FIELD STUDIES IN UTAH
Dwayne D. Stone, Professor Emeritus of Geology, Marietta College
Edward L. Crisp, Professor of Geology, West Virginia University
One hundred and fifty million years ago the future
Africa had already separated from the future USA by plates diverging from
the Mid-Atlantic Ridge (Figure 1). Note where future India and Antarctica
are located. Dinosaurs could travel from one future continent to
another until land areas became more separated.
Figure 1. Paleogeography of the Earth during Late Jurassic time showing
position of continents, oceans, and seas (From Scotese, C. R., 1997, Pangea
Begins to Drift Apart: http://www.scotese.com/late1.htm).
The Morrison Formation was named after outcrops
in the vicinity of Morrison, Colorado (near Denver). Outcrops of
the Morrison Formation are present in parts of Colorado, Utah, Arizonia,
New Mexico, Oklahoma, Nebraska, South Dakota, North Dakota, Wyoming, Idaho
and Montana (see Figure 2).
Figure 2. Late Jurassic paleogeography of the southwestern U.S. showing
the Morrison Alluvial Plain. Slightly modified from: Blakey, Ronald,
1997, Images from 1997 GSA talk (Blakey, Ronald C. 1997,
EVOLUTION OF THE PASSIVE-MARGIN TO ACTIVE-MARGIN TRANSITION, EARLY MESOZOIC,
WESTERN NORTH AMERICA: Geol. Soc. Amer. Abs. with Progs) at http://vishnu.glg.nau.edu/rcb/paleogeogwus.html.
The sedimentary rocks are conglomerates, sandstones,
mudstones (and shales) and limestones (mainly micrite) representing terrestrial
(land) environments. Coals from swamps are rare and there are no
marine beds in the formation. The environments of deposition include
rivers (meandering and braided) with floodplains and lakes. Volcanism
occurred during the deposition of the Morrison and much of the volcanic
ash is mixed with muds of the mudstones. Upon weathering the mudstone
outcrops with ash form a popcorn-like surface. Concretions are scatterred
in the mudstones and many are comprised of gray, very heavy barite (barium
sulfate, BaSO4). Carbonate nodules, developed as calcium
carbonate (CaCO3), were precipitated in ancient soils of the
Morrison. The Morrison rocks are gray, green, pink, white, yellow,
purple, violet, brown and reddish brown (see Figures 3 and 4). Much
of the coloration is due to iron minerals such as limonite (Fe2O3.
nH2O) (yellow) or hematite (Fe2O3) (purple
and reddish brown).
The fossils of the Morrison Formation include
both plants and animals. Plants were no doubt very plentiful in the
warm moist environment but most have not been preserved. There are
some logs and leaves along with pollen and spores and the sand-sized charophyte
oogonia from green algae that lived in the lakes and rivers. Lush
vegetation must have been present to support the huge plant-eating dinosaurs
that were present.
The invertebrate animals include coiled snails,
lake and river clams that are sometimes four inches long, concostraceans
(arthropods) and ostracodes (more arthropods). All are small to microscopic
except the clams (bivalves). Other invertebrates, such as insects,
were present but are rare.
The vertebrates include fish (lungfish in
burrows), frogs, salamanders, lizards, crocodiles, turtles, and small mammals,
but all are scarce. Dinosaurs are the most plentiful vertebrates.
Figure 3. Near horizontal strata of the Morrison Formation near Cleveland,
Figure 4. Dipping strata of the Morrison Formation at Dinosaur National
Monument near Vernal, Utah.
STRATIGRAPHY OF THE PERMIT AREAS
The rocks that you will see during the Utah Dinosaur
Expedition in May of 2000 are diagramed below (Figures 5 and 6).
The Morrison Formation is 500 to 1,000 feet thick in this region.
The two younger members of the Cedar Mountain
Formation were named in 1997 by Kirkland and others. All of the above
have dinos but bones in thick sandstones and conglomerates are usually
too difficult to remove.
Cedar Mountain Formation - Lower Cretaceous
(120,000,000 years old) - nonmarine.
Mussentuchit Member - gray mudstone, thin
Ruby Ranch Member - gray and green mudstone
with abundant irregular carbonate nodules that may cover some slopes.
