By Scarlett Hunt

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Identifying Track Makers

• By Scarlett Hunt

2

• The importance of fossil trackways to
  palaeontology is noted in this quote from Lockley
  Hunt
• Every tetrapod animal can potentially make
  hundreds of thousands, even millions, of tracks
  in a lifetime, whereas it only has one skeleton
  consisting of a few hundred bones.

3

• Palaeontologists try to glean as much
  information as possible from dinosaur tracks.
  They can examine the patterns, spacing, size,
  shape and depth of prints. They take into
  account the sites palaeoecology and
  biostratigraphy and the many variables which
  affected the formation of the print.
  Paleontologists then use this information to
  speculate about dinosaur anatomy, posture,
  locomotion, speed and behaviour. By piecing
  together these clues from the past,
  paleontologists hope to identify trackmakers and
  better understand their anatomy and behaviour.

Dinosaur Ridge, Colorado
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The placement, number and pairing of tracks can
tell palaeontologists whether the trackmaker
moved bipedally (two-legged), quadrapedally
(four-legged) or with a combination of both.

• Bipedal dinosaur trackways contain similarly
  sized and shaped
• prints in pairs. Each print alternates
  -usually from left to right.
• They make tend to make very narrow trackways
  which may
• appear to be in a straight line.

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If there are predominantly hind prints but a few
front prints, the animal is considered a
facultative biped, meaning that it usually walked
on its back legs but was able to walk on all four
when it chose.
When only hind prints are visible the animal is
considered an obligate biped, meaning that it
walked on only its back legs.
6

• The manus and pes prints of quadrupedal dinosaur
  tracks usually have different sizes and shapes.
  The rear prints are larger and broader in shape
  than the front. Trackways show the front print
  slightly in front of the back print on each side
  of the trackway.

The front foot of a quadruped animal is called
the manus, whereas the back foot is called the
pes.
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• A pattern of distinct foreprints and hindprints
  indicates that the animal was an obligate
  quadruped it walked only on four legs. The
  pattern may show the foreprints alternating with
  the larger hindprints or the foreprints may be
  embedded inside the larger hindprints (as
  underprints).
• When there is a pattern of hindprints and
  foreprints with a few foreprints missing, the
  animal is a facultative quadruped who was capable
  of walking on two legs but usually did not.

In Clayton Lake State Park, Oklahoma
approximately 500 footprints of iguanodonts are
remarkably preserved . The three-toed footprints
indicate that the animal usually walked bipedally
but occasionally leaned forward to walk on all
fours. The tracks are easily recognized because
of their square heels and lack of claw marks.
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• Footprint anatomy and characteristics are used to
  differentiate between possible track makers.

Site in Eastern Utah NOTE A theropod track is
perpendicular to the sauropod trackway
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• Theropods Long narrow digit marks ending in
  sharp thin claw marks. The back ends are
  typically V-shaped.
• Coelurosaurs Digits close together and clear toe
  pads.
• Carnosaurs Widely spread out, large robust
  prints. Pads are less distinct.
• Ornithopods Well-rounded back ends. Short
  blunt digit marks showing a hoof-like claw.
  Frequently show three toes. Wider tracks than
  theropods.
• Ankylosaur More robust and compact than
  ceratopsian prints.
• Sauropod Rear prints bear-like or else
  triangular. The front prints resemble elephant
  tracks. Crescent-shaped or missing front prints
  because of mud pushing or overlapping by back
  prints.
• Chart and information taken from An Overview of
  Dinosaur Tracking by Glen Kuban

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According to the author of www.palaeo.gly.bris.ac.
uk /Palaeofiles/Tracks/Report9, The stature and
build of the legs and feet will affect the area
over which pressure is exerted. Wider feet will
have a snowshoe effect and therefore leave less
of an impression. Column-like legs with compact
feet will carry the mass of the body over a
smaller area. This will exert a high pressure
and produce a more profound disturbance of the
substrate.
The soft tissue of an animals foot can greatly
affect the shape of a print. It can be entirely
different from what you would expect to find
based on the skeleton alone. For example, Robert
Bakker speculated that duckbilled hadrosaurs had
plump paws similar to a camels foot. This would
produce a webbed footprint.
PROBLEM One mystery is why the front prints show
only blunt digits marks, whereas skeletal remains
of sauropod front feet include a large pointed
claw. Glenn Kuban speculates that perhaps the
single claw was held in an elevated position or
else the claw was tucked within the fleshy pad at
the front of the foot.
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Size is another consideration when examining
dinosaur footprints. Obviously, the size of the
footprint is relative to the size of the foot
which made it.

