Susan Hoi: A Glimpse of Prehistoric Thailand

 

This was what prehistoric Krabi looked like- a typical tropical freshwater swamp dominated by Nipah palms, Nypa fruticans. Photographed in Kuala Selangor, Malaysia.
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Noon at Krabi, Thailand. The fierce sun beats down on a still swamp. Humid whiffs of air from deep peat wind their way out of sturdy intermingling roots of swamp plants. The plants jostle and crowd for every space available in between to capture the glaring sun light for their photosynthetic leaves. Their verdant swaying fronts in the midday breeze capture the flickering reflections of sunlight from a large pool of water nearby. The rippling surface of the water stretches quite a distance, lapping on the mud banks on the other side of the slow meander. Looking down at the shallows, beneath the drifting of faint silt in tea-coloured water,  hundreds, if not thousands of wriggling and crawling snails made their way slowly across the silty bottom. Typical scene in this region of mud, water and mangroves, you might say. Except that the snails are not living in mangrove forests and the water is fresh. And most importantly, the time is some millions of years ago...

 

The signboard welcoming us at the entrance.

"THE WORLD MOLLUSC FOSSIL SITE-KRABI-THAILAND" displays the signboard welcoming us. The time is 5pm and the sun is dipping silently into the Andaman Sea to the west. The rays, although still casting its golden shine on Krabi's coast, is no way near its fiery midday equivalent. We held our breath. Cramming in a van for 3 excruciating hours from Phuket to Krabi with a driver that drives more like a jet pilot have us fatigued. We are only too eager to burst out of the van and indulge in something more productive, fulfilling. The van finally pulled over a car park lined with stores selling typical seashell souvenirs. There's no doubt what this place is famous for!

The information plaque for Susan Hoi.

Rocks surrounding the two headlands of Ban Laem Pho are the centrepieces of this unusual attraction. (image from Google Earth)

Susan Hoi Jedsibhalanpi or more accurately known as Susan Hoi literally means "seventy-five million years old shell cemetery". You might be wondering how did they found out the age of the shells but I'll come back to that later. Located 7km south of Krabi town at the jutting headlands of Ban Laem Pho coast, Susaan Hoi is a collection of 3 geological formations containing fossilised freshwater shells numbering in the millions. Although inconspicuous and insignificant from afar, the rocky capes are wonders in themselves. It is thought that this geological curiosity is among the only sites around the world, the other being in Japan and the US. This statement is doubtful since there are many fossilised shell beds (shell assemblages) including a recent discovery in Mae Moh coal deposits of northern Thailand, also of freshwater origins. Closer to home, Krabi itself boasts another site in a coal mine with the same layer of fossil freshwater shells believed to be from the same formation as Susan Hoi's.

Tens of thousands of fossil shells cover the entire rock layer.
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A detached slab showing the thick deposit of fossil shells.

This brings us to the questions: What exactly is the Susan Hoi formation? and how old is it? Let's answer the latter, for a start. Susan Hoi is, admittedly, not seventy-five million years old. The naming error stems from an old assumption that Susan Hoi comes from the Tertiary period, where the 75 million years ago period is located. It is younger, though no geologists have come to terms with its exact date yet. Primarily, there are two camps when it comes to dating these fossils. On one side, scientists who analysed ancient pollen grains deposited along with the fossil shells concluded that Susan Hoi could only be between early and mid-Miocene (that is, between 23.03 and 5.33 million years ago). On the other hand, paleontologists discovered fossilsed fishes and turtles in the deposits dating back to the Eocene period (56 to 34 million years ago). With such conflicting claims, no dating consensus can be made save the error of the 75 million years old phrase. However, what is more definite can be found in the study of the evolution of the environment leading to Susan Hoi's formation.

Slabs of hard fossil rich rocks break and collapse onto the beach as waves washed away softer deposits around it.

Cracks form across the fossil shell bed as a result of endless weathering from wave action in this dynamic coast.

Waves have been pounding hard on the Susan Hoi's rocks for millenia. In the process, softer deposits and the topsoil layers have gave way and washed down into the sea, leaving the more sturdy layer of fossil shells (a.k.a. shell matrix) jutting out of the formation. Eventually, prolonged weathering cracked the exposed matrix and they collapsed to a pile of giant slabs. In such an event, sections of the entire formation can be seen from a cliff face, especially the more exposed parts of the capes. This gives geologists opportunities to study each layer of rock and interpret them.

