Charleston Center for Paleontology

If you follow our content, you’ve seen the “Cookie Cutter” shark. But did you know there is a “Cookie Cutter” cat as well?

Meet Xenosmilus hodsonae, a saber-toothed ambush predator that inhabited the savannahs and woodlands of Florida in the early Pleistocene.

While not the only saber-toothed cat with serrated teeth, Xenosmilus was unique in that it was missing a typical dental feature – a gap called a diastema between its upper canines and incisors – that resulted in a single continuous cutting edge.

Additionally, Xenosmilus’ large incisors were positioned in a semi-circular shape and, unlike most saber-toothed cats whose strongest bite forces occur at their carnassial teeth, Xenosmilus’ occurred along those anterior teeth. This led early researchers to theorize that it used its upper teeth to remove large, semi-circular chunks of flesh from its prey, and earned it the “Cookie Cutter” nickname.

The Xenosmilus shown this is on display at the Mace Brown Museum of Natural History.

Catsharks are small, bottom feeding sharks with elongated “cat-like” eyes. They have a long presence in the fossil record and are known from locations including the P*e Dee (Late Cretaceous), Harleyville (Eocene) and Summerville (Oligocene & younger) here in South Carolina. In fact, catshark teeth from two of these sites made news in recent years.

In 2020, researchers from the Horry County Museum and South Carolina State Museum added several species to the state fossil record that were previously unknown in South Carolina. These species came from the P*edee Formation and included one catshark, Scyliorhinus ivagrantae.

In 2022, researchers from the South Carolina State Museum, University of South Carolina Aiken, and McWane Science Center in Alabama named a new species of catshark from the Oligocene-aged Ashley Formation in Summerville.

Using matrix collected from large fossil excavations from 2007 to 2015, the researchers discovered and named a new species, Scyliorhinus weemsi.

The catshark tooth pictured this is from the third mentioned location, Harleyville.

Hesperotestudo crassiscutata is a giant land tortoise that inhabited coastal South Carolina in the Pleistocene. First described from the Peace River in Florida, fossils have been found up the East Coast to North Carolina and in Gulf Coast states.

With a carapace length of up to 6 feet, they were comparable in size to extant Galápagos tortoises.

It is debated whether they went extinct in the latest Pleistocene or early Holocene, but it is believed to be due to rapid climate changes, habitat loss, and human impacts.

While some researchers believe that their presence indicates milder (frost-free) climates during the Pleistocene, others believe they were adapted for the cold.

Pictured this are a femur and nuchal bone fragment on display at the South Carolina State Museum.

Charleston has yielded a plethora of new taxa and greatly increased our understanding of cetacean evolution, but it can also provide valuable insight into past climate change and how future changes may impact the oceans and marine ecosystems.

The Eocene-Oligocene boundary saw major global climate changes. Lower global temperatures and a massive expansion of polar ice occurred, marking the first Antarctic glaciation event in several hundred million years.

Sea levels and temperatures dropped, and changes in circulation patterns and water chemistry followed.

The changes led to the extinction of some marine life but also allowed others to diversify and develop new feeding strategies (see Part 1 from last week).

The Oligocene formations in the Charleston area can help us better understand how these changes affected the different taxa and what impacts we may see from our warming climate.

Pictured this : a drawer in the collections at the Mace Brown Museum of Natural History

Did you know that fossil remains of around 30 species of cetaceans have been found in the Charleston area? These include the first echolocating dolphins, toothed baleen whales, toothless suction feeders, and the first filter feeding baleen whales - most of which we have discussed in previous posts. So, why is Charleston a hotspot for cetacean fossils?

The Oligocene was an important time in cetacean evolution, but most marine Oligocene exposures are below sea level today, making the Charleston Embayment unique.

Around 25 new taxa have been named from two Oligocene formations in the area – the Ashley and the Chandler Bridge. Some taxa found here have never been found anywhere else, making it an incredible research location. For more on the Oligocene of Charleston, see part 2 next !

The specimens pictured are on display at the Mace Brown Museum of Natural History.

Since summer (and travel season) is here, this , we’re looking at a few local fossils that visitors may come across but not be familiar with (see photo captions for details).

Our June in review…🦣
-
Wishing everyone a lovely July, and a fantastic holiday weekend!
-
-

Although both belong to the Proboscidea order, mammoths and mastodons were quite different. This , we compare the basic structure and function of their molars.

Happy ! Similar to other types of fossils, the colors in “petrified” wood depend in part on the mineral content of the surrounding sediment and groundwater as the fossilization process occurs (with wood, that is often permineralization or mineralization along with replacement). For example, the orange and brown hues seen in the pictured tree trunk are likely the result of iron.

This large trunk (on display at the South Carolina State Museum) was uncovered in northeastern South Carolina. Although the exact age hasn’t been determined, it is believed to be at least several million years old.

This , we’re looking at shark dermal denticles (also called placoid scales), which are composed similarly to shark teeth.

Dermal denticles have multiple functions including defense from parasites and predators, protection from abrasions, reduced drag and turbulence as they move through the water, and even bioluminescence in some deep-water sharks.

There's a great deal of diversity in dermal denticles. They can differ by species, gender, age, the environment the shark inhabits, and even by their location on the shark’s body.

Pictured today are some dermal denticles from sharks in the Galeomorphi superorder, collected and photographed by our friend, Ken Marks.