• Some of the larger sauropod tracks are over a
  metre long and as deep as bathtubs.
• One of the smallest theropod tracks ever found is
  from Nova Scotia. They are named Grallator.

www.ldeo.columbia.edu
www.boutell.com
www.ourworld.compuserve.com
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Dinosaur tracks known from Broome, Western
Australia
Sauropods. Up to 80 cm in length. Stegosaur.
Five-fingered manus prints 21 cm in length,
associated with three-toed foot prints. Only
stegosaurs are known to have had this combination
of five fingers/ three toes.
Wintonopus latomorum ("Foot from Winton").
Ornithopod tracks ranging from 3 to 27 cm
(averaging 7-8 cm) in length Megalosauropus
broomensis. Large theropod tracks 53 cm in
length, from a creature perhaps 9 to 10 metres in
body length.
13
Number of digits is a factor when determining
the identity of a track maker.
Scientists use Roman Numerals to count fingers
and toes. They are numbered from the inside to
the outside. For example your thumb would be I
and baby finger would be V.
When counting phalanges (bones) in the digits,
they are numbered from the palm of the hand
outward.
Small Raptor Foot
Small Allosaurus Hand
Each finger or toe is also part of a phalangeal
formula for the hand or foot. For example a
human hand is 2,3,3,3,3 because the thumb has 2
bones and each other finger has 3. A theropod
foot has the formula 3,4,5.
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• The rear feet of saurpods contained 5 digits,
  decreasing in size from the inside towards the
  outside of the foot. The inner 3 or 4 digits
  bore large claws. Front prints do not show toes.
• Some quadruped ornithopods have 3-toed tracks for
  their pes imprints but manus prints do not show
  obvious toes either.
• Iguanodont rear footprints contained 3 wide,
  blunt digits like most other ornithopods. Their
  feet bore 5 digits of varying length.
• Ankylosaur and ceratopsian footprints each have 4
  digits on the back feet and 5 on the front feet.

• Most bipedal dinosaurs actually possessed 4
  digits on each foot, but one digit (the hallux)
  was small and held in an elevated position at the
  inside rear of the foot. When recorded at all,
  hallux marks are usually small and shallow.

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• Foot movement and position affect the resulting
  print.
• Quadrupeds tend to walk in a plantigrade manner,
  by impressing their soles and heels as they walk.
  This creates elongated tracks.
• Bipeds habitually walk in a digitgrade manner,
  with their toes starting the formation of the
  print. Some bipeds are noted to have walked in
  a plantigrade or plantigrade-like manner
  occasionally.

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• Quadrupedal dinosaurs walked diagonally, by
  moving the right manus and left pes at about the
  same time, alternating with the left manus and
  right pes. Trackways show the manus print
  slightly in front of the pes print on each side
  of the trackway.
• Note Tracks attributed to Iguanodonts show a
  strong inward (pigeon-toed) rotation of their
  feet.

Animation of the foot order of a preserved
sauropod trackway. www.projectexploration.org/
jobaria/Rearing4.html
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Fossilized tracks can show significant anatomical
features. Details of skin texture, claws, skin
creases and tail marks are sometimes preserved in
the fossil record.
Fossils of Anomoepus have been found in Holyoke,
Massachusetts, and New Jersey, USA. The tracks
were named by E. B. Hitchcock in 1848.
NOTE The tail drag below the front prints at
the far left.
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Matching skeletons to footprints can help
identify track makers.

• However, one of the problems is that foot bones
  are small and hard to find. Often trackways are
  given their own names because the animal is known
  only by its footprints these are called
  ichnofauna. The name of the animal and the name
  of the trackway it made may be different.
• Dilophasaurus is however very unusual in that its
  skeletons have been found in relatively close
  proximity to footprints plausibly made by the
  dinosaur.
• Hadrosaurs are probably the best known
  ornithopods that left tracks attributable to the
  trackmaker.

