What Are Fossil Footprints?

 

Fossil footprints are ancient traces of living animals — termed trace fossils.  Trace fossils also include eggs, faeces (coprolites) and trails and burrows of invertebrates (animals with no backbones). 

You are probably more familiar with the skeletons of extinct animals, such as the iconic dinosaurs, which fill the halls of our museums — these are termed body fossils.  They tend to steal the excitement of children away from footprints, and very often, from scientists too.  In fact, although fossil footprints sparked much excitement with their first discoveries in the early 19th century, it is has only been relatively recently that we are beginning to realise just how important they really are.

Fossil  footprints show us how extinct animals moved; they are geological “movies” of dinosaurs going about their daily business.  They record the dynamic interaction between the animal and the ground upon which it walks.  Fossil footprints also help us to understand extinct animal behaviour (e.g. did they live in herds, did they hunt in packs?);  they help us to understand their ecology (what other animals did they live with?);  they help us to understand their environment (did it contain rivers, lakes or was it near the coast?).   Very often, fossil footprints may be the only traces of extinct animals (in a particular area).

Indeed, as the great Sherlock Holmes quipped in A Study in Scarlet, “There is no branch of detective science which is so important and so much neglected, as the art of tracing footsteps”.

 

Above: Fossil footprint of a three toed dinosaur.  Such footprints are records of how extinct animals moved; note the claw mark (top, centre) indicating that the toe was dragged through this sediment (photograph from the Middle Jurassic, Yorkshire coast).

 

This is the first in a series of articles aiming to introduce the reader to the study of fossil footprints, with a particular focus on my area of study, dinosaur footprints.

‘Mutant’ Turtles at Crystal Palace Park? The Story of the Dicynodon

 

As the new Teenage Mutant Ninja Turtles (2014) film pounces onto British cinemas, I thought it timely to introduce you to the strange turtle-like animal statues at Crystal Palace Park — animals that you have probably already passed many times rushing to see the dinosaur statues…

These two strange animal statues (termed Dicynodon) can be found to the right-hand side of the (large) dinosaurs and the marine reptiles.  The statues are actually on the other side of the Primary Island to the Labyrinthodon, (as shown in the photograph below).  But you should be able to see them if you follow the path around.

 

Above: Photograph showing location of Dicynodon on Primary Island.

 

Above: Close -up of two Dicynodon statues

 

As you can see from the photographs, these two strange statues have shells like turtles.  But have a closer look, what else do you notice?

You should be able to see tusks, giving them a strange sabre-toothed appearance (in photo, can only be seen in one animal, but they both have them).  It is from these features, that they were named Dicynodon (from the Greek words meaning “two tusks or canine teeth”).  Now if you are a fan of prehistoric animals you have probably seen many strange creatures; the four legged carnivore with a huge sail on its back (Dimetrodon), the exotically frilled Triceratops and its kin, or the prehistoric shark with an ‘ironing board’ like spine on its back (Stethacanthus).  But you are unlikely to have seen sabre-toothed turtles. But did these animals really exist?   In order to answer this question, we need to take a look back at the history of the Dicynodon models.

The famous sculptor of the models, Benjamin Waterhouse Hawkins, built the models under the scientific guidance of famous British anatomist, Richard Owen.  Richard Owen was particularly good at solving palaeontological puzzles, a few years earlier being able to predict the existence of a giant flightless bird (later described as the moa) from a single bone fragment alone^1,2,3.  However, in the case of these strange Dicynodon, all he really had to work with were a few skulls he was sent from South Africa (along with a few vertebrae)^4,5.  These heads were very strange indeed, showing a combination of tusks, but with the toothless beak of turtles.  So what did the rest of the bodies look like?  It seems that Owen was unwilling to reconstruct an entire body, however, judging from the lack of such reconstructions, though he did speculate that the animals were amphibious⁵.

 

Above: The skull of Dicynodon lacerticeps (from Owen 1845⁵).

 

Now, in order to breathe life into these extinct animals, and reconstruct the bodies, Hawkins would have to edge further into the dark of the “speculation zone”, even if Owen was not prepared to.  So, it seems Hawkins gave these Dicynodon statues shells.  Exactly why he did this, we can really only speculate.  This could be due to Owen’s interpretation of the animals as amphibious, or from his description of the turtle-like beaks.