Lignite (coal) mixed with clays and fragments of Viviparid snail fossils found beneath the rock layer.

Beneath the shell layer, geologists found a dark band of lignite (better known as coal) interspersed with shale and clay and even some Viviparid snails-indicating an ancient freshwater swamp. Some plants living among its watery habitat, often shed its leaves, while other that died  collapse into the water. These organic material decompose and sink into the depths of the swamp, eventually compressed by the pressure of water and soil deposits above. This compressed layer then becomes lignite. Clay and shale, meanwhile, had their origins as silt and sand washed down from the interior and settled between the dead plants in significant quantities. To produce such thick deposits of silt, one may imagine huge amount of rain battering down on mountains and river banks. In other words, southern Thailand might have been tropical even before Susan Hoi's formation! (Not that this is strange, it is just that climate and environment of the past in many places differ significantly from today's.) Indeed, fossil pollen analysis indicate tropical plants thrive during that period.

As sea levels began to rise, saltwater incursion occurs across the Krabi floodplain, aiding the spread of brackish water habitats, followed by the more salty mangrove wetlands. Pictured here is the floodplain as seen from the limestone peak at Wat Tham Suea.

 

One of the mangrove plant species is the Rhizophora sp., seen here in present day Krabi.

 

This freshwater swamp, however, disappear completely after several million years. It is then that the shell bed enters the scene. Apparently, salt water had begun to invade the freshwater swamps, leading to the formation of brackish water habitat instead. Brackish water simply means a mixture of salt and freshwater. This means death to the previous occupants including the freshwater swamp plants, hence the absence of lignite in the shell beds. The disappearance of the freshwater plants allowed the growth of certain algae, which in turn allowed molluscs to thrive. Typical swamp molluscs such as Viviparid snails, Melanoides snails and Mya arenaria clams began to appear in profusion. The algae increase heighten activities of grazing and filtering decomposed materials. Sand and silt continued to deposit along with the mollusc shells. This goes on for several million years. by then, the shell and silt became cemented and formed a 1m thick deposit.

 

Typical brackish water habitat supports a large specialised molluscan community as seen in this example in Pulau Tioman, Malaysia.

 

The fossilsed Viviparid snails (family Viviparidae), Taia sp.(?), bounded by clay.

 

Another species present is the smaller, tall spired Melanoides sp. snails (family Thiaridae).

Peculiarly, this shell deposit stopped short of continual growth and was obliterated by a thick layer of sand, clay, gravel and red laterite! What happened? What occured to the swamp...and the snails? Some people speculate that this may be a result of a severe storm which carried tonnes of earth from upstream and dumped them onto the riverine community. Others said it could be a sudden geological uplift of the floodplain, draining out all the swamp water. Or is it? Either way, the entire swamp ceased to exist. This was replaced by the dryland rainforest which grew on the firm earth burying the shell deposits.

 

As weathering continues, exposed fossil shells will erode. Here the severity of erosion is shown by the reduced striation features found on the Viviparids as compared to the previous two pictures.

 

As erosion continues, even the shape of the shells began to look indiscernible.

 

Fossil casts of the freshwater Viviparids embedded in red clay exposed as erosion rounded the fossil -rich pebbles.

As time passes, the coast gradually crept back towards the shell beds. Wave action have been breaking up all the soil and rocks between the sea and shell deposits. finally, the sea is now lapping once again at the doorstep of the ancient swamp fossils.

Rocks less exposed to wave action produce more pronounced details of the ten of thousands of ancient freshwater shells.

