PRESBYORNIS ISONI
By Ron Ison, 5/94

I have been collecting fossils, on and off, for over twenty years, and fairly intensely for the past ten. I enjoy many aspects of collecting, but in the back of my mind was the almost forgotten dream of finding something new, something unknown.

It is a pleasure to be the first human to touch something that is millions of years old, but to find something new to paleontology is such an unbelievable and intensely-exciting experience as to be mind numbing. I finally found my new species, just barely. Had the scope of my collecting been more narrow, it would have been lost to the wind and pounding surf. It was not nearly as glamorous as I had envisioned. There was not high drama or deprivation, nor death-defying act of courage, but perhaps that is what generated the disbelief and denial that was my initial reaction.

On the day it happened, I decided to collect shark teeth along the Potomac River in Maryland. The exposures here are of the Aquia formation which is Paleocene (Landenian) in age. It is believed to be 61 to 62 million years old.

I arrived at one of the more productive areas to find the beach covered in a thick layer of sand. Unfortunately, when the sand is washed up on the beach, the collecting is lousy.

After finding only a few small shark teeth and Myliobatis bars, I began to make a concerted effort to find fossil turtle remains which I had been collecting for Dr. Robert Weems of the U.S. Geological Survey in Reston, VA. Turtle remains are fairly common at this site, consisting primarily of isolated carapace fragments with an occasional limb bone thrown in for good measure.

After checking the beach as I walked north, with poor results, I turned around and checked the cliff exposure on the way back. I was looking for lignitized fruits, nuts, pinecones, and also for Dr. Weems. These are rare items and extremely fragile.

I soon found some fragments of turtle and lots of uninteresting lignitized wood. What next caught my attention was a 3 to 4 inch, well-formed, light tan coprolite, probably crocodile. I rarely collect coprolites, but they occasionally contain fish remains, especially scales. These neatly packaged fossils can be important in establishing the dietary habits of ancient creatures.

As I moved along the bluff scanning for fossils, I noticed a long, skinny "coprolite" in the cliff which I carefully excavated. It was the same tan color as the others, but it was unusually smooth. A couple of hours and a few more boring fragments later, I decided to call it a day.

It took a couple of days to find time to clean up the materials, but I finally managed to get to it. None of the shark teeth or turtle bits were very interesting, but a couple of coprolites had good paperweight potential.

I left the unusual smooth coprolite as my last project. As I began to remove marl from the specimen, it began to look like a bone. I cleaned off one end and found a broken, hollow end. My first thought was crocodile. As I cleaned off the other end, I was pleased to see a complete joint. Unfortunately, the widening of smooth bone was not very diagnostic of anything that I could think of. When I cleaned off the other side, I was washed with a wave of disbelief. I was looking at a large bird humerus.

Bird bones from the Paleocene in this area are extremely rare and small. To the best of my knowledge, there are only about a dozen known, none of which have been identified due to their worn or fragmentary nature. There I was, staring at a large, well preserved specimen. I knew it had to be bird, but I refused to believe it, knowing that a mistake on my part could mean bitter disappointment I tried to make it a crocodile. No, I tried to turn it into a turtle. No. I got a second opinion from Dr. Weems. He looked at it and asked, "Where did you find this ... bird?" Yes!

I called Dr. Storrs Olson of the Smithsonian Division of Birds. I told him what I had and where it was from. He told me it was probably crocodile or turtle. I, in turn, told him to talk to Dr. Weems. He called me back and asked if he could see it.

I was going to mail it, but decided to take it to the museum in person. When Dr. Olson looked at my prize, he became excited and asked me if he could make a cast of it. I told him that due to the rarity of bird fossils from the Aquia I felt it belonged in the museum. Dr. Olson thanked me for donating the specimen and told me he would let me know when he got it identified.

To make a long, complicated process less tedious, I'll get to the point. It turned out to be a new species of Presbyornis that was much larger than its contemporaries in the group. It is a precursor to the ducks, geese and swans and looked something like a crane or heron with a duck's head. When I asked Dr. Olson what he was going to name it, he said, "We'll call it Presbyornis isoni".

I recently received the pre-press copy of the paper, so I guess I can quit holding my breath, it's official. After all of the joy and wonder that paleontology has given me, I have made my small contribution in return. I hope that someday some, if not all, of you can experience what it's like to find something like this. Good hunting and good luck.