A Rare Florida Exposure Once Known Only Through Drilling

We are no strangers to shark teeth. Rick grew up hunting fossils in Venice, Florida, often called the shark tooth capital of the world, and has been searching for teeth since before he could walk. Henry found his first tiger shark tooth in the surf of St. Pete Beach, Florida when he was just 7 years old and has it to this day. Over the years, we have explored Florida's fossil-rich rivers, including the Peace, Myakka, Suwannee, and Steinhatchee, as well as remote creeks, Bone Valley mines, construction sites (with permission), and other hard-to-access locations in search of ancient life. In 2019, Rick and Henry located a scientifically significant paleontological vertebrate site, turned it over, and donated a massive collection of Columbian Mammoth fossils to the Florida Museum of Natural History.

Seven years ago, another Dig Dive Discover team member, Derek Demeter, avid fossil hunter and astronomer for Seminole State College of Florida, stumbled upon a rare find in a private creek.

As Derek began to work an interesting clay that outcropped every so often in the creek, he noticed two unusual things. First, the teeth were stunning. The state of preservation was unbelievable as they were being mined in situ and not naturally eroded, but he also noticed they had a pearlescent feature. The enamel was almost translucent with a high gloss and brilliant chatoyance. The colors were notable, with a range similar to Bone Valley or Gainesville, featuring stunning whites, gunmetal blue, and beautiful shades of honey and amber.

He hunted the teeth for several months before inviting Rick and Henry to the site, where another discovery was made. The clay produced some fossils that should, by all rights, should not be exposed in Florida.

Teeth like angustidens began to point to an Oligocene layer, something extraordinary in Florida. While these fossils are known from South Carolina's rich Oligocene deposits, finding them here is remarkable, as this layer lies deep underground across most of the state and is typically accessible only through core sampling.

Derek set out to understand the exposure, working with museums and researchers to learn more about the layer and its unusual fossils. Analysis revealed exceptionally well-preserved teeth preserved within a decayed, phosphate-rich clay. Many are stained fiery red by iron oxide, while others range from lavender and blue to pearl white. The teeth are primarily composed of fluorapatite, the standard replacement mineral in fossil shark teeth, but the clay contains unusually high concentrations of silica. Some specimens are believed to contain traces of opal and agate, occasionally displaying a remarkable translucency when held to the light. Gypsum crystals within the layer suggest periods when ancient sea levels dropped and the deposit was exposed to the air, adding yet another clue to the story of this remarkable site. After several more years of research, Derek provided some more details.

A Nursery for Giants

Derek Demeter

The site itself appears to have been a sheltered, shallow-water environment, perhaps an estuary, bay, or coastal lagoon where juvenile animals congregated. Rays, sharks, barracudas and other bony fish, dugongs (related to today's manatees), sea turtles, and even a rare genus of early dolphin known as the Squalodontids have all been recovered here.

Squalodontids were toothed whales that lived during the late Oligocene into the middle Miocene, about 28 to 15 million years ago, and were likely distributed throughout warm waters worldwide before going extinct with no living descendants. Sampling conducted with the University of Florida's Department of Paleontology has confirmed the presence of several species known only from Oligocene and early Miocene deposits.

The crown jewel of these finds is Otodus angustidens, the direct ancestor of the legendary Otodus megalodon. O. angustidens represents a key evolutionary stage in the lineage of giant prehistoric sharks, living during the Oligocene epoch approximately 33 to 22 million years ago and known for its large triangular teeth, sharp serrations, and distinct lateral cusplets. Oligocene formations are among the defining environments for this species, and its presence in Florida is remarkable. The abundance of angustidens teeth at this site, typically small and broken, strongly suggests this was a place where juveniles regularly fed and shed teeth. This interpretation aligns perfectly with what scientists have documented elsewhere: in the Oligocene Charleston Embayment of South Carolina, over 92% of O. angustidens teeth belong to juveniles, with the area confirmed as the first documented paleo nursery for the species. Our Florida site may represent a similar phenomenon, a prehistoric nursery ground in our own backyard.

Also recovered are teeth from the snaggletooth shark (Hemipristis), whose tooth morphology differs subtly from the more common Hemipristis serra typically found in Florida. Hemipristis serra first appeared in the late Oligocene and persisted into the early Pleistocene, with teeth found in Tertiary fossil deposits along the Atlantic coast from Maryland to Florida. Whether our variant represents a transitional species in the Hemipristis lineage is a compelling question that further study will need to answer. Additionally, the sand tiger shark Araloselachus cuspidata is well represented at the site, with some specimens reaching an impressive size.

Resources: 

https://www.floridamuseum.ufl.edu/exhibits/blog/florida-oligocene-painting-by-david-miller/