As a Ph.D. program at Southern Methodist University in Dallas, Texas, I started my new career in 1990 under Prof. Louis L. Jacobs. My dissertation topic was mid-Cretaceous archosaurs from Texas.
Fortunately, I got some good materials to study. My first paper was about a pterosaur. The specimen was only a partial snout, but it was the first tooth-bearing pterosaur ever found in North America and showing English affinity rather than Brazilians. A similar type of snout was reported from England by Richard Owen in 1859, and he named it Coloborhynchus, but the name became dead by a Brazilian scholar afterward. However, I found the same kind of pterosaur in North America over one century later and re-erected the genus name and named it a new species, Coloborhynchus wadleighi. It was published in Palaeontology in 1994, which was my first paper for a vertebrate fossil.
From the intensive fieldwork, I got a new crocodilian (Woodbinesuchus byersmauricei) and a derived hadrosaurid (duck-billed dinosaur) hind limbs and ankylosaur (armored dinosaurs) materials from the Woodbine Formation near DFW airport.
One of the most important specimens was a nodosaur skull. It was recovered from marine sediments. The skull remained exposed on the seafloor for a few years based on the size of oysters attached to the skull. It has bony eyelids but not able to cover eyeballs completely unlike those of Euoplocephalus. It turned out the most primitive nodosaur skull in North America. I named it a new genus and new species, Pawpawsaurus campbelli and it became the first dinosaur that I named.
And also, I had a good opportunity to study ichnology by describing a new bird, theropod, and hadrosaur footprints. This experience gave me a good instruction about how to approach the footprint study and helped me a lot when I studied Korean dinosaur footprints later.