Collecting fossil shark teeth

 

Carcharocles megalodon
Carcharocles megalodon

I’ve been collecting fossil shark teeth now for about seven years and I wanted to tell you about what is a rewarding, educational and fun hobby. What started as just a couple of teeth bought from a fossil shop has now reached over one hundred ‘display’ specimens, representing over ninety species including some pretty rare ones, and hundreds more in my ‘swap or sell’ collection. My interests and preferences in shark tooth collecting have grown and changed as my collection (and experience!) has expanded over the years. I’ve also learnt some good lessons over the years and wanted to share these with you in the hope that I might tempt more people into this fascinating hobby.

 

Ethics. Firstly I don’t collect jaws or modern teeth. EVER. I refuse to contribute to market pressure that increases the threats that sharks face. They have enough. Even if I knew one hundred percent that a modern tooth hadn’t caused the death of a shark, such as being collected from the bottom of an aquarium, I still think it has no place in my collection. Having one is a slippery slope and there are some internet dealers who will advertise ‘sustainably sourced’ teeth that have in fact come from fisheries bycatch. By buying one you are saying that there is a use for the bycatch when actually it would be better if we looked to address the issue and reduce bycatch of sharks. It has been estimated that one hundred million sharks are killed by humans every year; there is no sense in collectors adding to this tragedy. The reality is that nearly all modern shark lineages are at least a few million years old and fossil examples can be found for extant species if you know where to look or who to ask. You can collect teeth both ethically and without compromising your collections potential.

 

Information. The most important thing in any collection and especially a biological one is to keep records and label your specimens. Luckily I decided very early on that this was important to me and now add labels to teeth as soon as they come into my collection. Each tooth has a label with at least the Genus, Species, Age and Locality. Furthermore I also keep an Access database with many additional items of information about each specimen contained such as Source, Cost, and particular Stratigraphy etc. Whilst this may seem excessive it is important that any specimens you collect yourself have at least basic information accompanying them or they are scientifically worthless.

 

Display. There are many ways to display fossil shark teeth and my own collection has changed over the years. One of the most basic and common ways to display teeth is in a Riker Mount; essentially a black box with a see through lid and soft mounting fabric inside. Many collectors use these but often forget to add information labels, essentially reducing their teeth to nothing more than decorative stones. I keep mine in individual plastic display boxes which not only protects the specimen well but keeps the information label with it. At first I had my teeth simply arranged on a shelf in their little boxes but after I had about forty specimens I purchased some larger acrylic display boxes that stacked together. These worked well initially but they do get scratched and look old fairly quickly.

My first display cases.
My first display cases.

As my collection grew I purchased lighted glass display cabinet as well as some acrylic stands and steps to better display the specimens. These looked great and were a fantastic talking point for guests! I even added some plastic prehistoric shark models to allow visualisation of the living animals.

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My latest incarnation of collection display is a little less aesthetically pleasing but far more practical. I now have a metal Bisley drawer set. This allows me to keep all my collection, plus swaps, spare boxes and mounting materials together and in a compact storage option. This has been especially useful for moving and taking my collection to display for special events. Ultimately display is personal preference and there are many more options than the ones I have highlighted – just don’t forget the information labels!

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Specialisation. When you first start collecting a fossil shark tooth is a fossil shark tooth and you simply collect whatever you can. As your collection grows however you can find that your collection may become unwieldy and you may need to specialise. What you specialise in is entirely personal preference and what you find most interesting. It could be a particular family, a particular locality or a particular geological age or something else entirely. Your interest may even change over time. I have found myself being drawn to the smaller sharks and especially the catsharks or Scyliorhinidae so for the foreseeable future this is where my collection will begin to focus.

 

Source. Where do you acquire specimens from? Like I said I started with just a few specimens from a local fossil shop but most fossil shops will stock only two or three species and often with poor locality information. If you are lucky enough you may live near a local fossil hunting site. In the UK there are many good hunting grounds including Bracklesham Bay, Burnham-on-Crouch, the Isle of Sheppey and others. It is wise to do a little research online to find if you can collect fossils close to your location and www.ukfossils.co.uk is a great place to start. Just remember to collect safely, check tides if appropriate and always ask the landowners permission before collecting.

If like me you live far from good collecting areas then purchasing over the internet is the best option. I’ve listed a few great internet resources at the end of this blog. A word to the un-initiated. Be cautious if you are purchasing shark teeth through online auction sites. There are some good dealers that sell this way but specimens often come poorly labelled or with little information. That said some items are often mislabelled and if you are prepared to do some research you can often pick up a bargain, purchasing a rare specimen labelled as a more common one. You have to know what to look for though. Alternatively there are many excellent established dealers with their own websites (see the foot of this blog post). Fossil shark teeth vary in price depending on species, quality, locality and rarity. You can pick up some specimens for just a few pounds each or you could buy a seven inch pristine Carcharocles megalodon tooth for upwards of ten thousand pounds so there is something for every budget.