The only way to demonstrate conclusively that
any one species of dinosaur was responsible for a
particular type of footprint is to discover the
skeleton of the animal preserved at the end of
its fossil trackway. (Thulborn, 1990).
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REPRINT FROM DINOSAUR TRACKS by TONY THULBORN
Chapman and Hall, 1990
Dinosaurs with tridactyl feet tended to produce
three-toed footprints, those with slender feet
tended to produce narrow footprints, and so on.
In other words, it may be assumed that each
footprint is a reasonably faithful impression of
the foot that made it. The obvious way to
discover which sort of dinosaur was responsible
for a trackway is simply to match up the
footprints with dinosaur feet of the most
appropriate shape and size. Such matching up of
dinosaur footprints against dinosaur feet has
long been standard practice (see diagram).
Sometimes the fossil footprint is compared
directly to an actual foot skeleton
alternatively, one may work from the evidence of
the footprint alone, attempting to visualize the
shape of the foot that might have produced it. On
occasion, it is useful to follow the reverse
procedure, by predicting what sort of footprint
would be produced by a particular foot skeleton.
This last exercise entails something more than
laying out the foot bones on a sheet of paper and
tracing round them with a pencil. Instead it is
necessary to arrange (or at least envisage) the
foot bones in a life-like attitude, with the
bases of the digits lifted from the substrate and
the metapodium inclined up and backwards. Then,
when they are projected on to the horizontal
plane, these inclined elements will appear
properly foreshortened, as they would be in an
actual footprint.
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• Indirect information can be interpreted from the
  tracks in-situ. Palaeontologists speculate about
  the movement of individuals or groups, social
  behaviour related to grouping, action sequences,
  distribution of groups, populations, ecology and
  food chain, relative ages of individuals in the
  group, etc.

Eubrontes giganteus tracks is at Dinosaur State
Park in Rocky Hill, CT
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• Paleontologists may estimate an animals speed by
  combining factors into an equation determined by
  R. McNeil Alexander in 1976.
• V
• Alexander estimated from a range of dinosaur
  skeletons that the hip height ranged from 3.6 to
  4.3 times the foot length. The hip height
  equals 4 times the foot print length has become
  widely used as a convenient and easily remembered
  rule of thumb.

0.25(stride length)1.67(leg length)-1.17(gravi
tational constant)0.5
Using Alexanders equation, the follow speeds
were calculated by R. A. Thulborn (1982,
University of Queensland, Australia) Sauropodamo
rphs to 5 km/h (same as person walking)
Stegosaurs and ankylosaurs to 6-8 km/h Most
sauropods walked 12-17 km/h, max. of
20-30 km/h Large theropods and ornithopods to 20
km/h Ceratopsians to 25 km/h Small theropods,
ornithopods to 40km/h Ornithomimids to 60 km/h
People are estimated to run up to 23 km/h
(fast sprinting speed)

22
According to Professor Paul Eric Olsen in his
lecture notes on www.ldeo.columbia.edu
On-line calculator for determining dinosaur
speeds on the University of Sheffield, England
webpage www.shef.ac.uk/es/DINOC01/
dinocal1.html
23
Palaeontologists look for evidence of
sophisticated social behaviour in trackways and
for evidence of interaction between animals.
Unfortunately patterns of movement in groups or
individuals is very speculative at best.
24

• In the Paluxy riverbed of Glen Rose, Texas,
  palaeontologists claim to have found evidence of
  an action sequence frozen in time. Roland Bird
  and crew examined a large set of sauropod
  trackways. They discovered that a set of large
  carnosaur tracks parallels the sauropod tracks.
  This lead Bird and others to speculate that they
  record an ancient chase scene.
• Other critics point out that the paces are rather
  small and show unhurried gaits. They concede
  that the carnosaur may have been stalking the
  sauropods from a distance, or more likely was
  simply using the same path at a different time.

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In Davenport Ranch, Texas tracks of 24
apatosaurus are preserved in a group. The
largest prints are on the outside while the
smaller prints are in the middle of the group.
Robert Bakker inferred that the bulls or senior
cows may have guarded the young. Martin
Lockley speculated from tracks that large
sauropods led their herds and walked in a
staggered or spearhead formation.
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Palaeontologists try to reconstruct food chains
and ecological systems from trackway
evidence. Tracks should provide a more valid
census of a living community than remains at the
majority of skeletal sites. (Lockley, 1986)
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• In Brule, Nova Scotia palaeontologists have found
  evidence of a primitive conifer forest ecosystem
  from the Permian Period (285 MA). Animal tracks
  meander along the forest floor between fossilized
  Walchia stumps found in their original growth
  positions.

Palaeontologists have tried to make a census of
the community by counting tracks. Tracks have
been identified as belonging to Dimetrodon,
Varanops, Gilmoreichnus, an animal from the
family Araeoscelis, and a temnospondyl amphibian
(cacops?), Because of the regular spacing of
tracks of the same type of animal many believe
that these tracks are the oldest evidence of
herding behaviour in animals. They suggest that
the tracks indicate a follow the leader pattern
of movement.

• The reptilomorph called Seymouria dragged its
  tail as it walked. Remarkably the Brule trackway
  shows that the tail drag was raised in narrow
  areas between trees.