We know now, that Hawkins was incorrect in giving these animals shells — the Dicynodon turns out to be more closely related to mammals (“mammal-like reptiles”).  However, perhaps we should not judge Hawkins too harshly, as what we must bear in mind is that he was working with very fragmentary material known at the time (we now have more complete material for the Dicynodon and closely related species).  More importantly, the Hawkins’ reconstructions, still standing 160 years later, are ‘living’ testaments to the changing process of science — reconstructions change with new discoveries and theories, so we can go back and question older reconstructions, or ideas critically. We can say “we have got it less wrong now”.  Ideas, like animals, evolve too.

The sabre-toothed Dicynodon, ‘mutant’ turtles no more.

 

For my more comprehensive historical look at the Dicynodon, visit the Friends of Crystal Palace Dinosaurs website, where this research was first published.  I would be happy to answer any questions related to this topic, so please leave a comment.

 

References

1. Owen, R. (1840). On the bone of an Unknown Struthious Bird from New Zealand, Meeting of November 12, 1839. Proceedings of the Zoological Society of London (Vol. 7, pp. 169-171).

2. Owen, R. (1843).  On the Remains of Dinornis, an Extinct Gigantic Struthious Bird.  Proceedings of the Zoological Society of London (pp. 8-10).

3. Dawson, G.  On Richard Owen’s Discovery, in 1839, of the Extinct New Zealand Moa from Just a Single Bone. BRANCH: Britain, Representation and Nineteenth-Century History. Ed. Dino Franco Felluga. Extension of Romanticism and Victorianism on the Net. Web. [Last accessed 20 September 2014].

4. Bain, A. G. (1845). II.—On the Discovery of the Fossil Remains of Bidental and other Reptiles in South Africa. Transactions of the Geological Society of London, 53-59.

5. Owen, R. (1845). III.— Report on the Reptilian Fossils of South Africa: Part I.  — Description of Certain Fossil Crania, Discovered by AG Bain, Esq ., in Sandstone Rocks at the South-Eastern Extremity of Africa, Referable to Different Species of an Extinct Genus of Reptilia (Dicynodon), and Indicative of a New Tribe or Sub-order of Sauria. Transactions of the Geological Society of London, 59-84.

Can You Spot the ‘Missing’ Footprints at Crystal Palace Park?

There is a curious note in the Crystal Palace Park guide; Geology and Inhabitants of the Ancient World¹, about a series of footprints, which was installed with the extinct animal models in the Crystal Palace Park, in 1854. However, whereas the dinosaurian behemoths, such as the iconic Megalosaurus and Iguanodon, loom over captive audiences, and are impossible to miss, the footprints are nowhere to be seen....but perhaps we have found a clue…

Above: A series of footprints like these (Chirotherium) was supposedly installed in the Park².

Well, firstly, you might ask, who cares about footprints? In scientific circles today, fossil footprints are considered invaluable tools to unlocking secrets about the way extinct animals moved, behaved and interacted within their environment. They are essentially a window into the past. By the mid-19th century, the study of footprints was an exciting new frontier of palaeontology. Discoveries had recently come to light from Dumfriesshire, Scotland³; Hildburghausen, Germany⁴; Cheshire and Merseyside⁵ (UK) and the Connecticut Valley, US⁶. With so few bones and complete skeletons described worldwide at the time, footprint discoveries represented, in some cases, the only clues of the animals; the only real means by which the intangible past could become tangible; the only way we could make that connection to strange bygone eras and understand the seemingly invisible creatures⁷.

This Victorian fascination with fossil footprints was reflected in the large number of museum displays at the time; for instance, footprint slabs on display at the, then, British Museum galleries⁸ (now part of the Natural History Museum collection). Casts of footprint slabs were also available for purchase from Ward's 1866 Catalogue of Casts of Fossils⁹; there was clearly a demand to display and marvel at these natural curiosities.

Left: Image from Ward's (1866) Catalogue of Casts of Fossils, showing a cast of what is labelled as Chirotherium, on sale for $10.

So it's not surprising then that Benjamin Waterhouse Hawkins would include footprints as part of his prehistoric landscape at Crystal Palace Park. Following the "sanction and approval" of the celebrated British anatomist, Richard Owen¹⁰, guiding the creative hand of Hawkins, these footprints (then, under the name of Cheirotherium) accompanied their presumed animal creators; three models of Labyrinthodon; essentially giant amphibians which Owen interpreted and described from fragmentary material in Warwickshire¹¹.

 

Above: The 'Labyrinthodons' are the first animal models which one discovers in the Park, if one works their way through the geological time sequence reconstructed by Hawkins (photograph  taken in 2014).

