Creature Feature 23

Greetings, everyone! This week, we're going to talk about a group of freshwater fish that are found in Hell Creek. This group is amiidae, which are more commonly referred to as Bowfins!

Amiid fish models, WIP. Due to lack of adequate fossil reference material, appearance is based on modern relatives.

Currently, there are two species of fish from Hell Creek currently assigned to the family Amiidae - these are Kindleia fragosa, and Melvius thomasi (Pearson et al., 2002). The former appears to have been extremely common, with over 2,600 specimens assigned to the species. Melvius thomasi is less common, with only 67 specimens from the taxon found in Hell Creek (Pearson et al., 2002).

The family Amiidae is a lineage of basal ray-finned fishes, consisting of four subfamilies. All four are known from as far back as the Jurassic (Grande and Bemis, 1998), though the only living member of this family is the modern bowfin, Amia calva. The modern bowfin is commonly found throughout the eastern United States, and in southeastern Canada. Their habitat includes the drainage basins of the Mississippi river, the Great Lakes, and many rivers that flow along the Eastern seaboard and Gulf of Mexico (Fuller, 2006).

Bowfins today prefer vegetated, swampy water, lowland lakes and rivers, and are even occasionally found in brackish water. Their color and pattern allows them to camouflage themselves in slow-moving water where vegetation helps to conceal them from both potential predators and their prey. They will often hide among roots and submerged logs (Rudolph and Robison, 2004; Laerm and Freeman, 2008). They also are able to breathe air as necessary, which allows them to tolerate low-oxygen environments (Rohde, 2009).

Modern bowfins are ambush predators, traveling into shallow water at night to prey on smaller fish and invertebrates such as crawfish, aquatic insects, and mollusks (Indiana Department of Fish and Wildlife). Juveniles tend to preferentially target invertebrate prey, whereas the adults primarily eat other fish - however, they are known to be highly opportunistic, and it is unlikely that they will turn down any easy meal (Rohde, 2009). They are quite agile and quick fish with ferocious appetites (Stewart and Watkinson, 2004; Schultz, 2010).

One thing that readers will note with this Creature Feature is that I mostly talked about modern relatives of the extinct Amiid taxa found in Hell Creek. This is because I have been unable to find any in-depth information on paleoecology/paleobiology of the Hell Creek amiid fish, and as such I have given information on the closest modern relative. Given that they are in the same family, it seems reasonable to assume that their habits would be at least somewhat similar. After all, the habitats where modern Amia are found today were rather abundant in Hell Creek, which would explain their common occurrence.

Well, I hope this has given you a bit more information on the Amiid fish of Hell Creek! Tune in next week for another Creature Feature!

Acknowledgements:

 Pearson, D. A.; Schaefer, T.; Johnson, K. R.; Nichols, D. J.; Hunter, J. P. 2002. Hartman, John H.; Johnson, Kirk R.; Nichols, Douglas J., eds. Vertebrate Biostratigraphy of the Hell Creek Formation in Southwestern North Dakota and Northwester South Dakota. Geological Society of America Special Paper 361 (Boulder, Colorado). The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An integrated continental record of the end of the Cretaceous: 145-167.

Grande, L.; Benis, W. E. 1998. A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. An Empirical Search for Interconnected Patterns of Natural History. Memoir (Society of Vertebrate Paleontology) 4: 1-679.

Fuller, Pam (April 11, 2006). Amia calva. USGS Nonindigenous Aquatic Species Database. US Geological Survey. Retrieved June 14, 2016.

Rudolph, John Miller; Robison, Henry W. 2004. Fishes of Oklahoma. University of Oklahoma Press. p. 58.

Laerm, Joshua; Freeman, B. J. January 2008. Fishes of the Okefenokee Swamp. University of Georgia Press. p. 37.

Rhode, Fred C. 2009. Freshwater fishes of South Carolina. University of South Carolina Press. p. 80.

Indiana Department of Fish & Wildlife. Bowfin (Amia calva). Indiana Department of Natural Resources. Retrieved June 14, 2016.

Stewart, Kenneth; Watkinson, Douglas. 3 May 2004. Freshwater Fishes of Manitoba. Univ. of Manitoba Press. p. 51.

Schultz, Ken. 15 December 2010. Ken Schultz's Field Guide to Freshwater Fish. John Wiley & Sons. p. 64.