Rock-forming fossils

[pefty]

Just as a curiosity, I thought I'd compile a list of fossil groups that are known to be so abundant in places as to be rock-forming, i.e., to form coquinas, often of a single species. I started the list but there are probably many examples I am unaware of. For example, hyoliths...?

Care to add to the list?
 

• Various pelecypods (including modern/subfossil examples)
• Various gastropods (including modern/subfossil examples)
• Some rugose, tabulate, and scleractinian corals (including modern/subfossil examples)
• Some crinoids (as encrinite)
• Some ophiuroids (but really just thin beds?)
• Some ammonoids?
• Some belemnoids?
• Some orthocerids etc. (mostly early Paleozoic)
• Some nautiloids (Alaska Devonian example)
• Some lingulate brachiopods (mostly Cambrian) 
• Some strophomenide and orthide brachiopods (mostly early Paleozoic)
• Some pentameride brachiopods?
• Some tentaculitids (e.g., Arkona)
• Some hyolithids?
• Some trilobites (mostly Cambrian)
• Some trepostome bryozoans
• Various sponges, notably stromatoporoids and chaetetids
• Some algae such as Tasmanites, diatoms (as diatomite), coccolithophores (as chalk), red algae (as rhodolite), etc.
• Some radiolarians
• Various plants in coal swamps  (as coal)
• Microbes such as cyanobacteria (as microbialite, laminite, stromatolite, thrombolite, oncolite, etc.)

 

Any others?

[Thomas.Dodson]

I've seen some very specific definitions of what makes true coquina. There are exposures of the Fox Hills Formation (Timber Lake Member) in Morton County, North Dakota that have been described as "coquina".  I visited one that was almost entirely the bivalve Dosiniopsis deweyi (probably 99%).

 

This piece broke off from the overlayer. It was about .7 meters if I recall correctly.

[pachy-pleuro-whatnot-odon]

Do Triassic marine bone beds count? These beds are so cramped full of bones that you could easily call them rock-forming. In addition, they are often reworked, bones broken down, re-settled, etc. so that even smaller gaps would be filled with bone. However, there's always some matrix in between.

 

Anyway, interesting list you've compiled there!