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United States Department of Agriculture

 Forest Service FS-1157 May 2020

The Story of

Dinosaur Lake

See, Learn, Explore!

The purgatoire valley dinosaur tracksite

FOOTPRINTS OF DINOSAURS FROZEN IN STONE

Illustrations by Nancy Lamm
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Dinosaur skeletons capture the imagination of everyone. Images of fearsome Allosaurus and gigantic Apatosaurus allow us to imagine 

what these dinosaurs once looked like. Bones, however, are not the only 

fossil remains of the dinosaurs. Just as importantly, fossilized footprints 

left by dinosaurs allow us to learn how these creatures moved and how 

they lived. The image of a herd of massive Apatosauruses with adults 

and juveniles plodding along in a group while being trailed by carnivores 

tells a story of survival, of hunting techniques, and how these creatures 

lived their lives 150 million years ago. This is the story of the tracksite at 

Dinosaur Lake in the Purgatoire Valley.

Imagine the age of the Earth as the length of a football 

field. The Earth was formed at the left end zone and 

the history of the Earth proceeds to the right, down 

the 100-yard length of the field. Every yard line 

represents 45 million years (45,000,000 years). Major 

events in the history of the Earth are shown with the 

yardage left to score a touchdown at the PRESENT 

DAY goal posts. 

10 20 30 40 50 40 30 20 10

10 20 30 40 50 40 30 20 10

EARTH’S BEGINNING

PRESENT DAY

FORMATION OF EARTH

4.5 BILLION YEARS

100 YARDS TO SCORE

FIRST HUMANS

2.3 MILLION YEARS

LESS THAN 2 INCHES 

TO SCORE

FIRST MAMMALS

210 MILLION YEARS

4.7 YARDS TO SCORE

FIRST DINOSAURS

230 MILLION YEARS

5.1 YARDS TO SCORE

FIRST LAND PLANTS

450 MILLION YEARS

10 YARDS TO SCORE

FIRST MARINE ANIMALS

WITH HARD BODY PARTS

575 MILLION YEARS

12.8 YARDS TO SCORE

MULTI-CELLED ORGANISMS

1.1 BILLION YEARS

24.4 YARDS TO SCORE

COMPLEX CELL STRUCTURE

2.1 BILLION YEARS

47 YARDS TO SCORE

EARLIEST FORMS OF LIFE

BACTERIA, STROMATOLITES (DOME-LIKE 

LAYERED ALGAL STRUCTURES)

3.5 BILLION YEARS

78 YARDS TO SCORE

CENOZOIC ERA

65 MILLION YEARS

TO THE PRESENT

PALEOZOIC ERA

LASTED FOR

370 MILLION YEARS

MESOZOIC ERA

LASTED FOR

165 MILLION YEARS

DINOSAUR LAKE

THE PURGATOIRE VALLEY DINOSAUR TRACKSITE

THE AGE OF THE EARTH

AS THE LENGTH OF A FOOTBALL FIELD

A bird’s eye view of “Dinosaur Lake”, the Purgatoire Valley Dinosaur Tracksite at the Comanche National Grassland in southeastern Colorado

THE AGE OF THE EARTH

AS THE LENGTH OF A FOOTBALL FIELD

The ages of the geologic eras are shown as shaded 

portions at the far end of the field. The Dinosaur Lake 

activity book addresses the incredible history of the 

Mesozoic Era, the Age of Dinosaurs, in southeast 

Colorado. The Mesozoic Era lasted for 165 million years, 

from 230 million years ago to 65 million years ago when 

the dinosaurs became extinct and the Cenozoic Era, the 

Age of Mammals, began. Man appeared on the scene 

just inches from the goal line.
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LEGEND

DISCOVERY OF NEW FILTER FEEDING 

FISH FOSSIL, 

RHINCONICHTHYS PURGATOIRENSIS

TRACKWAYS AT “DINOSAUR LAKE” 

