Flexomornis howei: A tale of amateur and professional cooperation

Kris Howe (USA)

When you think of Texas, what comes to mind? It may be wide open spaces, longhorn cattle, cowboys and ten gallon hats. Now, there’s something else to add to the list – the oldest, definitive bird fossil in North America. That bird is Flexomornis howei, from the Woodbine Formation (lower Middle Cenomanian) near Grapevine, Texas.

I first encountered the bones while prospecting potential fossil sites around Grapevine Lake. This is located just north of Dallas-Forth Worth International Airport, in north-eastern Tarrant County. One exposure near the lake soon produced a large number of fossils eroding out on the surface. They included petrified and carbonised wood, amber, at least two types of turtle, two types of crocodile, numerous remains of bony fish, shark teeth and vertebrae, parts of an ornithopod, a nodosaur, ostedeoderms, and a few scraps of small theropods.

In addition, there was also a cluster of delicate and unusual bones that looked like nothing I had ever seen before. I contacted Dr Ron Tykoski, at the Museum of Nature and Science in Dallas, for help with the identification. Dr Tykoski had been very helpful in the past with tough identifications, so I knew he could help. He inspected the bones and said that they looked like they were from a bird, but he was hesitant to get too excited – there were no known birds from the Woodbine Formation. Dr Tykoski took the bones across the hall to show them to Dr Tony Fiorillo, the curator of the museum’s collections. After several minutes studying the fossils, Dr Fiorillo said that he also thought they looked like bird bones, including the right scapula, a partial right carpometacarpus, a partial tibiotarsus, a possible partial humerus and several broken bone shafts.

This started the long process of research. Drs Tykoski and Fiorillo spent months pouring over every Mesozoic bird reference they could find. After about six months, I got a phone call from Dr Tykoski, who said that they believed I had found a new species, but they were still checking everything to be sure. A couple months after that, Dr Tykoski called to say that it was almost certainly a new species and that they wanted to name it in my honour. Wow! What a surprise. He told me that they were going to name the bird Flexomornis howei and explained that the name meant ‘Howe’s bent shoulder bird,’ referring to the unusual curvature of the broad-bladed scapula.

Flexomornis is a member of the avian lineage called Enantiornithes. It was a medium-to-large-sized bird for the time, approximately the size of a roadrunner. In fact, it may have lived a lifestyle similar to modern roadrunners along the shores of the North American Western Interior Sea. Until the discovery of Flexomornis, only one other enantiornithine bird was known to have a broad, curved scapula – Elsornis keni – from the Djadokhta Formation (Campanian) of Mongolia. Because of this shared feature and similarities in the carpometacarpus of the hand, it is possible that Flexomornis and Elsornis may have a relatively close relationship to each other among enantiornithine birds.

Postscript

In spring 2009, I collected an avian coracoid bone from another location in the Woodbine Formation, approximately a kilometre from the Flexomornis howei site. I regularly re-visit this new site in the hope of finding additional bird fossils. In June 2009, my fellow fossil enthusiast, Joe Fritsch, discovered part of the caudal fin of a large fish eroding out of the lower Britton Formation (Eagle Ford Group, Upper Cenomanian) in a small creek in Dallas County. On further inspection,

I found additional areas where bones of the fish were exposed. Joe and I spent several days diverting the flow of water away from specimen and then excavating it. The fish was nearly complete and 170cm long. I am currently preparing the specimen and have tentatively identified it as Pentanogmius sp. This species is already known from the Niobrara Chalk (Santonian) of northern Kansas, USA. If the initial identification of the new specimen is confirmed by professionals, it will extend the known range of this fish back in time by approximately ten million years.

The story of Flexomornis howei is one of mutual respect and cooperation. The staff at the Museum of Nature and Science are highly qualified individuals who understand the service that sincere amateur fossil collectors can provide to science. If I had not been out collecting fossils, Flexomornis would not have been discovered. If Drs Tykoski and Fiorillo were not receptive to amateur efforts, Flexomornis would not have been recognised for what it was. This story shows that combined effort between amateurs and professionals pays off for all in the end.