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Home , Caithness, Coccosteus, Dipterus, Glyptolepis (fish), Mybster, Osteolepis

The Story Begins… Ancient Geography Achanarras Quarry Site of Special The Lake Environment Preservation of the Scientific Interest (SSSI)

Imagine an ancient tropical lake so deep and dark has not always looked like it does today. Achanarras Quarry was once part of Lake Orcadie Lake Orcadie expanded and contracted as the The fish are preserved in that the bottom had no oxygen or much life of any 400 million years ago it was south of the equator and there, in what is known as the fish bed, you can Middle climate varied. At times of low flagstones of the fish bed. The sort. Most living things had to live in the shallows and part of a huge mountain range, higher than the find more of fish water supply, when the climate was warm and dry, it detail of preservation is such that where the unpredictable climate made them Alps, that stretched from North America to . than anywhere else in Scotland. These include was reduced to a salty inland desert drainage basin. delicate fin structures and even vulnerable to storms and changes in temperature or The mountains were formed when ancient oceans of armour-plated fish, the ancestors of However during wetter and probably cooler periods, skin outlines are seen in the best salt levels. In this fragile home fish suffered were destroyed and continents collided together. species we see in the fishmonger’s today. The the lake filled and overflowed, allowing fish to migrate specimens. The fish carcasses occasional mass deaths and their dead bodies Millions of years of erosion gradually wore down the armour plating offered some protection from larger into it from the sea. The fish bed was deposited were gently covered by sediment floated out and sank into the mud at the bottom of high peaks and powerful washed the sand predators, whose fossils can also be found. when the lake was full, and the water tens of metres and gradually buried and during the lake. 4000 years went by, 2 metres of mud and and mud into lakes. In the lakes it settled in layers Achanarras Quarry SSSI is renowned all over the deep. Fine layers in the bed record a seasonal this phase the internal structure fish bodies accumulated……and there the fish lay, and helped preserve the remains of plants and world for its well preserved fish of the Middle climate as the sediment was being deposited over of most of the fish decayed. perfectly preserved and undisturbed for the next . This is what happened at Lake Orcadie Devonian age (385 million years ago) and is some 4,000 years. The fish mainly lived in the shallow Further burial squashed the fish 385 million years. and other similar lakes that existed in the area that managed by Scottish Natural Heritage (SNH). oxygen rich water of the lake margins and mass flat and the lake mud was now lies between and . deaths might have been caused by algal blooms (a converted to solid rock. Many Now step forwards through time. rapid increase in the population of simple plants) millions of years later the rocks The dinosaurs came and went. removing oxygen from the water, storm activity, and were uplifted, eroded and finally Lake Orcadie where the fish used the water getting too hot or salty. All these quarried to reveal the fish bed. to live is long gone. But the processes cause fish mortality events even today. amazing fossilised fish are still here in the Flagstone. They were discovered when Achanarras Quarry was first worked for flagstones and roofing slates in the 1870s and their story helps us understand and the geological formation of Scotland.