Joining forums is another great way to acquire material too. Often other collectors will offer to swap specimens and it’s also a great way to learn new things and meet new people. There are some very knowledgeable and generous people to be found on online fossil forums. Just remember they are a community however and you have to give something back.

 

Collecting shark teeth is a great way to learn about the evolution of these fascinating animals as well as venture into scientific disciplines such as palaeontology, marine biology and even museum curation! I would encourage anyone with an interest in sharks to give it a go.

Don’t forget to follow my Twitter feed as each day throughout June I’ll be highlighting a specimen from my collection.

 

www.buriedtreasurefossils.com – One of the most comprehensive dealer websites stocking many top quality and rare species.

www.megalodonteeth.com – A great, easy to navigate site run by a very friendly dealer. A good place for beginners and experienced collectors.

www.lowcountrygeologic.com – A well-presented site with a good selection of species.

www.fossiliferous.co.uk – A fantastic UK based site run by a very friendly dealer. He collects all material himself so every specimen comes with excellent information.

www.heskensfossils.nl – Some unique and rare specimens.

www.ukge.com – Excellent source of collecting equipment and display material.

Current research

My current research is focussed on developing molecular markers for deep water sharks and is being conducted at Edge Hill University with fellow early career researchers David Goodson, Thom Dallimore and Carl Barker. Deep water sharks are poorly understood relative to their shallow water counterparts but are often even more vulnerable to anthropogenic pressures. Deep water fishing fleets are increasing in size every year and it is well known that many deep water sharks aggregate in single sex or age cohort groups meaning a single trawl can have a very significant impact to localised populations. It is vital that we understand more about these deep water species in order to effectively manage conservation efforts. Key to this understanding is knowledge on population structure and connectivity. The vital first step on this road is the development of molecular markers to enable comparisons.

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The shark samples I am working on all come from the Rockall Trough, an area of deep water off the coast of Scotland, and were collected whilst on board the FRV Scotia during a Marine Scotland deep water survey. I am principally targeting the sharks Galeus melastomus and a selection of sharks from the genus Apristurus, including some additional samples very kindly supplied by Dr Ana Verissimo of CIBIO – University of Porto. I am also attempting to replicate the excellent work completed by Helyar et al (2011) who developed microsatellite markers in Centroselachus crepidater. Whilst initial thoughts were to jump straight to population examination through the use of Amplified Fragment Length Polymorphisms (AFLPs) we were encouraged to attempt to develop microsatellite markers by Dr Jim Provan (Queens University Belfast) whilst presenting a poster at the BES Ecological Genetics Group 59th Annual Conference. With his guidance that is exactly what myself, fellow Technician David Goodson and PhD students Carl Barker and Thom Dallimore are now attempting. Please follow me on Twitter for updates and other exciting Marine Vertebrate news.

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Helyar, S., Coscia, I., Sala-Bozano, M., & Mariani, S. (2011). New microsatellite loci for the longnose velvet dogfish Centroselachus crepidater (Squaliformes: Somniosidae) and other deep sea sharks. Conservation Genetics Resources, 3(1), 173-176.

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The origins of great whites

There is great debate within the scientific community with regards to the true ancestral origins of the modern White Shark Carcharodon carcharias. There currently exist two main hypotheses on the correct phylogenetic placement of C. carcharias. Both hypotheses talk in terms of sharing a more recent common ancestor with an extinct species (Smith 1994). The older of the two hypotheses suggests that C. carcharias is descendant from the ancestral lineage of megatoothed sharks such as Carcharodon megalodon and that the megatoothed sharks should be placed within the family Lamnidae. The more recent hypothesis suggests that C. carcharias is descendant from the ancestral lineage of the extinct Mako shark Isurus hastalis and that the megatoothed sharks should be separately placed within the family Otodontidae. It is important to be clear that neither theory suggests an absolute direct descendancy from the afore-mentioned species as the scarcity of fossil evidence could not support such a claim.

