Park Paleontology Vo l u m e 8 N u m b e r 1

Spring 2 0 0 4

National Park Service

U.S. Department of the Interior

 Table of Contents

The Diversity and Stratigraphic Distribution of

Pre-Dinosaurian Communities from the

Triassic Moenkopi Formation, Capitol Reef

National Park and Glen Canyon National

Recreation Area, Utah........................... 1

Discovery of Cretaceous Marine Reptiles at

Glen Canyon National Recreation Area.. 4

Denali Geologist’s Name Graces Fossil... 5

An Unlikely Giant in Capitol Reef National

Park................................................... 6

Fossils from Glen Canyon NRA Travel to

France.............................................. 7

Park Paleontology 1

Geologic Resources Division, Paleontology Program

Debra L. Mickelson

Department of Geological Sciences

University of Colorado at Boulder, UCB

399

Boulder, Colorado 80399

mickelsd@ucsu.colorado.edu

Recent discoveries in the Moenkopi

Formation (Early Triassic) of Capitol

Reef National Park (CRNP), and Glen

Canyon National Recreation Area

(GCNRA), Utah have revealed

important new terrestrial and

subaqueous vertebrate track localities.

These well-preserved tracks occur on

multiple stratigraphic horizons and are

the oldest and most laterally extensive

track-bearing horizons documented in

the Western U.S. Ichnogenera

(Chirotherium), (Rhynchosauroides), and

(Rotodactylus), are the dominant forms.

Rare fish fin drag marks (Undichna) and

fish skeletal remains have been

identified in the Torrey Member and

equivalent strata of the Moenkopi

Formation.

Tracks are preserved either as positive

relief “casts” filling impressions in the

underlying mudstones or on plane bed

surfaces as negative relief

“impressions”. Exposed traces occur

on the undersides of resistant

sandstone ledges where the mudstone

has eroded away and in finer grained

sediments such as mudstones and

siltstones. The Torrey Member

represents deposition on a broad, flatlying coastal delta plain. Both

nonmarine (fluvial) and marine

(principally tidal) processes influenced

deposition. Even-bedded mudstones,

siltstones, claystones, and fine grained

sandstones, containing abundant ripple

marks and parallel laminations

dominate lithologic types. Ichnites

indicating swimming/floating behavior

are associated with the walking

trackways. The water depth was

sufficiently shallow to permit the

vertebrates to touch the substrate with

manus and pedes when moving

through the water.

Tracks form locally dense

concentrations of toe scrape marks

which sometimes occur with complete

plantigrade manus and pes impressions.

Well preserved, skin, claw, and pad,

impressions are common. Occasional,

well developed, tail-drag marks

frequently occur in many of the

trackway sequences. Fish fin drag

marks and fish skeletal material are

preserved with tetrapod swim tracks.

In addition to vertebrate ichnites, fossil

invertebrate traces Arenicolites,

Paleophycus, Fuersichnus,

Kouphichnium (horseshoe crab),

centipede, and fossil plants of

Equisetum are abundant.

Lateral correlations of the

ichnostratigraphic units identified in the

Moenkopi Formation throughout Utah’s

National Parks will aid interpretations

about the paleoecology, and diversity

of the Western Interior during the

Middle Triassic-“the dawn of the

dinosaurs”.

 Significance

 • Terrestrial tracks in an apparently

marine influenced facies of the

Moenkopi Formation

 • Distribution of Middle Triassic PreDinosaurian Communities

 • Diversity of Middle Triassic PreDinosaurian Communities

There are Three Lines of Evidence of

Tidal Influence

 • Tidal point bars present

 • Presence of mud draped features;

pulses of water and suspended load

being dropped; an indication of

fluctuating currents

 • Presence of vertebrate and

invertebrate traces

Location Map of Glen Canyon National

Recreation Area and Capitol Reef

National Park

THE DIVERSITY AND STRATIGRAPHIC

DISTRIBUTION OF PRE-DINOSAURIAN

COMMUNITIES FROM THE TRIASSIC

MOENKOPI FORMATION, CAPITOL REEF

NATIONAL PARK AND GLEN CANYON

NATIONAL RECREATION AREA, UTAH

 continued on page 2
2 Park Paleontology

Significance and Three lines of evidence

Stratigraphic measured sections of

GCNRA and CRNP and Smith’s Model of

“Meandering River Estuarine Systems “.