Buckhorn Conglomerate Member - low cliff-forming
hard gravel-rich brown distinctive unit with chert pebbles. Some
pebbles have Paleozoic corals. In some places contains silicified
Morrison Formation - Upper Jurassic
(but may be Lower Cretaceous near the top) (150,000,000 years old) nonmarine.
Brushy Basin Member - multicolored mudstones,
thin brown limestones, brown discontinuous sandstones. This unit
has most of the dinosaur bones.
Salt Wash Member - noted for thick brown sandstones
and minor amounts of mudstones.
Figure 5. Generalized stratigraphic section of most of the Jurassic
and Cretaceous rocks that will be present in our study area.
Figure 6. Measured stratigraphic section at Theropod Coprolite
locality east of Ferron, Utah.
Figure 7. Paleogeography of Utah during Late Jurassic
(top), areal extent of the Morrison Formation (left), and stratigraphic
section of east-central Utah.
Figure 8. Cross-bedding in a Morrison sandstone unit
with horizontal bedding in the pebble conglomerate above the hammer (Photo
by E. L. Crisp, May 1999).
Figure 9. Molds of freshwater clams in a fine sandstone
of the Morrison Formation (Photo by E. L. Crisp, May 1999)
DINOSAUR BONES OF THE MORRISON FORMATION
Dinosaur bones are black, blue, red-brown, gray
or pitch black. They have been replaced(chemical
exchange of calcium phosphate by iron minerals, silica, or other minerals)
and permineralized (the filling of
the tiny bone cavities [pores] by minerals). The permineralized portion
will appear as specks that may have several colors in the same broken bone.
Some bones retain their original outlines and will be in the form of small
particles, owing in part to weathering (freezing and thawing) or the action
of rootlets near or at the outcrop for many years. Many bones deeper
in the rock may be more intact but practically all the bones are broken
(or cracked). Some dino bones, even leg and large vertebrae, are
crushed. These were probably not replaced or permineralized until
hundreds of feet of overlying sediments accumulated. The downward
pressure distorted the bones. Others will retain their original cross-sections
and are unsquished. Replacement and permineralization probably occurred
"rapidly" before too many overlying sediments were deposited. Do
keep in mind that these Morrison bones were covered by at least a mile
of sedimentary rock before mass movement and erosion exposed them at the
Mentally trace some of the Morrison rocks
across the valleys from one hill to another. Visualize all the dinos
that might have been in these rocks. Their former locations are now
represented by air. Such a sad thing. Think about the appearance
of a 2000 hillside a few thousand years into the future, with "new" dino
bones sticking out of the rocks. We're pretty lucky to be here in
Emery County, Utah, and see the dinos that will vanish in the future if
DINO TRACE FOSSILS AND OTHER RARITIES
In addition to normal dino bones be on the lookout
1. Footprints or trackways.
Many show that three toes touched the ground but other dinos had four or
five toes. These can occur as depressions (external
molds) on the original tops of sands (now sandstones) or as
fillings (casts) that will project
downward from a bed, again usually sandstone. Most of the tracks
made in mud are not preserved so we can gaze down at them.
Figure 10. Theropod footprint near Moab, Utah in the
Salt Wash Member of the Morrison Formation (Photo by E. L. Crisp, May 1999).
Figure 11. Iguanodontid footprints (upper part
of photo) and a small theropod footprint (lower) in the
Cretaceous Dakota Sandstone near Morrison, Coloroado (Photo
by E. L. Crisp, October 1999).
2. Poop. The old turds
are called coprolites and some from
the big plant eaters would have been gigantic. They will probably
appear at first to be concretions and the original shapes have probably
been distorted. Perhaps some carbonized plants will be present. Allosaurus
(and other theropod) potty should have
bits of bones and teeth. During May of 1999 Dr. Stone found two large
theropod coprolites in the Brushy Basin Member of the Morrison Formation
and during August of 1999 we removed one of those for transport back to
Marietta College. The main body of this coprolite was 5 feet long.
It is the oldest and largest theropod coprolite ever found.