Coccosteus Pterichthyodes

Directions to the Quarry Industrial history of Achanarras Modern Achanarras Other Fossil Sites in The Scottish Fossil Code Fossil Fish On travelling North up the Quarry SSSI Caithness A9 towards turn of Caithness left on to the B870 at . This turning is THE 385 MILLION YEAR OLD STORY The Achanarras Now, parts of the tips are turned over regularly Fossils can be found at many other sites in At Achanarras Quarry, just before you reach the OF ACHANARRAS QUARRY village of Spittal. On the Quarry started as using a mechanical excavator. This action provides Caithness. These often contain fish beds of the Scottish Fossil Code B870 take the first turning a small farm more material for collectors to search for fossils, and different ages from that at Achanarras. By has replaced the fossil on the right (about 1km quarry in 1870. ensures that this internationally important locality comparing the species found at each site the history collecting permit system west of the Mybster junction beside a forestry Later it was does not become of Lake Orcadie, and which fish species lived at that was previously in operation there. Searching plantation). Both of these worked by the overgrown. These particular times, can be revealed. Most of the other for and collecting fossils is permitted subject to turnings are marked with Thurso Flagstone activities have sites are on private land where you will need the visitors following the Fossil Code. You can brown tourist signs for Quarry, and by resulted in several owner’s permission to collect fossils. The most download a copy of the Scottish Fossil Code from ‘Achanarras Quarry’. 1891 the fish bed was exposed. The quarry fell into new species being important areas are also protected as Sites of the SNH website (www.snh.org.uk/fossilcode/). th This track will take you to disuse in the early 20 Century, but was worked for found and Special Scientific Interest (SSSIs). There is the Please read the information about fossil collection at the quarry car park. Once at the car park, there is a panel roofing slates in 1959-61. In the early 1970s there described. opportunity to see some preserved fossils at the Achanarras Quarry SSSI on arrival to the car park. with a map indicating where the quarry is located. was minor quarrying activity. Wheeled wagons on Digger turning over quarry material Caithness Horizons Please shut any gates you open behind you as you walk to rails, called bogies, were used to take the waste The facilities at Achanarras were upgraded in 2008. museum in Thurso. Scottish Outdoor Access Code the quarry. from the quarry to the outer tip. During working the You can now discover more about the fish, walk a Further Information The Scottish Outdoor Access Code Please note that there are no toilet facilities at the site. water was drained from the quarry by means of a geological ‘timeline’, search for fossils, find out what For further information on local applies to all land in Scotland. The access siphon. It took about 10 days to empty. The last has been happening in the fossil world and record geology and fossils see track to Achanarras Quarry is through time it was drained was in 1980 for a scientific your finds at Achanarras. Excursion guide to the private land and the Access Code should study of fossil distribution through the fish bed. Geology of East therefore be followed at all times. Please Achanarras Quarry is also located in a and Caithness. N H Trewin and A Hurst (eds) Dunedin read the safety notice on arrival to the For the next 20 years collectors scoured the tips for wild area with interesting plants Academic Press. 2009 quarry car park. Contact details fossils and it became increasingly difficult to find and animals. Watch out For imaginative time-travel stories of excursions to famous Please let SNH know if any rare or particularly fine fossils new specimens. for frogs by the quarry Scottish fossil localities (including Caithness fish, and the are found. pool in the early spring, and of and Skye) see Fossils Alive! by N H Trewin (Dunedin Academic Press, 2008) Scottish Natural Heritage nesting birds such as North Area Office oystercatcher, curlew, lapwing and skylark. You may For more information on the geology and landscape of The Links, Business Park, Golspie, KW10 6UB even be lucky Scotland please visit the SNH website to view the online T: 01408 634063 E: [email protected] publication: Scotland: The Creation of its Natural Landscape, enough to spot a www.snh.org.uk and other regional publications in the series A Landscape hen harrier Fashioned by Geology. © Scottish Natural Heritage 2009 hunting over the heather . Acknowledgements Majority of text, photographs and sketches by Professor Nigel H. Trewin, University of . Bogie used to carry quarry waste A Guide to Achanarras Fossils

Armoured Fish - the Placoderms Spiny-finned fish, the Acanthodians Fish fins , Rhamphodopsis, Homosteus, Actinolepis and Pterichthyodes are representatives of Various species of Diplacanthus, Cheiracanthus and Mesacanthus occur at Achanarras. They the extinct group of armoured placoderm fish. The head and part of the body is covered with bony are all characterised by spines supporting the fins, and a covering of tiny scales. They are plates. All except Pterichthyodes lacked scales on the rest of the body, so internal features can be frequently poorly preserved with a tendency for the head to be fragmented. seen in fossil specimens. DORSAL Mesacanthus Coccosteus Homosteus This small fish is common In this common 30cm long A large fish with and is seldom larger than Achanarras fish, the head and an armoured body 5cm. Several may be part of the body are covered in up to 40cm long. found on a single slab of rock. It was probably a shoal fish feeding on bony plates with an ornament of The tail has not microorganisms (tiny, microscopic plants and animals) in the lake water. This small bumps. The rest of the body been found yet! fish was probably a snack for the predator fish. had no scales so the internal Isolated thick bony skeleton can be seen in fossils. The had sharp-edged plates that acted armour plates are Diplacanthus like shears; probably used to take bites from prey. Analysis of stomach sometimes found contents shows that in the quarry. The This fish is characterised by two dorsal Dipterus and flattened shape of the fish indicates a fins with supporting spines, and strong acanthodians were on bottom-dwelling habit, possibly a large pectoral fin spines. Specimens more ANAL PELVIC the menu. scavenger. than 10cm long are rare. Two species CAUDAL PECTORAL (PAIRED) are present at Achanarras. (TAIL) (PAIRED)

