Cambrian Fossils in the

Tapeats Sand Stone

Middle Cambrian Life was very similar to many of the animals in the Tapeats time.
Updated 10/10/16

Tapeats Sandstone.

The Tapeats outcrops along the base of the Mogollon Rim at around 5000 feet elevation, including the Payson area. There are sporadic outcrops from here to the Grand Canyon, especially around Ashfork. The Tapeats age varies from place to place, however dating the depositional time of sandstone is difficult, and you must date underlying and overlying sediments which have either volcanic ash or basalt to use standard nuclear dating methods. Near Payson, it appears a bit older because of the lack of trilobite trails and may be nearly Ediacaran in age (570 Billion). Mostly in the Canyon it contains abundant trilobite material and would be lower middle Cambrian in age, around 510 Billion old.

To see the Tapeats at the Grand Canyon, you really have to hike down inside on to the Tonto Platform. A great place to see Tapeats lithology and fossils is on Plateau Point. The Tapeats contains few body fossils because of the energetic sandy enviorment during deposition, however extensive trace fossils are locally abundant. These include trilobite traces of various types, varieties of worm burrows, mollusk like feeding traces, and tons of U tube structures from various elongated worm like animals, some larger than garden hoses.

U Tube Burrows - Actinocolites (Correphoides)
  Click image to see Full Size

 This trace fossil was created most likely by an marine annellid worm in the shallow water tidal zone. When you find these in the field, the most common appearance is the bottom of the U tube preserves as a slit seen on the left here, and other times less often, you can see the twin openings which marked the top surface of the sediment. This specimen shows both. Look for the pairs of tiny holes in the surface of this rock, that is the twin openings of a U tube marine worms home. When the annellid dies, the twin holes can become filled with sediments and preserve as fossils.

This particular fossil has an identity crisis as well. In the old books, it is referred to as "Correphoides". But decades later someone discovered that this name was all ready in use by a deep water marine fish that is still alive today. So the trace was renamed "Actinocolites". Trace fossil nomenclature is constantly in flux, the field is getting much better, but has been fraught with misidentifications, dual naming and separate naming of simple morphological variations in a single ichnospecies. This is like naming every breed of dog ever a different species - when they are actually variations in ONE species - Canis Familiaris.

  Click image to see Full Size
 Another nice hand sized specimen shows the more typical field appearance of numerous slits about an inch long in the sediment.
  Click image to see Full Size
 This nice specimen shows mostly the twin holes found at the top of the burrows. This particular group is a very small sub species with holes only 1/16 of an inch in size.
  Click image to see Full Size
 Close up of above specimen showing a pair of holes that are bridged with the starting point of the bottom of the U tube. We have also found on occasion the patterns in the burrow between the holes of the organism being buried slowly over time and it constantly moving upward making another new base of the U tube. The ghost pattern of the slow lifting up of the organism leaves a different looking side view on the trace of many bottoms superimposed. This is called Diplocraterion when found this way.
  Click image to see Full Size
 Actinocolites - side view showing U tube morphology. The twin holes would be at the top on this view.
  Click image to see Full Size
 Larger hole pairs in tight group. Some funneling at the top of the holes as the organism moved about at the top of its burrow in a circular feeding pattern.
  Click image to see Full Size
 Side view of same specimen showing the U tube side as it goes into the rock, which was at one time a nice sandy tidal zone in shallow energetic waters.
Funnel shaped openings on linear Burrows - Monocriterion
  Click image to see Full Size
 Similar to Skolithos, these interesting burrows are also created by some form of annelid worm animal, and would sweep their bodies at the single opening in a circular pattern in search of food. This leaves a funnel shaped opening at the top. This was a very recent find last year, we had never found these before! From up on the top of the hill at the Payson Airport.
Linear Vertical Burrows - Skolithos Linearis
  Click image to see Full Size
 Simple linear vertical burrows with no flaring at the top. Most likely makers were again annelids. This is the top of a slab that shows the filled in round holes from the burrows.
  Click image to see Full Size
 Side view of Skolithos found at same site, showing the filled in burrows in cross section as they dug down about an inch or two into the sandy sediments.
  Click image to see Full Size
 I found this one - my first specimen of Skolithos - at the Verde river north of Payson along the roadway. This side view shows short linear trails from the top going into the sediment.
Various Arthropod Traces
  Click image to see Full Size
 I have not been able to positively identify this trace fossil. The most promising candidate would be a bilaterally symmetrical animal, possibly an arthropod of some sort as it raked its way through the sediments. Perhaps a bifurcated shrimp like animals tail as it raked the sediment.
Tapeats Sandstone in the Grand Canyon
 
 Left: From inside the Grand Canyon on one of our many adventures within, this is a shot of the Tapeats Sand Stone on top of the Vishnu Schist which is Precambrian. Bright Angel Trail south.
 Ive been down into the Canyon scores of times photographing fossils and sedimentary strata for decades now. Here I am in the Vishnu near the river on Kaibab trail.
  Click image to see Full Size
Tapeats on Plateau Point is packed with Cambrian trace fossils in the Tapeats. Here is Actinocolites on a big slab. The slits you see here are of course the bottoms of the U tubes, and shows the "packing density" of these organisms.
  Click image to see Full Size
 This gem, also on Plateau Point is Rusophycus, a trilobite resting trace. They would dig in and leave this bifurcated pattern. This is an in fill, on its back - so flip it upside down to get a sense of what the burrow actually looked like.
 
Paleo HOME