Figure 12. Drs. Stone and Crisp with main body of theropod coprolite,
August 1999 near Ferron, Utah (Photos by E. L. Crisp, August 1999)
Figure 13. A chunk of theropod coprolite from the
Brushy Basin Member of the Morrison Formation. Note the bone fragments.
Found by Debbie Summerville, May 1999 near Moore, Utah (Photo by E. L.
Crisp, April 2000).
3. Skin imprints. Visualize
the surface of a modern lizard or crocodile. Irregular branching
and joining lines or semicircular spots close to a bone on the mudstone
or sandstone might be the external mold of dino skin.
4. Eggs. Many dino eggs
are elongate and several inches in length. They occur as clutches
of six or more or as egg fragments on the surface of the ground.
5. Nests. Dino egg nests
will in cross-section view be depressions that can be several feet across.
Some constructed a circular high ridge around the central depression.
It would be nice to find eggs in a nest.
6. Tooth marks. A lenticular
hole like would have
beeen made in a bone by one Allosaurus
or Ceratosaurus tooth.
Scratch marks were created by numerous teeth abrading a bone.
7. Pathologic bones. These
are bones that were broken while the animal was alive and then healed by
additional calcium phosphate. These may appear as swellings.
During intercourse (also known as having sex) bones, such as the ribs of
females, might have been injured by the front legs of a panting male.
Dr. Stone can draw a picture of this event. Occasionally
a carnivores tooth has been found embedded in a repaired bone with calcium
phosphate added to this foreign object.
If you find what appears to be footprints, poop, skin imprints, eggs
or nests, do NOT remove or dig into them.
Show the sites to your leaders. The same is true for a skull with
teeth. Do NOT attack it - get HELP!
DINOSAURS OF THE MORRISON FORMATION
Figure 14. Skull of Camarasaurus in the Morrison Formation
at Dinosaur National Monument (From: http://www.discovery.com/exp/fossilzone/park-dinonatmon.html).
The Late Jurassic Morrison Formation contains
a diverse assemblage of dinosaur remains. Some of the largest dinosaurs
that ever lived (sauropods) are represented in Morrison deposits (see the
skull of Camarasaurus in Figure 14). Also some of the smaller
dinosaurs that existed are represented in the Morrison Formation (example:
adult length 4 to 6 feet). The world famous Cleveland-Lloyd
Dinosaur Quarry near Cleveland, Utah (see Figure 15 for quarry
Dr. Stone worked three
summers during the 1960s when he was a graduate student in paleontology
at the University of Utah under the direction of
Madsen - see Figure 16) has rendererd about 10,000 bones of
Morrison dinosaurs, ninety percent of these belonging to the theropod Allosaurus.
Forty-four different individuals of Allosaurus are represented in
the bones at the Cleveland-Lloyd Dinosaur Quarry. Several other Morrison
dinosaurs have also been found there, including two theropods that have
not been found anyplace else, Marshosaurus and Stokesosaurus.
The other major Utah dinosaur quarry in the Morrison Formation is at Dinosaur
National Monument. Figures 17 and 18 show the dinosaurs that have
been found in the Morrison Formation at Dinosaur
National Monument near Vernal, Utah.
Figure 15. Location of Cleveland-Lloyd Dinosaur Quarry in Emery
County Utah. Note the position of the WVUP and Marietta College 2000
exploration areas. These areas are roughly on strike with the Upper
Jurassic Morrison Formation (Brushy Basin Member) rocks that are found
at the Cleveland-Lloyd Dinosaur Quarry (Slightly modified from: Madsen,
Figure 16. Dwayne D. Stone (left) taking a measurement
on the floor of the Cleveland-Lloyd Dinosaur Quarry in the 1960s and James
H. Madsen Jr. (right) displaying an Allosaurus skull reconstructed
by him from bones of the Cleveland-Lloyd Dinosaur Quarry (from: Stokes,
MORRISON FORMATION DINOSAURS FOUND AT DINOSAUR NATIONAL MONUMENT
Figure 18. Common Ornithischian dinosaurs and Theropods
(Saurischians) from the Morrison Formation (From: U.S. Park Service, Dinosaur
National Monument, at http://www.nps.gov/dino/dinos.htm).
