Rockport Quarry Limestone

Rockport Quarry Limestone
Stratigraphic range: Middle Devonian (Givetian) [1] PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Traverse Group
Underlies	Ferron Point Formation [1]
Overlies	Bell Shale [1] [2]
Thickness	Approximately 14 meters [2]
Location
Region	Michigan
Country	United States

The Rockport Quarry Limestone is a geologic formation in Michigan. It preserves fossils dating back to the middle Devonian period.

Stratigraphy of the Devonian deposits of the northern part of the Lower Peninsula of Michigan, showing the Rockport Quarry Limestone

Fossil content

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.

Vertebrates

The Devonian vertebrate fauna of the Rockport Quarry Limestone is the most diverse in Michigan. ^[1]

Acanthodians

Acanthodians reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
?Machaeracanthus	?M. sp.		A single specimen (UMMP 13047). [1]

Cartilaginous fish

Cartilaginous fish reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Phoebodus	P. cf. P. sophiae	Alpena, Michigan. [3]	A tooth. [3]	An early elasmobranch.
?Tamiobatis	?T. sp.	"At the abandoned Kelly Island Limestone Quarry at Rockport State Park, Alpena County". [1]	A single small spine (UMMP 13147). [1]	A ctenacanthoid.

Placoderms

Placoderms reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Dinomylostoma	D. sp.		[1]	An arthrodire.
Dunkleosteus	D. sp.	Rockport Quarry, Alpena County. [1]	A single incomplete right anterior ventrolateral (UMMP 16152). [1]	An arthrodire.
Holonema	?H. rugosum		A single specimen (UMMP 3898). [1]	An arthrodire.
	H. sp.		26 specimens. [1]	An arthrodire.
Mylostoma	M. sp.		A single specimen (UMMP 13612). [1]	An arthrodire.
Placodermi		At the abandoned Kelly Island Limestone Quarry at Rockport State Park, Alpena County. [1]	2 specimens (7M, VP. 522.) [1]	Placoderms of unknown affinity.
Protitanichthys	P. rockportensis		59 specimens. [1]	An arthrodire.
Ptyctodus	P. sp.		A single specimen (UMMP 13045). [1]	A ptyctodontid.

Invertebrates

Brachiopods

Brachiopods reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Chonetes	C. mediolatus		[4]	Also found in the Bell Shale, Ferron Point Formation and St. Laurent Limestone.
Pentamerella	P. sp. B	Basal 8 inches of the formation. [4]	2 specimens. [4]
Pholidostrophia	P. gracilis gracilis		[4]	Also found in the Bell, Ferron Point and Genshaw formations.
Schizophoria	S. ferronensis	Basal 8 inches of the formation. [4]		Also found in the Bell Shale, Ferron Point Formation and Silica Shale.
Schuchertella	S. crassa		[4]	Also found in the lower Bell Shale, Ferron Point Formation and Arkona Shale.
Spinulicosta	S. mutocosta		[4]	Also found in the Bell, Ferron Point, Four Mile Dam, Beebe School, Thunder Bay and Potter Farm formations.
Strophodonta	S. extenuata rockportensis	Lower 8 inches of the formation. [4]
Tylothyris	T. rockportensis		[5]	Appears to be endemic to the Michigan Basin.
	T. subvaricosa		[5]	Also found in the Cedar Valley, Milwaukee, Mineola, Bell, Ferron Point, Genshaw, Alpena, Gravel Point, Norway Point and Potter Farm formations.

Bryozoans

Bryozoans reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Fenestellidae	Species A		[2]
	Species B		[2]
	Species C		[2]
Trepostomata	Species A		[2]
	Species B		[2]

Crustaceans

Crustaceans reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Ostracoda			[2]
Phlyctiscapha	P. rockportensis	Basal part of the formation. [6]		An ostracod.

Echinoderms

Echinoderms reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Crinoidea			"Observed as disaggregated ossicles, ossicles stacked en echellon, and fragments of columnals". [2]

Molluscs

Molluscs reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Cephalopoda			"All specimens collected as single-hand specimens". [2]
Gastropoda			[2]

Sponges

Sponges reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Clathrodictyidae			[2]
Idiostromatidae			[2]
Stromatoporidae			[2]

Trilobitomorphs

Trilobitomorphs reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Trilobitomorpha		200 m south of the large sinkhole on the west wall of Rockport Quarry. [2]

Plants and algae

Plants and algae reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Calcisphera	C. sp. A	"Abandoned quarry of the Onaway Limestone Company on the shore of Black Lake". [2]
	C. sp. B	"Abandoned quarry of the Onaway Limestone Company on the shore of Black Lake". [2]
Rhodophyta	Indeterminate	200 m south of the large sinkhole on the west wall of Rockport Quarry. [2]
Vermiporella			"Observed as transverse sections, most specimens now irregular in shape due to crushing". [2]

Cyanophytes

Cyanophytes reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Genus and species indeterminate	Indeterminate		"Spherical bodies 3-5 microns in diameter". [2]
Oncolite				"Some post-depositional crushing of the sample has occurred". [2]
Renalcis		"Abandoned quarry of the Onaway Limestone Company on the shore of Black Lake". [2]

Foraminifera

Foraminifera reported from the Rockport Quarry Limestone
Genus	Species	Presence	Material	Notes	Images
Family indet.			"Found sparsely as solitary individuals in 6 specimens". [2]
Nodosinellidae			[2]

See also

• Earth sciences portal
• Michigan portal
• Paleontology portal

• List of fossiliferous stratigraphic units in Michigan

References

1. Stack, Jack; Sallan, Lauren (20 September 2018). "An examination of the Devonian fishes of Michigan". PeerJ. 6 (2): e5636. doi: 10.7717/peerj.5636 . PMC   6151260 . PMID   30258725.
2. Cookman, C. W. (1976). "Petrology of the Rockport Quarry Limestone (Middle Devonian Traverse Group) Alpena, Presque Isle and Montmorency Counties, Michigan". S2CID   130419618.{{cite journal}}: Cite journal requires |journal= (help)
3. Swinehart, Anthony L.; Hoenig, Matthew M. J.; Ginter, Michal (July 2020). "A New Addition to the Devonian Elasmobranch Fauna of Michigan, U.S.A." The American Midland Naturalist. 184 (1): 109–115. doi:10.1637/0003-0031-184.1.109 (inactive 12 July 2025). ISSN   0003-0031.
4. 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". hdl:2246/1258.{{cite journal}}: Cite journal requires |journal= (help)
5. Rogers, Frederick S.; Pitrat, Charles W. (1987). "Distribution of Tylothyris (Brachiopoda) and Its Occurrence in the Traverse Group (Middle Devonian) of Michigan" . Journal of Paleontology. 61 (3): 494–507. Bibcode:1987JPal...61..494R. doi:10.1017/S0022336000028651. ISSN   0022-3360. JSTOR   1305304. S2CID   130922140.
6. Kesling, R. V. (1953). "A New Beyrichiid Ostracod from the Middle Devonian Rockport Quarry Limestone of Michigan". S2CID   127104889.{{cite journal}}: Cite journal requires |journal= (help)