4cm tall Fossil Carcharodon carcharias tooth from Miocene (~20 million year old) sediments in the Atacama Desert of Chile. (Photo credit: Wikipedia)
4cm tall Fossil Carcharodon carcharias tooth from Miocene (~20 million year old) sediments in the Atacama Desert of Chile. (Photo credit: Wikipedia)

Proponents of the megatoothed descendancy hypothesis (Applegate and Espinosa-Arrubarrena, 1996; Gottfried et al., 1996; Martin, 1996; Gottfried and Fordyce 2001; Purdy et al., 2001) base their conclusions upon aspects of shared tooth morphology between the modern C. carcharias and principally the extinct C. megalodon. These similarities include: similar tooth morphologies between juvenile C. megalodon and adult C. carcharias; fine tooth serration in both adult C. carcharias and C. megalodon; shared chevron-shaped neck area on the lingual surface of the upper anterior teeth, a mesially inclined large intermediate tooth and second anterior teeth symmetry (Gottfried et al., 1996; Gottfried and Fordyce, 2001; Purdy et al., 2001). Under this phylogenetic regime the megatoothed sharks are placed within the family Lamnidae and retain their genus Carcharodon.

The evolutionary history of Carcharodon megalodon is well understood from a large quantity of fossil evidence including many transitional specimens. The direct ancestry of C. megalodon can be traced at least as far back as the late Pliocene in the form of the large mackerel shark Otodus obliqus although if Cretolamna appendiculata is considered a chronospecies then this ancestry can be extended into the Lower Cretaceous. O. obliqus had large non serrated teeth with distinctive side cusps. During the middle Eocene the side cusps of O. obliqus reduced in size and the edges developed slight serration. This Eocene species is classified as Carcharocles auriculatus. A massive increase in shark body size accompanied by further reduction in teeth cusps and increased development in serrated edges marks the introduction of Carcharocles angustidens during the late Oligocene. Carcharodon megalodon finally evolved from C. angustidens during the early Miocene and is characterized by a further increase in body size, further development in serrated tooth cutting edges as well as a complete loss of teeth side cusps. The megatoothed descendancy hypothesis suggests that the origin of Carcharodon carcharias is derived in a form of dwarfism of Carcharodon megalodon (Ehret et al 2009).

The Isurus hastalis descendancy hypothesis argues that owing to a shared overall tooth shape and labio-lingual flattening in tooth morphology in both the later ‘broad-form’ I. hastalis (specifically the suggested transitional fossil Isurus xiphodon as described by Purdy et al. 2001) and Carcharodon carcharias, the megatoothed sharks should be viewed as a distinct and non related taxon (Casier 1960). This phylogenetic regime would see the megatoothed sharks placed in the separate family Otodontidae, containing other extinct genera such as Otodus and Parotodus, with Carcharodon megalodon being renamed as Carcharocles megalodon (Casier, 1960; Glickman, 1964; Capetta, 1987). Proponents of the Isurus hastalis descendancy hypothesis also argue that not only are tooth serrations in the megatoothed sharks much finer than those found in C. carcharias but that megatoothed sharks teeth lack enameloid in the neck area whereas C. carcharias does not (Nyberg et al. 2006).

The evolution of Isurus hastalis itself is reasonably well documented in the fossil record. All Mako sharks can find their ancestry in the Eocene epoch (approximately 50mya) with the arrival of Isurus praecursor. During the Oligocene epoch a new Mako shark, Isurus desori, appears in the fossil record. Fossils of Isurus desori are found to be almost cosmopolitan in their distribution and it is from this species that Isurus hastalis is likely to have evolved during the early Miocene. Initial forms of Isurus hastalis are relatively small and considerably longer than their width, thus these initial forms are often referred to as ‘narrow-form’ with later examples being referred to as ‘broad-form’ as their width increases in the mid to late Miocene (Alter 2013).

Casier (1960) makes suggestion of a possible transitional fossil in Isurus escheri where teeth were found to show slight fine marginal serration. Isurus escheri inhabited the waters of the Atlantic Ocean around the mid Miocene (approximately 10mya) and likely derived from the ‘narrow-form’ Isurus hastalis. Unfortunately it would appear that Isurus escheri would be an evolutionary dead-end as fossil evidence of their existence disappears within just a few million years.

True Carcharodon carcharias fossils with all modern characteristics represented have been dated back to the late Miocene with specimens being recovered from California, Maryland and Japan showing that by this time C. carcharias was already thriving across the Pacific and Atlantic Oceans (Gottfried and Fordyce, 2001; Stewart, 1999, 2000, 2002; Hatai et al., 1974; Tanaka and Mori, 1996; Yabe, 2000). A fossil recovered from Peru and described by Muizon and DeVries (1985) was suggested as another transitional fossil in favour of the Isurus hastalis descendancy hypothesis on account of weak tooth serrations but this evidence is countered by Purdy (1996) and Purdy et al. (2001) who observe that this fossil (known internationally as the Sacaco sp. on account of its discovery in the Pisco formation of the Sacaco basin, Peru) is predated by the aforementioned C. carcharias discoveries.

