The wind was blowing from the east before sunup, and a faint predawn illuminated whitecaps on the bay. My plan for kayak fishing Isla Asunción had become out of the question. If the wind was already up before the sun, it was going to be windy all day.
Still, I’d come to Asunción — 500 miles south of Ensenada — to dedicate my time to fishing. So I decided to look for 50- to 60-footers: cetacean-eating sharks so massive and voracious that they made a major impact on the entire marine communities in which they thrived; sharks so omnipotent in their environment that when they disappeared some two and a half million years ago, the baleen whales they fed upon began growing larger — into the leviathans we see nowadays on whale watch tours. Megalodons would be my target.
Their teeth, anyway. Though most people here, both locals and expats, had advice on where to look in general, I wanted to increase my odds of discovery by learning which specific sediments on which to concentrate my search.
The earliest record of fossilized shark’s teeth is noted in Pliny the Elder’s Naturalis Historia, the first example of an encyclopedia. Pliny, who lived in first century Greece, thought that the triangular objects fell from the sky during lunar eclipses. During the Renaissance, they were thought to be the petrified tongues of snakes and dragons, and were called ‘tongue stones’. Thought to have an anti-toxicity quality, tongue stones were used in the treatment of snake bites and other poisonings. Some believed that tongue stones would ward off bad spirits, and thus they were made into pendants, worn for good luck. So it was that, though they had been noted for centuries, Italian naturalist Fabio Colonna was the first to correctly identify them as ancient shark’s teeth in the year 1611.
When megalodon existed, the earth was mostly covered in warm, shallow seas. The ensuing ice age pulled water to the poles, and in time, the sea level fell, oceans cooled, and shallow seas dried up. Megalodon’s demise was most likely due to lack of food sources and freezing ocean temperatures. The whales they co-evolved with were mammals that could thermoregulate and adapt to the cooler conditions. Unable to adapt and pursue their prey, it is widely believed megalodon starved into extinction.
Other than the bite marks left in the fossilized bones of their prey, the only remaining signs of the giant, cartilage-framed fish that can be found today are their teeth, vertebral centra, and rarely, fossilized feces. With so little evidence, there is ongoing debate about the habits and maximum size of megalodon, though it is generally believed they disappeared two and a half million years ago.
In the northwestern corner of the state of Baja California Sur, the remains of megalodon are found near mesas a few hundred feet above sea level, and usually miles inland.
Around five million years ago, the newly-formed Gulf of California waters extended north to near Palm Springs, and the San Diego area was on the peninsula of Baja California. Colorado River sediments, gouged out of the Grand Canyon, filled in a stretch of the upper portion of the gulf, blocking the ocean’s incursion into the northern end of the rift by creating a natural dam that separated the Gulf of California from the Salton Trough, the depression where the Anza-Borrego Desert and the Salton Sea now sit. (The Salton Sea’s surface is 226 feet below sea level.)
As the effects of ice ages and plate tectonics raised peninsular ranges and altered sea levels, the ancient sea floor pushed inland and upward along the peninsula. Over time, erosion carved out canyons and mesas, and today, what used to be hundreds of feet beneath the surface of the Pacific Ocean now sits high on canyon walls and on the tops of the mesas.
The mesa tops, which are composed of cemented shell, bone and rock, used to be ocean floor before the collision of the Pacific and North American plates along the San Andreas Fault raised the mountains to the west of the fault and ripped the rift valley that eventually sank, filled with water, and became the proto-Sea of Cortez, right along the fault line. I asked geology expert and San Diego State’s professor emeritus Pat Abbott about the seemingly fused material of the mesa caps, and the yellowish earth beneath.
His response: “The rock is not fused; it is cemented. The fossils are made of calcium carbonate (CaCO3), the principal component of cement. Many of the shells are made of unstable CaCO3 and they partially dissolve, and then precipitate as a whitish-color cement that binds the sediment into a rock (analogous to the white minerals around the faucets in your house). The yellowish material is not soil, it is sedimentary rock of sandstone and mudstone. Having sharks’ teeth and whale bones in them would not be a surprise.”
As the old seafloor-capped mesas erode and crumble to the valley floors, the bits of fossilized bone, shell, rock, and shark’s teeth are knocked loose from the sandstone beneath and strewn along the path. Over time, the mesa caps recede, the sandstone also erodes through the action of wind and rain, and more fossils are exposed. Therefore, the edges of the slides down to the base of the mesas is where I focus my attention when looking for sharks’ teeth and other fossils.
On my first couple of outings, I started looking along the big arroyos that cut deep into the soil and expose the old sea floor high on their edges a couple miles inland. I found some fossilized bone and tooth shards. It was enough to get my blood pumping, but I didn’t find anything truly remarkable. And searching the deep arroyos required a lot of hiking, as I generally parked on top where faint two-tracks allow vehicle passage, then walked into the depths of the canyon.
