit.[2] An elasmonematid, very rare in the Four Mile Dam Limestone.
Bembexia B. (Genuspira) nodosa Upper limestone unit.[2] About 35 specimens.[2] An eotomariid and the most abundant gastropod in the formation.
Dictyobembix D. bella Upper limestone unit.[2] 5 specimens.[2] An eotomariid.
Mourlonia M. lirata Upper limestone unit.[2] An eotomariid.
Murchisonia M. (Murchisonia) subulata Upper limestone unit.[2] A murchisoniid, extremely rare in the formation.
Naticopsis N. sp. Upper limestone unit.[2] A neritopsid, extremely rare in the formation.
Palaeoscurria? P.? sp. Upper limestone unit.[2] 3 poorly preserved ventral molds.[2] A metoptomatid.
Platyceras P. (Platyceras) bartlettense Dock Street Clay Member.[2] A platyceratid.
P. (Euthyrachis) indianense Dock Street Clay Member.[2] A platyceratid.
P. (Orthonychia) variabilis Upper limestone unit.[2] A platyceratid.
Pseudozygopleuridae? Genus A Genus A sp. A Upper limestone unit.[2] Relatively numerous steinkerns.[2]
Pseudozygopleuridae? Genus B Genus B sp. B Upper limestone unit.[2] One very poorly preserved steinkern with a few small shell patches (YPM 23684).[2]
Spiroscala S. sp. Upper limestone unit.[2] One specimen (UMMP 47377).[2] An eotomariid.
Straparollus S. (Philoxene) sp. Upper limestone unit.[2] 3 poorly preserved specimens.[2] An euomphalid.
Trepospira T. (Angyomphalus) bella Upper limestone unit.[2] A raphistomatid, very rare in the Four Mile Dam Limestone.
Turbinilopsis T. anacarina Upper limestone unit.[2] Abundant specimens.[2] An anomphalid.

Sponges

Sponges reported from the Four Mile Dam Formation
Genus Species Presence Material Notes Images
Anostylostroma A. anacolumna On Thunder Bay River.[6] A stromatoporoid.

Trilobites

Trilobites reported from the Four Mile Dam Formation
Genus Species Presence Material Notes Images
Cordania C. rara [7]
Dechenella D. (Monodechenella) macrocephala [7] Also found in the Hamilton Group.
D. (Basidechenella) rowi [7] Also known from the Hamilton Group.
Eldredgeops E. rana [7] 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.[7] Also found in the Norway Point and Gravel Point formations.
G. traversensis Dock Street clay member.[7] Also found in the Gravel Point Formation.
Phacops P. rana [7] Reassigned to the genus Eldredgeops.
Proetus P. (Crassiproetus) traversensis [7] Also known from the Gravel Point Formation.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 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.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25 2.26 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.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Orr, R. William (1971). "Conodonts from Middle Devonian Strata from the Michigan Basin". {{cite journal}}: Cite journal requires |journal= (help)
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 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". {{cite journal}}: Cite journal requires |journal= (help)
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Watkins, J. Lloyd (1959). "Middle Devonian Auloporid Corals from the Traverse Group of Michigan". Journal of Paleontology. 33 (5): 793–808. ISSN 0022-3360.
  6. ↑ 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.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Stumm, Erwin (1953). "Trilobites of the Devonian Traverse Group of Michigan" (PDF). University of Michigan Press - Museum of Paleontology.
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