The following is a section from the website (http://www.ugs.state.ut.us/dinojur.htm)
of the Utah Geological Survey describing the dinosaurs of the Morrison
Utah Geological Survey - Dinosaurs and Fossils
Jurassic Dinosaurs of Utah
The Morrison Formation
Utah's State Fossil, was the dominant predator of North America during
Late Jurassic. It is known from numerous skeletons, ranging from 10 to
40 feet in length,
from the Cleveland-Lloyd Dinosaur Quarry in east-central Utah. Mounted
from Cleveland-Lloyd Allosaurs, are displayed in over three dozen museums
world. With sharper teeth and a more graceful build, Allosaurus
rivals Tyrannosaurus rex
as the supreme meat-eater of the Mesozoic.
the correct name for the dinosaur better known as Brontosaurus.
Apatosaurus is probably the most commonly
known, but not the most common of the
four-footed, long-necked sauropod dinosaurs. This
heavily built quadrupedal giant of the
Jurassic Period weighed more than 30 tons, or as
much as six average elephants. With
lengths approaching 90 feet, the Apatosaurus
was a giant in the Age of Dinosaurs.
a slender, long-necked, long-tailed sauropod. Because of its graceful anatomy,
some paleontologists have argued that this sauropod could stand on its
hind legs and reach high into the trees for food, perhaps to heights of
50-60 feet. A skeleton from Dinosaur National Monument was mounted
in the standing position was recently unveiled at the American Museum of
Natural History in New York. However, recent studies of its skull and neck
suggest that with its close relatives Apatosaurus and Diplodocus,Barosaurus
spent most of its time grazing low growing plants.
was the largest and heaviest dinosaur known from the Morrison Formation
of Utah. This supergiant weighed as much as 80
tons, or the combined weights of 15 large
elephants. Ultrasauros, a supergiant from
the Morrison Formation of Colorado was a giant
specimen of Brachiosaurus, and may have
weighed as much as 100 tons. Brachiosaurus
is the giraffe-necked sauropod, with tall front
legs and a long neck designed to reach far
above the ground. Bones of this Late Jurassic giant
have also been found in eastern Africa.
was the most common dinosaur of the Jurassic Period. Even with their
relatively short neck and tail, this sauropod reached lengths of 50 feet
and weighed as much
as 25 tons. The spoon-like teeth chopped coarse vegetation (primarily conifers,
and ferns), their principal food.
Camptosaurus was a
medium-sized, bipedal herbivore of the Late Jurassic that weighed up to
1,000 pounds and reached lengths up to 23 feet. This ornithopod was ancestral
to many of the highly successful plant-eating dinosaurs of the Cretaceous,
such as the duckbills and Iguanodon.
was a large but slender predator of the Late Jurassic. With a strange horn
on the top of the head between the eyes, this active meat-eater may have
engaged in head-butting combat. Like Brachiosaurus, bones of Ceratosaurus
have also been found in eastern Africa.
"double-beam" dinosaur named for unusual support structures beneath its
tail, was a long and slender relative of Apatosaurus.
Several nearly complete skeletons
have been found at Dinosaur National Monument.
Casts of Diplodocus skeletons,
averaging 87 feet in length, were sent to museums
around the world by Andrew Carnegie in
the early part of this century, including the Vernal
Field House of Natural History.
is a common, small ornithopod first found at Dinosaur National Monument.
is the rarest, oldest, and first-discovered sauropod dinosaur in western
North America. Its bones were found by the Macomb
Expedition to southern Utah in
1857. Because of its stratigraphic position at
the bottom of the Morrison Formation
(Tidwell Member), this dinosaur may be ancestral
to some or all of the other North
American sauropods of the Late Jurassic Morrison
is another small, rare theropod. It reached lengths up to 16 feet and was
named after O.C. Marsh, a famous
paleontologist from the 1800s.
the plated dinosaur, was one of the major plant-eaters of the Jurassic
Most paleontologists believe its triangular bony
plates were set in two rows along the
backbone in a staggered arrangement. The function
of the plates is controversial. Perhaps
they were for protection, but some paleontologists
think that they may have collected solar
radiation for thermal regulation. Even though it
is the state dinosaur of Colorado, it is
common in Utah.