Paradox in this dynamic coast: 

Where the old (fossils) meets new (the orange nerite snail, Nerita chameleon (Linnaeus 1758) )

Paradox in this dynamic coast: 

Where the old (fossils) meets the young ('spiral' eggs belonging to an unidentified species of mollusc)

 

Paradox in this dynamic coast: 

Where the primitive (fossil snails) meets the advanced (an Onch Slug, family Onchidiidae)

As I stand on the cape, gazing out to the Andaman, I contemplated Susan Hoi's eventual fate. The final rays of sunshine touch gently on broken pieces of fossil rocks illuminated by saltwater spray from relentless pounding of waves down at the waterline. It was such a brief exposure, in geological time, that has afforded us an opportunity to reveal the amazing history of this natural wonder. I knew that, very soon, the shell cemetery will be no more. Mere pebbles rolling beneath the waves, ever breaking into smaller pieces, ending back into the sea, just like a few million years ago.

Sunset over Susan Hoi.

Useful further reading:
1. Udomkan, B, Ratanasthien, B, Takayasu, K, Fyfe, WS, Sato, S, Kandharosa, W, Wongpomchai, P and
Kusakabe, M 2003, 'Fluctutaion of Depositional Environment in the Bang Mark Coal deposit, Krabi Mine, Southern Thailand: Stable Isotope Implication', ScienceAsia, vol. 29, pp. 307-317.
Link: [http://www.scienceasia.org/2003.29.n4/v29_307_317.pdf]

2. Watanasak, M, Songtham, W, Mildenhall, D 1995, 'Age Of The Susan Hoi (Shell Fossil Cemetery) Krabi Basin, Southern Thailand', International Conference on Geology, Geotechnology and Mineral Resources of Indochina (Geo-Indo '95), pp163-168. Link: [http://library.dmr.go.th/library/7427.pdf]

3. Boonchai, N, Grote, PJ and Jintasakul, P 2009, 'Paleontological parks and museums and prominent fossil sites in Thailand and their importance in the conservation of fossils' in Paleoparks- The protection and conservation of fossil sites worldwide, ed JH Lipps, BRC Granier, Brest, Book 2009/03, Chapter 7. Link: [http://paleopolis.rediris.es/cg/CG2009_BOOK_03/CG2009_BOOK_03_Chapter07.html]

The Patamakanthin's Shell World-Sharing the Love of Shelled Molluscs

It is a sweltering noon on Christmas Day in Phuket's newly opened Jungceylon Shopping Mall, located in the tourist district of Patong Beach. Rows of upper-end coffee shops and retail outlets line both sides of the open air, street style mall. The air is thick with celebratory music blaring from the loudspeakers of a nearby fashion and design show. Coupled with the endless crowd moving across the plaza in all directions, one might wonder why I would be interested in this highly anthropogenic environment. But I am here because of a very special person, a person that has been on my must-see list for years.

"Welcome to Phuket!" exclaimed Jom Patamakanthin, as he let us (my family and me) into his golden-bronze Isuzu 4WD. Fresh from a busy schedule of meetings and office work,  Jom has made extra effort to personally pick us up from our hotel to his museum. Earlier on, he has even arranged the hotel's room prior to our arrival in Phuket! Surely, he must be packed full of enthusiasm to welcome us with such kind hospitality! And as I discover later, what brimful of enthusiasm he has!

Born to a father who treasures every piece of shelled-mollusc and a mother who relentlessly encourages him to pursue his interests, Jom is literally given the position to hold the baton as one of Thailand's leading shell expert. Jom's father, Somnuek Patamakanthin, has been the household name in not just shell-collecting circles but also in the fields of conchology and malacology within and beyond the shores of Thailand. This is due to his interest in shell collecting since he was a child, 50 years ago. His helpful and friendly nature has enabled him to exchange shells with like-minded hobbyists as well as donating his specimens to scientists for research purposes. It is such rare opportunity that has allowed him to bridge the often divisive gap between marine scientists and shell collectors. In fact, Somnuek's contribution extends beyond science and hobby.

"You see the logo up on that building?" Jom pointed to a large shopping centre while driving through the central Phuket region, "That's Stellaria solaris, the Sunburst Carrier Shell," he revealed. Jom related that few years ago, his father generously borrowed the designer of the Central Festival Shopping Centre many of his shell books to draw inspiration for the mall's logo. Besides the logo, Somnuek's generosity has also given the designer ideas on the mall's interior decor.