PURGATOIRE VALLEY DINOSAUR TRACKSITE

VOLUNTEER CAROL McCLURE'S DISCOVERY, 

ELASMOSAUR SKELETON 

WASHED UP ON AN ANCIENT SEASHORE

DISCOVERY OF FOSSIL REPTILES AND AN 

AMPHIBIAN LEAD TO REDESIGNATION OF 

BEDROCK STRATIGRAPHY

Source: Bruce A. Schumacher, 2002; Geologic 

 Column, Comanche National Grassland, 

 southeastern Colorado

MIOCENE CRETACEOUSJURASSICTRIASSIC

QUATERNARY ALLUVIUM

OGALLALAH FORMATION

NIOBRARA FORMATION

CARLILE SHALE

GREENHORN

LIMESTONE

GRANEROS SHALE

DAKOTA

SANDSTONE

PURGATOIRE

FORMATION

MORRISON

FORMATION

RALSTON CREEK

CHINLE EQUIVAL.

JELM

SANDSTONE

TRIASSIC

UNDIFFERENTIATED

PERMIAN UNDIFFERENTIATED

ALLUVIUM

CONGLOMERATE 

CHALK

SHALE

SANDSTONE

LIMESTONE

EVAPORITE / SALT

SILICEOUS SAND

UNDIFFERENTIATED

PLANT FOSSIL

FOSSIL WOOD

AMMONITE

CLAM

FISH SCALES

DINOSAUR BONE

FOOTPRINT

SHARK TOOTH

DUNE SAND

M

E

S

O

Z

O

I

C

C

E

N

O

Z

O

I

C

The Phanerozoic Eon is the last 13.3 yards to score 

on the football field shown on the previous page. It 

is divided into three eras, which are further divided 

into periods as shown in the table below. We know 

more about the Phanerozoic Eon than any other 

time in Earth’s history. Why? Mainly because during 

the Phanerozoic Eon, animals with hard body parts 

first appeared on the Earth and more readily left 

behind fossil remains. Soft-bodied animals lacking 

hard body parts before the Phanerozoic are rarely 

preserved. Fossils are the primary means to provide 

an accurate estimation of the age of rock layers. 

Geologists have put together the history of the Earth 

by studying the rock layers and the fossils in them. 

Geologists know that limestone is often deposited on 

ocean floors, sand collects on a beach or desert, coal 

is formed in swamps, and ash and lava are ejected 

from volcanoes. Younger sediments are deposited 

on top of older rock layers and layers of various ages 

contain their own distinctive kinds of fossil evidence. 

From this and other information, geologists have 

recreated the history of the Earth. The history 

of the area that is now southeastern Colorado is 

summarized below.

THE PHANEROZOIC EON “TIME OF REVEALED LIFE” 

 THE PHANEROZOIC EON “TIME OF REVEALED LIFE”  

This image is what geologists call a stratigraphic 

column. It is a drawing of what rocks look like in an 

area along with the age, thickness, and appearance 

of the rocks. The legend shows what each symbol 

stands for. This stratigraphic column represents 

rocks from the Mesozoic era, the Age of Dinosaurs, 

found on the Comanche National Grassland. Many 

of the fossils found are shown by the symbols and 

include dinosaur bones, tracks, fish scales, clams, 

petrified wood, and plant fossils. The discoveries 

described in this activity book are shown on the 

stratigraphic column.

THE PHANEROZOIC EON “TIME OF REVEALED LIFE” THE “AGE OF THE DINOSAURS” AT DINOSAUR LAKE
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Jurassic

Period

The Purgatoire Valley Dinosaur Tracksite in southeast 

Colorado was once the shoreline of a vast lake fed by sluggish 

streams. This was during the Jurassic Period, and many 

different kinds of dinosaurs walked the land. The shoreline 

conditions at Dinosaur Lake were perfect for making and 

preserving tracks. Mud along the lake shore was soft, allowing 

dinosaurs to leave deep impressions with their heavy footfalls. 

The water level in the lake rose and fell, at times covering the 

tracks with layers of mud that, over the years, turned into 

limestone. Rivers flowing into the lake deposited fine clay 

that was compacted into shale. Soil formed on the exposed 

land surface and, over time, was compacted into colorful red, 

purple, gray, and green mudstones. These sediments are filled 

with fossil bones and tracks of the many kinds of dinosaurs 

that lived during the late Jurassic Period.