Vertebrate tracks of Chirotherium.

Known to occur at Glen Canyon

National Recreation Area and Capitol

Reef National Park.

Vertebrate tracks of Rotodactylus.

Known to occur at Capitol Reef National

Park.

Geology

The Torrey Member of the Moenkopi

Formation has been the subject of

investigation for almost 50 years.

However, these studies were more

broad based regional studies, and only

recently has the Torrey Member been

studied in stratigraphic detail with

emphasis on the extensive tetrapod

track-bearing surfaces of predinosaurian communities present

within it. At present, the multiple

track-bearing horizons are known to

extend throughout much of Utah’s

National Parks. Currently, the Torrey

Member vertebrate tracks are the

oldest and most laterally extensive

megatracksite horizons ever recorded.

Following the deposition of the Sinbad

Member in a clear shallow sea, a

change in tectonic and/or climatic

conditions caused the progradation of

a major delta succession into Utah.

This delta complex is preserved as the

Torrey Member.

Basal deposits of the Torrey Member

include interbedded siltstones,

dolomites, and very fine-grained

sandstones that were laid down in

advance of the prograding delta. This

sequence grades upwards into ledgeforming coarser grained sandstones and

interbedded siltstones. Several trackbearing horizons are present within this

delta-plain facies. The facies includes

channel deposits of large-scale trough

cross bedded fine to medium grained

sandstone that was deposited within

the fluvial-dominated reaches of the

upperdelta-plain. Multiple tetrapod

track horizons have been identified

within these deposits.

Channel bodies dominated by ripple to

large-scale trough cross bedded

sandstones and interbedded mudstones

are organized into inclined heterolithic

packages. Also present within these

sandstone and mudstone-dominated

channels are large-scale soft sediment

deformational features and clay-draped

ripple- and dune-scale bedforms.

Tetrapod tracks and fish-fin drag marks

are typically associated with these

deposits. These inclined barforms are

likely pointbar deposits that

experienced tidal influence and may

represent the more seaward lower

delta-plain expression of the sandstonedominated fluvial channels.

A threefold lithofacies classification

model produced by Smith (1987) was

adapted to describe depositional

environments of the Torrey Member

delta-plain channels. Outcrop measured

sections (a west to east trend) are

similar to Smith’s, (1987) lithofacies

classification for meandering river

estuarine systems.

Vertebrate Ichnology

Chirotherium Tracks: Relatively narrow,

quadrupedal trackways indicating the

normal tetrapod walking gait; in the

walking gait a small pentadactyl manus

impression regularly occur immediately

in front of, but never overlapped by a

much larger, pentadactyl pes which

generally resembles a reversed human

hand. Manus and pes are digitigrade,

and in large forms the pes tends to be

plantigrade; digits I-IV point more or

less forward, manus digits IV is always

shorter than III being largest; the

footprints may or may not show

specialized metatarsal pads. Clear

impressions often show a granular or

beaded skin surface (skin impressions).

Associated swim tracks are common

and often indicate current flow

directions and water depths.

Rotodactylus Tracks: Long-striding,

trackways of a medium pentadactyl

reptile are well preserved with rare

skin and claw impressions. These

tracks commonly occur with smaller

Rhynchosauroides footprints. The

manus is always closer to the midline

and in some cases overstepped even in

the walking gait by the much larger

pes in a moderately narrow trackway

pattern; pace angulation (pes) as high

as 146 degrees in a running trackway

and as low as 93 degrees in a walking

trackway. The pes impression

indicates a foot with an advanced

digitigrade posture, and with a strongly

developed but slender digit V rotated

to the rear where it functioned as a

 continued on page 3
Park Paleontology 3

Vertebrate tracks of Undichna (fish fin

drag marks). Known to occur at Glen

Canyon National Recreation Area.

