Gun River Formation

The Gun River Formation is a geologic formation in Quebec. It preserves fossils dating back to the early Silurian period.

Description The formation is divided into 4 members (from the base up): the Lachute, Innommée, Sandtop and Macgilvray members. The formation was deposited some 40–80 km offshore from the stable Laurentian craton, underwater at depths of 30 to 60 meters.

Fossil content Vertebrates

Conodonts Genus Species Presence Material Notes ImagesAnticostiodusA. fahraeusi Anticosti Island. A. boltoniAnticosti Island.IcriodellaI. deflectaProbably instead belongs to the Jupiter Formation.

Invertebrates Brachiopods Genus Species Presence Material Notes ImagesBrachyprionSandtop and Macgilvray Members.A strophomenid.CooliniaSandtop and Macgilvray Members.FenestrirostraF. glacialisLowermost part of the formation.A rhynchonellidalso found in the Merrimack Formation.F. pyrrhaLachute Member.A rhynchonellid.'Gotatrypa''' |'G.' sp. |Innommée Member.

| Hyattidina| | Sandtop to Macgilvray Members. | | An athyrid.

|Joviatrypa| |Uppermost Macgilvray Member.

|Kulumbella|K. xacta|Upper Macgilvray Member. | |A pentamerid.

|Mendacella| |Innommée Member. | |A dalmanellid.

|Meristina| |Innommée Member.

|Pentamerus|P. palaformis|Top of the formation (uppermost Macgilvray Member). | |Also found in the Jupiter Formation.

|Stegerhynchus|

|rowspan=2|Stricklandia|S. gwelani|Top of the formation (Macgilvray Member). | |Also found in the Jupiter Formation.

|S. sp. |Innommée Member. |A509 (7 broken valves on a slab). |Also found in the uppermost Merrimack Formation.

|Sypharatrypa|S.'' sp.Innommée Member.

Bryozoans Genus Species Presence Material Notes ImagesPhaenoporaP. superbaAlso found in the Becscie Formation.PtilodictyaP. canadensisUSNM 143039.P. sulcataUSNM 143039, 143050; YPM 3063/98, 3063/104.

Corals Genus Species Presence Material Notes ImagesAcidolitesA. arctatusA heliolitid.BrachyelasmaCrassilasma Helicelasma PalaearaeaCap aux Goélands (Uppermost Macgilvray Member).Small colonies.The only rugosan coral known from the formation, also found in the Menier formation.PaleofavositesP. capaxMultiple colonies.A tabulate coral.

Crinoids Genus Species Presence Material Notes Images Dendrocrinus EumyelodactylusMacgilvray Member.LaurocrinusMacgilvray Member.StupatocrinusMacgilvray Member.

Graptolites Genus Species Presence Material Notes Images ParaclimacograptusP. cf. innuitus Deeper water facies of the Sandtop Member.

Sponges Genus Species Presence Material Notes ImagesCamptodictyonA stromatoporoid. Clathrodictyon A stromatoporoid.

See also

List of fossiliferous stratigraphic units in Quebec

References