The remnants of prehistoric elephant relatives have been uncovered by paleontologists in a record-breaking find.
Although the animals probably perished at different times, potentially hundreds of years apart, their bodies were found in the same spot, where they remained buried until early 2022. They were gomphotheres — an extinct ancestor of modern elephants — and lived about 5.5 million years ago, during the Miocene epoch.
A team of researchers and volunteers at the Florida Museum of Natural History have discovered this ancient “elephant graveyard” by chance. Initially, at the Montbrook Fossil Dig, they found fragments and isolated bones of gomphothere skeletons – nothing extraordinary in the light of past findings. A few days later, however, volunteers unearthed a remarkably intact foot that appeared enormous.
“I started coming upon one after another of toe and ankle bones,” Dean Warner, a retired chemistry teacher and Montbrook volunteer, said. “As I continued to dig, what turned out to be the ulna and radius [long arm bones] started to be uncovered.”
Subsequently, the team successfully recovered an entire skeleton, which sparked tremendous excitement among them.
“It was very exciting because this gave us an opportunity to not only see what an adult [gomphothere] would have looked like, but also to very carefully document each and every bone in its skeleton,” said Jonathan Bloch, a curator of vertebrate paleontology at the Florida Museum of Natural History who co-led the excavation. “That’s exciting from a scientific perspective if you’re trying to understand the anatomy of these animals and something about their biology and evolution,” Bloch told Live Science.
“This is a once-in-a-lifetime find,” Bloch said in a statement. “It’s the most complete gomphothere skeleton from this time period in Florida and among the best in North America.”
However, it quickly became apparent that the deceased animal was not solitary. Ultimately, the team successfully retrieved complete skeletons from an adult specimen and, notably, at least seven juvenile individuals.
Based on the researchers’ estimates, the adult gomphothere discovered in the excavation stands at an impressive height of 8 feet (2.4 meters) to its shoulders. Its skull and tusks measure over 9 feet (2.7 meters) in length, which is comparable to the size of a contemporary African elephant (Loxodonta africana). This extraordinary dimension establishes a local record for the largest gomphothere found in the area.
“Modern elephants travel in herds and can be very protective of their young,” explained Rachel Narducci, collection manager of vertebrate palaeontology at the Florida Museum, “but I don’t think this was a situation in which they all died at once. It seems like members of one or multiple herds got stuck in this one spot at different times.”
The researchers speculate that that the animals met their demise over the course of several centuries. The adult gomphothere likely drowned at the specific location, while the other animals might have died elsewhere and subsequently been carried by water currents, eventually accumulating at a bend in the river. Jonathan Bloch likened this accumulation to a “bone jam,” which is similar to a logjam formed when an excess of loose logs obstructs a river.
“We’ve never seen anything like this at Montbrook,” Narducci added. “Usually, we find just one part of a skeleton at this site. The gomphotheres must have been buried quickly, or they may have been caught in a curve of the river where the flow was reduced.”
Distinguishing species within the gomphothere family typically relies on variations in tusk shape and body size. The ancient Montbrook gomphotheres possess distinct enamel banding on their tusks, and are thus classified under the genus Rhynchotherium – elephant relatives that flourished in open savannas across Africa, Eurasia, and the Americas millions of years ago.
As temperatures cooled around 14 million years ago, grasslands gradually supplanted the savannas in these regions. Intensified competition for limited resources following the arrival of mammoths and elephants eventually led to the extinction of gomphotheres approximately 1.6 million years ago.
According to the researchers, this recent finding will contribute to a deeper understanding of the lives of these ancient proboscideans and the habitats they inhabited. Eventually, the public will have the opportunity to view the largest specimen on exhibition. Bloch and his team intend to assemble the fossils from the adult gomphothere and showcase it alongside the impressive skeletons of mammoths and mastodons currently exhibited at the Florida Museum of Natural History.
“There’s so much we can learn from these things and we’re excited to do it in future,” Bloch concluded.