Sedimentary rock formations are often described as layers of 

a cake stacked on top of each other, with oldest on the bottom to youngest on the top. One challenge to geologists is 

that bedrock of a particular geologic formation can change 

horizontally; a sandstone might gradually grade over distance 

to a silty sand and then to a siltstone. This can make identifying 

bedrock in different locations challenging. Fortunately, if 

similar fossils can be found in different locations, we know the 

deposits are similar in age regardless of the character and color 

of the rock formations. Discovery of just fossil fragments of the 

three animals above (aetosaur, metoposaur, phytosaur) led to 

reclassifying the bedrock they were found in from Jurassic age 

to older Triassic age. Why is this important? Like explorers and 

map-makers, paleontologists work to clarify our knowledge of 

the Earth as it used to be thousands or millions of years ago.

Triassic

Period

MUDFLATS AND STREAMS

AN INLAND SEA IN COLORADO

A trio of Triassic creatures is living along the banks of a stream in the drawing above. The crocodile-like 

reptile in the lower part of the drawing is a phytosaur, a predator that grew as long as 12 feet. Walking 

along the stream is an armored plant eater with long shoulder spikes, called an aetosaur. Crawling out of 

the stream is a metoposaur, a massive-headed amphibian that fed mainly on fish.

Mudflats and Streams

The Tracks of Dinosaurs on the 

Shoreline of Dinosaur Lake

Cretaceous 

Period

THE TRACKS OF DINOSAURS ON THE 

SHORELINE OF DINOSAUR LAKE

During the Cretaceous Period, a shallow sea completely covered 

what is now Colorado. Marine fossils like the ones shown above 

are found in Cretaceous sediments in the Purgatoire River 

area. Fossil remains of the long-necked elasmosaur, a type of 

plesiosaur, were found by a volunteer (see page 11) along with 

the squid-like ammonites. The fish swimming along with wideopen mouths were an especially important discovery. These 

big-mouthed fish are called Rhinconichthys and until recently 

only two other such fossils were known worldwide (one from 

England and one from Japan). Their wide mouths opened like a 

parachute and their gills served as a sieve to strain plankton from 

the water. Why is this discovery important? It ties in the fossil 

record globally and it stands as one of the few known examples 

of filter-feeding vertebrates (like modern manta rays and blue 

whales) in Mesozoic oceans. The complete name of the fossil is 

Rhinconichthys purgatoirensis which means “fish like a whaleshark from purgatory.”

An Inland Sea in Colorado

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Around 150

Million

Years Ago

Around 200

Million

Years Ago

Around 93

Million

Years Ago
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Meet the Track Makers

at the Purgatoire Valley Dinosaur Tracksite

Theropods were “bipedal” meaning 

they walked on two feet. Their hind feet 

had three toes and their tracks tended 

to be long and narrow with sharp claw 

impressions. Theropods are carnivores 

(meat-eaters).

Theropods

Ornithopods

TRACK FACTS

• Paleontologists have found that they 

can calculate the height of a theropod 

dinosaur from the length of its track. 

The hip height of a theropod is about 

4 to 5 times the length of its track. See 

the illustration on the right.

• How would you calculate how fast a 

dinosaur moved? The speed (velocity) 

of a walking or running dinosaur is 

calculated from the height of the dinosaur 

(determined from the length of its track), 

the length of the stride (measured at the 

track site), and the acceleration due to 

gravity, a constant factor.

Fossil tracks present at the Purgatoire Valley 

Dinosaur Tracksite were made mainly by three 

types of dinosaurs: theropods, sauropods, and 

ornithopods. Meet the three dinosaur groups 

who left their tracks on this ancient lake shore.

Ornithopod tracks look a lot like theropod tracks 

with three toes. Ornithopod tracks, however, tend to 

be more round and pigeon-toed, with rounded toes 

lacking claw impressions. Ornithopod dinosaurs 

could rise up on their hind legs, but traveled mostly 

as quadrapeds using both arms and legs. As with 

sauropods, larger and more deeply impressed pes 

prints means that most of the weight was centered 

over the hips. The manus (front) prints are much 

smaller than the pes (hind) prints. Ornithopods are 

medium-sized herbivores (plant-eaters).