Based upon the simplified evidence presented it would seem that the decision is of only two possible phylogenies. It seems this view is now over-simplified as new fossil and genetic evidence (Martin 1996; Martin et al 2002) shows that the Carcharodon lineage may have split from that of the Mako sharks much earlier than suggested here and that Isurus was not in fact a true Mako but truly of the Carcharodon lineage and should therefore be placed in the genus Cosmopolitodus to indicate as such (Glikman 1964).

For now there remains great scope for research into the ancestry of Carcharodon carcharias and it is likely that debate over the matter will continue for decades to come.

 

 

In addition to the literature cited below I would refer the reader to an excellent online article by Steven A. Alter based on his many years as a collector/dealer:

http://megalodonteeth.com/origin-of-the-modern-great-white-shark

In addition to the many excellent articles published online by Jim Bourdon at:

http://www.elasmo.com/

 

 

Cappetta, H. 1987. Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii; in H.-P. Schultze (ed.), Handbook of Paleoichthyology. Volume 3B. New York, NYVerlag Dr. Gustav Fischer193 pp.

Casier, E. 1960. Note sur la collection des poisons Pale´oce`nes et E ´ oce`nes de l’Enclave de Cabinda (Congo). Annales du Muse´e Royal du Congo Belge (A.3) 1, 2:1–48.

Ehret, D. J., G. Hubbell, and B. J. Macfadden. 2009. Exceptional preservation of the white shark Carcharodon (lamniformes, lamnidae) from the early pliocene of peru. Journal of Vertebrate Paleontology.  29:1 1-13.

Glickman, L. S. 1964. [Sharks of the Paleogene and their Stratigraphic Significance] . Nauka Press, Moscow: , 229 pp. [Russian].

Gottfried, M. D., and R. E. Fordyce. 2001. An associated specimen of Carcharodon angustidens (Chondrichthyes, Lamnidae) from the late Oligocene of New Zealand, with comments on Carcharodon interrelationships. Journal of Vertebrate Paleontology 21:730–739.

Gottfried, M. D., L. J. V. Compagno, and S. C. Bowman. 1996. Size and skeletal anatomy of the giant “megatooth” shark Carcharodon megalodon; pp. 55–89 in A. Kimley, and D. Ainley (eds.), Great White Sharks: the Biology of Carcharodon carcharias. San Diego, California: Academic Press.

Martin, A. F. 1996. Systematics of the Lamnidae and origination time of Carcharodon carcharias inferred from the comparative analysis of mitochondrial DNA sequences; pp. 49–53 in A. Kimley and D. Ainley (eds.), Great White Sharks: the Biology of Carcharodon carcharias. San Diego, California: Academic Press.

Martin, A. F., A. T. Pardini, L. F. Noble, and C. S. Jones. 2002. Conservation of a dinucleotide simple sequence repeat locus in sharks. Molecular Phylogenetics and Evolution 23:205–213.

Nyberg, K. G., Ciampaglio, C. N., and G. A. Wray. 2006. Tracing the ancestry of the great white shark, Carcharodon carcharias, using morphometric analyses of fossil teeth. Journal of Vertebrate Paleontology 26:806–814.

Purdy, R. 1996. Paleoecology of fossil white sharks; pp. 67–78 in A. Kimley, and D. Ainley (eds.), Great White Sharks: the Biology of Carcharodon carcharias. San Diego, California: Academic Press.

Purdy, R., Schneider, V. P., Applegate, S. P., McLellan, J. H., Meyer, R. L., and B. H. Slaughter. 2001. The Neogene sharks, rays, and bony fishes from Lee Creek Mine, Aurora, North Carolina; pp. 71–202 in C. E. Ray, and D. J. Bohaska (eds.), Geology and Paleontology of the Lee Creek Mine, North Carolina, III. Smithsonian Contributions to Paleobiology no. 90.

Smith, A. B. 1994. Systematics and the fossil record: documenting evolutionary patterns. Blackwell Scientific Publications, Oxford, England.

Stewart, J. D. 1999. Correlation of stratigraphic position with Isurus-Carcharodon tooth serration size in the Capistrano Formation, and its implications for the ancestry of Carcharodon carcharias. Journal of Vertebrate Paleontology 19(3, Supplement):78A.

Stewart, J. D. 2000. Late Miocene ontogenetic series of true Carcharodon teeth. Journal of Vertebrate Paleontology 20(3, Supplement): 71A.

Stewart, J. D. 2002. The first paleomagnetic framework for the Isurus hastalis-Carcharodon transition in the Pacific Basin: The Purisama Formation, Central California. Journal of Vertebrate Paleontology 22(3, Supplement):111A.