Invertebrate trace fossils of

Fuersichnus, Palaeophycus, Arenicolites.

Known to occur at Glen Canyon

National Recreation Area and Capitol

Reef National Park.

rotated backward but it has a propping

function. Digit IV on both manus and

pes is longer than III; digit I may fail to

impress; claws are evident and distinct

on digits I-IV. Scaly plantar surface

(well defined skin impressions) are

often preserved in exquisite detail and

is characterized by transversely

elongate scales on the digit axis

bordered by granular scales.

Rhynchosauroides Tracks: Dense

concentrations of Rhynchosauroides

tracks are commonly associated with

the trackways of Chirotherium and

Rotodactylus. These small lacertoid

footprints are generally characterized

by deeply impressed manus and a

faintly impressed pes. Trackways

exhibit a relatively wide pattern with

pentadactyl footprint relatively distant

from the midline. The pace angulation

is low, below 90 degrees – 100 –120

degrees if figured from the manus

pattern. Most often only 3 to 4 digits

are preserved with occasional tail drag

marks. The digits are slender and

relatively longer in the pes than in the

manus and both sometimes exhibit

distinct claw impressions. Swim tracks

are common.

Undichna Fish Trails: The Moenkopi

Formation is known for its exceptional

vertebrate fossil record. Fish are rare

and have been little studied in detail,

and fish trails (fish fin drag marks) have

never been recorded. The purpose of

this study is to describe the first known

occurrence of fish trails (fish fin drag

marks), Undichna from the Early

Triassic Torrey Member of the

Moenkopi Formation. This ichnogenus

has been reported in abundance from

the Late Paleozoic, Permian,

Cretaceous, and more recently from

the Eocene. Undichna from the Torrey

Member of the Moenkopi Formation

represents the first and only known

occurrence of fish trace fossils in the

Triassic in the Western U.S.

The fish fin trace fossils are preserved

as convex hyporelief sandstone casts

with filled imprints preserved in

underlying mudstone. Exposed traces

occur on the undersides of resistant

sandstone ledges where the mudstone

eroded away. Undichna commonly

occur with locally dense concentrations

of swim traces of Chirotherium.

Occurring in clusters, one isolated fish

fin trace consists of a single, slightlyasymmetrical, sinusoidal trail. The

trace is 56 cm. Long and includes 6.5

cycles with wavelengths varying from 9

to 10 cm and amplitudes of 3.5 to 4.5

cm.

The trails were most likely produced by

a fish with a large caudal or anal fin

able to reach the sediment without any

other fin doing so. The low

wavelength to amplitude ratio is most

consistent with a caudal fin. This

occurrence of Undichna is similar to

other previous descriptions and it

confirms that the preservation of these

trails are favored in fine-grained

sediments. Importantly, these traces

coupled with Chirotherium, and

Rhynchosauroides, swim tracks, all

indicate fluctuating water depths.

Invertebrate Ichnology

Fuersichnus, Palaeophycus, and

Arenicolites: The Torrey Member of the

Moenkopi Formation assemblage

studied is considered herein as an

example of the Glossifungites

ichnofacies and commonly occur with

vertebrate swim tracks. This

ichnofacies has been restricted to firm

but unlithified nonmarine and marine

surfaces. The Glossifungites

ichnofacies is characterized by low

diversity and high density assemblages

which include Fuerichnus,

Palaeophycus, Arenicolites, and

Skolithos.

The ichnogenus Fuersichnus is a

relatively rare trace fossil that has been

documented from Triassic and Jurassic

nonmarine deposits and only recently

documented in marine deposits from

the Upper Cretaceous . The

ichnogenus consits of horizontal to

subhorizontal, isolated of loosely

clustered, U-shaped, curved to bananalike burrows, characterized by

distinctive striations parallel to the

trace axis. It is interpreted as a

dwelling structure probably produced

by crustaceans or polychaetes.