Sauropods were “quadrupedal” meaning they walked 

on four feet. Their hind prints (pes) are more rounded 

and much larger than the fore prints (manus). Often the 

smaller front footfall is “overprinted” by the larger hind 

prints. Their toes are not as apparent in tracks as the 

theropods. Sauropods are large herbivores (plant-eaters).

Sauropods

Tracksite Tracksite

Tracksite

Track Diagram

Track Diagram

Track Diagram

hip height Hip Height

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The Purgatoire Valley Dinosaur Tracksite is the 

largest such tracksite in North America and is among 

the largest dinosaur tracksites in the world. Over 

1,600 footprints representing at least 120 different 

dinosaurs have been discovered so far. Erosion along 

the Purgatoire River first exposed the tracks, and later 

deposition of sediments by the river covered them. 

Excavation of the river gravel by paleontologists is 

revealing more and more tracks, and the site is getting 

bigger. Trackways are important because they give us 

insight into the lives of the dinosaurs. From tracks, 

we learn how dinosaurs moved, if they ran or only 

walked, and if they lived solitary lives or in herds. 

From the sediments in which the tracks were made, we 

gain understanding of the environment in which the 

dinosaurs lived.

The newest trackways unearthed at the Purgatoire site 

include a group of five parallel sauropod trackways. 

Parallel and subequally spaced trackways are strong 

indicators of animals moving together in a group, or 

a herd. This group of five parallel trackways includes 

both large (pes length 70 cm) and relatively small 

animals (pes length 55 cm), indicating that the herd 

was represented by animals of different ages, and thus, 

a “family” unit.

In one remarkable instance, the tracks of an Allosaurus 

have been discovered right on top of one of the 

sauropods, a track pattern called “overprinting.” 

This Allosaurus was not alone, there are many other 

Allosaurus tracks moving in the same direction. We 

can speculate that a group of allosaurs were trailing the 

sauropods, similar to lions stalking a herd of elephants 

today.

Some sauropod tracks have become so familiar that 

they have been given nicknames by the volunteers 

excavating them: Mama, Junior, and Baby Cakes 

suggests a family of sauropods walking along the shore 

together. Tony is a much larger sauropod traveling 

alone, so this may represent a different species or a 

different gender. Limpy implies a dinosaur with a sore 

leg and a pronounced limp which is reflected in its 

trackways, with left to right steps always shorter than 

right to left steps. Stucky’s imprints begin shallow, and 

gradually become so deeply impressed in the limestone 

that volunteers jokingly suggested they might find the 

bones of Stucky—stuck in his or her last footsteps. 

TRACKS AT DINOSAUR LAKE TELL US

Colorado looked very different during the Mesozoic 

Period. It’s hard to imagine that our home, 

characterized by lofty mountains, rugged canyons, 

and open prairies, was once covered by an ocean and, 

before that, by a broad, shallow lake with a fluctuating 

shoreline where dinosaurs strolled and, even before 

that, a vast dune sea (like the planet Tatooine in Star 

Wars). How do we know what conditions were like 

100 to 200 million years ago? Geologists know that 

“the present is the key to the past.” 

What this means is that the geologic events we 

observe today also took place in the past and shaped 

our world in a manner similar to what we see today. 

Volcanoes, floods, winds, oceans, and rivers behave 

in the same manner throughout time and leave 

recognizable deposits. Geologists can study a rock 

formation and determine the environment in which 

it was deposited, based upon similar environments 

present on the Earth today. 

Fossils preserved in rocks provide the best clues about 

what ancient environments were like and what kinds 

of life existed. As you have learned from this activity 

book, dinosaur fossils don’t always mean just bones. 

Fossils are any evidence of previous life, such as the 

footprints of long extinct creatures in the sands of 

time. Geologists compare fossils from various bedrock 

formations all over the world and from this, can build 

a picture of what our changing world was like over 

millions of years. 

