Fossils of Arizona

Photographic Atlas - Main Page
Updated 6/6/17
This collection of images of Arizona fossils is the result of decades of time well spent in the field around our great State. We have spent thousands of hours collecting, documenting and taking photos of fossils covering a wide range of ages from Precambrian to Holocene. In addition, countless of hours have been spent at organizing, identifying (if possible) and properly storing and labeling the specimens. Fossils that are too large or were not removable have been extensively photographed in the field. Lets start here now with Arizona's earliest fossils, from the Precambrian limestones, cherts and shales of the Mescal Limestone in the north central part of our State.
Precambrian Strata: Mescal Limestone.
Click image to go to Write up.
 Synopsis: The Mescal Limestone of Central Arizona and the base of the Mogollon Rim contains locally abundant stromatolites and algal mats. Though "stroms" are considered to be trace fossils, they represent the remains of the largest life forms present 1.2 Billion years ago in the Proterzoic Era.
Cambrian Strata.

The Cambrian fossils of Arizona occupy a special place in our hearts, the unique and primitive lifeforms are our favorite members of our collections. We have spent more time in the Cambrian than any other time period, with the exception of the Mississippian. The Tonto Group to the North and Cambrian in south eastern Arizona are from the same ocean - but differ in naming and on some of the fossil types found in each formation. To keep organized, I will cover these formations separately, from the shallow tidal flats of the Tapeats and Bolsa Quartzite, to the deep water limestones of the Muav and Abrigo formation. Here is a listing of the Cambrian formations we will be discussing here in Arizona:

Northern Arizona - Mogollon Rim through to the Grand Canyon:

1. Tapeats Sandstone (Beach, tidal flat, shallow water)
2. Bright Angel Shale (Muddy sediments including deeper water shales, mudstones, claystones)
3. Muav Limestone (Deep water limestones)

South Eastern Arizona - South of Tucson to South eastern border.
4. Bolsa Quartzite (Beach, tidal flat, shallow water)
5. Abrigo Formation - Shale Member (Muddy sediments including deeper water shales, mudstones, claystones)
6. Abrigo Formation - Limestone Member (Deep water limestones)

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 Synopsis: Tapeats of the Mogollon Rim / Payson / Grand Canyon Area.

From the south limits of the Town of Payson, to the East Fork of the Verde River north of town, the Tapeats outcrops frequently and is the basal sedimentary unit in the region overlaying the 1.8 billion year old Pre Cambrian granites. In most areas it is less than 50 feet thick, and contains a few sedimentary structures and strongly graded bedding which highlights it origins - Near shore tidal flat and sand bar lithology. We are quite familiar with this formation - Our house is right on the outcrop! Fossils are very sparse and consist of primarily trace fossils.

(Zacanthoides Trilobite)  Click image to go to article

 Synopsis: Bright Angel Shale of Northern Arizona.

Most paleontologist are led to believe that the Lower Middle Cambrian Bright Angel Shale can only be found in the depths of the Grand Canyon National Park, and therefore is not open to collecting for the general public. After much research spanning years pouring over old - and nearly unobtainable geologic maps, professional papers and Bulletins, we found that this is not the case. There are half a dozen small areas far outside the Canyon (south), and isolated outcrops in the Juniper Mountains in Northern Arizona. We spent over a year finding and evaluating these outcrops - when accessible, and found two in particular that were highly fossiliferous. Besides hordes of Cambrian trace fossils, we found a plentiful but low diversity of fauna similar to the Burgess Shale in British Columbia, and the Chenchang Fauna in China. Phyllums include at least half a dozen species of Trilobites, Hyalithids, inarticulate Brachiopods, a colonial hydrozoan like animal, and trace fossils from arthropods, mollusks, and annelids.

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