Of course, there's no doubt that Jom has been heavily influenced by his father. Being a self-taught scholar with a peculiar taste for an unorthodox way of learning, Jom has surprised his peers with his high academic results. "People kept asking me," Jom recalled, " 'Hey Jom, how do you study in such a crowded place?' ", referring to his favourite haunt- the shopping malls. "Focus..... and commitment," Jom quipped with a smile.

Perhaps that is the philosophy that is fueling his enthusiasm in shells. Jom has been exposed to the world of shells since childhood but it had never occurred to him that it will play a big part of his life soon. The moment came when Jom was introduced to the shell trade and exchange arena in his early teenage years. "It is the moment that I said to myself 'This is my future!' " Jom remembered. He started to extend his social circle into both the shell-enthusiasts and the scientific community, mirroring his father's move. In the years since then, Jom and Somnuek have their names honoured by having many new species and subspecies named after them, such as Conus patamakanthini (Delsaerdt 1997), Alycaeus somnueki (Panha & Patamakanthin 1999), Haliotis ovina f. patamakanthini (Dekker, Regter & Gras, 2001) and Epitonium patamakanthini (Gittenberger & Gittenberger, 2005).

But arguably the biggest contribution the Patamakanthins have on the molluscan world is the Shell World, a collection of museums that house tens of thousands of species of shelled molluscs, ranging from the downward minuscule to the goliaths of shells. Having spent years exchanging specimens and information between friends, the father and son decided to shift their paradigm to a new level- to bring the world of shelled molluscs to the general public. Utilising their enormous wealth of specimens from their collection, they laboriously studied and prepared thousands of exhibits.

In November 1997, Somnuek founded the first private shell-museum in Thailand (and probably the only one in this part of the world) with his brothers and sisters. Located in the popular Rawai district of Phuket, the Phuket Seashell Museum made waves across the world's mollusc-loving community. It has earned the praise of many as being among the best private and shell museum in the world. Not long after, Jom endeavoured an ambitious plan to extend his family's enterprise by establishing another shell museum in the popular resort island of Sentosa, Singapore. He spent many days designing and outlining the exhibits for his future museum. Alas, his plan collapsed due to difficulties with land issues. Not intending to back down, he started anew back in his country. Along with his shell-collecting friend, Ms. Oraphin Sirirat, Jom established the Bangkok Seashell Museum. By now, the Patamakanthin's labour of love have been recognised by many who had visited and been awed by their treasured collection.

Recently, Jom announced that he will continue to seek new locations fit for more shell museums, which led me to one question everyone's eager to find out: Why build so many shell museums? To that, Jom answered with such down-to-earth honesty and humility, "I'd like to share my knowledge with everyone......and to make and meet new friends along the way."

The entrance to Jom's newest shell museum in the newly opened Jungceylon Shopping Mall, Patong, Phuket. Note the gate's design is inspired by the spider conch, Lambis sp.

The sheer number of species and specimens on display easily outnumber an exhaustive list of superlatives fit for describing it!

The museum display starts with the nolluscs of a bygone era, such as this precious assemblage of Morroccan Nautilus, Cenoceras sp.

The multitude of fossil molluscs in display is an accumulation of specimens from years of exchange with friends from all across the world.

Looks like the shell museum has plenty to satisfy aspiring paleontologists too, with ammonites from various ages.

Jom also has a collection of curious marine-life encrusted objects. "Sometimes, beauty comes in unexpected forms," he said.

Even a collection of all known species and subspecies of present day living nautiluses (the "living fossils") are on display, many of them rarities such as Nautilus macromphalus (Sowerby 1849) and Allonautilus scrobiculatus (Lightfoot 1786).

Even rarer than nautilus, the slit shells (family Pleurotomariidae) is another group of living fossils dating back to more than 500 million years ago. the "wow" factor here is: the sheer number of specimens (and species) on display.

Sitting on the pinnacle of the slit shell section are these two giants-where old meets new. On the left is the world's largest living species, Entemnotrochus rumphii and on the left, a fossilized pleurotomarid.

Jom recalled that his friend found this extremely well-preserved fossil in a French limestone formation many decades ago. He had been waiting for the right time and technology to appear before extracting the shell from the limestone. With cutting edge 21st Century technology, he employed professional jewellery craftsmen to laboriously chip out the deposit and polish the fossil.

