Distinguishing Theropod tracks from Ornithopod Tracks

Recently, Everything Dinosaur posted an article about a new study of the Dinosaur Stampede National Monument (Queensland, Australia), in which a three-dimensional Australovenator foot was used to assess what type of dinosaur was responsible for producing a set of eleven, large, three-toed footprints.  In this innovative research, conducted by scientists from the Australian Age of Dinosaurs Museum of Natural History and the University of Newcastle (New South Wales), it was concluded that the tracks could have been made by a meat-eating dinosaur.

Theropod and Ornithopod Tracks

Previous research had challenged the interpretation that the trace fossil site preserves evidence of a dinosaur stampede as a substantial group of smaller plant-eating dinosaurs evaded an attack from a big theropod.

Other interpretations of the Dinosaur Stampede National Monument have suggested that the hundreds of tracks preserved at this location, some seventy miles south of the town of Winton in Queensland, do not represent evidence of a large, meat-eating dinosaur attacking a flock of smaller dinosaurs.  Some scientists have contradicted this analysis and proposed that the bigger, tridactyl tracks were made by a big ornithopod, a herbivorous dinosaur, something like a Muttaburrasaurus.

Could the Larger Tracks at the Dinosaur Stampede National Monument have been made by a Muttaburrasaurus?

Muttaburrasaurus scale drawing.  Picture credit: Everything Dinosaur

Picture credit: Everything Dinosaur

The picture (above) shows a Muttaburrasaurus scale drawing. The drawing is based upon a dinosaur model from the CollectA range.

To view this range of prehistoric animal models: CollectA Age of Dinosaurs Popular Models.

The Confusion Between Bipedal Plant-eaters and Bipedal Meat-eaters

Having published our article, we were then emailed and asked to explain how it was possible to confuse the footprints of a large bipedal, herbivorous dinosaur with those of an equally sized carnivorous dinosaur.  So, here are some pointers about the differences between the types of tracks, plus an explanation as to why it can be so hard to pin down which type of bipedal dinosaur left prints and tracks.

For those scientists that study dinosaur footprints, being able to distinguish the prints from a meat-eating theropod from those of a large, herbivorous ornithopod is a challenging task.  If the prints are ideally preserved with lots of detail, identification can be relatively straight-forward, if the body fossils of a dinosaur could be found close by, then there would be further evidence to support a diagnosis, but sadly, discovering exquisitely preserved dinosaur tracks – these are very rare events indeed!

It is Not Easy Identifying/Classifying Dinosaur Footprints

A huge dinosaur footprint spotted at a school. Picture credit: Everything Dinosaur.

An Identification Guide

The track made by a theropod dinosaur (the pes of a meat-eating dinosaur), if perfectly preserved, should show sizeable claw marks on the end of the toes.  The toes themselves should look quite slender and in general terms the print should look longer than it is wide.  The length of the foot when compared to the width should give the track a characteristic “v shape”.

The well-preserved track of a large ornithopod, a plant-eater should lack distinctive claw marks.  The ends of the toes should be more blunt and rounded in appearance.  The toes tend to be quite wide and the foot proportions are different.  For example, the foot may be much wider.  The wider pes as a proportion of overall foot length gives the track a “u shape”.

Ornithopod versus Theropod Footprint – Identification Guide

Theropod print compared to an ornithopod print. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Identifying the Dinosaur from the Footprint – Problems

The fact that something so ephemeral as a single track or a trackway can survive for millions of years is remarkable.  However, over time these trace fossils can become distorted making identification extremely difficult.  Features, once very striking are easily masked by the effect of weathering and erosion.  Any repairs undertaken or attempts to preserve the prints could also lead to the loss of definition, causing further problems when it comes to making an assessment as to what type of animal produced the tracks.

Unauthorised attempts to make casts could also result in considerable damage to the track(s) thus further hampering identification.

It does not matter, whether the track represents a natural cast (created by sediments filling in a track), or whether it is a true track (the impression preserved in the ground made by the foot itself), determining what type of creature made the prints is an extremely difficult process.  Some of the most difficult tracks to interpret of all are undertracks.  An undertrack is formed below the sediment as surface material is compressed downwards as the organism moved across the area.  These undertracks lack many types of marks made only at the surface, scratches, scuffs, clear claw impressions or any evidence of a tail drag.

The thousands of dinosaur tracks at the Lark Quarry site (Dinosaur Stampede National Monument), are truly a remarkable record of the behaviour and activity of a group of dinosaurs.  What exactly those tracks represent is open to different interpretations – but that’s science for you.