Why does the Earth continue to change throughout 

time? The major driving force is “plate tectonics,” the 

movement of large plates of the Earth’s crust, driven 

by the molten “internal heat engine” of the Earth’s 

core. Plate tectonics results in the changing shapes 

and global positions of continents and oceans over 

geologic time. As the Earth’s plates slowly move across 

our globe, volcanoes and earthquakes bear witness 

to the immense powers at play. Mountains are thrust 

upward and then eroded down by wind and water 

until they are flat and valleys are filled with rock and 

debris washed down from highlands. Change is truly 

constant in our world!

Track Facts

• A running dinosaur has a longer stride than a walking 

dinosaur. This is true of many animals including humans. 

Test this by walking a specified distance and counting 

your stride as you walk. Next run the same distance and 

count your strides. You will have fewer strides when you 

run. By studying the tracks, paleontologists can tell which 

dinosaurs mostly walked (quadrupedal sauropods) and 

which dinosaurs sometimes ran (bipedal theropods). The 

speed of dinosaur movement can even be calculated from 

measurements taken of the tracks. Sauropods walked about 

4 to 6 miles per hour, while one theropod was estimated to 

run at 25 miles per hour. 

• Tracks are measured by steps, the distance measured from 

one foot to the next, and by strides, the distance measured 

from the same foot. This is illustrated in the ornithopod 

tracks on the left. Juvenile dinosaurs can be identified in a 

herd by the size of the track and the length of the stride.

• Quadrupeds walk on four feet but their fore and hind 

prints look very different. Front footprints (manus) are 

smaller than back footprints (pes).

• Dinosaurs did not drag their tails. Notice that none of 

the three types of trackways shown in this activity book 

have any evidence of tail drags (as common with lizard or 

alligator tracks).

WALKING THEROPOD

RUNNING THEROPOD

STEP STRIDE

MANUS PES

What the tracks at Dinosaur lake tell us THE AGE OF THE EARTH

AS THE LENGTH OF A FOOTBALL FIELD THE PRESENT IS THE KEY TO THE PAST

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Want to visit the Purgatoire Valley Dinosaur 

Tracksite? You can! The Purgatoire Valley Dinosaur 

Tracksite is located on the Comanche National 

Grassland, public land that is open for visitors. A 

visit requires some careful planning and scheduling. 

You can take a scheduled tour and drive to the 

site with a Forest Service guide. The road is rough 

and will require a 4-wheel-drive vehicle. Guided 

auto tours are offered on Saturdays in May, June, 

September, and October. Plan on spending all day on 

the tour. Bring your lunch and enough water for the 

day. Visit Recreation.gov and search for “Picket Wire 

Canyonlands” to learn more.

You can also hike, mountain bike, or horseback ride 

to the tracksite on your own starting at the Withers 

Canyon trailhead. The trail drops 250 feet into the 

Purgatoire River valley at Withers Canyon and 

follows the valley floor past an old Hispanic mission 

and cemetery. Except for the guided auto tour, there 

is no motorized access to the tracksite.

Caution!

The hike to the dinosaur tracks is long, an 11.3-

mile round trip, and there is no drinking water or 

other services in the canyon. You are responsible for 

your own safety! Know your abilities, pack enough 

water, and be prepared for changing conditions. 

Visit the Comanche National Grassland office in La 

Junta, Colorado, to learn all about making the hike 

or scheduling a tour. In addition, you can visit the 

USDA Forest Service website for more information: 

www.fs.usda.gov/goto/psicc/com.

With a little bit of imagination and some dinosaur models, you can create your own tracksite. 

• In a shallow box or on a paper plate, spread some self-hardening clay

 (Mexican Clay found in craft stores is an example).

• Using twigs, rocks, and sand, create an ancient Jurassic landscape.

• Finally, think about the dinosaur activity you want to display---

 perhaps a carnivore out hunting or a family of sauropods strolling

 along a prehistoric beach.

• Using small plastic dinosaur models, make some tracks in the clay.

 Congratulations! You have just created a prehistoric landscape!