The ichnogenus Palaeophycus a

common trace fossil that has been

documented from Pre-Cambrian to

Holocene nonmarine and marine

deposits. Branched, and irregularly

winding, cylindric or subcylindric tubes,

that sometimes cross-cut one another.

These horizontal galleries most often

have vertically striated lined burrows or

rarely nearly smooth surface textures.

Palaeophycus represents passive

sedimentation within an open dwelling

burrow constructed by a predaceous or

suspension-feeding animal.

The ichnogenus Arenicolites are simple

U-tubes (paired tubes) without

spereite, perpendicular to bedding

plane; usually varying in size, tube

diameter, distance of limbs, and depth

of burrows; limbs rarely somewhat

branched, some with funnel-shaped

opening; walls commonly smooth. A

common trace fossil documented from

Triassic to Cretaceous from marine and

nonmarine deposits. The Torrey

Arenicolites are very consistent in size,

shape, and distance apart from each

other and are interpreted as made by

annelid worms.

 Summary

 • Occurrence of terrestrial and subaqueous tracks in the Moenkopi

Formation.

 • Tracks occur in marine influenced

environments.

 • Implication is that these animals

may have tolerated brackish water

conditions.

continued on page 4
4 Park Paleontology

Additional Reading

Blakey, R.C., 1973. Stratigraphic and

origin of the Moenkopi Formation

(Triassic) of Southeastern Utah. The

Mountain Geologist 10(1):1-17.

Blakey, R.C., 1977. Petroliferous

lithosomes in the Moenkopi Formation,

Southern Utah: Utah Geology

49(2):67-84.

Hintze, L.F., 1988. Geologic History of

Utah: Brigham Young University

Geology Studies Special Publication 7:

202 pp.

McAllister, J.A., 1989. Dakota

Formation tracks from Kansas:

Implications for the recognition of

tetrapod subaqueous traces. pp. 343-

348. in GIillette, D.D., and Lockley,

M.G., eds., Dinosaur Tracks and

Traces: Cambridge University Press,

New York,

McAllister, J.A., and Kirby, J. 1998. An

occurrence of reptile subaqueous

traces in the Moenkopi Formation

(Triassic) of Capitol Reef National Park,

South Central Utah, USA. Journal of

Pennsylvania Academy of Science, 71,

Suppl. And Index:174-181.

 Discussion

Several important discoveries have

been made during the course of this

research in GLCA and CARE. The

Torrey Member of the Moenkopi

Formation trackways are first

described in detail from this

stratigraphic unit and suggest a great

potential for finding other footprint

sites in this Formation. This unit is

widely exposed not only in Capitol

Reef, and Glen Canyon Recreation

Area, but also, Zion, Canyonlands, and

Arches, National Parks. Lateral

correlations in Utah’s National Parks of

the Moenkopi’s extensive track bearing

horizons provide a good basis for

correlation with the entire region.

As a non-renewable resource on public

lands, fossil footprints provide an

opportunity for public education,

scientific research, monitoring

programs, and an administrative

opportunity and challenge for both

scientists and land management

authorities.

McKee, E.D., 1954. Stratigraphy and

History of the Moenkopi Formation of

Triassic Age: The Geologic Society of

America Memoir 61:1-133.

Mickelson, D.L., Huntoon, J.E.,

Worthington, D., Santucci, V.L., Clark,

T, 2000. Pre-dinosaurian community

from the Triassic Moenkopi Formation

Capitol Reef National Park: Geological

Society of America (Abtracts) 32(7).

Peabody, F.E., 1948. Reptile and

amphibian trackways from the Lower

Triassic Moenkopi Formation of Arizona

and Utah. University of California,

Bulletin of the Department of

Geological Sciences 27: 467 p.

