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Anthony Swinehart created this model of Phoe­bodus sophiae after dis­cov­ering its remains in Michigan. Courtesy | Anthony Swinehart

Just across from Donna the tricer­atops in Hillsdale’s Daniel M. Fisk Museum of Natural History lies a tiny tooth about three mil­limeters in length. It is a tooth that rep­re­sents the glory days of Michigan’s history, when it was a shallow tropical sea poised mere miles from the equator and filled with an assortment of tropical fishes, sharks, bra­chiopods, corals, and reefs. It is a tooth that would have been found in the mouth of a two foot long shark that might have swum through campus over 400 million years ago. 

When he found this small tooth in a pub­licly acces­sible fossil hunting site in Michigan, Pro­fessor of Biology Anthony Swinehart was able to identify its owner as Phoe­bodus sophiae, a shark that lived in the Devonian period between 419 and 368 million years ago. Swinehart’s specimen is only the third shark of this species dis­covered in North America, and only the third species of shark from the Devonian period ever found in Michigan. Swinehart is now working with the world’s foremost shark expert, Chuck Ciampaglio, to con­tinue on-site research into the species and search for more spec­imens and pos­sibly new species. 

“The find was somewhat serendip­itous,” Swinehart said, “but luck is where oppor­tunity meets prepa­ration.” 

His story begins on a routine fossil hunt on August 23 in Northern Michigan. In addition to teaching biology courses at Hillsdale, Swinehart curates the campus museum, so he often spends his weekends combing through the silt and rock in search of fossils. 

“I just want to get spec­imens for the museum,” Swinehart said, “but as I do that, I am an oppor­tunist. If I see some­thing that is unusual and hasn’t been fully explored yet, I will take that path, and that’s what this leads to.” 

This par­ticular trip, Swinehart was searching for “blue bits,” which are the color of fish material from Devonian rocks. The Devonian is known as the age of fishes. It was a time of sig­nif­icant radi­ation of dif­ferent species of fishes and the origin of many lin­eages of fishes. Swinehart said this makes it important for under­standing the evo­lution of the fishes and sharks both pre­ceding and fol­lowing the period. 

“I was thinking of armor from armored fishes and I found some, but I was picking up every blue bit I saw,” Swinehart said. “And I saw a blue bit about the size of the head of a pin, and I thought, ‘Well, some­times these are just the tip of the iceberg. So I col­lected all the blue bits and when I got this one out and looked at it under the micro­scope, it was a shark tooth.” 

This tooth belonged to a species of shark never before dis­covered in Michigan, and one of only three Devonian species found in Michigan to date. 

It was Phoe­bodus sophiae.

Besides opening up the species to new loca­tions, Swinehart’s specimen is also the oldest of the species in all North America, and pos­sibly the world, by 1.6 million years— and Swinehart found it in an already well-doc­u­mented public dig site. 

He explained that once a site has been thor­oughly explored, sci­en­tists tend to move to “greener pas­tures,” where they have a better chance of finding exciting new spec­imens. 

For Swinehart, though, combing through these sites only adds to the adventure and the chal­lenge.

“There is always some­thing more we can dis­cover,” Swinehart said, “it just takes dili­gence. So, when I go fossil hunting, I am on my hands and knees. You can’t find new, unique things without really getting dirty and being thorough.” 

The skeletal structure of Devonian period sharks renders them par­tic­u­larly dif­ficult to find, Swinehart said. With car­ti­laginous spinal cords and skulls instead of bone, most of their skeleton — except their teeth and other small remains — breaks down instead of fos­silizing. This con­tributes to the under-rep­re­sen­tation of known shark species from this period. 

For some per­spective, these teeth are so tiny that typ­i­cally sci­en­tists dis­cover them only by bathing whole swaths of rock in acetic or formic acid for several weeks until every­thing else dis­solves and the teeth sink lazily to the bottom for easy obser­vation and cat­a­loguing. 

But Swinehart, with his thick, coke-bottle glasses inches from the earth, found his tooth the old fash­ioned way. And he plans to find more. 

“I mean, what are the chances that that is the only one in a hundred acre quarry,” Swinehart said. “There are probably more. They just went unno­ticed. I guess it’s pos­sible that it’s one of extremely few. We are going to find that out. We are doing more research, too.” 

Matthew Hoenig ’17 studied under Swinehart while at Hillsdale. Though he didn’t enter Hillsdale dreaming to become a pale­on­tol­ogist, after a couple of dinosaur digs with Swinehart — during one of which he helped excavate Linda the tricer­atops — he said pale­on­tology became his passion.   

Working on digs with Swinehart was “very enjoyable,” Hoenig said. “I am glad to be able to con­tinue to do so.” 

Having just fin­ished his master’s in earth & envi­ron­mental science at Wright State Uni­versity where his research involved car­ti­laginous fishes and sharks from Iowa and Illinois, Hoenig was a perfect can­didate to help Swinehart con­tinue his research. 

“I helped him identify the tooth and also put it in pale­on­to­logical context as far as the age of the rock and com­paring that rock to the age of other local­ities from around the globe that have members of this genus,” Hoenig explained, helping to reveal the greater sig­nif­i­cance of this par­ticular tooth. 

Because of this, the tooth sets the species, and the entire genus, back as much as 1.6 million years, it also com­pli­cates the pos­sible use of Phoe­bodus sophiae as a proxy index fossil. It was thought to be restricted to the Middle Givetian Age. The new find occurs within the Early Givetian. Index fossils are fossils of species that came into being and went extinct within a short period of time and are also found worldwide. Once estab­lished, sci­en­tists use index fossils to date other neigh­boring fossils when datable igneous rocks are not locally present. Until Swinehart’s recent dis­covery, the Phoe­bodus sophiae appeared to be a good can­didate for a proxy index fossil— a proxy stands in when no tra­di­tionally estab­lished index fossil is present. Though slightly less accurate, a proxy still allows sci­en­tists to place a fossil’s date with rel­ative cer­tainty. 

The com­pli­cating fossil is now located in the Hillsdale’s very own Daniel M. Fisk Museum of Natural History right next to a life sized model of Phoe­bodus sophiae that Swinehart himself created — rather uncon­ven­tionally. 

“I am a rather frugal indi­vidual and some of the mate­rials used to sculpt things are quite expensive,” Swinehart said. “I mushed alu­minum foil into the general shape, I wrapped it in masking tape, then I used note­cards for the fins and a two part sculpting epoxy to cover it.” 

He topped off his dis­covery with an orange rubber anemone he pur­chased from Walmart for $2.50 to rep­resent a living horn coral. 

Swinhart and his research partners will con­tinue updating the museum exhibit with any new dis­cov­eries and data they find.