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• Amphibian trackways in the cliffs near Diligent
  River, Nova Scotia have preserved evidence of the
  palaeoenvironment. There are five remarkable
  sets of footprints, three with tail and body
  drags. Fern stems and fronds, load casts, tree
  rootlets, drag marks and rain drop impacts were
  also preserved on the surface of the rocks.

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• In A Study of Small Dinosaur Footprints-Gary
  Gaulin challenges the view that ornithischian
  dinosaurs were strictly herbivores. He examined
  a site which contained insect trails along
  Anomoepus scambus trackways. Notably there was
  no preserved evidence of vegetation. He
  theorizes that these small dinosaurs fed on small
  insects.

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• A foot print gives only an imperfect idea of a
  trackmakers foot structure. The tracks that we
  see are affected by local variations in the
  physical properties of the substrate and
  dynamic interaction between foot and substrate.
  
• Thulborn Wade 1989
• The impact and effects of variables need to be
  considered carefully nature of the substrate
  erosion weathering infillings laminations
  kinematics irregular movements unconformities
  hiatuses undertracks and rock change.

Sauropod footprint from the Islet of Fenoliga,
Istria.
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• The substrate content, quality and fluidity may
  greatly affect the final appearance of a trackway
  or individual print.
• In An Overview of Dinosaur Tracking Kuban
  states that When a track is made on very soft
  substrate, some sediment may slump back into the
  print. This phenomenon, called mud-collapse or
  mud back-flow, often distorts and reduces track
  features. Digit marks may become mere slits.
  Soft sediment can also result in undertracks. If
  the substrate is very firm, portions of the foot
  may record only lightly, if at all.

Tracks in Courtedoux, Switzerlandof at least 14
sauropods and two tracks of a carnivor.
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• In small and poorly preserved tracks it is
  difficult to distinguish between ornithopod and
  theropod tracks. For example, small carnosaur
  species or juveniles of a carnosaur species may
  make tracks mistaken for large ornithopod tracks
  when their digits are partially mud-collapsed.
  This would make them appear to be shorter and
  blunter and therefore more ornithopod-like.

A three-dimensional computer reconstruction (top)
shows a theropod foot at three stages in creation
of a deep track, moving right to left. A
photograph of a deep Greenlandic footprint is
shown below it.Image Stephen Gatesy, Brown
University
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Erosion can distort or blur track features or
even obliterate them. It can also create
depressions of its own which can be mistaken for
fossil tracks.
34

• Infillings damage track features.
• An overlying layer may be scoured away with some
  remains trapped in some of the track depressions.
  This may exhibit little or no topographical
  relief.

35

• Thin laminations can cover a print or trackway.
  They may or may not reveal the the contours of
  the tracks below. Upper layer depressions are
  known as overtracks. They may be mistaken for
  true tracks on the original surface.

36

• According to the author of www.palaeo.gly.bris.ac.
  uk /Palaeofiles/Tracks/Report9,
• Increasing speed will alter the angle at which
  the foot contacts the ground and affect the force
  with which the foot strikes the substrate
• A foot print is usually made in three phases,
  termed touch-down, weight-bearing and kick-off.
  (Thulborn Wade, 1989).
• Many animals perform a small rotation of their
  feet during the progress of a footfall (Phil L.
  Manning, pers.comm.). This rotation, within the
  print, will naturally obscure some of the finer
  details of the foot structure. However, if
  recognized it may tell us a great deal about the
  trackmakers locomotion.

This three-dimensional computer image
reconstructs theropod foot movements through
sloppy mud. Penetration through the ground
surface is shown in red. The first toe, which is
not reversed as in modern birds, creates a
rearward pointing furrow (a,b) as it plunges down
and forward. The sole of the foot leaves an
impression at the back of the track (c) because
it is not lifted as the foot sinks. All toes
converge below the surface and emerge together
from the front of the track (d). Image Stephen
Gatesy, Brown University
37

• Because tracks are created by foot shape and
  movement, irregular movements can create unusual
  shapes. Slips, slides, injuries and deformities
  related to animal movement or foot anatomy can
  make interpretation of tracks challenging.

38

• Other factors affect the formation of tracks
• Undertracks can occur when tracks are made upon
  other previously laid tracks.
• Rock change may destroy evidence of tracks.
• A hiatus is a geological period of time without
  deposition containing fossils. No trackways are
  formed.

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Paleontologists will continue to painstakingly
examine evidence from the past in order to
reconstruct and describe it for others. They
will skillfully examine direct evidence, make
interpretations, consider the affects of
variables, and may encounter monumental problems
along the way. In the future we may see more
importance placed upon Ichnology (the study of
trace fossils) and on the identification of
species from their tracks.