The Dinosaur Lake Tracksite is part of a National 

Grassland, an outdoor museum, and a research site all 

rolled into one! How do you take care of such a unique 

site? Managing and preserving an “in situ” (meaning 

”in place”) fossil site is quite a challenge, especially a 

site as large as the Dinosaur Lake Tracksite. People 

want to visit the tracksite, to view for themselves 

the 150-million-year-old footprints. The Purgatoire 

River, the same force which naturally exposed the 

footprints, is now beginning to permanently erode or 

bury portions of the site. Research at the Purgatoire 

Valley Dinosaur Tracksite requires hours of labor while 

being careful to preserve the bedrock environment 

containing the tracks. The Forest Service is tasked 

with all of these challenges at the Comanche National 

Grassland. 

Protection from erosion

The Purgatoire River in flood stage is a powerful 

force, sweeping away rocks and carving new channels. 

The force that once exposed the dinosaur tracks also 

threatens to destroy them by eroding the bedrock 

containing the tracks. “Rip-rap” is a funny term for 

rocks carefully placed along a stream bed to prevent 

erosion. Look at the drawings below to see how 

rip-rap will prevent erosion of the tracksite. In the 

drawing on the left, the river is eroding the soft shale 

and undermining the tracksite. In the drawing on the 

right, rip-rap serves as a barrier to stream erosion. By 

using eroded limestone blocks of the tracksite itself, the 

erosion prevention looks natural.

Revealing New Tracks and New Science 

New dinosaur tracks are being excavated at the 

Purgatoire Valley Dinosaur Tracksite, but only tracks 

covered by modern stream gravel. The gravel is not 

part of the actual tracksite. The illustration on the right 

shows the difference between gravel and bedrock at a 

tracksite. The tracks are in bedrock.

Educating the public

The Dinosaur Lake Tracksite is on public land at the 

Comanche National Grassland and belongs to the 

public. Furthering scientific knowledge by learning as 

much as we can about this unique resource ensures 

that it will never be lost, even after the Purgatoire 

River ultimately destroys portions of the site. The 

Forest Service Mission is ”Caring for the Land and 

Serving People,” which includes being stewards of 

all our natural resources, including fossils. Volunteer 

opportunities occur frequently to maintain the site, to 

assist in excavating trackways, and to allow the public 

to become part of the research process.

GRAVEL BEDROCK

BEDROCK

RIP-RAP

RIP-RAP

SHALE

SHALE

Taking care of the tracks Visit the Purgatoire Valley Dinosaur Tracksite 

Make your own dinosaur tracksite!

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gastrolith

gastroliths 

(gizzard stones)

Fossil Bones found at

Carol’s field site (shaded in black) 

Carol McClure is a lady from La Junta, Colorado, and 

has volunteered at paleontological excavations on 

the Comanche National Grassland for over 20 field 

sessions. In her spare time, Carol also went exploring 

for fossils on her own. What Carol discovered made 

all of the exploring and hard work worthwhile. Carol 

found an Elasmosaur, a type of plesiosaur shown 

in the drawings below. Elasmosaurs were fearsome, 

amazingly long-necked marine reptiles, swimming 

and feeding on small prey in the shallow seaway that 

covered Colorado during the Cretaceous Period. 

Carol’s plesiosaur died and was washed up on the 

shoreline of the ancient sea (drawing on the right). 

Its bones were scattered in the waves and fossilized, 

waiting to be discovered 90 million years later by a 

dedicated volunteer.

Field of Fossils

The drawings below shows what Carol identified in 

the field as fossil bones. The bones were excavated 

in the field and taken to a paleontological laboratory 

where they were cleaned and identified. Only a small 

number of the total bones in the skeleton were 

found, as shown in solid black on the drawing below, 

but the discovery is scientifically important because 

elasmosaur skeletons are very rare. What kind of food 

do you think elasmosaurs might have hunted for?

Gastroliths

Many “gastroliths” were found in the fossil 

assemblage of Carol’s plesiosaur. What is a 

gastrolith? In the drawing above, look for the round 

object which is, in fact, a rounded pebble. Gastroliths 

are also called gizzard stones and served a similar 

purpose as gizzard stones ingested by modern 

chickens. Smooth stones are swallowed and lodged 

in the reptile’s digestive system to help grind up food. 