was a rare carnivorous dinosaur reaching lengths of 13 feet, and was named
for a prominent Utah geologist,
the late Dr. William Lee Stokes. Its bones and
braincase anatomy indicate that it may be an ancestor of the gigantic
Tyrannosaurus that lived 85 million years
later at the end of the Cretaceous Period.
the largest Jurassic theropod known in Utah. Reaching nearly the size of
Tyrannosaurus, it was able to terrorize even the
giant sauropods. Although rare it is known
from a couple of sites.
CLASSIFICATION OF MORRISON DINOSAUR GENERA
The following is one classification scheme with
the Morrison Formation dinosaur genera:
Dinos are divided into two superorders
based on the arrangement of the pubis and ischium bones in the hips.
Portions of the two bones are nearly parallel in Ornithischian dinosaurs
(see Figure 19 below).
Figure 19. The Saurischian hip structure (left) and the Ornithischian
hip structure (right) (from: Poling, Jeff at http://www.dinosauria.com/dml/dmlf.htm).
In addition to the hip structure, all Ornithischian
dinosaurs have a predentary bone in the lower jaw of the skull which is
not present in the Saurischians (see Figure 20 below).
Figure 20. A Saurischian skull (right) and an Ornithischian skull
(left) (from: Poling, Jeff at http://www.dinosauria.com/dml/dmlf.htm).
Using cladistics we could show the major groups
of dinosaurs as a cladogram (Figure 21). Cladograms show hypothetical
evolutionary relationships based on shared derived characters within a
Figure 21. Major groups of dinosaurs (from: Poling, Jeff at http://www.dinosauria.com/dml/clado/dinosauria.html).
A cladogram of the Saurishia is shown in Figure
Figure 22. A cladogram of the Saurischica (from: Messing, Charles
G, 2000, http://www.nova.edu/ocean/biol1090/W10C-JURALIFE2.htm).
One interpretation of the relationships of
the Sauropodomorpha is shown in Figure 23. In this interpretationCamarasaurusandBrachiosaurus
are in the family Brachiosauridae and Diplodocusand
are in the family Diplodocidae. Some paleontologists separate the
family Camarasauridae from the Brachiosauridae (as shown in Figure 22 above).
Figure 23. Major groups of Sauropodomorpha. Characters
are - 1, small head and peg-like teeth
(and elongated cervical vertebrae); 2,
addition of extra cervical vertebrae to the neck; 3,
apron-like pubis; 4, fore limbs as
long as or longer than hind limbs, making the back slope posteriorly; 5,
teeth restricted to front of mouth; 6,
armor. (from: Olsen, Paul, 2000, http://rainbow.ldeo.columbia.edu/courses/v1001/morisson14.html).
A general cladogram of the Theropoda is shown
in Figure 24. In this cladogram Ceratosaurus would be placed
in the Ceratosauria, whereas most of the other Morrison genera (except
would be placed in the Carnosauria. Theropods such as Tyrannosaurus
and kin would be placed on a branch between
Ornitholestes and Deinoychosauria.
Cretaceous theropods such as Deinonychus and Utahraptor would
be placed in the Deinoychosauria.
24. Cladogram of Theropoda (from Olsen, 2000).
1. three-toed foot
2. digits IV and V lost on hand
3. long arms
4. semilunate carpal
5. fused pelvis
6. large hole in lacrimal bone in skull
7. ?no unique derived characters?
8. giant, hook-like claw on digit II of pes
9. flight feathers
Figure 25 is a cladogram of the Ornithischia
and shows the position of Stegosaurus in the group Stegosauria.
The three Morrison ornithopods, Dryosaurus, Camptosaurus,
and Othnielia would be placed in the Iguanodontia, however, some
paleontologists would place Dryosaurus and Othnielia intermediate
between Hypsilophodontidae and Iguanodontia.
Figure 25. Cladogram of the Ornithischia (from: Messing, Charles
G., 2000, http://www.nova.edu/ocean/biol1090/W10D-JURALIFE3.htm).