Further articles on the Lark Quarry dinosaur tracks:

Could Australovenator have made some of the tracks at Lark Quarry?: Lark Quarry Dinosaur Footprints – Scientists Re-examine the Evidence.

Lark Quarry Tracks Re-examined: A New Interpretation of the Lark Quarry Fossils.

Visit the award-winning Everything Dinosaur website: Everything Dinosaur.

Scientists Reconstruct Dinosaur Foot to Help Interpret Tracksite

The famous dinosaur tracks at Lark Quarry, (Dinosaur Stampede National Monument), near the town of Winton (Queensland, Australia),  have been the subject of research for decades.  Unlike dinosaur bones and teeth that can be transported a huge distance from the place where the dinosaur died, footprints and tracks preserve evidence of activity and behaviour.  The majority of trace fossils provide direct, in situ evidence of the environment at the time and location where the animal was living.

Different Interpretations of the Dinosaur Tracks

At Everything Dinosaur, we think the first, formal attempt to interpret the numerous dinosaur tracks preserved in the finely grained sandstone at the Lark Quarry site took place in 1984.  Eleven, large, three-toed prints were interpreted as having been made by a big meat-eating dinosaur that had lunged at a flock of small ornithopods that it had cornered.

The tracks were interpreted as a “dinosaur stampede” as the smaller plant-eating dinosaurs panicked and tried to avoid the jaws of a ten-metre-long theropod.  The ichno genus (a name given to an animal known only from trace fossils), Tyrannosauropus was erected.  Over the years, a number of other interpretations have been put forward, including the hypothesis that the big tri-dactyl prints don’t represent a predator but were made by a large ornithopod, something akin to a Muttaburrasaurus.  Other interpretations of this famous fossil site include that the tracks were made by dinosaurs as they swam and waded across a body of water.

Swimming Dinosaurs Hypothesis: Dinosaurs Not Stampeding but Swimming.

No Tyrannosauropus at Lark Quarry After All: Lark Quarry Tracks Made by a Big Plant-Eating Dinosaur.

Dinosaur Foot Reconstruction – A New Analysis of the Tracks

Distinguishing between the three-toed prints of meat-eating dinosaurs and those of similar sized plant-eaters, which also walked on three toes is a tricky business.  However, in an innovative piece of research, a team of scientists from from the University of Newcastle (New South Wales) and the Australian Age of Dinosaurs Museum of Natural History in Winton, set about reconstructing the foot of an Australian Theropod dinosaur Australovenator wintonensis in a bid to reproduce the tracks in similar sediment, which could then be compared to the fossil trackway.

Reconstructing the Foot of Australovenator

Reconstructing the left foot of Australovenator.

Picture credit: PeerJ

The picture above shows (A) calculating the claw length of Australovenator and (B-D) the four claws associated with the left foot of the dinosaur with reconstructed sheaths.  The bones of the foot have been reconstructed (F) and using Emu feet for an anatomical comparison, (G) shows the foot reconstructed with tendons added, whilst (H) is the skin covered biologically restored foot (left pes) of Australovenator.

Australovenator wintonensis

A three-dimensional foot of Australovenator was created as fossils of this Megaraptoran theropod are known from similar aged strata as the Lark Quarry tracks.  In addition, Australovenator is the only meat-eating dinosaur from Australia which has had its foot bones discovered.  The researchers used a variety of substrates to test the prints, scuff marks and scratches made by the large dinosaur and they concluded that their recreated impressions were reminiscent of the trace fossils.  This suggests that the eleven, large, three-toed tracks at Lake Quarry (now known as the Dinosaur Stampede National Monument), could have been made by an Australovenator-like carnivorous dinosaur.

An Illustration of Australovenator wintonensis Crossing the Lark Quarry Sediments

Australovenator making tracks.

Picture credit: Travis R. Tischler

The CollectA Australovenator Dinosaur Model

Australovenator was a member of the Allosauria clade of theropod dinosaurs.  Fossils of this six-metre-long carnivore were discovered in 2006.  Although the fossil material was far from complete, the Australovenator genus was formally erected by Australian palaeontologist Scott Hucknull in 2009.  CollectA introduced a model of Australovenator just three years after the scientific description.  Models of Megaraptoran theropods are quite rare, it is great to see that CollectA have added an Australovenator replica to their “Prehistoric Life” model range.

To visit the Everything Dinosaur website: Everything Dinosaur.

The CollectA Australovenator Dinosaur Model

The CollectA Australovenator replica.

To view the full range of CollectA dinosaur and prehistoric animal models: CollectA Prehistoric Life Models.