Ocean deposits are made up of fine-grained mud, 

silts, and limestones. Where would an Elasmosaur 

that lived in the ocean, and couldn’t travel over land, 

go to find large rounded pebbles? It is not unusual 

to find rounded stones along with some dinosaur 

skeletons as well and these, too, are fossils. They are 

evidence of former life.

CAROL McClure’s PLESIOSAUR 

A STORY ABOUT A VOLUNTEER AND HER DISCOVERY

Paleontologists or 

Archaeologists...

What’s the Difference?

Many people don’t know the difference between 

paleontologists and archaeologists, perhaps because the tools 

and techniques used in excavation are similar. The difference 

is simple. Archaeologists study evidence of human cultures, 

while paleontologists study evidence of prehistoric life 

(plants and animals) other than humans. The span of time 

studied by paleontologists is millions of years while the span 

of time studied by archaeologists is thousands of years. A 

paleontologist is both a geologist and a biologist, a scientist 

who strives to understand the Earth, its history, its life both 

past and present, and its resources.

TOOLs Of the Trade

Photo Scale

Dental Pick

Small Brush

Trowel

Shovel

Rock Hammer

Whisk Broom 15
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CODED MESSAGES

Try to decipher the messages below. Each letter in the alphabet represents another letter.

Write your answer below the code. A clue is given below. Answers are on the last page.

PDBFLRXH AHRVTL ZHFIDPN DBCFHSRADFB FB QFU PDBFLRXHL EDINP

BKM DSWAMYB OQGTYSCW BWSNZYQBM QG GTWBK SEMWQNS QY

DTNSBMO QG BKM FCWASBTQWM WQHMW HSDDMJ

MESSAGE #1:

MESSAGE #2

TRACKSITE PUZZLE

A. A sauropod family B. A running theropod C. A walking theropod

D. A large theropod, possibly an Allosaurus E. A single sauropod F. A walking ornithopod

WORD SEARCH

Try to find the following words in the grid below. Answers are on the last page.

GRAVEL LIMESTONE SHALE BEDROCK TRACKSITE

THEROPOD ORNITHOPOD SAUROPOD STRATA MESOZOIC

TRIASSIC JURASSIC CRETACEOUS PURGATOIRE RIP-RAP

PLESIOSAUR MUD STRIDE STEP TOE

EROSION MANUS PES DINOSAUR VOLUNTEER

BRUSH TROWEL SHOVEL BONE GASTROLITH

PALEONTOLOGY ALLOSAURUS CLAW FOOTPRINT FOSSIL

MESSAGE #1 CLUE: P REPRESENTS THE LETTER D; MESSAGE #2 CLUE: B REPRESENTS THE LETTER T

A lot of Jurassic dinosaurs have walked across the puzzle below and left their tracks in the soft sediment. See if you can identify the 

following track makers. Draw an arrow to show the direction that each one is traveling.. Answers are on the last page.
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CODED MESSAGES:

ANSWER PAGE

WORD SEARCH:

SCRAMBLED WORDS:

1. DINOSAUR TRACKS PROVIDE INFORMATION ON HOW DINOSAURS LIVED

2. THE LARGEST DINOSAUR TRACKSITE IN NORTH AMERICA IS LOCATED IN THE PURGATOIRE RIVER VALLEY

1. THEROPOD 2. ORNITHOPOD 3. SAUROPOD 4. TRACKS 5. PLESIOSAUR

6. RIP-RAP 7. GASTROLITH 8. TROWEL 9. ROCK HAMMER 10. ECHINODERM

TRACKSITE PUZZLE

A. A sauropod family

B. A running theropod

C. A walking theropod

D. A large theropod, possibly

 an Allosaurus

E. A single sauropod

F. A walking ornithopod

A

E

F

B C

D

SCRAMBLED WORDS

These words from the Dinosaur Lake activity book are scrambled. Try to spell the word. 

As a hint, there is a drawing of what each word is. Answers are on the next page.

 

1. O O E R D H P T

2. R I P O O O T N H D

3. D S U P A O R O

4. A S C T K R

5. S S I L R P U O A E

6. P A P R R I

7. T T L A S G O H R I

8. L W O E R T

9. O K C R M R E M A H 

10. M R H E N C I O E D
USDA is an equal opportunity provider, employer, and lender.