Collectors Stumble on a Sinkhole That 'Swallowed' Animals 500,000 Yrs Ago in Florida, Find Well-Preserved Fossils
Fossil collectors are always looking to discover valuable objects frozen in time. Recently, some of those collectors were elated to find a treasure trove of prehistoric materials from under the Steinhatchee River in Florida, according to the Florida Museum. The materials unearthed from the underwater site came from an ancient graveyard dating back roughly half a million years. Over 500 fossils were dug up from the river bed that was covering an ancient sinkhole.
The mound of fossils consisted of well-preserved bones from ancient mammals that included horses, armadillos, sloths, and a new species of tapir. Almost 500,000 years ago before the formation of the river, a sinkhole that had opened up in Florida's Big Bend region had claimed the lives of countless animals that passed over it. With the water washing over the sinkhole over time, sediments started covering up the remains of those dead animals, resulting in their natural preservation. The fossils weren't discovered until 2022 when fossil collectors Robert Sinibaldi and Joseph Branin found the spot during one of their diving expeditions in the river.
Branin spotted the fragments of a horse's skull and teeth sticking out of the sediments and later on, the duo found a hoof core and a tapir skull. "It wasn’t just quantity, it was quality," Sinibaldi said in a statement released by the Florida Museum of Natural History. "We knew we had an important site, but we didn’t know how important." The museum analyzed the discovery of the fossil hunters and figured that they belonged to the middle of the Irvingtonian North American Land Mammal Age that lasted from 1.6 million to 250,000 years ago.
"The fossil record everywhere, not just in Florida, is lacking the interval that the site is from," Rachel Narducci, a vertebrate paleontology collections manager at the Florida Museum and coauthor of a study on the sinkhole site, published his statements in the journal, Fossil Studies. Fossils from this particular period are rare because the animals were going through evolutionary transitions back then. One of the major discoveries from the sinkhole was the fossil of an extinct giant armadillo-like creature called Holmesina.
"It’s essentially the same animal, but through time it got so much bigger and the bones changed enough that researchers published it as a different species," Narducci said, per the study. "This gave us more clues into the fact that the anatomy kind of trailed behind the size increase. So they got bigger before the shape of their bones changed." Narducci also revealed that they needed to conduct further studies on the skull of the potentially newfound species of the tapir.
"It might be a new species. Or it always could just be that you picked up the oddball individual of the population," he shared. Out of the 552 fossils that were unearthed, 75% of them belonged to an early species of horses. The researchers concluded that the area around the sinkhole might have once been a vast grassland where the horses dwelled. "For the first time, we had individuals that were complete enough to show us upper teeth, lower teeth, and the front incisors of the same individual," Richard Hulbert, lead author of the study, said in the statement, stated Live Science, hoping to know more about the diets of the horses back then.