When they were kids, Royal Mapes’ older brother collected fossils. The younger Mapes coveted the collection, fascinated by the delicate fragments of history. He begged his brother to share, but to no avail. If Mapes wanted fossils, his brother told him, he’d have to find his own.

So Mapes, not to be outdone in this sibling rivalry, did just that. He has spent most of his adult life in the pursuit of the fossilized remains of times past, earning a reputation as a master of the dig site and amassing an enviable trove of prehistoric remnants. Some time ago, he decided to turn his focus to ammonoids, the now-extinct cousins of modern-day octopus, squid, and Nautilus. He works out of two labs at Ohio University, every inch of both crammed with the results of more than 70 digs in 37 states and 12 countries.

Ask, and Mapes probably could offer a detailed account of the geological importance of every rock and fossil in the drawers and boxes and on the shelves and tables of his labs. But inquire about the contents of the five 70-pound white canvas bags that sit on the floor of his main-campus work area, and his tone becomes urgent. For within those bags could lie fossils with preserved soft tissue containing the key to the reconstruction of an animal that has been gone from the Earth for 65 million years. 

Squid, cuttlefish, octopus, and Nautilus belong to a class of invertebrates known as cephalopods. Ammonoids, a subclass of that group and the focus of Mapes’ studies, flourished in the world's saltwater seas and oceans 400 million to 65 million years ago. 

Ammonoids were either straight or coiled, but it is the latter shape, with a spiraled structure that closely resembles a modern Nautilus, that is most familiar to even the novice fossil collector.
 
While ammonoid fossils have been found all over the world, in North America only a handful of samples collected from a site on Buck Mountain, Nevada, has yielded evidence of soft tissues. Those samples were collected in 1981 by Mapes, a professor of invertebrate paleontology. The discovery that the fossils contained soft tissue was so unexpected that for more than a decade, Mapes didn’t realize what he had. When the magnitude of his find was clear, he began making plans for a return trip. 

“If we found this once,” Mapes recalls thinking, “chances are likely we’ll find more and better the next time.” 

With support from an Ohio University Research Committee grant, Mapes returned to Buck Mountain in the east central part of the state in July to collect 350 pounds of rock-encased fossils, which currently fill the white canvas bags in his lab. With only five days to canvass a 2 1/2-square-mile site, Mapes and two fellow scientists from Japan spent more than eight hours a day looking for and recovering fossils. Ammonoids varied in size from less than one millimeter to about the size of a half dollar, so their fossilized remains aren’t always easy to spot. Every potential fossil-bearing rock had to be broken open and scrutinized. Such work in the Nevada summer, where the temperature emanating from the rocks topped 100 degrees, was hot, dirty, back-breaking. And fun.

“It’s a treasure hunt,” says Mapes, who has been drawn for 30 years to the hunt for a long sought-after prize: a peek beneath the hard outer shell of an animal that has fascinated him for decades.

Scientists know that just beneath the surface of the ammonoid’s shell lay the siphuncle, a tube that held the animal’s veins, arteries, and other soft tissue. It is the contents of this tube that have eluded study, as these materials usually aren’t preserved in fossils. Without soft tissue, scientists can’t know such details as how these animals ate, reproduced, or escaped predators. More importantly, they can’t know what the organs and vital body parts of the animal looked like. It’s easy to see their shells resembled a modern Nautilus, but what if, Mapes ponders, the animal inside the shell was more similar to a squid? The animal had gills for taking in air and tentacles around its mouth that it used like feelers — but scientists don’t know how many gills or tentacles it had. What if, unlike the four-gilled Nautilus, an ammonoid had two gills, like a squid or an octopus? Such an assertion would toss researchers in the field into heated debates and could lead to major changes in the cephalopod evolutionary chart.

“Or, what if it turns out that ammonoids only had one gill?” Mapes asks. “It would be a whole new subclass!” 

Mapes’ mind has been full of such “what ifs” for years, but the excitement began to build when, in the early 1990s, he discovered that the fossils he’d collected from Buck Mountain in 1981 contained preserved soft tissue. Only three of 20 samples collected that year actually contained tissue. But he is hopeful that he will find more tissues among the 800 samples collected on his return trip this summer. 

While Mapes is anxious to see inside the fossils he’s collected from Nevada, he’ll just have to sit tight for a while. Preparing a fossil for analysis is done in phases, and as the researchers have never before extracted soft tissue from a fossil ammonoid, there will no doubt be additional steps added to the process. 

First, the Buck Mountain fossils must be separated from the chunk of rock in which they were discovered, which is accomplished using what Mapes calls “brute force.” In other words, he smacks the rocks with a hammer and knocks the fossils out. Such a method isn’t always precise, Mapes admits, gesturing at the several bottles of Elmer’s glue scattered around the lab. Then, they must grind the samples down with a device similar to a sander to make them fit under the lens of a scanning electron microscope. The researchers next use different acids to dissolve the limestone material that surrounds and fills the fossils, a painstaking process that requires exact timing: Soak the fossil too long in the acid, and there’s nothing left to analyze. So, Mapes and his assistants soak the fossils for a while, place them under the microscope to measure their progress, and soak them some more.

This step alone can take hours or days, and that’s without the heightened sensitivity Mapes will require for the preparation of the precious Buck Mountain samples, which he hopes will contain tissues from animals’ organs and body structures. If they do, Mapes may be able to draft the first-ever complete portrait of ammonoids. 

Mapes plans to devote time this year to perfecting the analysis technique in preparation for detailed studies of the Buck Mountain fossils. But he’s already planning more field trips to collect other remains that must be gathered before they are lost to the forces of nature or the progress of new buildings and roads. As he looks around the fossils and rocks that cover the tables and fill the narrow drawers of the cabinets in his main lab, Mapes admits that many of these samples may one day reveal they hold no fossils, no answers, no buried treasure. Sometimes, he says, a rock is just a rock. But until he knows for sure, he won’t stop looking. 

More information on this and other research in the College of Arts and Sciences is available on the Web.

Kelli Whitlock is editor of Perspectives. Rick Fatica is a photographer for Media Services.