Smith, D.G., 1987. Meandering river

point bar lithofacies models: Modern

and ancient examples compared: pp.

83-91 in Ethridge, F.G., Flores, R.M.,

and Harvey, M.D., (eds.). Recent

Developments in Fluvial Sedimentology

Contributions from the Third

International Fluvial Sedimentology

Conference, The Society of Economic

Paleontologists and Mineralogists,

Special Publications 39.

Smith, J.F. Jr., Lyman, L.C., Hinrichs,

E.N., and Luedke, R.G. 1963. Geology

of the Capitol Reef Area, Wayne and

Garfield Counties, Utah: Geological

Survey Professional Paper no. 363:99

pp.

What Is Ichnology?

Fossils can be divided into body fossils,

preserved parts of the plant or animal, and trace

fossils, indirect evidence of their presence.

Ichnology is the study of plant and animal

traces. The implication of this definition is that

the traces made by plants and animals reflect

some sort of behavior or in the case of animals

their mode of locomotion. The best known

trace fossil are tracks but burrows, nests, and

gnaw marks on bones or plants are also types

of trace fossils.

Ichnology can be divided into two major

subdivisions: paleoichnology (the study of

ancient traces) and neoichnology (the study of

modern traces). Most ichnologists are involved

in paleoichnology but a considerable number

also study neoichnology for the comparison of

modern equivalents (and their trace makers) to

ancient traces. Technically speaking, wildlife

biologists or ecologists who study tracking

(identification of animals and their behavior on

the basis of their tracks and feces) are

neoichnologists, although they probably would

not recognize such an designation if you told

them.

.

http://www.emory.edu/COLLEGE/ENVS/

research/ichnology/

Discovery of

Cretaceous Marine

Reptiles at Glen

Canyon National

Recreation Area

David D. Gillette

Museum of Northern Arizona

3101 N Fort Valley Road

Flagstaff, Arizona 86001

dgillette@mna.mus.az.us

Ninety million years ago dinosaurs ruled

the land on a globe that had been

inundated by rising sea level. The

North American continent had become

two islands separated by an inland

seaway that isolated eastern North

America from western North America.

That shallow sea became home for a

myriad of sea-going animals and plants

that we now find as fossils in the

shales and limestones that

accumulated in the Cretaceous Inland

Sea. During the past five years,

paleontologists from the Museum of

Northern Arizona and our colleagues

have discovered a variety of new and

sometimes spectacular marine

vertebrates from the Tropic Shale,

which represents the accumulation of

muds and siltstones in that warm,

tropical sea. The most abundant are

the plesiosaurs, giant marine predators

that competed with sharks as the

dominant terrors of the Cretaceous

sea.

Our field investigations have focused

on the Cretaceous vertebrate fauna of

southern Utah in Glen Canyon National

Recreation Area (National Park Service)

and Grand Staircase-Escalante

Paleontologists from the Museum of

Northern Arizona answer questions

about the plesiosaur during an open

house at Glen Canyon National

Recreation Area

continued on page 5
Park Paleontology 5

Brachiopod

 or

 Bivalve?

National Monument (Bureau of Land

Management) where continuous

exposures of the Tropic Shale offer

unparalleled opportunity for studies on

biodiversity of the final stages of the

Age of Dinosaurs. Plesiosaurs seem to

be the most abundant, and certainly

the largest of the Cretaceous marine

predators in the Tropic Shale fauna.

From several partial, but nevertheless

spectacular skeletons, we have pieced

together enough to display one

example of the genus Trinacromerum,

a short-neck plesiosaur with the ability

to swim at astounding velocity, by

some calculations as fast as 30 miles

per hour or more. That mounted

skeleton was on display at the Museum

of Northern Arizona from April 2003

until May 2004. It is now scheduled to

become a year-long exhibit in 2004 and

2005 at the John Wesley Powell

Museum of Page, Arizona, the town

closest to the field area in Glen Canyon

National Recreation Area.