So, where are the footprints now?  I have spotted what we think may be the only surviving footprint, or pair of footprints¹²  in a photograph  taken by Professor Joe Cain in 2013.  However, strangely, I have only spotted it in just one photograph, and in numerous other photographs of the same models... well, it's just not there!

Above: Labyrinthodon with footprint, or pair of footprints, highlighted (taken in 2013)

 

Above: Photograph taken from same angle (2008): where is the footprint?

 

During a recent visit to the Park, I was still unable to spot the footprints, even using my binoculars and a powerful optical zoom camera (I could not get onto the islands without special permission from Park officials).  Unfortunately, the spot has overgrown with plants, frustratingly obscuring any possible footprints.

It's well known to scientists who study footprints (known as ichnologists) that footprints can be highly elusive to the human eye. The slightest change in lighting, for instance, can unveil or shroud these prehistoric enigmas. This is because they are often of low relief and, paradoxically, if you're staring straight down at one...you could likely miss it.

The secret to spotting footprints, which any ichnologist will tell you, is to look for them when the sun is at a much lower angle, for instance, at daybreak or dusk. Then, get down as low as possible, and look across the surface (bedding plane) to spot the 'newly' emerging footprints.

We do know that our image was taken only in 2013, and no conservation work has been undertaken around the models since then. So it's possible that the footprint has been infilled with loose sediment or dirt. So we need to get out there with a brush....(under the watchful eyes of Rangers of course).

So, if you have had the fortune to visit the fantastic Crystal Palace Park, look at your photographs....  If you spot anything that looks like a footprint then tweet the Friends of Crystal Palace Dinosaurs at @cpdinosaurs or add a post on the Friends’ Facebook page. Or, if you happen to visit the Park again, don't just visit the dinosaurs....give the 'Labyrinthodons' some of your time; start footprint spotting....

"There is no branch of detective science which is so important and so much neglected, as the art of tracing footsteps" — Sherlock Holmes, A Study in Scarlet.

 

(Note: I have posted a virtually identical piece earlier on the Friends of Crystal Palace Dinosaurs website).

 

References and Notes

1 Owen, R, and Hawkins, B. W. (1854). Geology and Inhabitants of the Ancient World. Crystal Palace Library. 39 p.

2 From Kaup, J. J. (1835). Das Tierreich 1. Johann Philipp Diehl, Darmstadt: 116 p.

3 Duncan, H (1831) An Account of the Tracks and Footprints of Animals Found Impressed on Sandstone in the Quarry of Corncockle Muir in Dumfriesshire. Transactions of the Royal Society of Edinburgh,11:194-209.

4 Kaup, J. J. (1835). Mitteilung über Tierfährten von Hildburghausen. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, 1835:327–328.

5 Cunningham, J. (1838) An Account of the Footsteps of the Chirotherium and Other Unknown Animals Lately Discovered in the Quarries of Storeton Hill, in the Peninsular of Wirrall between the Mersey and the Dee. Proceedings of the Geological Society of London, 3: 12-14.

6 Hitchcock, E. (1836) Ornithichnology-Description of the Footmarks of Birds, (Ornithichnites) On New Red Sandstone in Massachusetts. American Journal of Science, Series 1. 29:307-340.

7 For an example of how footprint evidence may be the only proof of an animal's existence, in the geological record, see Tresise, G. R. (1989) The Invisible Dinosaur. National Museums and Galleries on Merseyside. Eaton Press, Wallasey, Merseyside. 32 p.

8 Mantell, G. A. (1851) Petrifactions and Their Teachings; or, a Handbook to the Gallery of Organic Remains of the British Museum. Henry G Bohn, London.

9 Ward, H. A. (1866). Catalogue of Casts of Fossils: From the Principal Museums of Europe and America, with Short Descriptions and Illustrations. Benton & Andrews, printers.

10 Hawkins, B. W. (1854). On Visual Education As Applied to Geology. Journal of the Society of Arts, 2: 444-449.

11 Although Cheirotherium is the correct spelling in Greek for hand beast, Chirotherium (the incorrect spelling) was used first and therefore, under the provisions of the International Code of Zoological Nomenclature, is the valid name, used now. It is now thought that this type of footprint was made by animals more closely related to crocodiles, than to amphibians (see Tresise 1989, above for more details).

12 There is a short note in McCarthy and Gilbert (1994) (full reference below) that one of these footprints still survives.

McCarthy, S. and Gilbert, M. (1994) The Crystal Palace Dinosaurs: The Story of the World's First Prehistoric Sculptures. Crystal Palace Foundation.