This month’s blog from our Community Geologist, Dr Ian Kille, connects writing in wet cement with trace fossils and Mystery Rock 16 from last month’s newsletter. If you’d like to receive our monthly newsletter and get involved with our Stone Sourcing activities, sign up as a volunteer here.
Pottery kilns are greedy for power, so in preparation for installing a large second-hand kiln, I had a three-phase supply installed. This required cutting through a concrete path to make a trench and, when the cable had been laid, remaking the concrete path. It was the first big concreting project I had ever done, so when I had finished it, I neatly wrote the names of the people who had helped make it, including my older son Craig, along with the date. It maybe that in a few hundred million years a geologist, of a highly evolved rat species, will unearth this concrete patch and use it as evidence in a paper on the ritual behaviour of primitive hominids in relationship to concrete structures.
If that writing is preserved over the millennia, it will have become a fossil. A particular sort of fossil.
When I hear the word fossil, the immediate images that come to mind are of ammonites, crinoids, shepherd’s crowns, trilobites and corals. Dinosaurs come to mind too, massive bones, lines of vertebrae, teeth and horns. These are the remains of the actual creature, usually their hard parts and often with their skeletons or shells replaced by a different mineral. The soft parts of an animal are rarely preserved, requiring an exceptional combination of speed of burial and environmental chemistry. Without this the remains would be predated, physically broken up, decayed, oxidized or dissolved. When this intersection of favorable circumstance does happen, it results in fossils which are amazing and tell us so much more about the animals – for example the recent discoveries in China of 
feathers on a number of dinosaur fossils.
For most ancient creatures, the information we have about their cells, muscles, nerves, brains, hearing, seeing and so on can only be inferred from the hard parts to which they attach or within which they are contained. We can measure skull cavity sizes to infer brain size, bone size and density along with muscle attachment points to work on musculature. We can also see the gas chambers and siphuncle of ammonites which tell us a bit about their flotation mechanism. We can also put these ammonites into a flume to see how water-dynamic their shapes are and infer something of how well adapted they are for moving.
All of these things are fascinating and help build a picture of what these animals were like and what they were capable of. What they don’t tell us is what they actually did. If Hamlet had looked at Yorick’s skull without knowing him well, alas he would not have been able to say anything of his infinite jest.
For ancient creatures, there is however, another type of fossil which helps us understand more of what these animals actually did. These are trace fossils, and ichnology is an important branch of paleontology which not only tells us what animals did, but also provides another set of diagnostic information which helps us understand the environment in 
which they are preserved.
The most obvious of trace fossils are footprints and trackways. Some of these even make an appearance in Roman remains. Just like my writing in the drying cement, there are some tiles at an undisclosed site where the paw prints of a dog can be found. Whether this is a particular 
dog that likes the feel of clay, or a potter’s dog that the owner wanted immortalized or whether potteries were particularly dog-rich environments is not clear. It simply tells us that dogs were around and dipping their paws where they probably weren’t welcome!
Fossil footprints and trackways are not uncommon, with dinosaur footprints making news in recent years with discoveries in the Jurassic strata on the Isle of Skye as well as in the Cretaceous rocks of the Isle of Wight. More locally, tracks discovered by Maurice Tucker, have been found in the lower Carboniferous rocks at Howick on the Northumberland coast. These proved to be from an early amphibian, 
probably from the Temnospondyl group and are one of the oldest amphibian footprints ever found.
Not all trace fossils are so obvious or so glamorous. Many of them are simply burrows or feeding trails and unlike the footprints, it is often hard to work out what animal made them. This is in part because many burrowing animals only consist of soft parts, so that what they did in chewing their way through soft sediment is the only record of their existence. This reminds me of a lecture we had at college from Professor Jim Kennedy on early molluscan evolution and their development to manage the relative positions of mouth and anus in their simple guts. My recollection is that Jim said something along the lines of, “much of their evolutionary effort was directed at working out how not to crap on their own heads”. This seems like a hard almost futile existence, but evolution is nothing if not a long game!
The rocks of the Carboniferous Period in Northumberland and beyond have a rich variety of trace fossils preserved within its many kilometers of deltaic and marine limestones. This month’s mystery rock, number 16 in a series, is one of them. This particular gem comes from the geologically fabulous Cocklawburn Beach just south of Berwick upon Tweed. Until very recently I had thought that these beautiful three-dimensional patterns in these siltstones glorified in the name of Eione monilforme. However, in trying to discover what sort of creature made these remarkable traces, my learned colleagues pointed me towards a paper in which they have acquired the even more remarkable name of Neoeione monilforme. It is a shame that scrabble doesn’t allow proper names! As far as the animal is concerned, I quote from Dr Katie Strang’s reply (an expert on all things Carboniferous – particularly sharks) “It was originally thought to be made by a mollusc, but has now been attributed to a deposit-feeding endobenthic (ie a lived in sediment at the lowest level in a lake or the sea) worm-like animal, that actively back-filled its burrow, but…”. As with many things geological, there is clearly still room for speculation, debate and further observation…
…and maybe this is a fitting sentiment to end this piece. My concrete scribblings have lasted all of 10 years so far and maybe some of the pots that were made in the kiln will appear, at some distant point in the future, in a Raturnine archaeological trench as a definitive marker for the late Anthropocene.
Attributions
Iguanodon footprint along the foreshore at Compton Bay.from https://ukfossils.co.uk/2016/06/17/compton-bay/
Dinosaur footprint An Corran: from https://www.nature.scot/dinosaur-sites-skye-be-given-official-protection
Amphibian footprint from Howick: in David Scarboro and Maurice Tucker: “Amphibian footprints from the mid-Carboniferous of Northumberland, England: Sedimentological context, preservation and significance” Palaeogeography Palaeoclimatology Palaeoecology 113(2):335-34