That mounted skeleton is about 20 feet

long, with a skull and jaws more than

four feet long and containing about

100 piercing teeth. It is a composite

The plesiosaur, Trinacromerum, as it was

found at Glen Canyon National

Recreation Area.

Paddle of the plesiosaur during

excavation.

from two individuals, one from Glen

Canyon National Recreation Area, the

other from Grand Staircase-Escalante

National Monument, making this

exhibit an interagency display. During

the 2003 field season we completed

the excavation of another partial

skeleton from an individual that was

twice as long: at least 40 feet in length

and several tons in total weight.

Although we did not recover bones

from the head, we can estimate that

the skull and jaws were nearly eight

feet long. And that’s not the largest:

we have discovered incomplete

skeletons, mainly vertebrae, from a

variety that’s even larger.

Some say the Age of Dinosaurs was a

dangerous time to live on land. We say

that the Cretaceous Sea during the

Age of Dinosaurs was the most

dangerous place to live!

While brachiopods and bivalves (also known

as pelecypods) look superfically similar

because they have two external shells, they

are quite different. In fact they are placed in

two seperate phyla, with brachiopods in their

own phylum and bilvalves are placed within

the phylum Mollusca. One way to tell a

brachiopod from a bivlave is the plane of

symmetry - where the line goes that divides

the animal into mirror images. In the

brachiopods the plane of symmetry is at a

right angle to the shell, while in in a bivalve

the plane of symmetry passes between the

two valves of the shell so each half of the

shell is the mirror image of the other.

Brachiopods also have a structure known as a

pedicle which they use to attach to rocks

while bivalves have a muscular foot. Bivalves

breath and gather food using gills while a

brachipod does this with a structure known

as a lophophore.

Denali Geologist’s Name

Graces Fossil

While any employee of the National

Park Service can names lots of fringe

benefits of working in parks, one of

the more unusual ones is to have a

fossil named after you. The recipient

of this rather unusual claim to fame is

Phil Brease, an NPS geologist at Denali

National Park and Preserve. A fossil

Devonian brachiopod from the park

was described as a new species of

Myriospirifer, M. breasei by Jenaro L.

García-Alcalde and Robert B. Blodgett

in the Journal of the Czech Geological

Society. Blodgett is a geologist with

the United States Geological Survey in

Anchorage, Alasaka that specializes in

brachiopods. The brachiopod was

found by Blodgett, Brease, and Pam

Sousanes during a research trip in the

park in July 1996. A member of the

subfamily Eospiriferinae, this genus of

brachiopod was widespread within

Gondwana and Baltica during the

Devonian. Its presence in Alaska is

interpreted as being the result of

transport on accreted terrane rifted

from Sibera and joined to North

America during the late Mesozoic.

 Myriospirifer breasei Dorsal view

García-Alcalde, J.L. and R.B. Blodgett. 2001.

New lower Devonian (upper Emsian)

Myriospirifer (Brachiopoda, Eospiriferinae)

species from Alaska and northern Spain and

the paleogeographic distribution of the genus

Myriospirifer. Journal of the Czech

Geological Society 46(3-4):145-154.

Answer to name the fossil and the park. This is a

portion of a fossil termite burrow preserved in

the Navajo Sandstone at Glen Canyon National

Recreation Area.

Phil Brease, geologist at Denali National

Park
6 Park Paleontology

An Unlikely Giant in

Capitol Reef National

Park

Len Eisenberg

223 Granite Street

Ashland, Oregon 97520

erdelei@aol.com

Jay Chapman

370 South 36th Street

Boulder, Colorado 80305

jaychapman_v@hotmail.com

The discovery of giant stromatolite

fossils in the Navajo Sandstone is part

of a growing body of research

challenging some long-held

assumptions about the

paleoenvironment of the Navajo erg.