Jom also has a keen eye on any variations within a species, bringing seemingly common species such as these Trochus niloticus into new light. he even has a subfossil of the species (on the bottom right corner) unearthed from Phuket itself!

Turbans and Stars (shells, that is) of many species on display.

Arguably, the show-stealer of the day would be this amazing rotor blade-like variant of Angaria sphaerula (Kiener 1839).

The striking colours of so many scallops (family Pectinidae) on display baffles even the most seasoned of shell admirers.

A closeup of the candy coloured scallops of Lion's Paw, Nodipecten fragosus (Conrad 1849).

A mountain of spectacular thorny oysters, Spondylus versicolor (Schreibers 1793).

Another eye-popping spectacle is this metres high pile of Squamose Giant Clams, Tridacna squamosa. In case if you're wondering where on earth did Jom manage to get this much, this pile is retrieved from a collective number of decades-old shell middens (the place where shells are dumped after meals) along many of the Andaman coastal villages with the permission of Thailand's Fisheries Department.

A beautiful collection of porcellanous Turbinella fusus, the much rarer cousin of the Indian Chank, Turbinella pyrum.

Frogs (family Bursidae) and Tritons (family Ranellidae) are among the group of giants on display.

Comb murexes are one of those iconic shells that often graze beach-themed advertisements.

Jom even has a collection of large abalones (family Haliotidae) including the famous Californian Red Abalone, Haliotis rubra.

Bonnet shells (family Cassidae) displaying the multitude of species within its family.

The museum isn't just home to any shells. Many of its exhibits are in fact rare and endemics, euch as these "Glory Cone Shells" which includes Glory of the Seas Cone, Conus gloriamaris (Chemnitz 1777); Glory of Bengal Cone, Conus bengalensis (Okutani 1968); and Glory of India Cone, Conus milneedwardsi (Jousseaume 1894), among others.

Another family of many rare and endemics, the volutes (family Volutidae) are well known among shell enthusiasts.

But perhaps the most popular of all shells is the cowries (family Cypraeidae). Seen here are the rarest specimens of all: the Zoila Cowries, Zoila ketyana (Raybaudi 1978) (centre bottom); Melanistic cowries (the dark tint is a result of living in waters tainted with heavy metals) (left and right) and the "King and Queen of Cowries", as Jom puts it, the rostrate (deformed, curved up) money cowries, Cypraea moneta (centre top).

Clams such as these are unexpectedly gigantic!

There's even a section dedicated to non-marine molluscs, an often overlooked part of the world of shells. Seen here are the unbelievably beautiful Polymita landsnails, Polymita picta (Born 1778). (far from those drab looking snails in your garden!) Underlying the aesthetics, this group of snails is among the best candidate for demonstrating variation's role in the evolution of species. 

More candy-looking landsnails- Indonesia's Asperitas and Chloritis (centre right) and Papua's Papuinas (bottom left).

Just like landsnails, freshwater clams like these (mostly of family Unionidae) demonstrate speciation (species formation) with their endless forms of variants.

But perhaps the most surprising of freshwater molluscs would be this seemingly thalassoid (marine like) freshwater snail Tiphobia horei from Lake Tanganyika, East Africa.

If you're interested in seashells, land and freshwater shells, fossils or any molluscs or even natural history itself, do drop by and visit the Patamakanthin's Shell Museums. You will be amazed! Here are the museum details at the time of publishing:

Phuket Seashell Museum 12/2 Moo 2, Viset Road, Rawai, Muang, Phuket 83130 THAILAND. Phone: 076613666 Fax: 076613777 (link: http://www.phuketseashell.com/main.php )

Bangkok Seashell Museum Silom Road (next to Soi Silom 23, opposite Lerdsin Hospital), Bangkok, THAILAND. Phone (Ms. Sirinthip): 08 9681 3814

Shell World Museum Jungceylon Shopping Centre, Patong, Phuket, THAILAND. 

(link: http://www.tourismthailand.org/what-to-see-do/sights-attractions/info-page/destination/phuket/cat/12/attraction/6013/parent/323/lang/0/ )

(NOTE: My special thanks to Jom for his kind help in bringing us to his museum and spend time chatting and introducing us to his beautiful collection. )