Carrara Formation

The Carrara Formation is a geologic formation in California and Nevada. It preserves fossils dating back to the Cambrian period.

Geology

The Carrara Formation is primarily composed of olive-gray and greenish-gray siltstones and shales, as well as medium-gray limestone in the lower half of the formation, with medium-gray to yellowish-brown silty limestone and limy limestone in the upper half of the formation. The lower half also contains quartzite rocks, similar to that seen in the underlying Zabriskie Quartzite. In other areas of the lower half, there are olive-gray, greenish-gray or dusky-yellow siltstones and sandy siltstones, along with small amounts of sandstone and limestone. The upper half also contains fine to medium-grained quartzites, white in colour, forming a distinctive band. In other areas of the formation, it instead consists of inter-stratified siltstones, shales and very fine to medium-grained quartzite.

Members

The Carrara Formation contains in total nice Members, which are as follows, in ascending age:Eagle Mountain Shale MemberThimble Limestone MemberEcho Shale MemberGold Ace Limestone MemberPyramid Shale MemberRed Pass Limestone MemberPahrump Hills Shale MemberJangle Limestone Member

'''Desert Range Limestone Member'''

Paleobiota

The Carrara Formation contains an abundance of arthropods, like the spiny Bristolia, as well as ichnotaxon like Skolithos, a type of burrow trace fossil. It also contains some examples of Archaeocyatha, a clade of sponges that went extinct during this time.

Arthropoda

Genus	Species	Notes	Images
Houcaris	H?. magnabasis	Radiodont arthropod. Previously described as Anomalocaris magnabasis in 2019, but was reassigned to Houcaris in 2021, although this assignment is now up in the air with subsequent analysis suggesting H. magnabasis may not form a monophyletic clade with other species of Houcaris.
Ursulinacaris	H. grallae	A Hurdiid radiodont.
Bristolia	B. bristolensis	An olenellid trilobite.
Olenellus	O. clarkiO. terminatus	An olenellid trilobite. Fossil specimens from the Pyramid Shale Member have been found preserving the first evidence of chitin in trilobites.

Lophotrochozoa

Genus	Species	Notes	Images
Microcornus	Microcornus sp.	Lophotrochozoan hyolith.
Parkula	Parkula sp.	Lophotrochozoan hyolith.
Hyolithellus	Hyolithellus sp.	Lophotrochozoan hyolith.

Chancelloriidae

Genus	Species	Notes	Images
Allonia	Allonia sp.	Chancelloriid.
Chancelloria	Chancelloria sp.	Chancelloriid.

Porifera (Sponges)

Genus	Species	Notes	Images
Archaeocyathus	Archaeocyathus sp.	Archaeocyathide sponge.

Ichnogenera

Genus	Species	Notes	Images
Skolithos	S. linearis	Burrows.

Undescribed

Genus	Species	Notes	Images
Disc-shaped fossils	"Carrara specimens"	Disc-shaped organisms, resemble either porpitids or eldonids, especially to Discophyllum.