The Navajo Sandstone, a prominent

and well-exposed rock unit in the

Colorado Plateau, was once an

enormous, arid sea of blowing sands

(called an erg) often compared to the

present Sahara Desert. This early

Jurassic dune field covered close to half

a million square kilometers and

reached thicknesses in excess of 700

meters making it one of the largest

dune fields in the history of Earth.

Although the Navajo erg is generally

thought to have been an expansive

and lonely desert, new fossils found in

Capitol Reef National Park suggest

otherwise. During an extended

backpacking trip, the senior author

stumbled across what he described

looked “almost like a giant haystack”

or “a giant limestone onion slowly

being peeled.” This turned out to be

the serendipitous discovery of the first

known stromatolite in the Navajo

Sandstone and possibly the first

stromatolite within an erg setting.

Eisenberg, an independent geology

consultant, spent the next several

years researching the occurrence and

the discovery was reported in the

February, 2003 issue of Geology.

Stromatolites are bizarre fossils whose

biological origins were debated until

only a few decades ago. Today,

scientists generally agree that

stromatolites are layered colonial

structures predominately formed by

cyanobacteria. Stromatolites are the

oldest fossils on earth, dating back to

more than three billion years ago.

They were the dominant life form on

earth for over 2 billion years and are

thought to be primarily responsible for

the oxygenation of the atmosphere.

Living and fossil stromatolites are

usually no more than half a meter tall

and are found in marine environments.

In contrast, the Capitol Reef

Stromatolites are up to five meters in

height and appear in thin carbonate

beds associated with interdune

deposits.

The most important implication of the

fossils is the suggestion of large bodies

of standing water necessary to sustain

the towering stromatolites. “We need

to reevaluate the whole

paleoenvironment,” David Loope of the

University of Nebraska-Lincoln says.

“Until we had the stromatolites the

general picture was hyper-arid,” he

says. Dr. Marjorie Chan of the

University of Utah agrees, saying that

despite the dry and dusty impression of

the Navajo erg, “it in fact had water

and lakes.”

This is a dramatically different picture

of the Navajo than previously thought.

The Navajo erg “may not be analogous

to the present Sahara” in that it had

the “potential for heavy rain and long

lived episodes of water,” Loope says.

Long lived episodes of water would

also translate into extended periods of

erg stabilization.

Researchers have long “suspected that

the Navajo must have stabilized at

some point,” although this is the first

direct evidence of such stabilization.

Modern ergs are known to periodically

stabilize, a recent example being the

“greening period” of the Sahara

between four to ten thousand years

ago. Using growth rates for modern

stromatolites, it can be determined

that the fossil stromatolites grew over

a period of a few thousand to over ten

thousand years, putting them “right in

the ballpark, ...in the thousands of

years range,” with the duration of the

Sahara stabilization.

If the Navajo erg stabilized for thousands of years, it would mark a major

stratigraphic boundary within the

Navajo Sandstone. Right now, “the

The Capitol Reef Stromatolites stand out

like “haystacks” from the surrounding

rock because they are composed of

limestone, which is more resistant to

weathering in a desert environment

than the surrounding sandstone.

During the roughly 15 million years in

which the Navajo was deposited it

spread out over seven states, reaching

its maximum thickness in what is today

Zion National Park.

What Are

Stromatolites?

A stromatolite is produced by cyanobacteria.

The distinctive layers are produced as

calcium carbonate is precipitated over the

growing mat of bacterial filaments.

Photosynthesis in the bacteria depletes

carbon dioxide in the surrounding water and

makes it less acidic thus initiating the

precipitation of the calcium carbonate. The

minerals, along with grains of sediment

precipitating from the water become

trapped within the sticky layer of mucilage

that surrounds the bacterial colonies. As the

colony continues to grow upwards through

the sediment a new layer is formed. As this

process occurs over and over again, the

layers of sediment are created.

continued on page 7
Park Paleontology 7

Navajo is a big pile of sand and it’s hard

to know where you are

stratigraphically,”

“The next step is the “correlation of

these scattered outcrops” to help

“unravel the internal geometry and

history of the Navajo erg.”