There is a long, deep arroyo inland from San Roque that runs mostly east to west. In such country, for me, a short walk can turn into a long one as the thought of discovery prods me on. In the desert (and especially with the dogs), one has to be mindful of water, so I carried extra bottles, which made the hike tougher. I wanted to find a vehicle-accessible area where I could spend more time looking for fossilized sharks’ teeth and less time carrying 15 pounds of water up and down canyons.
A sprained ankle or broken leg while far from people (and with a pair of dogs) can become a big issue, especially with insufficient water. Both dogs are rescues: Taz is only six months old and not yet too bright, but Flash, with his border collie roots and a lot of time logged in desolate areas, is smart as a whip. Still, miles from anyone, I wouldn’t count on him bringing folks back to me like Lassie saving little Timmy from drowning in the well. He’d more likely just stay with me or bound off, chasing his favorite quarry: jackrabbits.
With this in mind, I asked around. Friends advised that other good areas to look were the stand-alone mesas, everything around them carved away by floods, wind, and time. One such mesa a couple miles inland became my favorite spot. It sits aside one of the several crisscrossing two-tracks that line the valley floors between the hills, arroyos, and mesas.
The faint road was passible in the Jeep, so I could park at the base on the southern side and begin my search there without having to hike at all. There is fossilized bone scattered around the base and sides of the mesa, from bits and shards to arm-sized chunks. Most, if not all of these fossils, are from whales and other marine mammals. As megalodon fed primarily on whales, where there are fossilized whale bones, there is a chance of finding a megalodon tooth.
I eventually named the mesa for friends whose children love to hunt fossils. I met the family in Bahia Asunción and became excited about the prospect of hunting fossils from their many stories of finds in the canyon lands east of the coast. They didn’t give exact locations, but after finding several signs of people poking into the sloughed sides of this particular mesa, a few of their stories came to mind; especially one where they had exposed a large chunk of bone on a hillside of yellowish earth.
I found exactly what they described one day while on the far north side of the mesa, and realized I’d been mostly finding their original finds. It is illegal in Mexico to remove any fossils from where they are found, and though my friends that inspired me had kept no fossils, I’ll just call it ‘Johnson Hill’ to protect the innocent.
In my first few trips to Johnson Hill, I found quite a few smaller shark’s teeth and shards from larger sharks. Of the shards, I found a few that were so large that they could only have come from megalodon. One I found in two pieces side by side, and though it amounted to only a little more than the bottom half of a tooth, they weighed almost a pound combined. Its size and serrated edges confirmed the origin: megalodon.
Broken down by time, these two matching shards, found inches apart, came from a single large megalodon tooth.
Even though most of the shark tooth hunting in the Vizcaino Desert is done inland, the largest single piece I found was on the beach by an arroyo mouth. It was eroded by time and travel; the tip missing, the sides worn to a polished state, and very little enamel was left on it. But by size alone it was easily identifiable as a megalodon tooth: if whole, it would measure somewhere around six inches along the angle. In the shark tooth-hunting community, sharks’ teeth are measured along the edge from the root to the tip, and the largest megalodon tooth found to date is seven and a quarter inches. By comparison, the largest tooth from a modern great white shark is just under three inches.
As the sea floor beneath sea level today is relatively new and the layers of shell that line the beachside bluffs are only tens of thousands of years old, the large tooth from millions of years ago had apparently been loosened from the ancient sedimentary sea floor inland, washed down the arroyo over time, and come to rest in the shoreline sand. A recent south swell had exposed it on the beach, where I found it lying at low tide not two hundred yards from my rented house at the edge of town.
For all my time surf fishing in Bahia Asunción — much more than I spend fossil hunting — it is the only fossilized tooth that I have found on the beach. My theory of the tooth’s origination inland was reinforced when I found a fossilized whale bone on the same stretch of sand, polished flat and round like the river pebbles that are often dug out of beachside bluffs near arroyo mouths and sold as decorative landscape material.
A lot like fishing
Here is where looking for shark’s teeth is a lot like fishing. When you do find one, you tend to look harder and more thoroughly in that area. This often results in more finds, which reinforce the thought that it is a better area, and so returning to it becomes likely. It’s the same thing with fishing. What works once becomes the go-to, and when you mostly do that one thing, you tend to catch more fish doing that one thing than anything else, thus reinforcing what actually might not be true: “knowing: the best baits, locations, and methods per species targeted.
After all, if it works, why fix it? Why change? In fishing, the term ‘honey hole’ is often used for a personal favorite spot. It’s bad enough with fishing, but with fossils that do not reproduce or relocate in short order, one’s honey hole will eventually get fished out.
Even though prohibited by federal law, many fossil hunters cannot resist the urge to pocket a special find. I knew there was a general rule, but having plenty of signs of fossil hunters in the dessert, and seeing fossils for sale in shops and by street side vendors, I had questions about the specific laws governing the collection of fossils in Mexico.