Rhamphodopsis Cheiracanthus This small (up to 15cm) and This fish only has a single dorsal fin on the scarce fish had a partly top of its body, and the spines are more armoured head and a naked delicate than those of Diplacanthus. body as in Coccosteus; Lobe-finned fish, Dipnoans and Crossopterygians hence the internal backbone can be seen in the fossil. There is a long whiplash tail, and the fish probably These fish have leaf-shaped paired pectoral and pelvic fins. The lobe-finned fish gave rise to swam rather like an . and later land-dwelling . Many representatives of these groups are – a zoological enigma found in Caithness, including Thursius, Gyroptychius and Tristichopterus. Three representatives Despite recent suggestions that Palaeospondylus is a larval (young) but nobody really are found at Achanarras. Pterichthyodes Actinolepis knows where this species fits in to the evolution of vertebrates. It is common at Achanarras, but This curious fish was first The first recorded Dipterus Osteolepis discovered by Hugh Miller Scottish specimen very rare elsewhere in Caithness and . It is not known from anywhere else in the world. This primitive lung fish This crossopterygian at Cromarty in the 19th of this fish was (Dipnoan) is the most lobe-finned fish has Century. The pectoral fins found at Achanarras It has a well-developed skull, back bone, and tail fin. It lacked common of the larger enamelled rhomboid are represented by paddles in 1998. It is very scales, but a faint skin outline can sometimes be seen. Most in the quarry. It scales. It is scarce that move with the box-like similar to forms specimens are preserved in a curved tadpole shape. has lobed pectoral and at Achanarras, but pelvic fins and rounded common in Orkney. body armour by ball and from the Baltic area scales. Its maximum length is about 40cm, but most found are The teeth were small socket joints. The jaws were and strengthens around 15 cm long. Flat tooth plates indicate that it had a varied but sharp and numerous. It probably preyed on weak and situated on the ideas that there diet of plants and small aquatic animals. It was probably capable small fish and other animals in the lake. Specimens underside of the . This was a connection between these areas in the of living in water with a low oxygen content and was able to gulp found are generally about 15cm long. bottom-dwelling fish found Devonian. It has bony plates that could easily be air. It is related to modern lung-fishes that inhabit rivers in its food by grubbing in the mistaken for Coccosteus, but has two distinctive Australia, Africa mud of the lake shallows. pointed plates bearing a row of spines. and South Coprolites, fish excrement America. Elongated solid black masses up to 5cm long, sometimes with a lumpy or rough surface texture are fish coprolites (excrement). They The shadowy agnathans have been found within Coccosteus, and sometimes contain fish Achanarella and Cornovichthys are recently described animals remotely related to the modern scales. This large lobe-finned fish grew to over 50cm and had strong sharp teeth. It was the top predator at Achanarras, and lamprey. They both lacked jaws and a backbone and are preserved as no more than a black stain specimens have been found showing the tail of a prey item sticking out of its mouth. It was a lurking predator like the on the rock. Achanarella is not rare, but Cornovichthys is only known from two specimens. (unrelated) modern pike. Individual Other fossils from Achanarras scales are up to 2cm in diameter with Achanarella There are few fossils apart from fish found in the quarry. Only a single arthropod and some plants have been found so far. a distinctive pattern; the name means Has a distinctive black blunt arrowhead-shaped head, sometimes showing a hole ‘carved scale’. Arthropods Fossil plants representing the mouth. The body is seldom more than a grey smear. It is common An arthropod is an animal with a hard, Fragments of plant on a few bedding surfaces. segmented outer skeleton such as a stems are found in spiders, scorpion, crabs and insects. The the fish bed and in only other animal, apart from fish, known the rocks above the Ray-finned fish, an Actinopterigian from Achanarras is a single shadowy fish bed. They specimen of an arthropod called floated out from the The sole representative of this group at Achanarras is considered to be a distant relation of Achanarraspis. It is probable that there shore, became modern bony fishes (e.g. trout and cod). were lots of small arthropods in the lake, waterlogged and sank to the lake floor but they were seldom preserved. where they were buried by mud. Cheirolepis Cornovichthys This fish is rare and grew to Shows big eyespots, and a dark mass within the body representing internal Please let SNH know if you find any fossils not on this sheet, (email: 30cm long. It is covered in tiny organs. The tail is unusual with the fin on the top side of the body, like an scales less than a millimetre in inverted shark tail. [email protected]) and take your find to an appropriate museum for size. The sharp teeth indicate that it was a predator. identification (see guidance in the Scottish Fossil Code, www.snh.org.uk/fossilcode/)