Further correlation of interdune

carbonate deposits could also suggest

a regional climatic event, helping to

improve climatic models of the Early

Jurassic.

“There is variability that we never

realized that was there,” Chan says.

“Just when you think you know it all,

we discover there’s a lot we didn’t

know.” The stromatolites in Capitol

Reef National Park have renewed

interest in the Navajo Sandstone and

provide insight into the biology and

environmental history of the Navajo

erg, all from a walk in the Park.

The best modern analogues to fossil

stromatolites can be found in Shark Bay,

Australia (above). Similar organisms,

identical in form and structure, can be

found in the outlet channel of Octopus

Springs in Yellowstone National Park

(below). Living stromatolites are rare

today and are usually only found in

hyper-saline waters.

The fossil stromatolites at Capitol Reef

are not easily accessible and somewhat

hard to find. If you’re up for a long

day-hike or an overnighter, one of the

best locations to see the stromatolites is

located along Cottonwood wash in the

central-eastern section of the Park.

Always check in with the park staff

beofre going on any overnight or

extended trips into the back country of

the park. As always, removal or

vandalism of any fossil is strictly

prohibited.

PLEASE NOTE

Fossils from Glen

Canyon NRA Travel

to France

Glen Canyon National Recreation Area

has a wide variety of fossils. While

those associated with the Jurassic

Navajo Sandstone are perhaps the best

known, fossils at Glen Canyon also

includes remains from the Ice Age.

The dry arid environment of the region

helps preserve soft tissue and organic

material including skin, horn and hoof

coverings and dung that is not often

preserved in the fossil record. Often

the preservation is just as spectacular

as the better known frozen fossils of

Siberia and Alaska. The same Navajo

Sandstone that includes dinosaur

tracks and termite nests often

weathers to form sandstone overhangs

or alcoves. During the Ice Age animals,

including mammoths, shrub oxen and

ground sloths often used these alcoves

for shelter and evidence of their

presence is indicated by not only their

preserved remains but their dung as

well.

The Muséum National d’Histoire

Naturelle Paris, France has recently

opened an exhibit entitled “Au Temps

des Mammouths”, (The Time of the

Mammoths” which will be open from

March 17, 2004 to January 10, 2005.

The exhibit is in The Grande Gallerie de

l’Evolution. 36, rue Geoffroy SaintHillaire. Among the various fossils

included in the exhibit is dung of the

extinct Columbian Mammoth from

Glen Canyon National Recreation Area

on loan from the park to the museum.

Arrangement of the loan was done

through Chris Kincaid, curator at the

park and Linda Clement, Staff Curator

for the Rocky Mountain Region

working with Jim Mead of Northern

Arizona University. Dr. Mead along

with Dr. Larry Agenbroad of the

university was involved in the original

excavation or the site and its scientific

study. Study of the dung has shown it

is composed of 95 % grasses and

sedges and has provided important

information about the diet of these

extinct animals.

The web site for the exhibit

 http://www.mnhn.fr/mammouths/
Park Paleontology is published intermittently

each year by the Geologic Resources Division.

It is available as a PDF file on the Internet at

http:www2.nature.nps.gov/grd/geology/

paleo/news/newsletter.htm

Copies may be printed from the internet for

free distribution.

Editor

Greg McDonald

Contributors

 Jay Chapman

 Len Eisenberg

 David Gillette

 Debra MIckelson

Comments? Write to:

Greg McDonald

Geologic Resources Division

National Park Service

P.O. Box 25287

Denver, Colorado 80225

National Park Service

U.S. Department of the Interior

Natural Resource Program Center

Geologic Resources Division

Paleontology Program

P.O. Box 25287

Denver, Colorado 80225

303 969-2821

First Class Mail

Postage and Fees

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City, State

Permit number

EXPERIENCE YOUR AMERICA

8 Park Paleontology

Name the fossil and the park. Hint: The park contains a large

artificial lake named for a geologist. Answer on page 5.