Online, I found a bit of “cultural heritage” law translated into English, which “grants extensive protection of fossil vestiges or remains of organic beings that inhabited the national territory in past eras and... are of paleontological interest.”
The penalty for removing archeological or paleontological items may include fines in the tens of thousands of pesos and possible jail time. Non-fossilized marine mammal bones, coral, and shells are also protected by law in Mexico. Fossil hunting in Mexico is akin to fishing in that way, too: some fisheries are CPR — catch, photograph, and release — only. That this area is a part of the Vizcaino Biosphere Reserve only makes the crime worse, so CPR-only is my fossil-hunting rule while in Mexico.
On the more geologically-passive southeastern North American continent, some megalodon tooth hunters dive and search the depths of often turbulent and low-visibility rivers or in near-shore ocean waters. There, the land forms are much older — a result of much less upheaval and buckling of plate tectonics than in the west. Shark tooth hunting is a popular hobby on the southeastern coast, especially since a perfect large specimen from megalodon can sell for up to a couple thousand dollars.
Here in the desert, or anywhere on land, exposed fossils are subjected to the forces of nature and erosion will take its toll; peeling enamel, rounding off edges and breaking them down to bits and pieces. To find a near-perfect specimen, a little educated digging will usually have to be done, because while still in the sandstone and mudstone, the teeth are protected from erosion. When they swam the oceans, megalodon were distributed globally and their fossilized teeth are found all over the world. Many are unearthed during road or construction projects or found along the seashore, but the majority of those found in excellent condition have been found underwater by divers specifically targeting megalodon teeth.
That those found underwater are usually found in visibility conditions measured in inches often makes fossil diving a dangerous hobby. Vito Bertucci, of Long Island, one of the most famous of the megalodon tooth divers, found so many that he was able to construct a complete replica of a megalodon jaw containing 182 fossil teeth, including four of the largest shark’s teeth ever found. The jaws were modeled after a modern great white by scaling the tooth and jaw relativity. The finished replica was nine-and-a-half feet high by eleven feet wide and had four rows of teeth. Though the paleontological community generally agrees on somewhere between 50 and 60 feet as the maximum length of megalodon, Bertucci’s model suggests 70 to 75 feet.
Most of the teeth and other fossils Bertucci found were in water so cloudy that in many cases only a tiny area under his dive light could be seen. Adding to the danger, the underwater locations usually searched are depressions full of debris — old crab traps and floats, tree branches, nets, and other potential hazards. Vito ‘Megalodon Man’ Bertucci died at the age of forty-seven in 2004 when he drowned while diving for fossils in the intercostal region of the Ogeechee River, a ‘blackwater river’ that runs from central Georgia to the Gulf of Mexico. A bag of fossilized shark teeth was found attached to his dive belt.
I am not a diver or fossil-hunting pro like the late Bertucci, though in the desert I do find visibility a common factor with those looking in murky water. When it comes to finding shark’s teeth on land, the closer I get my middle-aged eyes to the ground, the better. Fossilized bone and large shards of teeth can be seen easily enough when walking upright, but smaller shards and whole teeth from smaller sharks require stooping or even crawling along to increase the odds of discovery. Most of the area is small rocks mixed with bits of decomposing shells that often look a lot like a tooth from a distance of a few feet, and crawling there is hard on the knees.
One friend advised going upslope in a sitting position, scooting along and searching the less steep shoulders of the mesas and arroyos. I tried that a couple of times, but the dogs thought it was the initiation of play and I find roughhousing with two dogs on a sloughing hillside not too pleasant a game. The stooping tedious on my old carpenter’s back, and the crawling hard on the knees, I used an old claw hammer as a short cane to aid in the hunt. This way, I could get my eyes close to the ground with a little support. Stooped far over like a cartoon spinster with my 16-inch hammer-cane, I started finding more teeth.
As I had jumped the gun and collected quite a few shark’s teeth and bone fossils before checking Mexico’s specific laws concerning fossil hunting, I was glad that I stuck to mostly searching one small area. I could return my collection to the ancient soil pretty much where they were discovered near ‘Johnson Hill’. The area has been restocked, and though I am often tempted to keep a find, the thought of a hefty fine and jail time in Mexico outweighs the desire to keep it. Usually, that is. I recently found a very rare fossil that I had been searching for with no luck; a whale rib bone with markings consistent with a shark bite.
The nine-inch chunk of fossilized rib had two distinct oblong holes and opposing gouges that I wanted to study with a magnifying glass under better light. I also found a piece of a shark tooth nearby that fit the holes almost perfectly. I wanted a photo of that after a little bit of cleaning. I marked the spot, took both finds home, brushed out and examined the holes, and snapped a few photos. I returned the fossils on my next fossil-hunting trip out to the mesa.